The potential impact of statins on the risk of Parkinson’s disease (PD) is still controversial; therefore, we conducted a comprehensive meta-analysis of observational studies to examine the effect of statin use on the risk of PD. We searched electronic databases, such as PubMed, EMBASE, Scopus, and Web of Science, for articles published between 1 January 2000 and 15 March 2022. Cohort studies which examined the association between statins and PD risk in the general population were also included. Two authors assessed the data and extracted all potential information for analysis. Random effects meta-analyses were performed to measure the risk ratio (RR) and 95% confidence intervals (CIs). Eighteen cohort studies including 3.7 million individuals with 31,153 PD participants were identified. In statin users, compared with non-users, the RR for PD was 0.79 (95% CI: 0.68–0.91). In a subgroup analysis of PD, this association was observed with medium and high quality, and the studies were adjusted for age, gender, and smoking status. When the data were stratified according to the duration of exposure, long-duration statin use was associated with a decreased risk of PD . There was no significant decrease in the risk of PD in short-term statin users . Moreover, no significant difference in the reduction in the risk of PD was observed between men  and women . Although our findings confirm a reduction in the PD risk associated with statin treatment and suggest that statins play a clinically favorable role, these findings should be interpreted with caution. Future randomized control trials with an ad hoc design are needed to confirm the potential utility of statins in reducing the risk of PD. Parkinson’s disease (PD) is one of the major causes of death and disability globally . More thStatins, which are also called HMG-CoA reductase inhibitors, are considered a mainstay therapy in the management of dyslipidemia. They also have proven cardiovascular benefits, including illness and mortality reduction ,14,15,16The potential effect of statin therapy on PD risk reduction is not conclusive. To our knowledge, six meta-analyses have evaluated the association between statins and the risk of PD ,25,26,27We conducted this systematic review and network meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines .Popular electronic databases, such as PubMed, Embase, Scopus, and Web of Science, were searched for articles published between 1 January 2000 and 15 March 2022. Database searches were conducted by two experts’ independent authors with predefined strategies, and disagreements were resolved by the principal investigator. The following keywords were used to search articles: “statin(s)” OR “HMG-CoA reductase inhibitor(s)” OR “lipid-lowering drug(s)” OR “lipid-lowering agent(s)” OR “simvastatin” OR “atorvastatin” OR “pravastatin” OR “Fluvastatin” OR “rosuvastatin” OR lovastatin” AND (“Parkinson disease” OR “Parkinson’s disease” OR “PD”). Moreover, the reference lists of the included studies and previous reviews were screened for more studies that could potentially be included.The criteria for the inclusion of a potential study are as follows: (1) the study was an observational study (case–control and cohort study); (2) all or a subset of the participants had a history of PD; (3) the study evaluated statin therapies through a comparison between statin users and non-users; (4) the treatment duration was at least three months. Studies were excluded if they were published as reviews or case reports, or if they were not in English.A standard protocol was used to extract data from the included studies. The same two authors extracted data regarding study characteristics , patient characteristics , inclusion criteria for statin users, inclusion criteria for PD patients, and adjusted variables such as the comorbidity and concomitant drug use.Since all of the included studies were observational studies, the risk of bias in the included studies was assessed using the Newcastle–Ottawa Scale (NOS) . The NOS2), or heterogeneity (I2), among the intervention effects observed in different studies [p values were obtained from 2-sided tests, and effect sizes were considered statistically significant at p < 0.05. All effect sizes included in the pooled analyses were taken from a fully adjusted multivariable model.The primary outcome of interest was the PD risk. We calculated a random-effects estimate based on the DerSimoneon and Laird method . This is studies . The relp-value calculated using χ2 statistics and I2 statistics. The I2 values were categorized into four groups: of 0%~29%, 30%~49%, 50%~74%, and 75%~100%, representing unimportant, moderate, substantial, and considerable inconsistency, respectively [Subgroup analyses were also conducted to assess possible sources of heterogeneity and to determine whether several confounding and clinical factors were associated with any significant differences in the outcome. Those factors were the (a) study design; (b) regional impact; (c) quality of a study; (d) study year; € whether the study was adjusted for age, gender, and smoking status; and (f) the various type(s) of statins used in the study. We assessed the heterogeneity among the studies using a ectively ,33. We dp = 0.001). Significant heterogeneity was present across the studies  in the random-effect models  and 0.85 . There was significant heterogeneity among the studies .To make the findings more robust, we performed subgroup analyses using various study features  and clinical factors  . Ten cohp = 0.17), with significant heterogeneity among the studies . However, the pooled RRs for studies from Europe and Asia were 0.85  and 0.71 , respectively.Nine studies from North America evaluated the impact of statin therapy on the risk of PD. The overall pooled RR was 0.81  and 0.79 , respectively. Fourteen studies were adjusted for age when evaluating the risk of PD among statin users compared to non-users. The pooled RR for studies that adjusted for age was 0.80 . Moreover, thirteen studies adjusted for gender and ten studies adjusted for smoking status to assess the risk of PD with statin use. The pooled RRs were 0.84  and 0.79 , respectively.The overall pooled RRs for the risk of PD for high and moderate-quality methodologies were 0.79 , with a significant heterogeneity . The pooled RRs for studies using atorvastatin, lovastatin, and pravastatin were 0.73 , 0.89 , and 1.09 , respectively.Six studies examined the risk of PD with simvastatin; the pooled RR was 0.67  and 0.47 , respectively. The pooled RRs for PD risk for lipophilic and hydrophilic statin users were 0.86  and 1.03 , respectively. Furthermore, we assessed the impact of the duration of statin therapy and the risk of PD. Six studies examined the impact of shorter-duration statin use, defined as the use of statins for <1 year, on the risk of PD, and the pooled RR was 0.94 , with a significant heterogeneity . In contrast, for longer-duration statin use, defined as the use of statin use for >5 years, the pooled RR was 0.49 , with no significant heterogeneity .To assess whether gender, the nature of the statins used, or the duration of statin usage substantially influenced the main findings, we calculated the summary effect size and heterogeneity of the main analysis. The pooled RRs for PD risk in male and female users were 0.62  statin users. Furthermore, the use of lipophilic statins was associated with a decreased risk of PD, but there was no association between hydrophilic statin and PD risk. The primary findings of our study are consistent with the previous meta-analyses; that is, overall, the use of statins is associated with a decreased risk of PD.The previous meta-analysis suggests that statins may be beneficial for reducing the risk of PD ,23,24,25The exact mechanism describing how statins affect PD risk reduction has not been clearly elucidated, but several possible pathological mechanisms have been proposed. A preclinical study of the PD model showed that statins protected dopamine-containing neurons in the substantia nigra and striatum in the brain of 6-OHDA-lesioned rats. This finding presents an N-methyl-d-aspartate (NMDA) modulatory effect, providing a new paradigm to ameliorate anti-inflammatory activity in PD . PreviouIn the subgroup analysis stratified by region, we found a reduced risk of PD with statin therapy in all subgroups, although there was a non-significant reduced risk of PD in patients from North America. This finding can be partially explained by the different races in this region. In support of this finding, previous studies have documented statin response variation among races ,60. The As for individual statin use, simvastatin and atorvastatin showed a reduced risk of PD, whereas pravastatin showed no association with the risk of PD. The classification of statins can be a possible explanation for these variations. Pravastatin is a hydrophilic statin that is distributed mainly in the liver. Lipophilic statins  are widely distributed in all tissues  and can Our updated meta-analysis has several strengths and limitations. First, this is the most comprehensive meta-analysis performed on this subject; it comprises 18 observational studies with more than 3 million people. Second, our study contains broad subgroup and sensitivity analyses which can be helpful in making a fruitful clinical decision in the real-world clinical setting. Third, our study shows the impact of different types of statins such as atorvastatin and pravastatin on the risk of PD. It also shows the relationship between duration of statin use and PD risk. There were several limitations that need to be addressed. First, there was significant heterogeneity among the studies in the main and subgroup analyses. However, this heterogeneity can be explained by the different study designs, durations, and qualities and by regional effects. Second, our study was unable to show the impact of the statin dose on the risk of PD due to a lack of data. Third, all the included studies were observational studies. As such, there might be several potentially confounding factors, and the findings should be considered with caution.The findings of our updated meta-analysis show a significant PD risk reduction due to statin use. Moreover, the long-term use of statins (>5 years) significantly reduced the risk of PD. As the findings are mainly based on limited observational studies, there may be several potential confounding factors and different definitions of statin users and exposure. Therefore, our results should be used with caution; there is not enough statistical power to confirm or refute these observed associations. A study with a large sample size, high-quality methodology, and long follow-up (more than ten years) is needed to either confirm or refute these findings. Moreover, biological studies are required to verify whether a given association is causal or observed. Until higher-quality evidence is available, statins should only be prescribed for their original purpose (reducing cardiovascular risk); they should not be repurposed for PD risk reduction.


