Aim and Objective. In this study, we aimed to perform a meta-analysis to investigate the relationship between leptin and male infertility.  Leptin has an association with male infertility. However, only sporadic studies inconsistently reported the results. 2. The sources of heterogeneity were explored via metaregression, and stratified analyses, sensitivity analyses, and publication bias were performed.  This study was performed based on published articles related to leptin and infertile males. PubMed, Web of Science, Google Scholar, Ovid + Cochrane Central Register of Controlled Trials, Wiley Online Library, Chinese CNKI, Chinese Chong Qing VIP, Chinese Wan Fang, and China Biology Medicine databases were searched to identify all relevant studies. All eligible works of literature were analyzed by the “meta” or “metan” command in STATA version 12.0 software. The standardized mean difference (SMD) of leptin concentration in serum or semen and 95% confidence intervals (CIs) were estimated for all studies. The heterogeneity was described with Iz) z = 4.29; p < 0.001, and I2 was 97.3%, p < 0.001. The SMD of leptin concentration in semen was 3.274 , z = 5.64; p < 0.001, and I2 was 98.2%, p < 0.001. Notably, serum follicle-stimulating hormone (FSH) was slightly higher in infertile men . Other hormones, such as luteinizing hormone (LH) and testosterone, were also slightly higher, but the results were not statistically significant. In addition, sperm count  and sperm motility  inversely correlated with leptin levels in infertile males. Sperm abnormal forms did not show a statistically significant SMD of −0.076 .  Nineteen studies were included in the current meta-analysis, involving 1138 cases of infertile men and 756 controls. The SMD of leptin concentration in serum was 2.002 , Z-test ( Leptin plays a potential role in association with male infertility. This study may effectively reveal the relationship between leptin together with other hormones and its association with male infertility. These results may also provide opinions on precautionary measures. The proportion of infertile couples of childbearing age has been increasing every year. Infertility affects roughly 15% of couples of reproductive age, and the malefactor accounts for 20% to 50% of all cases . IncreasConsidering the sporadic prior research, we used the updated meta-analysis to investigate the relationship between leptin concentration and the association of male fertility dysfunction, and we aimed to provide new clues for the etiology of male infertility.A systematic search of PubMed, Embase, Web of Science, Google Scholar, Ovid + Cochrane Central Register of Controlled Trials, Wiley Online Library, China National Knowledge Infrastructure (CNKI), as well as the Chinese Chongqing VIP, Chinese Wan Fang, and China Biology Medicine (CBM) databases was conducted to distinguish all the applicable studies published on or before June 2, 2018, with the following search strategy: (“leptin” OR “LEP” OR “obese protein” OR “obese gene product” OR “adipokine” OR “adipocytokine”) AND .In this meta-analysis, published studies were eligible for inclusion if they confirmed all of the following criteria: (1) the articles should illuminate leptin with the risk of male infertility and should contain sufficient information; (2) studies were excluded if they were case reports, summaries, minutes of meetings, unpublished articles, letters, and repeated documents; (3) study design using a case-control study or cohort study; (4) studies published in both Chinese and English were included. As the last criterion, if there were more than two articles from the same team, the one with a larger sample size was included. Screening of documents was operated separately by two researchers, eliminating differences by discussing or consulting a third party.The following data were extracted: name of the first author, year of publication, country, body mass index (BMI), sample size (n), leptin test method, materials for the test, number of cases and controls, mean age, other hormones, and semen parameters.I2 and a pvalue of more than 0.05. I2 lower than 50% was defined as low heterogeneity. Funnel plots were used to assess publication bias. p < 0.05 was significant for the whole article.The whole meta-analysis and pictures were performed on STATA software, version 12.0. The aim was to clarify the relationship between leptin in serum or semen and the risk of male infertility. Among the 19 case-control studies, the SMD and 95% CIs were computed. The random-effect model was selected to evaluate statistical heterogeneity between different trials. Subgroup analysis was applied to analyze the relationships among 19 case-control studies and to identify the sources of heterogeneity. A quantified description of heterogeneity was performed based on The procedure of the meta-analysis is shown in T). The detailed information is presented in Among all 19 studies, 10 were performed in mainland China. Among all studies, materials were either serum or semen. Serum or seminal leptin was detected through an enzyme-linked immunosorbent assay (ELISA) based technique in 8 studies, while 11 studies used radioimmunoassay (RIA). In addition, the male infertility types and the corresponding number of studies were, respectively, obstructive azoospermia (OBST-NON-OBSTAZOOs), nonobstructive azoospermia (NON-OBSTAZOOs) , oligozoz = 4.29; p < 0.001), and obvious heterogeneity was found among various articles  (p < 0.001), and obvious heterogeneity was found among various articles . The result denoted that serum or seminal leptin in infertile males was higher than that in normal fertile men. However, the existence of heterogeneity could not be ignored. Stratified analysis, metaregression, and sensitivity analysis were used to explore the source of heterogeneity.The serum or semen leptin concentration was depicted by decimals on forest plots. The SMD, with its 95% CI, was estimated from 1138 cases and 756 controls based on a random-effect model Figures  and 3. T< 0.001) . The SMD< 0.001)  using thp < 0.001). However, the seminal leptin concentration was higher in cases using ELISA than those using RIA methods (SMD = 4.353 versus SMD = 2.637), but heterogeneity was still obvious . Simultaneously, there was no statistical significance between Europe and Africa regarding the SMD of seminal leptin concentration. The SMD of serum leptin in cases in Europe (SMD = 2.146) was similar to cases in Asia (SMD = 2.309), and the SMD of serum leptin in both continents were higher than that in Africa (SMD = 0.751). However, there was no statistical significance in cases in Europe  was higher than that in non-Chinese regions (1.479). The SMD of serum leptin in large samples (>50 cases) was 1.178, and in small samples (<50 cases), it was 2.623. However, the SMD of seminal leptin in cases in China (1.865) was lower than that in non-Chinese regions (4.694). The SMD of seminal leptin in large samples (>50 cases) was 3.910, and in small samples (<50 cases), it was 2.342. There was no remarkable difference between works of literature published before or after 2010, with an SMD of serum leptin of 2.128 and 1.869, respectively. In contrast, the SMD of serum leptin in works of literature published before 2010 was much lower than that after 2010 (1.667 versus 4.096).Eight studies provided data on other coexpression hormones . The SMD of FSH, LH, and T was 3.695, 2.224, and −0.331, respectively, whereas the results of LH and T were statistically insignificant. These three coexpressions of hormones and unignorable heterogeneity were studied. Other studies that provided coexpression hormones, such as prolactin (PRL) and estrogen, had insufficient information; thus, data were not analyzed in this study  was −4.533 , z = 4.37; p < 0.001 , and sperm motility (A and B) was −7.894, z = 5.68; p < 0.001 , whereas, sperm morphology abnormal forms (%) had insignificant outcomes results, SMD = −0.076 , z = 0.04; p=0.964  has pointed out that couples of normal childbearing age who have regular sex without using contraceptive measures for more than 12 months resulting in conception failure can be diagnosed as infertile. According to the survey by Esteves SC, about 10%–15% of noncontraceptive childbearing age couples in the world are unable to give birth because of various factors, of which 50% are malefactors [It has been suggested that leptin is a metabolic signal to the reproductive system. Adipokines attract substantial interest in the context of male infertility since they play a key role in regulating energy homeostasis, and aberrant secretion of adipokines is associated with the etiology of several reproductive abnormalities –17.in vitro studies in the adult rat testis [In light of progress in research on reproductive physiology, studies have shown that leptin is inextricably linked with reproduction, especially in male infertility , 19. Lept testis . The fint testis , 27.I2 = 96.2%) between studies in meta-analysis. Although heterogeneity can be considered by using the random-effect model, it would increase the probability of type-I error. The following factors may have contributed to the significant heterogeneity: (1) References from 2001 to 2016 are included. Three versions of the WHO laboratory manual for examination and processing were used, and criteria for human semen parameter standards and related definitions are inconsistent, such as, in the fifth version since 2011, “normozoospermic men” were defined as the semen parameter as ≥15×106 million of sperms/ml, ≥40% total motility, ≥32% progressive motility, and ≥4% normal forms, while in the fourth version since 2006, ≥20×106 million of sperms/ml, ≥75% total motility, ≥50% progressive motility, and ≥15% normal forms.. (2) The inclusion criteria of the case group are also inconsistent. In some reference experiments, only nonobstructive azoospermia patients were included, while in the other reference experiments, not only the nonobstructive patients but also the oligoasthenoteratozoospermic patients were included. (3) The demographic characteristics and genetic backgrounds were different in Europe, Asia, and African populations. (4) The studied infertile males showed different types of pathogenesis. (5) The literature published in different years were included in the studies. (6) There were different BMIs of patients in each primary study because obesity infertile and obese healthy males can lead to slightly increased leptin concentration. (7) Different measuring methods were used in the primary studies. (8) The included studies were of differing qualities. To identify the sources of heterogeneity, first, we carried out a sensitivity analysis that indicated the stability of the meta-analysis. Thus, we found that each study made almost no significant difference in the pooled effect estimate except for a study by Hofny et al. [In our study, serum leptin levels were measured in normal and infertile male subjects with different categories of infertile patients. Significantly elevated leptin concentrations were observed in infertile male patients. However, we found nonignorable heterogeneity I2 = 6.2% betwy et al. , 29.z = 4.29; p < 0.001, while I2 was 97.3%, p < 0.001. The SMD of leptin concentration in semen was 3.274 , z = 5.64; p < 0.001 , and the leptin concentration in semen especially in fertile males was over three-fold. Simultaneously, FSH also increased in fertile males with statistical significance. However, the mechanism of the contribution of leptin to male spermatogenic function is still elusive. In this study, both seminal and serum leptin were increased and correlated with male infertility. Some potential effects of leptin on the male gonads have been reported. It is suggested that leptin may regulate the secretion of inhibin B or may even be related to regulating the function of Sertoli cells. Leptin may affect both Sertoli and Leydig cells. These could be some of the ways through which it affects spermatogenesis [It is the first meta-analysis of the relationship between serum or seminal leptin concentration and the risk for male infertility. Nineteen studies were included in the current meta-analysis, involving 1138 cases of infertile men and 756 controls. We found that serum or seminal leptin was higher in infertile males than that in fertile ones. The SMD of leptin concentration in serum was 2.002 , ogenesis .Numerous studies have been carried out to determine the association of leptin in the regulation of the reproductive axis. Human fertility is associated with sperm quality and hormonal regulation of spermatogenesis. Significantly higher serum concentrations of leptin, FSH, and LH were found in infertile males. In contrast, T concentrations were found to be lower in infertile males. Inverse correlation can be explained by the paracrine inhibitory effect of leptin, FSH, and LH on T production by Leydig cells .Several limitations exist in this study and deserve discussion. First, the number of primarily included studies was very small. Second, the pathogenesis types of male infertility were complicated. The heterogeneity we found in the included studies may be different depending on the in-study methods, case-control selection, and statistical analysis tools. By using a random-effect model for more estimates, we addressed these issues. Studies that were restricted only to test methods and leptin detection in human tissues were included. Some studies based on animals were excluded. Notably, we could not exclude biases even though it had evident publication bias which was found in Begg's test. This study indicated that serum or seminal leptin was statistically associated with male infertility.In the present study, leptin plays a potential role in association with male infertility. Overall, higher leptin concentration in infertile males was associated with a slightly higher sex hormone concentration, such as FSH, LH, and T, which were inversely correlated with a lower risk of the sperm count and sperm motility. This result may provide an opinion on the diagnosis of male infertility etiology and provide a potential precautionary measure for infertile males, especially obese man, who always has higher leptin concentration in serum.This study suggests that serum and tissue leptin are associated with male infertility. However, the role of leptin in the regulation of the reproductive axis is still elusive. Further study is needed to explore the mechanism of how leptin is potentially associated with male infertility.