As a potential genetic biomarker, tumor mutation burden (TMB) has made progress in numerous tumors. There are limited data regarding TMB and its prognostic role is controversial in breast cancer. This systematic review and meta-analysis were conducted to assess the prognostic value of TMB on survival of breast cancer.I2 statistic and p-value. Using publication bias evaluation, sensitivity analysis, and subgroup analysis, the origin of heterogeneity was further investigated.The databases PubMed, Embase, Web of Science, and Cochrane Library were searched for articles published through May 31, 2022. Moreover, effective data were extracted from included studies and calculated pooled effects of hazard ratio (HR) for overall survival (OS) and progression-free survival (PFS) by STATA 16.0. Heterogeneity was conducted by the p > 0.01) and PFS  indicated no statistically significant difference in the high TMB and low TMB group. In immune checkpoint inhibitors (ICIs) subgroup, high TMB patients demonstrated benefit of OS  and PFS , whereas difference was not statistically significant in the non-ICIs subgroup . In addition, sensitivity analysis revealed that the pooled effects were stable. The funnel plot and Begg's test suggested the absence of publication bias.They were up to 1,722 patients collected from sixteen cohorts for this analysis. The pooled effects of HR for both OS , identifier: CRD42022342488.[The online version contains supplementary material available at 10.1186/s12885-022-10284-1. In accordance with global cancer statistics, nearly 2.3 million new cases of breast cancer have been diagnosed in 2020 . In addiTMB measures the number of somatic mutations within a tumor genome by the unit of mutations per megabase (Mut/Mb). The high TMB is associated with a high neoantigen burden, which makes tumors much more immunogenic . In compIn breast cancer, there is limited data regarding TMB and its prognostic role is controversial. Consequently, this systematic review and meta-analysis were conducted to assess the predictive value of TMB for breast cancer survival.This systematic review and meta-analysis were in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) . This prWe searched the databases PubMed, Embase, Web of Science, and Cochrane Library for articles published through May 31, 2022. The search terms were  AND (breast cancer OR breast neoplasms OR breast tumor OR cancer of breast OR human mammary neoplasm OR human mammary carcinomas). Subsequently, to collect as many pertinent studies as possible, we consulted the references of the identified articles. Conference abstracts published in the American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO) were also searched for relevant studies.The two researchers (KLY and LS) independently searched for and screened the articles based on the inclusion criteria. If their opinions differ, the third researcher will be asked to render a verdict (CHX).We conducted the research using the following criteria for inclusion: (1) Patients were diagnosed with breast cancer. (2) A clear TMB cut-off value was used to divide patients into two groups: those with high TMB levels and those with low TMB levels. (3) The clinical outcome was overall survival (OS) or progression-free survival (PFS). (4) The studies provided the hazard ratio (HR) and its 95% confidence interval (95% CI) related to the TMB level. In the absence of the aforementioned data, studies were required to provide Kaplan–Meier curves or original data to calculate HR and 95% CI. (5) Each study was composed in English.The following criteria determined exclusion: TMB consisted of three layers, incomplete data, reviews, meta-analyses, animal studies, fundamental studies, editorials, comments, and case reports.Each study's experiment information was collected as follows: title, first author, published year, type of study, region, sample size, breast cancer subtype, type of therapy, sample source, TMB detection method, TMB cut-off value, median TMB value and its range, clinical outcome, HR, and 95% CI.All studies were cohort studies, and the Newcastle–Ottawa Scale (NOS) was utilized to evaluate their quality. Each study was assessed from three aspects with a total score of 0–9. And the studies were divided into three grades based on their cumulative score, 8–9 as high-quality, 5–7 as intermediate-quality, and 0–4 as low-quality .I2 statistic and p-value, with I2 > 50% and p < 0.1 as significant heterogeneity [To assess the prognostic value of TMB on survival of breast cancer, we compared the different survival benefits between high and low TMB groups using pooled HR. All data analyses were calculated by STATA 16.0. When heterogeneity was significant, we conducted pooled HR utilizing the random-effects model; otherwise, the fixed-effects model was used. Heterogeneity was evaluated by the ogeneity .P > 0.05 in Begg’s test [In the meantime, the origin of the heterogeneity was investigated further by means of publication bias assessment, sensitivity analysis, and subgroup analysis. We drew the funnel plot to estimate publication bias and conducted Begg’s test to quantify the funnel plot. The publication bias was absent if the funnel plot was symmetrical and g’s test . A sensig’s test . In accog’s test .We collected a total of 3983 potential articles via two investigators largely independent searching. After eliminating duplicates, we used the title and abstract to identify the literature.1572 articles were excluded due to the fact that they classified the review, case report, editorial letter, and irrelevant topics. Subsequently, 254 articles were eligible for preliminary screening. Finally, 11 studies were included among the 254 eligible full-text articles. The flowchart for searching and identifying literature is presented in Fig. The sixteen cohorts from eleven studies were included, with a total of 1,722 patients. The baseline characteristics of patients, type of therapy, and TMB-relevant information was recorded at length in Table NOS only evaluated 12 cohorts for bias risk evaluation, because 4 cohorts from conference abstracts were not applicable. The results indicated 4 trials were of high quality and 8 trials were medium. The inclusion of the four cohorts described in the conference abstracts may diminish the overall quality of the included studies. And the four cohorts were comprised of hundreds of patients who provided independent cases and controls, ascertainment of exposure, and complete experimental results. We presume that it is essential to include these four cohorts in the meta-analysis, as they contributed significantly to the pooled result.p > 0.01) and PFS  indicated there is no significant difference in survival benefits between groups with high and low TMB . To ascertain forward the origin of heterogeneity among the included studies, a subgroup analysis was conducted.We calculated the pooled effects of HR for OS extracted from 13 cohorts, and for PFS extracted from 9 cohorts. The pooled effects of HR for both OS , although the variation was not statistical in the non-ICIs subgroup . For sample source subgroup analysis, when the sample source was blood, the OS of patients with high TMB was shorter than patients with low TMB . In terms of the tumor tissue subgroup, there was no statistically significant difference between the high and low TMB patient groups. . We conducted a subgroup analysis according to the median TMB cutoff value. In the TMB cutoff value > 5 Mut/Mb subgroup, more OS benefits were observed in patients with high TMB levels , while a worse OS was found in TMB cutoff value ≤ 5 Mut/Mb subgroup . Meanwhile, the heterogeneity of the ICIs subgroup and TMB cutoff value > 5 Mut/Mb subgroup were drastically reduced by subgroup analysis. The benefit of OS related to TMB level had little correlation with the pathological classification of breast cancer and TMB detection method.The results of the subgroup analysis for OS were depicted in Table p < 0.001). And in the TNBC subgroup, more benefits of PFS were obtained in the high TMB group . The subgroup analysis based on sample source revealed a correlation between elevated TMB and a longer PFS when the sample source was tumor tissue , while shorter PFS when it was blood . In the TMB cutoff value > 5 Mut/Mb subgroup, longer PFS was observed in high TMB group , while shorter PFS was obtained in high TMB group on the condition that the TMB cutoff value ≤ 5 Mut/Mb . Through subgroup analysis, the heterogeneity of each subgroup was significantly reduced. The correlation between TMB level and PFS was unrelated to the TMB detection method.The results of the subgroup analysis for PFS were exhibited in Table P = 0.855, PFS: P = 0.251) suggested publication bias was absent. In accordance with the GRADE criteria, the quality of evidence for OS and PFS was low.Sensitivity analysis exhibited little variation in the pooled effects after excluding each article in turn Fig. . The symOur study summarized the effects of HR collected from 1,722 breast cancer patients who were treated with immunotherapy, chemotherapy, targeted therapy, etc. The findings indicated that compared with the low TMB group, the advantage of OS and PFS in the high TMB group was not obvious. Moreover, both the OS and PFS analyses revealed a high degree of heterogeneity among the included studies. The results of subgroup analysis for OS exhibited that different types of therapy and TMB cutoff values may be the explanations for high heterogeneity. In subgroup analysis for PFS, the heterogeneity decreased substantially in other subgroups except for the TMB detection method subgroup.Although the association between TMB and the survival of patients with melanoma, lung, and colon cancer has been studied, the relationship in breast cancer needs to be verified –37. Our To our knowledge, there are still many controversies about the prediction of TMB on the survival of HER2 + breast cancer. A recent bioinformatics study revealed that the survival rate of HER2 + metastatic breast cancer was lower in the group with low TMB than in the group with high TMB . In anotAlthough the landscape of TMB was revealed in some studies for reference, the issue that how to establish the cutoff value of TMB in breast cancer is still critical . As earlThe sample source of TMB detection was usually tumor tissue or blood. Tissue TMB (tTMB) is employed commonly as most patients could get tissues for gene sequencing. Furthermore, blood TMB (bTMB) is an attractive alternative if tTMB is not able to be evaluated for lack of sufficient quantities. bTMB is the number of mutations of ctDNA (circulating tumor deoxyribonucleic acid) produced during tumor cell degradation . The quaThe detection method of TMB includes whole exome sequencing (WES) and next-generation sequencing (NGS), with upsides and downsides for both. Since the golden standard of TMB detection has been on the basis of the WES, much research about TMB is carried out by using WES technology. Nonetheless, the application of WES is restricted to a certain extent in clinical because it is expensive and complicated to operate . In compThis study is the first meta-analysis that investigated the relationship of TMB with the survival of breast cancer, which provides a reference for TMB studies in the future. In this meta-analysis, we calculated pooled HR to assess the prognostic value of TMB on breast cancer survival. However, several limitations of our analysis should be considered. Initially, a few important clinical characteristics, namely, age, menopause, surgery history, and combination therapy were not available to analyze in our study, which may affect the heterogeneity. Secondly, in the included studies, TMB was computed by a variety of methods. The majority of the studies reported the TMB calculation method in a unit of Mut/Mb and two studies in a unit of mutations. Thirdly, we excluded studies that separated TMB into three layers , resulting in publication bias. Despite the limitations, we observed most sources of heterogeneity through subgroup analysis.Our meta-analysis indicated that TMB as a prognostic biomarker is not generally applicable in breast cancer. The high TMB may be associated with prolonged survival only in ICIs therapy, nonetheless, the relation is not obvious in non-ICIs therapy. We endorse the use of TMB as a prognostic biomarker to identify more patients who may benefit from ICIs, ICIs in combination with chemotherapy, or targeted therapy. In addition, TNBC patients with high TMB tend to gain more clinical benefits than other breast cancer subtypes. We recommend that in TMB detection we may give preference to tumor tissue and cut-off value > 5Mut/Mb.Additional file 1: Supplementary Figure 1. Forest plot of subgroup analysis for OS on type of therapy.Additional file 2: Supplementary Figure 2. Forest plot of subgroup analysis for OS on breast cancer subtype.Additional file 3: Supplementary Figure 3. Forest plot of subgroup analysis for OS on sample source.Additional file 4: Supplementary Figure 4. Forest plot of subgroup analysis for OS on TMB detection method.Additional file 5: Supplementary Figure 5. Forest plot of subgroup analysis for OS on TMB cutoff value.Additional file 6: Supplementary Figure 6. Forest plot of subgroup analysis for PFS on type of therapy.Additional file 7: Supplementary Figure 7. Forest plot of subgroup analysis for PFS on breast cancer subtype.Additional file 8: Supplementary Figure 8. Forest plot of subgroup analysis for PFS on sample source.Additional file 9: Supplementary Figure 9. Forest plot of subgroup analysis for PFS on on TMB detection method.Additional file 10: Supplementary Figure 10. Forest plot of subgroup analysis for PFS on TMB cutoff value.


Previous studies have investigated the prognostic significance of glycolysis markers in pancreatic cancer; however, conclusions from these studies are still controversial.PubMed, Embase, and Web of Science were systematically searched to investigate the prognostic role of glycolysis markers in pancreatic cancer up to May 2022. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) related to overall survival (OS), disease free survival (DFS), recurrence-free survival (RFS), and distant metastasis-free survival (DMFS) were calculated using the STATA 12.0 software.P < 0.001) and Caucasians . Besides, analysis based on the expression levels of specific glycolysis markers demonstrated that higher expression levels of GLUT1 , MCT4 , and ENO1  were correlated with a poorer OS in patients with pancreatic cancer.A total of 28 studies comprising 2010 patients were included in this meta-analysis. High expression of the five glycolysis markers was correlated with a poorer OS , DFS , RFS  and DMFS  in patients with pancreatic cancer. In subgroup analysis, it was shown that higher expression levels of the five glycolysis markers were related to a poorer OS in Asians (HR = 1.85, 95% CI: 1.46-2.35, High expression of the five glycolysis markers are associated with poorer OS, DFS, RFS and DMFS in patients with pancreatic cancer, indicating that the glycolysis markers could be potential prognostic predictors and therapeutic targets in pancreatic cancer. Pancreatic cancer is the seventh leading cause of cancer-related death worldwide due to its poor prognosis with almost as many deaths n=466,003) as cases  , which w as casesMalignant proliferating cancer cells usually rewire energy metabolism manners to meet the requirements of rapid cell growth, division, invasion, and migration, which is an emerging hallmark of cancer known as “energy metabolism reprogramming” . It has Previous studies have shown that multiple key glycolytic enzymes such as glucose transporter 1 (GLUT1), monocarboxylate transporter 4 (MCT4), hexokinase 2 (HK2), pyruvate kinase M2 (PKM2) and enolase 1 (ENO1) are usually overexpressed in tumors and play critical roles in glycolysis pathway . TranspoAlthough emerging evidence has focused on the correlation between various glycolysis markers and pancreatic cancer, the conclusions remain controversial. In terms of GLUT1, previous studies investigating the relationship between GLUT1 expression and clinical outcomes of patients with pancreatic cancer have yet yielded conflicting results. For example, some studies have demonstrated the independent prognostic role of GLUT1 in pancreatic cancer –19, whilEligible studies relevant to the association of glycolysis markers and prognosis of pancreatic cancer were systematically searched in databases, including PubMed, Embase, and Web of Science, dated until May 2022. The language was restricted to English. The retrieval strategy was listed as follow: (glucose transporter 1 OR GLUT1 OR monocarboxylate transporter 4 OR MCT4 OR hexokinase 2 OR HK2 OR pyruvate kinase M2 OR PKM2 OR Enolase 1 OR ENO1) AND (pancreatic OR pancreas) AND (cancer OR tumor OR tumor OR carcinoma OR adenocarcinoma OR neoplasia OR neoplasm) AND .All included studies need to meet the following inclusion criteria (1): including patients with pathologically diagnosed pancreatic cancer; (2) glycolysis markers were measured using immunohistochemistry (IHC); (3) studies describing the correlation between the expression of glycolysis markers and survival outcome; (4) hazard ratio (HR) values and corresponding 95% confidence intervals (CIs) for overall survival (OS), disease free survival (DFS), recurrence-free survival (RFS) or distant metastasis-free survival (DMFS) were either reported or calculatable with the published data in studies. Exclusion criteria were as follows: (1) duplicated studies; (2) studies not based on humans subjects; (3) reviews, case reports, meta-analysis, and clinical trials; (4) studies without available data.The following information was extracted from each study: first author’s name, publication year, country, ethnicity, types of glycolysis markers, sample size, gender, follow-up duration, cancer subtype, detection method, cut-off values of glycolysis markers and outcome. If HRs and 95% CIs were provided in both univariate and multivariate analyses, the latter was adopted. If a study only had Kaplan–Meier survival curves, survival data was extracted from the curves by Engauge Digitizer software.Newcastle-Ottawa Scale (NOS) was applied to comprehensively evaluate the quality of the included studies . NOS conχ2 test and I2 statistic. The random-effects model was used when significant heterogeneity was detected (P < 0.1 or I2 > 50%); otherwise, the fixed-effects model was applied. Subgroup analysis was performed to explore the potential causes of heterogeneity. Publication bias was estimated using Begg’s funnel plot and Egger’s test. All statistics were analyzed using Stata software version 12.0 . P < 0.05 was considered statistically significant.The association of glycolysis markers with OS, DFS, RFS and DMFS was evaluated by pooled HRs and 95% CIs. The pooled odds ratios (OR) and 95% CIs were used to investigate the association between the expression of glycolysis markers with the clinicopathologic characteristics of pancreatic cancer. Heterogeneity among various studies was evaluated using The flow diagram for study selection is illustrated in P=0.871 and P=0.245, respectively).Sensitivity analysis indicated that no significant heterogeneity was present among the included studies Figure 22 = 56.3%, P=0.001), a random-effects model was applied. Then, subgroup analysis was applied to explore causes of heterogeneity. The regional subgroup analysis indicated that high expression levels of the five glycolysis markers correlated with poorer OS in Asians  and Caucasians  (P < 0.001), MCT4 , and ENO1  correlated with poorer OS in pancreatic cancer in the subgroup analysis based on the expression levels of specific glycolysis markers  suggested that different glycolysis markers may not be the main cause of heterogeneity.Next, the relationship between expression levels of the 5 glycolysis markers and OS in pancreatic cancer from 20 studies that included 1546 patients was evaluated. As described in 2 = 0%, P=0.398). However, subgroup analysis was not performed as the number of included studies was too small.A total of 2 studies related to GLUT1 that included 140 patients were included in the pooled survival analysis of DFS. As shown in 2 = 0%, P=0.591), therefore, a fixed-effects model was used to calculate the pooled HRs. Likewise, subgroup analysis was not possible due to the limited number of studies that reported RFS.A total of 252 patients from 4 studies were evaluated to examine the correlation between expression levels of GLUT1, HK2 and PKM2 and RFS, and the meta-analysis of these studies showed that upregulation of the three glycolysis markers indicated a poor RFS of pancreatic cancer  . Similarly, due to the limited number of included studies, subgroup analysis was not available.We then analyzed the data from 2 studies with 72 patients to determine the relationship between DMFS and the expression levels of HK2 and PKM2 in pancreatic cancer. We observed that significant correlation between expression levels of the two glycolysis markers and DMFS of patients with pancreatic cancer   based on the increased glucose metabolism of malignant cells has been