To study the prognostic value of the prognostic nutritional index (PNI) in advanced cancers receiving programmed death‐1/programmed death‐ligand 1 (PD‐1/L1) inhibitors.Online electronic databases were comprehensively searched and available literature was retrieved. We extracted available data from included researches and pooled the hazard ratios (HRs) and 95% confidence intervals (CIs) to learn the prognostic value of PNI on overall survival (OS) or progression‐free survival (PFS); and meanwhile calculated the relative risk (RR) with 95% CI to study the relationship between PNI and treatment efficacy (objective response rate [ORR] or disease control rate [DCR]) in late staged cancer receiving PD‐1/L1 inhibitors.p = 0.000), showing a correlation between low PNI and worse OS. Eight studies reported a relationship between PNI and PFS, and combined results revealed shorter PFS in patients with lower PNI, with an HR of 1.75 . Four studies explored the association between PNI and ORR and two studies explored the influence of PNI on DCR. An association between PNI and ORR  was observed, while no association between PNI and DCR  was observed by pooling these studies.Nine studies were finally selected for this meta‐analysis. We obtained data regarding PNI on OS from all nine studies, and the pooled HR was 2.31 (95% CI 1.81–2.94, In summary, this meta‐analysis indicated that a lower PNI was significantly correlated with decreased OS and PFS and played adverse roles in ORR in advanced cancer patients receiving PD‐1/L1 inhibitors. Therefore, PNI could be promising for predicting prognosis and treatment response in advanced malignancies treated with PD‐1/L1 inhibitors. This meta‐analysis accessed the prognostic value of PNI on survival on advanced or inoperable cancers treated with PD‐1/L1 inhibitor. The results of this meta‐analysis revealed that low PNI was significantly correlated with poorer overall survival and progression free survival of advanced cancers treated with PD‐1/L1 inhibitor. PNI was calculated as: 10 × albumin (g/dl) + 0.005 × total lymphocyte count , and Web of Science for relevant articles that investigated the prognosis of PNI in malignant patients treated with PD‐1/L1 inhibitors published before October 6, 2021. The searching strategy was:  OR (PNI)) AND (((((immunotherapy or immune checkpoint inhibitor) OR (programmed death ligand‐1 inhibitor)) OR (PD‐L1 inhibitor)) OR (programmed death‐1 inhibitor)) OR (PD‐1 inhibitor)). References in eligible studies were also carefully browsed to find potential researches.Candidates meet the following criteria were regarded eligible: (1) long‐term survival was provided: overall survival (OS) or progression‐free survival (PFS); reported treatment response data including objective response rate (ORR) or disease control rate (DCR) or provided sufficient data to calculate them; and (2) literature published with full text in English. (3) Hazard ratios (HRs) or relative risks (RRs) with 95% CIs were either reported directly or could be extracted from original articles.Exclusion criteria: (1) studies with insufficient data from which HRs or RRs and 95% CIs could be obtained such as reviews, case or series reports, conference abstracts, or comments; (2) studies in which patients received combined therapy (chemotherapy or target therapy or antiangiogenic therapy); and (3) overlapping or duplicated data.2.2The following information was extracted and recorded by two investigators independently: first author, country, publication year, patient numbers, cancer type, pretreatment PNI cutoff value, survival analysis mode, and number of patients respond to PD‐1/L1 inhibitors (ORR and DCR). We would use the reported HR with 95% CI if available. Otherwise, data were extracted from the Kaplan–Meier survival curves.2.3The Newcastle‐Ottawa Scale (NOS) tool was used to evaluate study quality. We considered studies with scores higher than six as high‐quality studies.2.42 < 50%), which indicated low (I2 < 25%) or moderate (I2 = 25%–50%) heterogeneity, otherwise a random‐effects model was adopted. Sensitivity analysis was performed to explore the influence of each individual study on OS and PFS. Publication bias was evaluated by funnel plots, Egger's test,stata 14.0 software (Stata Corporation) to conduct statistical analyses.Prognostic outcomes, including OS and PFS were primary endpoints of this study. HR with 95% CI was pooled to estimate the prognostic value of PNI in advanced cancer patients. RR with 95% CI was combined to explore the risk of PNI in PD‐1/L1 inhibitor treatment ORR and DCR. A fixed‐effects model was adopted when no significant heterogeneity was observed , with moderate heterogeneity . , with no significant heterogeneity   Figure .3.4p = 0.466 for OS, p = 0.902 for PFS). These results indicated no obvious publishing bias.Sensitivity analysis indicated that each individual study had no significant influence on observed effect size Figure  for PFS.3.5p = 0.072) , sample size (≥100 or <100), publication country (Japan or others), or cancer type (NSCLC or others). In the subgroups analysis of Cox regression analysis model, PNI did not predicted OS in univariate group Figure . Similar%)Figure .4Calculated based on serum albumin and total lymphocyte count, PNI is an easily obtained variable and reflects not only the nutritional status, but also the immune status. Since reported in the 1980s,p = 0.003) but no association with DCR . These opposing results between treatment responses could be explained by the limited study numbers, and we believe that the results will change with more studies reported in the future. Another study by Kim et al.We included nine studies with 660 advanced or inoperable cancer patients received PD‐1/L1 inhibitors treatment. To reduce heterogeneity, we excluded studies in which patients received combined therapy and included studies in which patients received PD‐1/L1 inhibitors. All nine studies reported OS data directly regarding the prognostic value of PNI in advanced or inoperable cancer. Among them, five revealed a significant association between low PNI and OS,PNI reflects both the patients' nutritional and immune status as it is derived from peripheral serum albumin and lymphocyte. Studies have shown that serum albumin and lymphocytes are independent prognostic risk factors for cancer patients. On the one hand, the low PNI is expected to detect malnutrition and is proposed to be pathogenic in the development of cancer‐associated malnutrition, leading to poor performance and increased mortality.Many factors such as Glasgow Prognostic Score, NLR, PLR, body mass index, and C‐reactive protein have been reported to reflect the immune or nutrition status.Some limitations should not be ignored in interpreting our results. First, the retrospective observational property of all the included articles and limited sample size led to the decline in the level of evidence. Second, not all of the survival analyses were conducted by multivariate analysis; thus, some confounding factors may exist. Third, heterogeneity was another issue that should be addressed because most studies were from Asian countries, and ethnic bias may exist. Furthermore, the PNI cutoff values varied between 31.1 and 48 in our meta‐analysis, which may significantly increase clinical heterogeneity. Last but not least, there were significant differences in cancer types, types and lines of PD‐1/L1 inhibitors in different studies, which may lead to significant clinical heterogeneity. Due to insufficient data available in the original article, we were unable to further conduct subgroup analysis based on PD‐1/L1 inhibitor subtypes and cancer types.5In conclusion, low PNI was significantly associated with reduced long‐term survival and treatment responses in patients with advanced cancer treated with PD‐1/L1 inhibitors. Therefore, PNI can be used as an auxiliary tool to predict prognosis and identify high‐risk patient receiving PD‐1/L1 inhibitors. More well‐designed and large sample studies are urgently needed to verify our results.The authors declare no conflict of interest.Qinghua Zhou and Pengfei Li conceived and designed the study; Pengfei Li, and Long Tian collected and analyzed the data; Pengfei Li and Yutian Lai contributed the materials/analysis tools and wrote the manuscript. All authors reviewed and approved the manuscript prior to submission.No ethical approval was required for the meta‐analysis as all data originated from previously published studies.


Head and neck cancer squamous cell carcinoma (HNSCC) is the sixth most common cancer internationally. Established risk factors include smoking, alcohol and presence of human papillomavirus (HPV). The incidence rate of new disease continues to rise, despite falls in alcohol consumption and a reduction in smoking, the rising rates are unlikely to be solely attributed to HPV status alone. Obesity and its associated conditions such as type 2 diabetes (T2D) are implicated in the risk and progression of a variety of cancers, but there is paucity of evidence regarding its role in HNSCC.A systematic review of cohort studies, reporting a risk of incident HNSCC, will be included. A systematic search strategy has been developed, multiple databases will be searched from January 1966 to November 2021, including Cochrane Library, OVID SP versions of Medline and EMBASE. The primary outcome will be incident HNSCC based on exposures of T2D, obesity, dyslipidaemia and hypertension as defined by the WHO. A combined risk effect across studies will be calculated using meta-analysis, although depending on the heterogeneity in study design, exposure and outcome reporting this may not be possible.No ethical approval is required for this systematic review. The review will be published in a relevant peer-review journal and findings will be presented at scientific meetings in both poster and oral presentation form.This study has been registered with the International Prospective Register of Systematic Reviews (PROSPERO) with study registration number CRD42021250520. This protocol has been developed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidance statement. This systematic review will be the first to comprehensively review the literature and provides a meta-analysis of the effect of metabolic disorders and the risk of incident head and neck cancer squamous cell carcinoma (HNSCC).The publication of this protocol provides a clear representation of the methods used in this review for transparency and to prevent future duplication.This systematic review will be one of the first to use the Risk Of Bias In Non-randomised Studies—of Exposures tool.Despite the metabolic disorders being described as separate entities, the authors recognise the potential for disease processes to be related.Among cohort studies, there is significant variability in terms of length of follow-up for the outcome of interest, HNSCC.Head and neck cancer squamous cell carcinoma (HNSCC), which includes cancer of the oral cavity, oropharynx, hypopharynx and larynx, is the world’s sixth most common cancer, with the highest incidence in men and those over 70 years old.9T2D is a common condition characterised by insulin resistance and hyperglycaemia, which results in whole-body metabolic dysregulation.22The complex metabolic changes associated with T2D, obesity, dyslipidaemia and hypertension may alter the risk of certain cancers, but the evidence for head and neck cancer is inconclusive. This study aims to identify, collate and synthesise all relevant studies including adult participants, to determine whether the risk of developing incident HNSCC is influenced by T2D, obesity, dyslipidaemia and hypertension, using relevant effect measures ). Where available, we will further stratify by subsite , as well as by HPV status.Do metabolic disorders affect the risk of developing head and neck cancer?Randomised controlled trials are informative for assessing causal effects; however, due to the nature of the exposures in this study, inclusion of this design is not feasible. Therefore, we will focus on observational  reporting the risk of metabolic disorders on incident HNSCC.Population: participants over 18 years old, of either sex, from any ethnic background.Exposures (1) T2D, (2) obesity, (3) dyslipidaemia and (4) hypertension. These will be collectively described as ‘metabolic disorders’.Comparison: participants who have not been diagnosed with the afore-mentioned metabolic disorders.Outcome: incident HNSCC.The study will report in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and has been pre-registered on International Prospective Register of Systematic Reviews (PROSPERO) in 2021.A systematic search strategy  has been2310.1136/bmjopen-2021-058392.supp1Supplementary dataThe results from searches will be imported into Covidence software, to improve reference management and workflow. This will also populate a PRISMA flow diagram.24All titles and abstracts will be screened by two authors AG and CR, with conflicts resolved by MG. Screening records and decisions will be kept in Covidence. Data will be extracted from titles that meet the inclusion criteria . The datThe WHO defines T2D as a chronic disease that occurs when the body cannot effectively use the insulin it produces and is largely the result of excess body weight and physical inactivity. A diagnosis of T2D was defined as symptoms such as polyuria or polydipsia, plusA random blood plasma glucose concentration≥11.1 mmol/L.A fasting plasma glucose concentration≥7.0 mmol/L (whole blood≥6.1 mmol/L).Two-hour plasma glucose concentration≥11.1 mmol/L, two hours after 75 g anhydrous glucose in an oral glucose tolerance test.Glycated haemoglobin (HbA1c) 6.5% or more (48 mmol/mol and above).Relevant International Classification of Disease (ICD) codes used to define T2D will also be acceptable.The WHO definition ofBMI of 30 or above must have been used to define obesity.Dyslipidaemia was classified as serum total cholesterol, low-density lipoprotein cholesterol, triglycerides, apolipoprotein B or lipoprotein(a) concentrations above the 90th percentile, or high-density lipoprotein cholesterol or apolipoprotein concentrations below the 10th percentile for the general population.The WHO definition of hypertension asA systolic blood pressure reading of ≥140 mm Hg.A diastolic blood pressure readings on both days of ≥90 mm Hg, must have been used.Relevant ICD codes used to define hypertension will also be acceptable.All diagnoses of incident HNSCC included in this study should have been confirmed by histology by a trained pathologist. Acceptable cancer diagnosis may be reported using ICD codes.The analysis and synthesis process will be performed in two phases. The first phase consists of estimating the effect of each metabolic disorder  on incident HNSCC separately for each included study. Effects should be reported as HR, standardised incidence ratio, OR or RR, with 95% CIs or in a format that will enable us to calculate these.2 statistic. Due to the heterogeneity in study design, exposure definition and outcome reporting in the included studies, meta-analysis may not be reasonable. If appropriate, to further explore the sources of heterogeneity if present, meta-regression analyses will be performed according to age, geographic location, year of publication, methods of exposure assessment, risk of bias score, length of follow-up, the number of cases and adjustment for confounding factors including smoking and alcohol use. Small study effects, which may reflect publication bias, study quality or other sources of heterogeneity, will be assessed using funnel plots and Egger’s regression asymmetry tests.The second phase will focus on estimating the combined effect across studies using meta-analysis, using metan software in Stata . Summary effects with their corresponding 95% CIs will be derived with the method of DerSimonian and Laird.Where possible, we will stratify by oral, oropharyngeal, hypopharyngeal and laryngeal subsite and by HPV status as post-hoc analyses, to determine if effects seen are specific to a particular anatomical region or associated with specific tumour types.https://www.bristol.ac.uk/population-health-sciences/centres/cresyda/barr/riskofbias/robins-e/).Two authors will independently extract the relevant risk factor information during data extraction using a preliminary version of the Risk of Bias in Non-randomised Studies—of Exposures (ROBINS-E) tool .


Previous studies have explored factors that influence the occurrence of hypothermia in very low/extremely low birth weight (VLBW/ELBW) infants, but the factors associated with hypothermia in VLBW or ELBW infants remain inadequately evaluated due to limited prospective data and inconsistency in study populations. Therefore, it is necessary to systematically evaluate the risk factors of hypothermia in VLBW/ELBW infants in order to provide a theoretical basis for clinical practice.PubMed and other databases were used to search for case-control or cohort studies on factors influencing the occurrence of hypothermia in VLBW/ELBW infants. The search time was set from database creation to June 30th, 2022. Literature screening, quality evaluation, and data extraction were performed independently by two investigators according to predefined inclusion and exclusion criteria. Meta-analysis was performed using RevMan 5.3.A total of 10 papers were finally included in this study and 12 factors were established by meta-analysis: body weight (six papers), failure to keep warm in time (three papers), neonatal resuscitation (seven papers), gestational age (three papers), premature rupture of membranes (three papers), maternal combined complications (four papers), cesarean section (six papers), antenatal steroids (four papers), multiple birth (two papers), small for gestational age (two papers), 1 min Apgar score (three papers), and 5 min Apgar score (three papers). Since only one study included race, age (hour), socio-economic status, and spontaneous labor, these factors could not be fitted into RevMan 5.3 for the analysis.Although there were differences in the study design of the included literature, the influencing factors described in each study were relatively similar. The influencing factors identified in this study may contribute to the construction of related intervention strategies for hypothermia in VLBW/ELBW infants. Neonatal hypothermia is characterized by an abnormal thermal state in which a newborn’s body temperature falls below 36.5 °C (97.7 °F). Its prevalence ranges from 31% to 78% worldwide . Based ovia the databases Embase, Cochrane Library, PubMed, and Web of Science. The search terms were: very low birth weight infant(s), very low birth weight, extremely low birth weight infant(s), hypothermia(s), accidental hypothermia(s), risk, relative risk, cohort studies, cohort. The search time was set from the establishment of the database to June 30, 2022. Inclusion criteria were followed using a clear definition of the concept of hypothermia, VLBW/ELBW infants, and relevant risk factors. Exclusion criteria consisted of normal weight neonates, unavailability of full text, unavailability of Odds Ratio (OR)/Risk Ratio (RR) values for relevant factors, and type of literature . The factors and search terms are shown in The relevant literature were searched using a combination of subject terms and free words The literature screening and data extraction were carried out individually by two researchers. Endnote software was used to eliminate duplicate literature, systematic evaluation, review, meta-analysis, and animal experiments. The remaining literature’s titles, abstracts, and full text were read through to complete the secondary screening and ambiguous literature were adjudicated by another researcher. The basic information, study characteristics, and outcome indicators of the literature were extracted by developing a literature extraction form based on the JBI evaluation manual .Since the types of literature included in this study were case-control or cohort studies, the Newcastle-Ottawa Scale (NOS) was used to evaluate the quality . This scI2 values. If P > 0.1 and I2 < 50%, it indicated that the heterogeneity among studies was small and it was appropriate to combine effect size using a fixed-effect model; if P < 0.1 and I2 > 50%, it indicated that the heterogeneity among studies was large and it was appropriate to combine effect size using a random-effect model. Begg’s test was used to test the publication bias of the included studies and P < 0.05 was considered statistically significant.Data analysis was executed using Review Manager 5.3. The RR or OR values were applied as the effect analysis statistic. We calculated