being used as a valuable functional imaging technology in clinical practice for various malignancies. Altered expression levels of GLUT has been demonstrated to be associated with enhanced FDG uptake quantified by standardized uptake values (SUVs) in tumor cells (max) and the expression of GLUT1  consisting of cancer cells, stromal cells, and extracellular components is considered to play a pivotal role in multiple malignant biological behaviors including carcinogenesis, proliferation, invasion, metastasis, angiogenesis, immunosuppression and chemoresistance. It should be noted that stromal cells could be induced by cancer cells to present a glycolytic phenotype and support mitochondrial oxidative phosphorylation (OXPHOS) in cancer cells to fuel cell proliferation and growth, which was described as “the reverse Warburg effect” . As a keSeveral limitations should be addressed for this meta-analysis. First, given the current lack of a universal cut-off value for various glycolysis markers, different cut-off values were applied in different included studies. Second, some of the HRs and 95% CIs were estimated by extracting data from the survival curves, which might produce statistical deviations. Third, many studies included did not provide follow-up durations and they may have contributed to the bias. Fourth, the sample size of some studies is small. Considering the limitations of the present study, additional high-quality, large-scale, long-term studies need to be conducted.This meta-analysis demonstrated that high expression of the five glycolysis markers correlated with poorer OS, DFS, RFS and DMFS in pancreatic cancer patients, suggesting that glycolytic pathway enzymes are potential prognostic biomarkers and promising therapeutic targets in patients with pancreatic cancer. However, due to the limitations of this study, more high-quality and well-designed studies need to be performed in the future.The original contributions presented in the study are included in the article/QX, CW, and RX conceived and designed the study. CW, RX, and JS drafted the manuscript, acquired the data, and performed the meta-analysis. YC, XY, and RR revised the manuscript for important intellectual contents. All authors read and approved the final manuscript.This study was supported by the CAMS Innovation Fund for Medical Sciences (2021-1-I2M-002), National Natural Science Foundation of China (82102810 and 81970763) and fellowship of China Postdoctoral Science Foundation (2022T150067).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


To estimate the progression rates to type 2 diabetes mellitus (T2DM) in women with gestational diabetes mellitus (GDM) diagnosed by the International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria.2 statistic. The pooled relative risk for incidence of T2DM and pre-diabetes between GDM participants and controls were estimated. Reasons for heterogeneity among studies were investigated by prespecified subgroup and meta-regression analysis. Publication bias was assessed by the Begg’s and Egger’s tests.Systematic review and meta-analysis were conducted by searching Medline, Embase, and Cochrane between January 1, 2010 and December 31, 2021 for observational studies investigating progression to T2DM after GDM. Inclusion criteria were IADPSG-diagnosed GDM, studies with both GDM and controls, postpartum follow-up duration at least one year. Data were pooled by random effects meta-analysis models. Heterogeneity was assessed by IThis meta-analysis of six studies assessed a total of 61932 individuals (21978 women with GDM and 39954 controls). Women with IADPSG-diagnosed GDM were 6.43 times  more likely to develop T2DM in the future compared with controls. For GDM women, the cumulative incidence of T2DM was 12.1% (95% CI: 6.9%-17.3%), while the pooled cumulative incidence of T2DM was estimated to be 8% (95% CI: 5-11%) in studies with 1 to 5 years of follow-up and increased to 19% (95% CI: 3-34%) for studies with more than 5 years of follow-up. Women with IADPSG-diagnosed GDM had 3.69 times  higher risk of developing pre-diabetes (including impaired fasting glucose and/or impaired glucose tolerance) than controls. Meta-regression analysis showed that the study effect size was not significantly associated with study design, race, length of follow-up, and maternal age (P>0.05). Overall, the studies had a relatively low risk of bias.Women with IADPSG-diagnosed GDM have higher risk of developing T2DM and pre-diabetes. The risk of T2DM in GDM women are higher with longer follow-up duration. Our results highlight the importance of promoting postpartum screening and keeping health lifestyle as well as pharmacological interventions to delay/prevent the onset of T2DM/pre-diabetes in GDM women.https://www.crd.york.ac.uk/prospero, identifier (CRD42022314776) Gestational diabetes mellitus (GDM) is an established risk factor for developing type 2 diabetes mellitus (T2DM) in later life. Previous meta-analysis has highlighted a nearly 10-fold higher risk of T2DM in women with GDM compared with controls . The IADThe application of this landmark IADPSG diagnostic criteria led to a rise in the prevalence of GDM globally, which contribute to a rise in the healthcare and economic burden worldwide –10. Due This systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-Analyses Of Observational Studies in Epidemiology (MOOSE) guidelines. The protocol of the study had been registered on the International prospective register of systematic reviews (PROSPERO) (registration number: CRD42022314776).We conducted a comprehensive literature search using Medline, Embase, the Cochrane Library, Scopus, AJOL, and Hinari for observational studies investigating progression to T2DM after GDM diagnosed by IADPSG criteria published between January 1, 2010 and December 31, 2021. We chose 2010 as the start date because the IADPSG GDM diagnostic criteria was released in 2010. The search strategy included keywords, medical subject headings (MeSH), and free text words covering “gestational diabetes mellitus” and “type 2 diabetes mellitus”, and was restricted to studies published in English and conducted on humans. The search strategy was shown in the Two authors (J.J. and YY.S.) independently reviewed the titles and abstracts to identify all potentially relevant studies. All duplicate records were removed. Full text of the relevant studies were obtained and screened in details according to the following predefined eligibility criteria: GDM diagnosed by IADPSG criteria, duration of postpartum follow-up at least one year, studies with both GDM women and controls (pregnant women without GDM). All reference lists from relevant reviews were hand searched for additional eligible studies. All conference proceedings, guidelines, consensus, opinions, protocols, dissertations, case series, qualitative studies, commentaries, editorials, perspectives, and letters were excluded. Disagreements between the two authors were resolved by third party consultation. The literature review and study selection process were summarized in a PRISMA flowchart Figure 1Two authors (J.J. and YY.S.) independently extracted information from the included studies according to the Cochrane Handbook guidelines, and findings were reported according to the PRISMA and MOOSE guidelines. The extracted data was exported to an excel sheet detailing the authors’ name, country of origin of the study, year of publication, study design, sample size (including the number of GDM and control), length of follow-up, participants’ age, race, diagnostic criteria for T2DM, incidence of T2DM and pre-diabetes (including impaired fasting glucose[IFG] and/or impaired glucose tolerance[IGT]) among GDM and control, etc. Disagreements were settled by consensus among all authors.The Newcastle-Ottawa scale (NOS) was used to evaluate the quality of non-randomized studies . The sca2 statistic, and graphically represented using forest plot diagram. Pre-specified subgroup analyses by race and length of study follow-up was performed to explore potential sources of heterogeneity among studies. Meta-regression models were fitted to estimate the effects of study heterogeneity and investigated the cumulative risk of developing T2DM by study length of follow-up. Sensitivity analysis were conducted by recalculating the pooled estimate with a named study removed at a time to estimate the effect of each individual study on the overall pooled estimate.The pooled relative risk for the incidence of T2DM and pre-diabetes between participants with GDM and controls was estimated. Data were pooled by random effects meta-analysis models with the Review Manager  using the DerSimonian-Laird method. In studies which no cases of T2DM and pre-diabetes was reported in any of the groups, a continuity correction was applied using the default value of 0.5 to avoid division by zero. Heterogeneity among the included studies was assessed by IThe initial comprehensive literature search identified 8152 records. After exclusion of duplicates, 7807 articles were screened, of which 373 studies were selected for further detailed review using the full text. One study retrieved from the reference lists of previous relevant reviews were also included. Finally, six studies, including a total of 61932 individuals (21978 women with GDM and 39954 controls) fulfilled all the eligibility criteria and were included in the meta-analysis. The study selection process was summarized in All six included studies underwent quality assessment with NOS scale received a total of six to eight stars, suggesting that the risk of bias is relatively low. A summary of the study quality assessment was shown in the All studies included in this systematic review and meta-analysis were observational studies, of which three were prospective cohorts and the other three were retrospective cohorts. One study was a multi-centered study including ten field centers , the resThe meta-analysis of the six studies evaluated a total of 61932 participants (21978 women with GDM and 39954 controls). Among the participants, 1342 women from the GDM group subsequently developed T2DM during postpartum follow-up, while 329 women progressed to T2DM in the control group. The pooled relative risk of developing T2DM in the GDM group was 6.43  compared with controls Figure 2The risk of T2DM were assessed by pre-specified subgroup analysis based on study length of follow-up. Studies were classified by their length of follow-up into two groups: 1-5 years and more than 5 years. The estimated pooled relative risk of developing T2DM was 4.38 (95% CI:1.18-16.34) for