a 95% confidence index (CI) for each effect size based on the dichotomous variables of the current study outcome. Moreover, heterogeneity of the enrolled studies was evaluated using a Chi-square test and n = 5), NOS score <6 (n = 1), systematic evaluation and meta-analysis (n = 3), unadjusted OR values (n = 1), language discrepancy (n = 2), and no clearly defined influence factors or OR values (n = 12). The literature screening process is shown in P value of Begg’s test was greater than 0.05, this demonstrated that the literature included in this study had no publication bias. This study has been registered on the PROSPERO platform under registration number CRD42022342782.Initially, 202 relevant papers were retrieved, 31 duplicates were excluded by Endnote software, and 137 papers were excluded after reading the titles and abstracts and according to the inclusion and exclusion criteria set for this study. A secondary screening of the remaining 34 papers was performed, and 10 papers were finally included. Reasons for exclusion included unavailability of full text , maternal combined complications, birth weight, multiple births, Cesarean section, premature rupture of membranes (PROM), failure to keep warm in time, neonatal resuscitation, antenatal steroids, and gestational age. As shown in P = 0.32, 95% CI [1.00–1.00]) of body weight on the occurrence of hypothermia was determined to be not statistically different by meta-analysis .The results of the meta-analysis of neonatal resuscitation are shown in I2 = 27%). As a consequence, the calculated OR value for gestational age was 1.10 .Three papers  were ultP = 0.32, 95% CI [0.93–1.25]).Premature rupture of membranes, a common risk factor for adverse outcomes in both obstetrics and pediatrics, has been shown to be related to the occurrence of hypothermia. Three papers  discusseP = 0.04, 95% CI [1.01–1.62]). The integration results are shown in Four papers  studied P = 0.006, 95% CI [1.15–2.41]).Six studies  on CesarThe use of antenatal steroids is common, controversial, and has been connected with the occurrence of hypothermia. In this section, four studies  were recP = 0.53, 95% CI [0.54–3.28]).Of the 10 included papers, two studies  were on P = 0.09, 95% CI [0.93–2.38]).Being SGA is associated with many adverse outcomes, including hypothermia. In this article, two studies  were incP = 0.28, 95% CI [0.8–2.16]), but a 5 min Apgar score was an influencing factor for the occurrence of hypothermia .Apgar score is considered a vital indicator for the evaluation of newborns. Five studies  were incFour other relevant factors could not be meta-analyzed because were included in only one study: race 1.3 (1.1~1.5), age 2.25 (1.13~4.47), socio-economic status 2.76 (1.56~4.9), and spontaneous labor 0.8 (0.7~0.9).Failure to keep warm in time involves low room temperature, prolonged time in the room, and no systematic use of hypothermia prevention. Studies have confirmed that for every 2–3 °C drop in deep body temperature, skin temperature drops by 4–6 °C within 30 min of birth. Therefore, to prevent rapid evaporation of heat from newborns, WHO recommends that room temperature should be maintained at 25 °C . ProlongNeonatal resuscitation includes resuscitation needed, intubation at delivery room, and history of neonatal asphyxia. Neonatal resuscitation may cause hypothermia due to the lack of cerebral blood flow, causing damage of brain tissue and the thermoregulatory center. On the other hand, the main focus of the medical staff during the resuscitation of an infant with asphyxia is on saving the infant’s life, but this may result in prolonged exposure and increased heat evaporation .It has been confirmed that VLBW/ELBW infants have a significant difference in body weight compared to full term infants due to their younger gestational age . Body weIn the literature we examined, maternal combined complications included gestational hypertension, gestational diabetes mellitus, and chorioamnionitis. Maternal combined complications are often associated with a risk of preterm delivery and related medications, such as hormones and magnesium sulfate, that are used more frequently and can easily lead to muscle relaxation and respiratory depression, increasing the risk of resuscitation and exposure of the child .The results of this meta-analysis indicated that Cesarean delivery is one of the risk factors for the development of hypothermia in VLBW/ELBW infants, which may be caused by the fact that maternal heat can be generated during the second stage of labor during vaginal delivery by exertion, which promotes the increase of neonatal body temperature. At the same time, the use of anesthetic drugs during Cesarean delivery is not conducive to the recovery of maternal and neonatal thermoregulatory center functions after surgery .Our meta-analysis suggested that the 5 min Apgar score was a factor influencing the occurrence of hypothermia in VLBW/ELBW infants. Hypothermia may be a result of the neonatal thermoregulatory center being impaired due to asphyxia or other complications. It is also possible that hypothermia is caused by neglecting the application of warming measures during resuscitation .Although this study was based on an evidence-based correlation approach to analyze the factors influencing hypothermia in VLBW/ELBW infants, there were several limitations in this meta-analysis. Above all, there was a large heterogeneity across some of the factors. Though we attempted to explore the sources of heterogeneity using subgroup analysis, the effect was minimal. After research and discussion, the reasons may be as follows: first, there were differences in the diagnosis of hypothermia among studies. Although WHO proposed a threshold of 36.5 °C for hypothermia, some of the studies used 36.0 °C or 35 °C as the threshold, which increased the heterogeneity among studies due to different inclusion criteria. In addition, there was inconsistency in the way neonatal temperature was measured. Among the included studies, neonatal temperature measurement methods included rectal, axillary and/or skin, and the inconsistency of temperature measurement methods may have led to differences in temperature reporting between studies, thus increasing the heterogeneity of the results of this meta-analysis. On the whole, there were large differences in temperature variation among different ethnic groups. The American Collaboration for Advancing Pediatric Quality Measures (CAPQuaM) confirmed by analyzing data on newborns in New York State that there were differences in temperature variation among different ethnic groups of newborns, and black infants were more likely to have hypothermia compared with white infants . In the Through literature generalization, we determined a total of 16 factors influencing hypothermia in VLBW/ELBW infants. Of these, four influencing factors  were included in only one study, and so the meta-analysis was not performed on them. The remaining 12 factors were included in the meta-analysis, and the results showed that failure to keep warm in time, neonatal resuscitation, gestational age, maternal combined complications, Cesarean section and 5-min Apgar score were contributing factors for hypothermia in VLBW/ELBW infants.10.7717/peerj.14907/supp-1Supplemental Information 1The appendix contains search strategies for 4 databases: PubMed, Embase, Cochrane Library and Web of Science.Click here for additional data file.10.7717/peerj.14907/supp-2Supplemental Information 2The appendix contains the results of the quality evaluation and risk bias assessment of the included literature.Click here for additional data file.10.7717/peerj.14907/supp-3Supplemental Information 3Click here for additional data file.10.7717/peerj.14907/supp-4Supplemental Information 4Click here for additional data file.10.7717/peerj.14907/supp-5Supplemental Information 5Click here for additional data file.


Ischemic stroke (IS), usually caused due to an abrupt blockage of an artery, is the leading cause of disability and the second leading cause of death worldwide. The association of the C-reactive protein (CRP) gene (s3093059 T/C and rs1205 C/T) polymorphisms and IS susceptibility has been widely studied, but the results remain inconsistent. Our study aimed to assess the association between CRP gene (s3093059 T/C and rs1205 C/T) polymorphisms and IS risk. PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, and WanFang databases were searched up to April 2022 to identify eligible studies. The Newcastle-Ottawa scale (NOS) score was calculated to assess study quality. The odd ratios (ORs) with a 95% confidence interval (CI) were calculated to assess the association between CRP gene (rs3093059 T/C and rs1205 C/T) polymorphisms and IS risk. Eighteen case–control studies with 6339 cases and 29580 controls were identified. We found that CRP (s3093059 T/C and rs1205 C/T) polymorphism was not significantly associated with the risk of IS in any genetic model . When stratified analysis by country, genotype method, source of controls, and NOS score, still no statistically significant association was found. Our study indicated that the CRP (rs3093059 T/C and rs1205 C/T) polymorphisms were not associated with the susceptibility to IS. With thUnderstanding the relationship between gene polymorphism and disease may help inform the design of pharmacotherapies by using multiple silico techniques ,13,14. A2This meta-analysis was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement .2.1A systematic literature search was conducted by using the combination of the following terms: “CRP,”, “CRP” “rs3093059,” “rs1205,” “polymorphism,” “variant,” and “IS” based on PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, and WanFang databases before April 2022. There were no language restrictions during the literature search. Additionally, the references of relevant articles were manually searched for potential studies.2.2The criteria for including studies in this meta-analysis were as follows: (1) the design of the study was case–control or cohort studies; (2) studies assessed the association between CRE gene polymorphism (rs3093059 or rs1205) and IS risk; (3) studies provided available genotype distribution in cases and controls; (4) the genotype distribution of control group conformed to Hardy–Weinberg equilibrium (HWE). The exclusion criteria were (1) studies that reported incomplete data or without data in cases and controls group; (2) duplicate data; and (3) review, case reports, or animal experiments.2.3Two authors independently extracted the following information from included studies: first author’s name, year of publication, country, ethnicity, genotype methods, genotype counts in cases groups and control groups, HWE results for control groups, and Newcastle-Ottawa scale (NOS) assessment. The NOS was calculated for the quality assessment of included studies. Discrepancies were resolved by consensus.2.4p < 0.05 which was considered statistically significant. To estimate a summary effect size for IS risk, the odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by using the command “metan” based on five genetic models: allelic model, heterozygous model, homozygous model, dominant model, and recessive model. The significance of the pooled OR was determined by Z-test. Between-study heterogeneities were evaluated with I2 statistic and Cochran’s Chi-square-based Q test. A fixed-effect model (Mantel–Haenszel method) was used when I2 was ≤ 50%. Otherwise, analyses would be performed with random-effect models (Mantel–Haenszel method). HWE was tested by Chi-square test in controls. Sensitivity analysis was used to verify the stabilities of synthetic results. Publication bias was assessed using Begg’s funnel plots and Egger’s regression by “metafunnel” and “metabias” commands. We also conducted subgroup analyses by country, genotype method, source of controls, and NOS score. Trim-and-fill method was performed to adjust OR value when publication bias was found.Meta-analyses were performed using the STATA version 12.0 , with a value of 33.1By retrieving relevant databases, 531 possible related articles were initially identified. 104 were excluded due to duplication, and then 398 articles were excluded through screening title and abstract. Finally, 18 articles ,33,34 we3.2p = 0.637; recessive, CC vs TC + TT: OR = 1.00, 95% CI 0.79–1.26, p = 0.975; dominant, TT vs TC + CC: OR = 0.91, 95% CI 0.75–1.10, p = 0.327; homozygote, CC vs TT: OR = 1.06, 95% CI 0.71–1.58, p = 0.786; heterozygote, TC vs TT: OR = 0.87, 95% CI 0.73–1.03, p = 0.112; allele, C vs T: OR = 0.95, 95% CI 0.80–1.14, p = 0.592) . We used meta-regression to detect the influence covariates and found the source of controls  the influence factor.The main results for the association between CRP rs3093059 T/C polymorphism and IS risk are summarized in = 0.592) . Moreove= 0.592) . Signifi= 0.592) . Therefo3.3p = 0.637), heterozygote , dominant , recessive , and allele  and IS susceptibility. The pooled results revealed that CRP polymorphisms  might not associate with IS risk.CRP, a glycoprotein released by the liver, has been regarded as an essential mediator and a hallmark of the acute-phase response to inflammation and is recommended for use in risk assessment in IS patients . CRP is in vitro and in vivo, getting deposited chronically within the brain after IS, and may play a role in perpetuating neuroinflammation after brain injury [As an inflammation-associated protein, CRP can be divided into two structurally and functionally independent forms: (1) net anti-inflammatory, serum-associated native pentameric CRP, and (2) pro-inflammatory tissue-associated, monomeric CRP (mCRP) ,42. Seven injury . Of courThough the clear mechanism is ambiguous, CRP is closely related to the occurrence, development, and outcome of IS. The results of clinical studies show that CRP levels increase in the first 48 h after onset, are still elevated at 7 days and remain high for 3–6 months after IS ,47. CRP To our knowledge, this study is the first meta-analysis to focus on CRP polymorphisms (rs3093059 T/C and rs1205 C/T) and IS risk and proved CRP rs3093059 T/C and rs1205 C/T polymorphisms have little association with the risk of IS. Based on the aforementioned analysis, our study still has some limitations and shortages. On the one hand, the data are still relatively small and may not provide sufficient power to estimate the association between CRP gene polymorphisms and IS risk. Few studies have investigated the association between the CRP gene and patients’ stroke subtypes and patient-based characteristics, which has to be confirmed in more populations. On the other hand, as a type of retrospective study, a meta-analysis may encounter recall or selection bias, possibly influencing the reliability of our study results. Therefore, more studies with larger sample sizes are needed to accurately provide a more representative conclusion.5The current meta-analysis result suggests that CRP (rs3093059 T/C and rs1205 C/T) polymorphisms might not be associated with the risk of IS. In addition, CRP genetic variant might be associated with multiple internal and external factors, which suggests that further efforts are needed to dissect subgroups and patients’ overall physical condition. However, large sample size and well-designed studies within different ethnic are needed to confirm the findings of our study


Although people with human leukocyte antigens (HLA) DQ2 and/or DQ8 are more likely to develop celiac disease (CD), the condition cannot be fully explained by this genetic predisposition alone. Multiple, as yet unidentified, factors contribute to the genesis of CD, including genetics, the environment, and the immune system. In order to provide insight into a prospective possibility and an expanded screening technique, we aim to undertake a comprehensive and meta-analytical study of the assessment and distribution of HLA class II (HLA-DQ2/DQ8) in adult CD patients. A systematic review was conducted using an electronic search of databases  from January 2004 to February 2022. DQ2/DQ2 homozygotes have the highest risk of developing CD. DQ2/DQ8 typing is an effective test to exclude CD from the differential diagnosis of a patient with CD symptoms. Although other non-HLA genes have been associated with CD, they are rarely considered at diagnosis because they account for only a small proportion of the heritability of CD. This finding, together with the information gathered previously, may be useful in considering widely available and economically feasible screening options for celiac disease in young people. Celiac disease is an autoimmune disorder triggered by eating gluten, a protein essential to wheat, barley, and rye, in those who are susceptible to it because of their genes ,2. CD haIn the United States, the rate of CD prevalence is 0.71% (1 in 141 people), which is on par with the rates seen in some European nations. CD is more common in Finland and Sweden, where the rate is 2–10%, than in Germany, where it is just 0.20% . Most inIt is believed that the prevalence rate in Africa is around 1.1%. In point of fact, the frequency of the HLA-DQ2 haplotype in the population, as well as the consumption of wheat, is greater in North Africa than it is in sub-Saharan Africa . PatientOur goal is to perform a meta-analysis of the study of HLA class II human leukocyte antigens (HLA-DQ2/DQ8) in adult patients with CD to provide light on a possible viewpoint and method for broader screening. In contrast to several other reviews, we are only interested in material pertaining to CD and not gluten intolerance or sensitivity .We did an extensive search on the Google Scholar, Science Direct, Pub Med, Embase, and Medline databases using the following keywords (HLA OR HLADQ antigens OR HLA OR HLADQ antigens OR human leukocyte antigen (leukocyte OR leukocytes) AND (antigen OR antigens)) AND (HLADQ2 OR HLADQ8 OR HLADQ2 and HLADQ8) OR ((celiac OR celiac disease OR CD) AND (HLA OR HLADQ antigens OR adult OR adults)). Our search was restricted to the English language, and one of the topic phrases we used was “celiac illness.” The topic terms of the technique for finding the frequency of predisposing genes were “HLA antigens,” “class II histocompatibility antigens,” or “major histocompatibility complex antigens,” and the text words were “DQ2” and “DQ8.” A manual search of the references of the studies whose complete texts were examined was another method that was used to locate the papers. When searching for publication, time, status, or the language of publishing, no constraints were used. Abstracts that were not also made available in full-text format were not considered for inclusion in this research.We conducted a meta-analysis of all available literature on the topic of HLA DQ and Celiac disease in adults.A.S. and K.O. both did the literature evaluation, read all of the entire texts, and independently selected which studies to include and which to exclude based on the inclusion and exclusion criteria. A discussion was used to iron out any differences of opinion between the 2 writers. In the event of a prolonged dispute, the senior member of the team (K.T) would go through the data and make a decision.The study must be designed for adults CD patients;Studies involving patients with CD and not gluten sensitivity;The study sample must be representative—the number of participants must be greater than 30;The test subjects may be related or unrelated and include both men and women;The data must include the haplotype distributions in terms of their frequency HLA DQ2 HLA DQ8.Prior to beginning the literature search, we established what would be considered included and what would be disqualified. Studies that matched the following criteria and were published as full articles or abstracts were included in this meta-analysis:Studies Treating Celiac Disease in Association with Another Disease;Studies that focus only on children;This includes many versions of the same article, letter, editorial, case series, narrative review, systematic review, or meta-analysis. Following the title and/or reading an abstract, we found that there were many articles that did not pertain to our topic;We also don’t include studies that don’t help us answer our research question.The quality of the included studies was independently assessed by 2 reviewers  using a checklist designed by Penny Whiting  using thBoth researchers (A.S. and K.O.) critically reviewed the included studies to extract the pertinent data separately, and any disagreements were settled by consensus. Author, year published, the year studied, country studied, population characteristics, study type, population characteristics , and diagnosis were all retrieved.For the meta-analysis, we performed the statistical analysis using the R studio software . The random effect model was used for the analysis. We calculated the odds ratios (OR) and 95% confidence intervals (CI).2- and chi2-heterogeneity. An I2 of 0–40%, 30–60%, 50–90%, and 75–100% represents heterogeneity between studies that are not significant, moderate, substantial, and considerable, with p < 0.10 indicating statistical significance.Heterogeneity was tested with IThe data were analyzed using Statistical Package for Social Science (SPSS) version 21. The frequencies of the clinical and histological characteristics were calculated as part of a descriptive analysis.n = 22 articles were subsequently obtained, and after a review of the full text, the references among these 22 studies were screened, and n = 7 studies that deal with CD in children were excluded, as well as two further studies.The predetermined search procedure yielded a total of 2969 items. The process of selecting the 13 studies for inclusion in the meta-analysis and the method used to exclude studies that did not meet the inclusion criteria are shown in the flowchart shown in We extracted 30,183 patients’ information from 13 studies. Independent references from 13 studies were included in this study. The largest sample size for the individual study was n = 25,025, and n = 49 was the smallest sample size. The other characteristics of this study are summarized in p-value = 0.0190) according to the random effects model. Although data from eight isolated studies suggest that HLADQ2 is a significant risk factor, three studies showed that it is not significant, and two studies are neutral for CD patients and report that HLADQ2 has no effect on CD. The overall effect was significant  and indicated a higher risk of expressing HLADQ2 in a patient with celiac disease. Of note, the heterogeneity (I2 = 97%) and heterogeneity tests were significant .The forest plot  shows thp-value of 0.9654 according to the random effects model). Although data from eight individual studies suggested that HLADQ8 was a risk factor, five studies showed that it was not significant. The overall effect was significant (p = 0.0001) according to the fixed-effect model and indicated a higher risk of expressing the HLADQ8 gene in controls. In addition, heterogeneity was significant (I2 = 79%) and the test for heterogeneity was significant .The forest plot  shows thp = 0.2663 according to the random-effect model). Although data from seven unique studies suggest that HLADQ2/HLADQ8 is a significant risk factor, five studies showed that it is not significant, and only one study is neutral for CD patients and states that HLADQ2/HLA DQ8 has no effect on CD. The overall effect is significant (p < 0.0001 according to the fixed-effect model), indicating a higher risk of expressing HLADQ2/HLADQ8 in CD patients. In addition, considerable heterogeneity (I2 = 97%) and test for heterogeneity were significant .The forest plot  shows thp = 0.1026 according to the random-effect model). Although data from three isolated studies suggest that the homozygous HLAQ2 allele is a significant risk factor, three studies showed that it is not significant, and only one study is neutral for patients with CD and states that the homozygous HLA DQ2 allele has no effect on CD. The overall effect is significant (p < 0.0001 according to the fixed-effect model), indicating a higher risk of homozygous HLADQ2 expression in CD patients. In addition, heterogeneity was considerable (I2 = 98%) and the test for heterogeneity was significant .The forest plot  shows thp = 0.1440 in the random-effects model), but in the fixed-effects model (p < 0.0001). Although data from five