studies with postpartum follow-up of 1-5 years, while for those with follow-up of more than five years, the pooled relative risk was 12.47 (95% CI:3.10-50.08). The pooled relative risks were not statistically significantly different between subgroups (P=0.28) Figure 4Further meta-regression analyses showed that the study effect size was not significantly associated with study design, race, length of follow-up, and maternal age (P> ˃0.05) Table 2.No indication of publication bias was detected among the included studies, with both Begg’s and Egger’s tests being statistically non-significant . No apparent asymmetry was observed in the funnel plots diagram of the six studies included in the meta-analysis . Overall, the studies had a relatively low risk of bias.The results of the systematic review and meta-analysis demonstrated that women who had GDM diagnosed by IADPSG criteria were 6.43 times  more likely to develop T2DM in the future compared with controls. In women with previous GDM, the cumulative incidence of T2DM was 12.1% (95% CI: 6.9%-17.3%), while the pooled cumulative incidence of T2DM was estimated to be 8% (95% CI: 5-11%) in studies with 1 to 5 years of follow-up and increased to 19% (95% CI: 3-34%) for studies with more than 5 years of follow-up. Women with IADPSG-diagnosed GDM had 3.69 times  higher risk of developing pre-diabetes than controls. Meta-regression analysis showed that the study effect size was not significantly associated with study design, race, length of follow-up, and maternal age  , 22 to “0 mg/dl, MTNR1B, TCF7L2, IGF2BP2, CDKAL1, GCK) are associated with increased risk of both GDM and T2DM, suggesting that these conditions might have a shared genetic background  showed that subsequent T2DM risk after GDM was significantly lower in women who following healthy eating patterns . AccordiMore up-to-date large randomized controlled trials with longer follow-up are needed to investigate the lifestyle and pharmacological intervention strategies to delay or prevent the progression from GDM to T2DM. In addition, further cost-effectiveness studies of these interventions should be conducted to promote the implementation of these interventions.This systematic review and meta-analysis assessed the most recently published studies on the risk of progression to T2DM in women with IADPSG-diagnosed GDM, with a relatively large total number of individuals, and postpartum follow-up duration ranging from 1.3 to 11.4 years. As the diagnostic criteria of GDM had changed over the past years, this meta-analysis provided up-to-date results using the specific IADPSG criteria. Nevertheless, several limitations should also be considered. Owing to limited availability of studies evaluating the risk of progression to T2DM in women with GDM diagnosed by IADPSG criteria, only a few studies fulfilled all the eligibility criteria and were included in this meta-analysis, resulting in inclusion of a relatively small sample size. Therefore, we were unable to investigate the progression to T2DM after GDM in certain subgroups, which could have been a cause of heterogeneity among studies. Furthermore, we were unable to identify the main sources of heterogeneity in our analysis, and a more in-depth analysis could have been performed if individual patient level data were available. In addition, the IADPSG criteria was released in 2010 and many of the women might have not been developed T2DM at the time of assessment. Therefore, more high-quality studies with longer and complete follow-up are needed to accurately evaluate the progression to T2DM in women with GDM.In conclusion, our systematic review and meta-analysis showed that women with GDM diagnosed by IADPSG criteria had higher risk of developing T2DM and pre-diabetes than controls. The risk of T2DM in women with previous GDM was higher in studies with more than 5 years of follow-up than 1 to 5 years. Our results highlight the importance of promoting postpartum screening and keeping health lifestyle, including physical exercise and balanced diet, as well as pharmacological interventions to delay or prevent the onset of T2DM/pre-diabetes in women with GDM.The original contributions presented in the study are included in the article/HY and JJ conceived and designed the study. JJ and YS conducted the study selection and data extraction. JJ and PZ conducted the study quality assessment and statistical analysis. JJ wrote the manuscript. HY, YW, SW, GS, and JY reviewed and edited the manuscript. All authors contributed to the article and approved the submitted version.This research was funded by the Youth Program of National Natural Science Foundation of China (82003528), the National High Level Hospital Clinical Research Funding  (22cz020301-4803014), the National Key Research and Development Program of China (2021YFC2700700).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The association of IFN-γ receptor 1 (IFNGR1) gene polymorphisms with tuberculosis (TB) susceptibility has not been systematically studied. We therefore conducted a meta-analysis to assess their association. Literature search was conducted in PubMed, EMBASE, Web of Science, and the Cochrane Library. Odds ratio (OR) and 95% confidence interval (CI) was pooled by the random-effect model. Statistical analyses were performed using STATA 12.0 software. Fourteen studies involved 7,699 TB cases and 8,289 controls were included in this meta-analysis. A significant association was found between the IFNGR1 rs2234711 polymorphism and TB susceptibility among Africans in dominant model , and among Asians in allele model , homozygote model  and additive model . In addition, a significant association was observed between the IFNGR1 rs7749390 polymorphism and TB susceptibility among Africans in allele model . No significant association was found between the IFNGR1 rs1327474 polymorphism and TB susceptibility. In summary, IFNGR1 rs2234711 polymorphism was associated with increased TB susceptibility in Africans and decreased TB susceptibility in Asians, while IFNGR1 rs7749390 polymorphism was associated with decreased TB susceptibility in Africans. Tuberculosis (TB), a chronic infectious disease caused by the bacterium mycobacterium tuberculosis (M.TB), affects several organs, but mostly attacks the lungs . Accordiin vitro studies have demonstrated that IFNGR1 plays a pivotal role in the progression of TB  AND tuberculosis. Further studies were identified from the reference lists, related articles and citation lists of each of papers identified from the initial searches.The studies included in our meta-analysis met all the following criteria: (1) studies had to assess the association between IFNGR1 gene polymorphisms rs2234711, rs1327474, rs7749390, and TB susceptibility; (2) studies had a case-control or cohort design; (3) studies provided odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) for at least for one model, or provided the allele frequencies to calculate the ORs and 95% CIs. Studies were excluded for the following criteria: (1) were reviews, meta-analysis, or case-reports; (2) provided no data about genotype distribution or allele frequency or ORs; (3) used duplicated data.via discussion with the third author.The following data were extracted from the included studies: first author, publication year, country, ethnicity of participants, genotyping method, diagnosis assays for detection of TB, sample sizes in case groups and control groups, genotype distributions and allele frequency or the most fully adjusted ORs and 95% CIs. Two co-authors independently extracted the data from each study and any discrepancies were resolved The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS) . StudiesP < 0.10) and Higgins I2 statistic .p > 0.05).The Begg's test and Egger's test were used to evaluate the publication bias of the included studies in this meta-analysis. The shape of Begg's funnel plot revealed no evidence of obvious asymmetry in all genetic models, which showed no potential publication bias . MeanwhiTo our knowledge, this is the first meta-analysis that systematically assessed the association of the IFNGR1 rs2234711, rs1327474, and rs7749390 polymorphisms with TB susceptibility. Based on 14 case-control studies with 15,988 participants, we found that IFNGR1 gene polymorphism was associated with TB susceptibility in some ethnic groups.Various gene polymorphisms in the IFNGR1 are suggested to be associated with susceptibility of diverse diseases, such as inflammatory and virus-associated disorders –38. For The rs2234711 polymorphism is located within the AP4 binding site in the 5' upstream region of the gene. This region has been associated with susceptibility to some infectious diseases, including TB , 37, 40.Gene polymorphisms are complicated and fluctuating, especially among different ethnicities and populations from different regions –43. StudThis meta-analysis indicated that Africans and Asians seem to be more sensitive to IFNGR1 gene polymorphisms compared with other ethnicities. It might be partially explained by the several factors. First, most of the original studies on TB were conducted in Asian and African populations, which provides more statistical power for detecting significant results. Second, the prevalence of TB was relatively high among Asians or Africans within the studies assessed here , 50, theThe present study systematically assessed the association between IFNGR1 gene polymorphisms and TB susceptibility. Strength of this meta-analysis was that the overall results were generally robust, as suggested by the subgroup analysis and sensitivity analysis. Nevertheless, some limitations should be noted. First, all included studies were case-control studies. Some included studies used matched controls , while others did not. Confounding factors, such as, age, sex, HIV status, and TB severity, were not adjusted, which may lead to underestimation or overestimation of the risk estimates. Second, the number of included studies were relatively limited, and there was significant heterogeneity across studies, the geographic region, characteristics of participants, diagnosed method, genotyping method may all contribute to the heterogeneity across studies, the strength of our findings may be weakened. Third, this meta-analysis included studies , 20, 30 In conclusion, this meta-analysis indicated that IFNGR1 rs2234711 polymorphism was associated with increased TB susceptibility in Africans and decreased TB susceptibility in Asians, while IFNGR1 rs7749390 polymorphism was associated with decreased TB susceptibility in Africans. This study provided