isolated studies suggest that the heterozygous HLAQ2 allele is a significant risk factor, one study showed that it is not significant, and only one study is neutral for CD patients and reports that the heterozygous HLA DQ2 allele has no effect on CD. In addition, heterogeneity was considerable (I2 = 94%) and the test for heterogeneity was significant .The forest plot  shows thp = 0.5999 according to the random-effects model). However, according to the fixed-effects model (p = 0.0002). Although data from two single studies suggest that the heterozygous HLAQ8 allele is a significant risk factor, three studies showed that it is not significant, and two studies are neutral for CD patients and report that the heterozygous HLA DQ8 allele has no effect on CD. Heterogeneity was significant (I2 = 89%) and the test for heterogeneity was significant .The forest plot  shows thThis research is the first comprehensive meta-analysis of the DQ2 and DQ8 heterodimers predisposing to CD that are encoded by the HLA-DQB1 and HLA-DQA1 alleles in adults with CD. Indeed, it provided 3158 adult CD patients and 26,863 controls for statistical analysis. Numerous commercial and university labs provide HLA genetic testing, which is used to diagnose celiac disease and find people at risk in the same families. Celiac disease HLA testing has a poor positive predictive value but a high negative predictive value. As a result, it is crucial for the practicing physician to know when to ask for an HLA genetic test . In sympRecent data on microbiome studies in CD show the importance of broader HLA screening, as some bacteria have been associated with CD in the absence of classical HLA risk alleles. Knowledge of the degree of relevance of classical HLA associations could be included in risk assessment algorithms in different populations, also taking into account a wider range of HLA haplotypes . We intrWe found that diarrhea constitutes a percentage (22%) in adult patients with CD. Among these, we found that diarrhea constitutes the highest percentage (18.6%) in adult CD patients. Some previous studies ,40 have p = 0.0190 according to the random effect model; p < 0.0001 according to the fixed effect model), and the odds ratio for the single dose of HLA-DQB1*02 in adult CD patients was also relatively increased in comparison to controls (OR = 2.14) However, these results were not significant according to p = 0.1440 of the random effect model, the fixed effect model shows a significant p = 0.0001. This result is similar to that [We observed that the risk of getting CD in individuals with DQ2, which is encoded by the HLA-DQA1*05 and DQB1*02 alleles, has been generally verified. This was the conclusion we came to after doing our research. According to the findings of this study, the odds ratio for the double dose of HLA-DQB1*02 in adult CD patients was significantly higher than in controls  . p = 0.5999 according to the random effect model is not statistically significant, but according to the fixed effect, the p-value is significant (p = 0.0002). These results were in agreement with the lower risk associated with the DQ8 variant previously described in Moroccan and Libyan patients due to the higher frequency of DQ8 in controls [In adult patients with CD, the frequency of HLA DQ8 is lower than in controls (OR = 0.79) controls .In the European population, the frequency of this variant is 17.8% in CD patients . The freThe condition is very infrequent in those who do not possess HLA-DQ alleles, according to the research of other scientists . CD is rIn our analysis, heterozygous DQ8 did not increase the risk of CD. An Arab population case-control research supported these findings, showing that the frequency of heterozygous HLADQ8 was identical in cases and controls, and so represented a risk for the general population  [p < 0.001, OR: 51.57) [In our analysis, heterozygous DQ8 did not increase the risk of CD; this result corroborates the previous observation that carriers of the heterozygous DQ8 genotype (2.11%) have lower EMA than homozygous DQ8 celiac individuals (8.42%) . The HLA: 51.57) .In The European population showed differences in effect and significance, and this difference could be due to combinations of population-related genetic and environmental factors. Many questions are still open regarding the role and interactions between genetic and environmental factors in the development of CD. Environmental factors are mainly associated with the introduction of gluten  . Asian pFull HLA-DQ genotyping might be kept for adults with clinical suspicion . However, many of the undetected cases might be attributed to extra-intestinal symptoms of unusual clinical presentations. Recent work by Verma et al. presented a quick HLA-DQ typing approach for identifying CD patients who have susceptibility genes. The researchers essentially ran polymerase chain reaction (PCR) on blood samples from CD patients, FDRs, and controls using a kit containing primers for HLA-DQ target alleles exclusively. In terms of the presence or absence of HLA-DQ2 and HLA-DQ8 alleles, they could exhibit good agreement with the findings obtained by traditional high-resolution HLA-DQ typing . AlthougThe results obtained confirmed that the DQ2 allele is the primary one related to CD due to its high frequency in adult patients in all studies; the homozygous and heterozygous status of HLADQ2 is present with increased frequency in most adult patients. The high immunodominance and the pathogenic mechanisms of gluten peptide presentation by DQ2 contribute to the close connection between HLA haplotypes and celiac disease. Although the classical DQ2/DQ8 associations with CD were confirmed in this meta-analysis, a minority of CD cases develop in the absence of predisposing HLA haplotypes. A detailed analysis of MHC in DQ2-negative CD should lead to a better understanding of the susceptibility genes for CD. Recent data on microbiome studies in CD  evidence


Background: More and more studies are focusing on the adverse effects and damage caused by PPI abuse, we carried out a systematic review and meta-analysis for assessing whether the proton pump inhibitor (PPI) leads to hepato-biliary-pancreatic cancer.Methods: PubMed, EMBASE and Web of Science were searched until 1 July 2022, 25 studies  included in this study. Pooled Odd Ratios (ORs) were used for random effect models. Sensitivity analysis and dose-response analysis, subgroup analysis were all conducted.Results: The aggregate OR of the meta-analysis was 1.69 : 1.42–2.01, p = 0.01) and heterogeneity  was substantial. According to stratified subgroup analyses, the incidence of hepato-biliary-pancreatic cancer was associated, expect for study design, study quality and region. Risk of hepato-biliary-pancreatic cancer is highest when people is treated with normal doses of PPI. The risks decrease and become insignificant when the cumulative defined daily dose (cDDD) increases.Conclusion: The use of PPI may be associated with an increased risk of hepato-biliary-pancreatic cancer. Hence, caution is needed when using PPIs among patients with a high risk of hepato-biliary-pancreatic cancer. Proton pump inhibitors have been the most widely used drugs since the 1980s for treating gastroesophageal reflux disease (GRED), H. pylori infection, Zollinger-Ellison syndrome and a number of other diseases caused by hyperacidity irreversibly inhibiting H+/K+-ATPase in stomach cell . These dHepato-biliary-pancreatic cancers, as the most important malignant tumors of the abdomen, are characterized by the influence of microbiome of hepatopancreatic ampulla and biliary tract and are significantly more difficult to treat and have a poorer prognosis than other malignant tumors . AlthougWe have clarified the association between PPI and risk of hepato-biliary-pancreatic cancer by including known studies in this meta-analysis. We likewise evaluated whether the risk of hepato-biliary-pancreatic cancer aggravates when the dose of PPI increases.This study is based on the aloe system assessment and analysis criteria (PRISMA) and the optional reporting items in the Corcoran manual . This reIncluding criteria:  ObservatExcluding criteria:  literatuTwo auditors independently examined titles meeting the including and excluding criteria and examined whether the information of study is insufficient. Subsequently, the full text of the selected articles was evaluated and two auditors extracted critical information which includes first author, year of publication, region/country, study design, exposure definition, cDDD independently. Any disagreement has been resolved by consensus between the two auditors or arbitrated by the third auditor. The quality of the observational studies was assessed by two authors using the Newcastle-Ottawa scale.Q and I2 statistics.ORs were used as a common measure of association between studies. Statistical analyses were performed using R (4.2.1). We derived aggregated risk estimates, which were expressed with 95% CI in total hepato-biliary-pancreatic cancer and in each cancer. Random effect models were used to take into account the heterogeneity of aggregate estimates. We used Cochran Q test to evaluate heterogeneity between studies, quantified using Cochran Subgroup analysis and meta-regression was performed (classification by study design .We also investigated a potential nonlinear dose-response relationship between cDDD and hepato-biliary-pancreatic cancer via restricted cubic splines and fractional polynomial models reported in The electronic searches resulted in 726 titles, of which 25 studies met the inclusion criteria for the meta analysis. 4 article did not meet the inclusion criteria for meta-analysis because they were review articles, the flowchart of study selection was demonstrated in I2 > 50% was found by heterogeneity test, we identified evidences of publication bias by the visual the results of Egger test (p < 0.001) . Subgroup analysis and meta-regression in different subgroups were performed (I2< 50%.All of the 25 studies (17 cases control  and 8 co< 0.001) , correcterformed . Differeerformed , a rereaA total of 12 studies reported the risk of liver cancer (3 studies reported intrahepatic bile duct cancer as an outcome and 9 studies reported the risk of hepatocellular carcinoma), which were analyzed separately and found that long-term PPI use increased the risk of liver carcinoma , hepatocellular carcinoma  were at risk of development. six case-control studies and five cohort studies (one case-control study reported the results of the cohort study) showed a significant association between long-term PPI use and the development of liver cancer when subgroup analysis was performed , and the risk of increased incidence of liver cancer after long-term PPI use was found in different geographical regions  .A total of 4 studies reported the risk of long-term PPI use and the risk of biliary system carcinoma, of which 2 reported the risk of gallbladder cancer  and 3 reported the risk of intrahepatic and extrahepatic biliary tract cancer , respectively, while the long-term use of PPI was associated with the overall risk , and long-term PPI use was significantly associated with the overall biliary tract cancer .15 studies  showed that long-term use of PPI drugs increased the risk of developing pancreatic malignancies  and that PPI uses increased the incidence of pancreatic tumors in different geographical populations .The WHO developed the anatomical therapeutic chemical (ATC) classification system in 1969, which established the defined daily dose (DDD) as the unit of medication frequency analysis. It is defined as the average daily dose of a drug used for the primary therapeutic purpose in adults . InformaIn order to better assess the association between cDDD and hepato-biliary-pancreatic cancers, we analyzed the association between cDDD and overall tumor risk in a comprehensive manner. The association of dose change with the risk of pancreatic cancer, hepatocellular carcinoma and biliary tract cancer was then analyzed separately.Fourteen studies provided information on hepato-biliary-pancreatic cancer risks correlated with cDDD of PPIs.The OR was highest at about 500 cDDD/per patient , which mCurrent guidelines for GERD, hemorrhagic ulcers and H. pylori infection use IPPs as the drug of choice, but PPI also have the potential to alter the structure of upper gastrointestinal pH, which has potential links to previous studies on the pathogenesis of hepato-biliary-pancreatic cancer, and our study supports the view that excessive use of PPI increases the risk of hepato-biliary-pancreatic cancer. This may lead clinicians to be more careful in choosing indications and to control the dose of the drug so that the disease population is treated properly without worrying about increased tumor risk.After analyzed 25 studies using a random effects model, including a total of 2741853 patients. This meta-analysis aimed to clarify that long-term use of PPI may increase the risk of hepato-biliary-pancreatic cancer.Based on the results of our study, a normal dose of PPI is associated with an increased risk of developing hepato-biliary-pancreatic cancer. However, as the dose increases, the positive correlation between the two diminishes (cDDD > 2000/per patient).Several mechanisms suggest a potential oncogenic effect of PPI in hepato-biliary-pancreatic cancer. These effects include an increase in levels of abnormal gastrointestinal hormones and intestinal microbiota, as well as the production of carcinogens.Prolonged use of PPI leads to a rise in gastric pH and an increase in gastrin production by G-cells with negative feedback. In addition to stimulating the secretion of digestive glands and accelerating nutrient absorption, gastrin seems to induce the development and growth of gastrointestinal cancers by binding to CCK-BR on the surface of the enterochromaffin-like cells (ECL) . In hepaA current study has proved long-term PPI use may pose a risk for gallbladder dysfunction and biliary complications , a retroThe distribution of microorganisms in the gastrointestinal tract depends mainly on the pH gradient and the abundance of oxygen, and the changes in pH due to long-term PPI use are limited to the duodenum and proximal small intestine , this paLong-term PPI reduces gastrointestinal microbial diversity by blocking gastric acid secretion and affecting gut microbiota diversity , it can Enterococcus faecalis and Escherichia coli may be associated with the progression of pancreatic tumors associated with pancreatitis  are theoretically superior to PPIs due to its pH stability in digestive tract and long half-life period , and havAlthough the results of this study corroborate the conclusion that long-term PPI may increase the risk of hepato-biliary-pancreatic cancer. However, there are still some shortcomings: if some measurement uniformities were available, we could have performed a dose or response duration analysis to evaluate the linear relationship, which would have helped quantify the association more accurately. and the dose and duration inconsistencies mentioned above may have contributed to this heterogeneity. Third, the relationship between long-term PPI use and biliary system cancer may be biased, the bias may be caused by the number of cDDD in the studies. In addition, the meta-analysis included only studies published in English, with smaller studies with cumulative results often unpublished, leading to potential biases.In conclusion, the results of this study corroborate the argument that the risk of hepatobiliary and pancreatic cancer is higher among IPP users. Whether the risk of cancer development was analyzed for hepato-biliary-pancreatic cancer or for single cancers, there was a positive correlation between the risk of tumor development and low doses, the risk of tumor development was highest at normal doses. However, no further increase in tumor risk was found with higher cumulative defined daily dose. Hence, further studies are needed to clarify and validate the mechanism. However, health professionals should carefully consider the prescription of PPI for patients at high risk of hepato-biliary-pancreatic cancer and control the misuse of medications.


Objective: Systematic review of the association of protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene 1858 and 1123 sites single nucleotide polymorphism (SNP) with the susceptibility of primary immune thrombocytopenia (ITP).Method: Database searched includes PubMed, Embase, Web of Science, CNKI, CBM, VIP and WanFang Data. The retrieval period is from the establishment of the database to 30 June 2021. After screening articles according to inclusion and exclusion criteria, the data were extracted and methodological quality of the included studies was evaluated. Meta-analysis was performed using RevMan 5.4 and Stata 16.0 software. The combined OR value and its 95%CI were calculated. Sensitivity analysis and publication bias assessment were performed. Trial sequential analysis (TSA) was performed using TSA 0.9.5.10 Beta software.Results: A total of 10 studies with 10 articles were included, with a total of 932 cases and 2,112 controls. The results of meta-analysis showed that for SNP1858, the susceptibility of TT genotype to ITP was 5.01 times higher than CC genotype . For SNP1123, G allele carriers were more susceptible to ITP than C allele carriers , and GG genotype carriers were 1.51 times more susceptible to ITP than CC genotype carriers . Although the results are statistically significant, the results of sensitivity analysis showed certain limitations of stability, and the TSA analysis still indicated the possibility of false positive. No significant publication bias was observed.Conclusion: PTPN22 gene SNP1858 (rs2476601) and SNP1123 (rs2488457) polymorphisms are associated with susceptibility to primary immune thrombocytopenia. Due to the limitation of the number and quality of the included studies, the above conclusions need to be verified by more high-quality studies. It is one of the most common hemorrhagic disease which is caused by decrease in platelet count (platelet count <100×109/L) . ITP can9/L) . In clin9/L) . The pat9/L) . Study h9/L) . Moreove9/L) .The etiology and pathogenesis of ITP also involve a variety of genetic risk factors. Studies has shown that PTPN22 gene has a significant role in the regulation of signal transduction through T-cell receptors (TCR)  which isPTPN22 gene has been proved by researchers to play an important role in type Ⅰ diabetes  and rheu(1) Case-control studies which evaluated the association between SNP1858 and SNP1123 polymorphisms of PTPN22 gene and susceptibility to ITP.(2) The case group of the case study consisted of patients with primary immune thrombocytopenia diagnosed clinically and pathologically, and the control group consisted of healthy people with no restrictions on gender and race.(3) Frequencies of alleles or genotypes in control groups and case groups could be obtained from the included articles.(1) Analysis data is incomplete or missing, and contact with the original author is not available.(2) The subject of the original study is not human.(3) Repeated publication and retrieved article.(4) For repeated publications by the same author, the one with the highest quality and the largest sample size was selected.PubMed, Embase, Web of Science, CNKI, CBM, VIP, and WanFang Data databases were searched. The retrieval period is from the establishment of the database to 30 June 2021. The references of the included literatures were retrospectively reviewed to supplement the relevant articles. The retrieval is carried out by the combination of free words and subject words. Search terms include ITP, Idiopathic Thrombocytopenic Purpura, Immune Thrombocytopenia, PTPN22, Protein tyrosine phosphatase non-receptor type 22, PTPN22 polymorphism, PTPN22 variants, PTPN22 genotype. Taking PubMed as an example, its specific retrieval strategies are shown in Two researchers independently screened the articles, extracted the data and cross-checked them. Disputes, if any, shall be settled through discussion or negotiation with a third party. When screening the articles, the title was first read, and after excluding obviously irrelevant literature, the abstract and the full text were further read to determine whether to be included. If necessary, contact the original study author by email or telephone for undetermined but important information for this study.The quality of the included case-control study was evaluated by referring to The Newcastle-Ottawa Scale (NOS), including whether the definition and diagnosis of the case are appropriate, whether the case is representative, whether the selection and definition of the control are clear, whether the case is comparable with the control, whether the investigation and evaluation methods of exposure are the same, whether the investigation methods of case and control are the same, and whether there is no response rate .α = 0.10). Encountering small statistical homogeneity between studies (p > 0.10), a fixed-effect model was used in the meta-analysis. Contrariwise, when huge statistical homogeneity between studies were exposed (p < 0.10), a random-effect model was used for meta-analysis. We also had Hardy-weinberg balance calculated based on the data of controls, and p < 0.05 was considered statistically significant. We performed sensitivity analysis with one-by-one exclusion method to see if one study greatly influenced the overall results. The publication bias was evaluated using Begg’s test and Egger’s test. p > 0.05 was considered the publication bias was minute. TSA was used to analysis the problem of random errors such as false positives and false negatives in the repeated updates of meta-analysis, and to calculate the sample size needed to draw a definite conclusion by TSA 0.9.5.10 Beta software  and its 95% confidence interval (95%CI) of alleles and genotypes. The calculation of heterogeneity between the results originated from each selected study was done utilizing chi-square test , so the fixed effect model was used for combined analysis. Taking genotype TT as the exposure factor and genotype CC as the non-exposure factor, the meta-analysis results showed that the incidence risk of ITP in the population with genotype TT was higher than that in the population with genotype CC , and the results were statistically significant , so the random effect model was used for combined analysis. The results of meta-analysis showed that there was no significant difference in the risk of ITP in the dominant model TT + TC vs CC group  , so the fixed effect model was used for combined analysis. The results of meta-analysis showed that there was significant difference in the incidence risk of ITP among the population of the recessive model TT vs TC + CC group. The incidence risk of ITP in the population of TT genotype was higher than that in the population of TC + CC genotype  , p = 0.002], and the susceptibility to ITP of patients with TT genotype was 5.39 times higher than that of patients with TC genotype  ,  0.0008] .2 = 4.63, p = 0.33), so the fixed effect model was used for combined analysis. Taking genotype GG as the exposure factor and genotype CC as the non-exposure factor, the meta-analysis results showed that the risk of ITP in the population with genotype GG was higher than that in the population with genotype CC , and the results were statistically significant , so the fixed effect model was used for combined analysis. The results of meta-analysis showed that there was a statistically significant difference in the risk of ITP in the dominant model GG + GC vs CC group. The risk of ITP in the GG + GC genotype was higher than that in the CC genotype  , so the random effect model was used for combined analysis. The results of meta-analysis showed that there was no significant difference in the risk of ITP between the implicit model GG vs GC + CC group  , p = 0.009] , = 0.009] .vs CC genotype of SNP1858 as an example, the maximum combined OR value was 9.61 [95%CI ] (excluding Lioger B 2016) and the minimum value was 3.69 [95%CI ] ] (excluding He L 2014) and the minimum value was 1.33 [95%CI ] (excluding Wan H 2020). Sensitivity analysis showed that the meta-analysis results were relatively stable.Sensitivity analysis was performed by one-by-one exclusion method. Taking TT p values were higher than 0.05, indicating no publication bias was