evidence that IFNGR1 rs2234711 might be involved in the pathogenesis of TB in certain ethnic groups. However, further studies with larger sample size and more stringent design are warranted to confirm the present findings among different ethnic groups.The original contributions presented in the study are included in the article/XY and JC conceived and designed the experiments. LC, FZ, and YW performed the experiments. LC, JC, and FZ analyzed the data. LC, XY, and YW contributed reagents, materials, and analysis tools. LC and FZ wrote the paper. All authors reviewed the manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Based on previous studies, it has been hypothesized that tube sterilization may be associated with a lower risk of breast cancer. This study aims to investigate the relationship between tubal ligation and the risk of breast cancer through a systematic review and meta-analysis.In this systematic review and meta-analysis, PubMed/Medline, Web of Science, Scopus, and Google Scholar were searched for relevant non randomized studies published up to November 2020. Then, we screened the papers to include the eligible papers in the meta-analysis. Finally, we pooled the extracted results of individual studies to estimate the summary effect size. All analyses were done using Stata software version 13 .I2 = 21.1%) and case control studies  revealed that tubal ligation was not significantly associated with breast cancer risk.Four hundred sixty-four papers were retrieved from PubMed/Medline (160), Scopus (165), and Web of Science (139), and 21 papers from Google Scholar and manual search of references in selected full texts. After the removal of duplicates and screening of the papers, 11 articles (6 cohort and 5 case-control study) were included in the final analysis. The results of cohort (RR = 0.99, 95% CI = 0.97–1.0, According to our findings, tubal ligation cannot be considered as a risk factor associated with breast cancer risk.The online version contains supplementary material available at 10.1186/s13643-022-02000-8. Permanent contraception, also known as female sterilization or tubal ligation, is a surgical procedure in which fallopian tubes are blocked or removed. This contraceptive method is one of the most popular methods of family planning around the world , 2, accoBased on previous studies, it has been hypothesized that tube sterilization may be associated with a lower risk of breast cancer , especiaNumerous case-control and cohort studies –9 have bIn previous meta-analysis studies, the protective effect of tubal ligation on endometrial  and ovarWith the inconsistency of previous study findings and also the fact that the last meta-analysis on this topic was conducted a decade ago when due to lack of evidence only PubMed database was searched , this stThe systematic review and meta-analysis were conducted following the standard guideline of “Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)”  and “CocTo extract the relevant articles, a specific search strategy was devised, using a variety of keywords, for the following three international databases: Medline via PubMed, Scopus, and Web of Science. Medical Subject Heading (MeSH) and our keywords  were searched in PubMed. The search was filtered to only subsume human and English language studies. The modified keywords were then used to search in Scopus and Web of Science databases. More detail on the search strategy is reported in Supplementary file To select the relevant articles, the retrieved articles were entered into Endnote version X8. Duplicate articles were removed in this stage. Then, the titles and abstracts of the remaining articles were screened and the irrelevant articles were excluded. After that, the full texts of the remaining articles were evaluated and unrelated articles were discarded. The required information was finally extracted from the remaining related articles. In cases where an article was relevant but the necessary data was not reported, the corresponding author was contacted. All stages of the study selection were performed by two people (AAH and SM). In the case of controversies, decisions were made in consultation with other authors.Non-randomized articles that were published in the English language, up to November 2020, and examining the association between tubal ligation and breast cancer were included in the study. Moreover, only case-control and cohort studies were included, and other types of articles namely randomized interventional studies, letters to the editors, case reports, case series, editorials, review articles, and commentaries were excluded.Data were extracted from the full-text of retrieved articles by the authors , and in the cases of disagreements, decisions were made in consultation with other authors. Data extracted from each article included first author’s name, year of publication, study design, type of effect size  and risk ratio (RR)), effect size ), place of study, the quality score of the article, and studied population. In cohort studies, RR was extracted, and in case-control studies, OR was extracted.Qualitative evaluation of the included studies was performed by two authors based on the Newcastle-Ottawa Quality Assessment Scale (NOS), adapted for case-control and cohort studies. This scale is introduced to assess the quality of observational studies. The NOS evaluates each study based on six items in three overarching headings of selection, comparability, and exposure. Each item is given a star and its score ranges from 0 to 9. The articles were finally categorized into three groups with a score of more than 6 as high, 3 to 6 as moderate, and less than 3 as low quality.I2 statistic with a chi-square test was used. Also, in cases where there was significant heterogeneity, the random-effect model was used, and in other cases, the fixed-effect model was conducted to pool the effect sizes with “metan” command [To check the heterogeneity across the studies, the  command . To expl command ), and fu command ) were us command . All anaThe PRISMA flow diagram regarding the selection of the articles is displayed in Fig. The eleven studies that met the inclusion criteria are summarized in Table The quality of each study was checked according to the NOS and all studies were of high quality. However, we could not check the quality of a study from Korea  due to aI2 = 21.1%) and case control studies  revealed that tubal ligation was not significantly associated with breast cancer risk  = 88.9%, estimate of between-study variance tau-squared = 0.066), and the results revealed that there is no significant heterogeneity among cohort studies , p = 0.275, I2 (variation in ES attributable to heterogeneity) = 21.1%, estimate of between-study variance tau-squared = 0.001). Therefore, a random-effects model was used to summarize the effect sizes in case control studies and fixed-effects model was used in cohort studies.The results suggested a significant heterogeneity between primary case control studies , I2 = 76.8%, random-effects model).Based on previous evidence –27, the p value = 0.462, Egger’s test p value = 0.36) and cohort studies .Begg’s and Egger’s tests were used to check the possibility of publication bias. The findings, however, suggested that there was no evidence of publication bias among case-control . In addition, the small confidence intervals obtained from the models implicate accurate results.Given that tubal ligation has a significant effect on reducing the risk of ovarian , 12 and From a total of 11 articles included in the meta-analysis, one study showed a significant increase  and one Previous studies have also suggested that women who have a history of tubal ligation are more prone to uterine surgery and hysterectomy , and bilOne of the important issues in meta-analysis studies is that the unadjusted data of individual studies are usually extracted and summarized. Fortunately, in this study, the adjusted effect size was reported in most of the primary papers where the effect of various confounding variables was controlled. Besides, the possibility of publication bias is another concern in these kinds of meta-analysis studies. Our analyses, however, showed that there is no evidence in favor of publication biases in individual studies. In this study, there was considerable heterogeneity between the included studies. Heterogeneity refers to any variation across primary included articles which mainly include clinical or methodological heterogeneity. No two studies can be identical, so systematic reviews require methods to evaluate the variability of studies to make reasonable decisions about data summarizing and comparisons . Due to One of the strengths of this study is that unlike a previous meta-analysis that only searched PubMed database a decade ago, three international databases including Scopus, Medline/PubMed, and Web of Science were searched and a general conclusion was made about the association between tubal ligation and breast cancer risk. One of the limitations of this study, however, is that only articles in the English language were reviewed. Moreover, due to the review nature of the study, it was not possible to assess the effect of time (number of years elapsed) since tubal ligation on the risk of breast cancer.It should be highlighted that combining different study designs and different effect sizes leads to increased heterogeneity between studies, and in some cases, it is not recommended to combine them. In this study, the results of case control and cohort studies were reviewed, and we analyzed the case control (odds ratio) and cohort studies (risk ratio) separately, and because the results of these two types of studies did not differ, the results of these studies were merged as an additional analysis with random-effects model.I2 statistic, and because of a significant heterogeneity, random-effects model preferred to the fixed-effects model. Accordingly, because the number of studies is usually small, there is also the possibility of small study bias that the results should be used with caution.In this study, the statistical heterogeneity quantified by the In this study, some of reported effect size were adjusted for potential confounders and some of them were not adjusted. According to the Cochrane Handbook, the use of adjusted model is preferable if both unadjusted and adjusted intervention effects are reported.In summary, in this study, we pooled the results of eleven individual studies and our findings did not suggest tubal ligation as a risk factor associated with breast cancer.Additional file 1. Search strategy.


I2 statistic and 95% prediction interval (95% PI). Additionally, publication bias and the quality of evidence were evaluated for all 37 unique associations. Only 4 associations had above the medium level of evidence, and the rest associations presented a low level of evidence. Among them, helicobacter pylori (HP), infection, and bacteria are associated with Parkinson's disease (PD), and the other one verifies that periodontal disease is a risk factor for all types of dementia. Following the evidence of our study, eradication of HP and aggressive treatment of periodontitis are beneficial for the prevention of PD and dementia, respectively. This umbrella review provides comprehensive quality-grade evidence on the relationship between microbial factors and neurodegenerative disease. Regardless of much evidence linking microbial factors to neurodegenerative diseases, these associations are not necessarily causal, and the evidence level is generally low. Thus, more effective studies are required.The role of microbiological factors in the development of neurodegenerative diseases is attracting increasing attention, while the relationship remains debated. This study aimed to comprehensively summarize and evaluate the associations between microbiological factors and the risk of neurodegenerative disorders with an umbrella review. PubMed, Embase, and the Cochrane library were used to search for papers from the earliest to March 2021 for identifying meta-analyses and systematic reviews that examined associations between microbiological factors and neurodegenerative diseases. AMSTAR2 tool was employed to evaluate the methodical quality of systematic reviews and meta-analyses. The effect size and 95% confidence interval (95% CI) were recalculated with a random effect model after the overlap was recognized by the corrected covered area (CCA) method. The heterogeneity of each meta-analysis was measured by the https://www.crd.york.ac.uk/PROSPERO/#searchadvanced, PROSPERO, identifier: CRD42021239512. With the aging process, neurodegenerative diseases, such as dementia, PD, motor neuron disease, and multiple system atrophy, are increasingly challenging to global public health. In 2016, the global number of individuals who lived with dementia was 43.8 million, increasing from 20.2 million in 1990. This increase of 117% contrasted with a minor increase in age-standardized prevalence of 1.7%, from 701 cases per 100,000 population in 1990 to 712 cases per 100,000 population in 2016  mice induced AD-like pathology, including amyloidosis and neurodegeneration in hippocampal and cortical regions  mouse model , especia plaques . Another regions . However regions , 10. Fur regions , while o regions , 13. Add regions .In this study, an umbrella review of existing systematic reviews and meta-analysis of evidence on microbiological risk factors for neurodegenerative diseases is performed to provide decision-makers with comprehensive, high-quality evidence on biological risk factors for neurodegenerative diseases, such as viruses, bacteria, and parasites.The umbrella review followed the guidelines for Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) . The PRIMeta-analyses or systematic reviews satisfying the following criteria were selected: (1) systematic reviews or meta-analyses investigated the association of microbiological or infection factors and neurodegenerative disorders , AD, all-cause dementia, PD, motor neuron disease, or multiple system atrophy); (2) studies were conducted on available Relative Risks (RR), Odds Ratio (OR), Hazard Ratio (HR), Standardized mean difference (SMD)/mean difference (MD); (3) articles written in English or Chinese were published in peer-reviewed scientific journals. PECO definitions: (1) The population included human participants aged 18 years and older. (2) Exposures were identified through a scoping search. The scoping search involved search terms for microbiological risk factors of neurodegenerative disease. Studies on the following microbiological risk factors were identified: infection, organism category . (3) The comparison group was composed of individuals who had not been exposed to microbiological risk factors in cohort studies or longitudinal randomized controlled trials, or who had not developed the neurodegenerative disease in case-control studies. (4) Outcomes of interest were neurodegenerative disease: AD, PD, cognitive decline, MCI, or dementia.Studies were excluded based on the following exclusion criteria: (1) no quantitative synthesis of the single study results was performed; (2) studies with duplicate publications on the same exposure and outcome; (3) guidelines, narrative reviews, literature reviews, genetic studies, and animal studies.Porphyromonas gingivalis,” “Gum infection,” “Chlamydia,” “Pneumonia,” outcomes such as “Neurodegenerative Diseases,” “dementia,” “Parkinson,” and “cognitive,” “Alzheimer Disease,” “Multiple System Atrophy,” “Lewy Body Disease,” “Motor Neuron Disease,” and terms referring to the study design including “systematic review” or “meta-analysis,” “Cochrane Database Syst Rev,” “pooling,” “clinical trial overview,” “Systematic Reviews as Topic,” “Meta-Analysis as Topic.” The full search strategy of PubMed is exhibited in Two researchers  independently searched systematic reviews and meta-analyses in three electronic databases  using a search strategy according to predefined inclusion and exclusion criteria. All language publications were searched without any restriction of countries from the earliest date to March 2021. The search terms consisted of terms of exposure such as “Organisms Category,” “Infections,” “virus,” “intestinal flora,” “Gingivitis,” “Bacterial Infections,” “microorganism,” “H pylori,” “toxoplasma gondii,” “Herpes virus,” “EB virus,” “fungus,” “spirochete,” “Two researchers  independently performed the study selection and data extraction from each included meta-analysis using a standardized form, which included the first author's last name, year of publication, type of studies included, number of databases, time frame for inclusion in the study, guidelines for reference, methods for quality assessment and publication bias of the original studies, heterogeneity, number of participants, country or region, number of original articles, and funds to support. Discrepancies were solved by consensus.For every primary study included in every meta-analysis, the same two researchers  independently extracted the data: name of the study, type of exposure(s) and comparisons, type of outcome(s), the number of cases and total participants, combined RR, or OR, or HR, or SMD/ MD and corresponding 95% CIs. No data were available in the meta-analysis, and the data were extracted from the original articles. Discrepancies were solved by consensus with the other two researchers .AMSTAR2 is an instrument used in assessing the methodological quality of systematic reviews, involving 16 items , high (CCA 11–15%), moderate (CCA 6–10%), or slight (CCA 0–5%). CCA is a validated method of quantifying the degree of overlap between two or more reviews and assists the decision process in handling overlaps.Associations assessed in two or more reviews overlapped if the same exposure and outcome were evaluated . MergingAll non-overlapping systematic reviews meeting the inclusion criteria were included in the analysis. Otherwise, the overlap between reviews was managed as follows.If a high degree of overlap (CCA ≥ 11%) between two or more reviews was found, preference was given to the review that  had the highest rating and, was higher methodological quality levels with AMSTAR2 quality assessment tools; was most recent; supplied pooled effect estimates or conducted a meta-analysis; had the highest number of studies or participants. If a slight or moderate degree of overlap (CCA ≤ 10%) was observed, both reviews were retained, and the findings were compared.p values were estimated using random effect models (Der Simonian Laird method). Besides, the 95% PI was also estimated. It accounted for the between-study heterogeneity and evaluated the uncertainty for the effect that would be expected in a new study addressing that same association ; more than 1,000 cases; the largest study was statistically significant (P < 0.05); not large heterogeneity (I2 < 50%); 95% PI not including the null; no evidence of small-study effects (P > 0.1); with evidential value and no evidence of p-hacking.Highly convincing evidence required highly statistically significant summary associations (p < 10−6 by random effects); more than 1,000 cases; the largest study was statistically significant (P < 0.05).Highly suggestive evidence required highly statistically significant summary associations (p < 0.001 (p < 10−3) by random effects and more than 1,000 cases.Suggestive evidence required only p < 0.05 by random effects).The nominally significant associations had weak evidence (P > 0.05). Statistical analyses and evidence ratings were conducted in R, version 4.0.2.No significance threshold was discovered for the random-effects meta-analyses  and PD, n = 2; Toxoplasmosis (acute infection IgM antibodies) and PD, n = 2; periodontal disease and dementia, n = 3. Sixteen reviews reported overlapping associations, including 42 unique