observed for the results relating ITP risk to PTPN22 gene polymorphism in the included studies. Taking TT vs CC group of SNP1858 as an example, Begg’s test showed that Z = 0.24, p = 0.806 > 0.05, which also indicated no publication bias.Publication bias analysis of PTPN22 gene SNP1858 and SNP1123 polymorphism and ITP susceptibility using Egger’s test was shown as vs TC + CC group as an example, the accumulated information amount did not reach the Required Information Size (RIS), and the Z-curve was about to intersect the TSA boundary line but have not yet , p = 0.01. The risk of ITP in population with homozygous GG genotype was 1.51 times higher than that in CC genotype , indicating that the G allele at SNP1123 of PTPN22 may increase the susceptibility to ITP.In this study, PTPN22 gene polymorphism and ITP susceptibility were systematically evaluated. The results showed that the OR value of ITP susceptibility of TT genotype relative to CC genotype in the SNP1858 polymorphism of PTPN22 gene was 5.01, with 95%CI  and Nearly 100 genes are associated with autoimmune diseases. PTPN22 has been confirmed to be associated with a variety of autoimmune diseases, including type Ⅰ diabetes, rheumatoid arthritis and systemic lupus erythematosus . The mosPTPN22 is also considered to be related to Csk composition in B cell. However, the intrinsic role of PTPN22 in B cell ontogeny, activation and dependent immune response has not been effectively confirmed. The study showed that there was no difference between the total number of peripheral blood B cells in PTPN22 knockout mice and that in normal mice . SimilarAs for the two SNPs in PTPN22 involved in our study, some experimental studies have proved that their mechanism of action may be related to the pathogenesis of ITP. Previous studies have shown that SNPs generated in the binding region of transcription factors may affect the binding characteristics of transcription factors, leading to differences in binding strength of transcription factors on alleles, which could cause differences in susceptibility of some diseases among populations . PTPN22 In this study, no significant publication bias was found through Begg’s test funnel plot and Egger’s test analysis. Therefore, the results have a certain credibility. However, the following limitations may still exist. First, the studies included in this article are all published studies, and the languages are limited to Chinese and English. Potential publication and language bias may still affect the results of meta-analysis. Secondly, the research on SNP1858 and SNP1123 polymorphisms of PTPN22 gene and disease susceptibility mainly focuses on solid tumors at present, and the number of studies on blood system is small, resulting in a limited number of studies and a limited number of cases and controls included in this study, thus reducing the representativeness of the conclusion, which is also indicated by TSA results. At the same time, due to the limitation of the number of studies included in this article, subgroup analysis on race and genotyping methods cannot be carried out. Besides, many of the studies we included have both children and adults involved in a single study, and did not provide data of different age groups separately. As a consequence, the total genotype data of different age groups is limited, and subgroup analysis based on age could not be carried out, which reduces the comprehensiveness of the results.In conclusion, as a susceptibility gene of autoimmune diseases, PTPN22 gene plays an important role in ITP. SNP1858 and SNP1123 polymorphisms of PTPN22 gene are related to ITP susceptibility. For SNP1858, population with TT genotype has high risk of ITP than those with CC genotype. For SNP1123, allele G may be a risk factor for ITP susceptibility. As an autoimmune disease whose pathogenesis is not completely clear, studying the correlation between ITP pathogenesis and PTPN22 gene SNP1858 and SNP1123, and then understanding the pathogenesis of ITP at the gene level can provide new ideas enlightening research about ITP mechanism and treatment. In the future, it is expected to carry out more case-control studies with multi-centers, large samples and good homogeneity, in order to more scientifically and accurately evaluate the correlation between PTPN22 gene polymorphism and ITP susceptibility, and provide more reliable evidence for basic research and clinical treatment.


Quantification of acquisition routes of antibiotic resistant bacteria (ARB) is pivotal for understanding transmission dynamics and designing cost-effective interventions. Different methods have been used to quantify the importance of transmission routes, such as relative risks, odds ratios (OR), genomic comparisons and basic reproduction numbers. We systematically reviewed reported estimates on acquisition routes’ contributions of ARB in humans, animals, water and the environment and assessed the methods used to quantify the importance of transmission routes.PubMed and EMBASE were searched, resulting in 6054 articles published up until January 1st, 2019. Full text screening was performed on 525 articles and 277 are included.S. aureus (n = 273), E. coli (n = 157) and Enterobacteriaceae (n = 99) being studied most frequently. Most estimates were derived from statistical methods (n = 560), mainly expressed as risks (n = 246) and ORs (n = 239), followed by genetic comparisons (n = 85), modelling (n = 62) and dosage of ARB ingested (n = 17). Transmission routes analysed most frequently were occupational exposure (n = 157), travelling (n = 110) and contacts with carriers (n = 83). Studies were mostly performed in the United States (n = 142), the Netherlands (n = 87) and Germany (n = 60). Comparison of methods was not possible as studies using different methods to estimate the same route were lacking. Due to study heterogeneity not all estimates by the same method could be pooled.We extracted 718 estimates with Despite an abundance of published data the relative importance of transmission routes of ARB has not been accurately quantified. Links between exposure and acquisition are often present, but the frequency of exposure is missing, which disables estimation of transmission routes’ importance. To create effective policies reducing ARB, estimates of transmission should be weighed by the frequency of exposure occurrence.The online version contains supplementary material available at 10.1186/s12879-022-07360-z. Infections caused by antibiotic-resistant bacteria (ARB) are a major global problem. Antibiotic resistance is as ubiquitous as bacteria are, and resistance genes can be found in humans, animals, water and the environment and can be transmitted between and within these reservoirs. The relative attribution of transmission routes differs between bacterial species and resistance elements .While many studies have determined risk factors for acquisition, infection or colonisation with ARB, the global urgency to reduce the prevalence of antibiotic resistance calls for accurate quantification of transmission routes and their relative importance . ChatterR0, defined as the expected number of secondary cases caused by a typical infected individual during its period of infectiousness in a completely susceptible population  an identical strain, which means that in 45% it could not be demonstrated that an infected family member was the source. In this case, a simple risk estimate would have been an overestimation as genetical analysis shows that not colonisations could be attributed to the colonised household member. R0 estimates also indicated pigs as an imported transmitter as pig to pig transmission of S. aureus studied in the Netherlands also had the highest pooled R0  ) .E. coli The human reservoir is a likely route of high E. coli transmission. Close contact with infected people was identified by OR and risk estimates as a high risk E. coli transmission route. Risk estimates based on genetic overlap showed that almost halve of the household members at risk had an E. coli acquisition genetically identical to their household member. OR and risks also indicate animal to environment and animal to human transmission, especially poultry, to be a higher risk route. Travelling to Asia was also identified by OR as high risk. Enterobacteriaceae Close contact was indicated by OR and PR to be high risk routes. Travelling to Asia was indicated to be high risk by OR and risk estimates. Figures on risk and OR when travelling to regions across the world can be found on GitHub .Despite a large number of studies which investigated the probability of acquisition when exposed, we did not identify data that link the probability of acquisition to a frequency of exposure. Information to provide an accurate qualification of the importance of transmission routes was not found.Nevertheless, some examples allowing quantification do exist. Cuny et al.  estimateThis systematic review shows that statistical methods, especially ORs and risks, are most often used to estimate transmission routes. Cross-reservoir transmission between humans and animals has been studied most commonly, whereas studies on transmission from the environment are scarce, as also indicated by a previous meta-analysis which only included significant transmission estimates . Comparison of transmission route estimates calculated using different methodologies was difficult as we found few transmission routes that were estimated using multiple methods in comparable populations. Also, no study was identified which conducted all methodologies on the same dataset to study a transmission route. Methods of estimation seems to influence the interpretation of what sources are more likely to cause acquisition. This review found multiple studies indicating that risk-based analyses which do not use genetic data, such as WGS, tend to overestimate the risk compared to studies using genetic data –14. DaviStrengths of this review include the assessment and comparison of various methods of estimation, reservoirs and transmission routes so that a complete overview of the current literature on ARB is provided. The first limitation of our study is data collection was done by one reviewer which might have caused discrepancies in data collection and analysis, however measures were taken to limit discrepancies such as a subset which was screened by two authors. Secondly, the extensive literature on the transmission of ARB precludes our search terms from identifying all studies in this area. By including synonyms, we tried to identify as many of the studies as possible. Moreover, publication bias could be present in different degrees for different methods of estimation. For example, whole genome studies that do not identify possible transmission chains may be published less frequently. However, publication bias also occurs for statistical methods of estimation such as OR that do not identify significant routes. Contrary to other reviews  we did iTo conclude, on the one hand, there is a plethora of estimates on the probability of acquisition for ARB transmission routes. On the other hand, the relevance of routes on a population scale is missing due to a missing link between probability of acquisition and frequency of exposure. This lack of knowledge prohibits an accurate prediction of the effectiveness of interventions which target one or more transmission routes. To better quantify acquisition risks in different transmission routes we recommend researchers to perform more focussed and more detailed studies. For instance, population-based studies in well described niches, such as hospitals, other health care facilities, or farms, in which samples can be collected longitudinally in all subjects and environments that may be involved in transmission, as has been performed by Pham et al. . By sampAdditional file 1. Supporting information including the search terms, Prisma checklist, frequency tables and a list of which studies were included in the review.Additional file 2. Transmission data identified in the systematic review by Godijk et al.Additional file 3. R Script of the systematic review by Godijk et al.Additional file 4. R script of the forest plots for the systematic review of Godijk et al.