meta-analyses. Overlapping associations included: HCV and PD, A total of 37 independent meta-analyses on the relationship between microbial risk factors and neurodegenerative diseases were obtained after a literature search, methodological evaluation, and removal of overlap. Neurodegenerative diseases in the 37 independent associations were classified as PD, AD, and all types of dementia. In addition, the microbial risk factors for each disease were categorized into bacteria, fungi, viruses, parasites, chlamydia, and other microorganisms, and the risk factors that were not a single organism were classified as other microorganisms. Furthermore, the level of evidence was assessed for each of the 37 independent associations. Specific evidence levels and classification information are provided in Chlamydophila pneumoniae, Chicken POX, small intestinal bacterial overgrowth (SIBO), and viruses, among which Chicken POX was a protective factor for PD but with a weak evidence level. The remaining 10 meta-analyses (53%) demonstrated no significant evidence, including measles, HBV, German measles, HSV, infuenza, mumps, scarlet fever, whooping cough, toxoplasmosis-IgG, and toxoplasmosis-IgM.A total of 19 of the 37 meta-analyses examined associations for PD. Among them, 3 meta-analyses (16%) were rated as level II evidence (highly evidence); these relationships were HP, infection, and bacteria, respectively. Additionally, 6 meta-analyses (32%) were evaluated as level IV evidence, including malassezia, HCV, A total of 15 of the 37 meta-analyses examined associations for AD. Specifically, 9 of 15 meta-analyses (60%) were evaluated as level IV evidence (weak evidence). These risk factors included Herpesviridae family infection (in case-control studies), Chlamydia pneumoniae, HHV-6, and EBV, Spirochetes, conservative Spirochetes, periodontal disease, toxoplasmosis, and HSV-1. The remaining meta-analyses, 6 of 15 associations (40%), were rated as having no evidence, involving the risk factors of the Herpesviridae family (in cohort and nested case-control studies), CMV (in case-control studies), CMV (in cohort and nested case-control studies), VZV, HP (in case-control studies), and HP (in cohort studies).Three of the 37 meta-analyses examined associations for all types of dementia. Periodontal disease was rated as level III evidence (suggestive evidence). The other two risk factors are sepsis and HP, which are rated as level IV evidence.An umbrella review was conducted to provide a comprehensive overview of the currently available meta-analyses of microbiological factors and neurodegenerative disorders. The evidence for microbial factors associated with the incidence of neurodegenerative diseases was summarized, and the evidence level was evaluated.None of the 37 independent associations in the 19 meta-analyses and systematic reviews identified were rated high-quality evidence. Among the single microbial risk factors, only HP was considered highly suggestive evidence (class II) related to the development of PD. Infection and bacteria were also considered highly suggestive evidence (class II) for PD. However, the two risk factors were synthesized by many microbial risk factors instead of single microbial risk factors. Since this comprehensive conclusion was significantly affected by different research scopes, the reliability of such evidence was very low and needed careful interpretation. Only one piece of evidence was assessed as the level of suggestion evidence (class III): the periodontal disease was the risk factor for all types of dementia. Meanwhile, other microbiological factors were assessed as weak (class IV).Significant heterogeneity existed in more than half of the studies. Six studies were influenced by small-study effects. Considering that heterogeneity reflects real differences between included studies, findings should be carefully interpreted when small studies have significant effects or when heterogeneity is large. P curves in only 10 studies exhibited a yes or no type, while other studies have the possibility of p-hacking existence.In our umbrella analysis, HP infection is the highly suggestive evidence level of PD pathogenesis, which is the highest level of evidence in our investigation of neurodegenerative diseases. Moreover, the other three meta-analyses in the literature were included in this paper. Although they did not become an item in the evidence table after the CAA method, the conclusions of these three meta-analyses are consistent with our evidence , 47, 48.Our umbrella review demonstrated that the evidence level of microbial risk factors associated with AD was weak, and no evidence of high grade was discovered. Single microbial risk factors included HSV-1, HHV-6, EBV, spirochete, Toxoplasma gondii, and chlamydia pneumoniae. Among them, the risk factors with more than 1,000 people included in the study were HSV-1, spirochete, and Toxoplasma gondii.Four studies within our search scope have performed meta-analyses on whether HSV-1 infection is a risk factor for the development of AD. After the data were processed by the CAA method, the most recent meta-analysis with the largest number of original documents was selected as the basis for the evaluation of the level of evidence. However, the conclusions of the other three meta-analyses were not entirely consistent with our selection. For example, the meta-analysis by Steel et al. indicated that HSV-1 infection increased the risk of AD, while the meta-analysis by Warren-Gash et al. drew the opposite conclusion , 12. A mBorrelia burgdorferi were at increased risk of developing AD  Congress held in July 2017 in San Francisco . Herreraoping AD . Moreoveoping AD , 76. Mecoping AD . Severaloping AD . A recenoping AD . Based ooping AD . Some reoping AD , which mToxoplasma gondii were 44.1 and 24.3% in AD patients and healthy controls, respectively. The difference in serum antibodies was statistically significant, and a positive correlation between toxoplasmosis and AD was considered  Mann = 8,275) cohort study. Their findings also revealed that periodontal disease was associated with dementia events (Pseudomonas gingivalis DNA and antigens of gingivalin in the brains of AD patients and elaborated that they play a central role in the pathogenesis of AD (Bacillus gingivalis in mice (Porphyromonas gingivalis in periodontal disease is underway for the treatment of mild to moderate AD (Our umbrella analysis demonstrated that Periodontal Disease is a risk factor for dementia with a moderate level of evidence. An epidemiological survey from Japan implied that poor oral health was significantly associated with cognitive impairment . AD is ta events . Additioa events . The exaa events . Second,is of AD , 96. Eveerate AD . AlthougThe main strength of the present umbrella review is the comprehensive overview of the published meta-analyses on the association between microbiological factors and the risk of neurodegenerative disorders. To our knowledge, we are the first to evaluate the methodological quality of the meta-analyses and the level of evidence for all these associations. The AMSTAR2 instrument was employed to assess the methodological quality of the included meta-analyses. Additionally, the CAA method was adopted to quantify the overlap of meta-analysis. The highest-quality and most recent meta-analysis was selected under the combination of these two methods, avoiding double counting and selection bias. Moreover, all meta-analyses were recalculated using the random-effects model, and the level of evidence was evaluated for each meta-analysis. Consequently, a comprehensive, up-to-date evidence hierarchy was provided for microbiological risk factors of neurodegenerative diseases, contributing to reliable clinical guidance and potential research directions.p-value, 95% PI, and evidential value for P-curve cannot be calculated due to the small number of original studies included in some meta-analyses. Therefore, the evidence level of this part could not be evaluated.Some limitations exist in our umbrella review. First, all the meta-analyses included were based on observational studies. However, confounding factors were inevitable as the data in our study were derived from observational studies . Second,A comprehensive overview of current meta-analyses of microbial risk factors and neurodegenerative diseases is presented in this paper. Although numerous studies suggest that multiple microbes are associated with neurodegenerative diseases, the overall level of evidence is not high. It is revealed that HP infection is a risk factor and Class II evidence for PD, and periodontitis is a risk factor and Class III evidence for dementia, laying a foundation for HP removal and periodontitis treatment and enlightening a new direction for research on the treatment of PD and dementia. More high-quality research is required in the future.The original contributions presented in the study are included in the article/JL conceived the study. JL, CX, XW, and DJ designed the study. XW and TL collected data and performed the analysis with input from XZ, RW, SG, FY, YW, and QT. XW and JL wrote the manuscript with contributions from all authors. All authors critically revised and approved the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.