I2 = 60.6%). Moreover, a similar association was observed between the NEAP and fracture risk . The results of five studies from four publications revealed no significant association between dietary PRAL score and femoral and spinal BMD . However, being in the highest category of NEAP was significantly associated with a lower femoral and spinal BMD . It was showed that adopting diets high in acidity was not associated with risk of fractures. We also found a significant negative relationship between NEAP and BMD. However, DAL based on PRAL was not associated with BMD.Findings on the association between dietary acid load (DAL) and bone health are conflicting. This study aimed to summarize available studies on the association between DAL and risk of fractures or bone mineral density (BMD) in adults. Online databases including PubMed, Scopus, and Embase were searched for relevant studies published up to June 2021, using pertinent keywords. We identified observational studies  investigating the association between DAL and risk of fractures or BMD, then selected studies following these reported criteria: RRs with corresponding 95% CIs for the relationship between DAL and fracture risk; correlation coefficients for the association between DAL and BMD; and mean ± SD of BMD values across the categories of DAL. Overall, 17 studies with 80545 individuals were included. There was no significant relationship between the PRAL and fracture risk (Pooled RR: 1.18; 95% confidence interval 0.98 to 1.41,  Osteoporosis is a major health threat characterized by skeletal fragility and microarchitectural deterioration –3. FactoThis meta-analysis was conducted using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.We developed and performed the literature search (FG), and two reviewers (FG and MS) screened the titles and abstracts. The same two reviewers independently assessed the full text of the articles for eligibility. Differences were resolved by discussion. PubMed, Scopus, and Embase databases were searched to identify relevant papers published up to June 2021. We used a search strategy that included truncated free text and exploded MeSH terms . No restPublished studies were included if they had the following criteria:  observatWe excluded letters, comments, reviews, meta-analyses, and ecological studies.Required data were extracted from qualified studies by two independent investigators (MS and SN) using an abstraction form: first author's name, publication year, study design, demographic characteristics of participants (age range or mean age and sex), geographical location, sample size, number of fracture cases, method of assessing outcome, dietary assessment tool, RRs for fracture, mean ± SD of BMD values in the highest and lowest categories of DAL or regression coefficients for BMD and confounding variables that were adjusted in the statistical analyses. Numerical estimates were extracted from graphs by using a web plot digitizer . Any disThe methodological quality of studies was evaluated using the Newcastle–Ottawa scale (NOS), designed for nonrandomized studies . Studies2) the means and corresponding SDs in the highest and the lowest categories of DAL were used to calculate the weighted mean difference (WMD) as the effect size in the meta-analysis. In cases of the absence of SD data, we calculated it by using SE and sample size.We included the RRs and 95% CIs for fracture to compare the highest vs. the lowest categories of DAL through the meta-analysis. In the analysis of continuous data  and unrelated studies (n = 530), 17 relevant studies remained for full-text review   , indicatI2 = 54.1%, Pheterogeneity = 0.14)  .I2 = 76.5%, Pheterogeneity = 0.002)  .I2 = 56.7%, Pheterogeneity = 0.05)  .I2 = 82.1%, Pheterogeneity <0.001)  .I2 = 93%, Pheterogeneity <0.001)  .The present study is the first meta-analysis summarizing observational evidence on the association between indices of diet-dependent acid load and risk of fractures and BMD. Our results showed no significant association between DAL, represented by PRAL and NEAP, and risk of fractures. In addition, we found that high NEAP scores were significantly associated with a slightly lower femoral and spinal BMD. However, there was no significant association between dietary PRAL score and BMD.The social and economic burden of osteoporotic fractures is increasing worldwide as the population ages. Fracture prevention has therefore become a major public health priority. Dietary variables have an important role in these conditions. Some diet components might have potential effects on the acid-base balance of the body due to the PH-altering features . Animal The current study provides reliable evidence on the association between DAL and bone health. We failed to find a clear association between DAL (based on PRAL and NEAP) and risk of fractures. A meta-analysis of cohort studies that examined the association of protein intake and bone health throughout the life course reported that total, animal, and plant protein intake was not associated with risk of osteoporotic fractures in healthy adults . A prospThe present review found that NEAP was inversely associated with a slightly lower BMD. However, there was no significant relationship between PRAL and spinal and femoral BMD. It appears that the different nutrients used in the calculation of NEAP and PRAL could be a contributing factor to the observed variations . CompareSeveral mechanisms have been proposed to explain how DAL might affect bone health , 48, 49.Our meta-analysis has several strengths, including a comprehensive literature search on the association between DAL and bone health. Another advantage is that we evaluated the associations between PARL and NEAP separately. However, several limitations should be acknowledged. While all included studies except four have high quality based on NOS, causality cannot be established due to the observational nature of the included studies. Therefore, this review for a definitive conclusion emphasizes adding high-quality intervention studies. Secondly, residual confounders due to unmeasured behavioral and biological factors or measurement errors in covariates cannot be completely ruled out. Thirdly, in most studies, food and nutrient intakes were assessed by food frequency questionnaires, measurement errors were inevitable. Fourth, we did not perform subgroup analysis for some outcomes because of the low number of related reports. Fifth, different methods for BMD assessment were used in the included studies, and the units ofBMD varied in different studies. Finally, there was some evidence of considerable heterogeneity among included studies which could be explained by variations in the amount of DAL, follow-up period, exposure assessment methods, and adjustments for confounding factors.In the current meta-analysis, adherence to diets with high acidity potential was not associated with risk of fractures. Furthermore, we found a significant weak association between NEAP and BMD. However, DAL based on PRAL was not associated with BMD. These findings thus have important public health implications. The current study provides further evidence that higher DAL is not associated with fracture risk and is weakly associated with BMD. However, these findings should be interpreted with caution and further large intervention trials are required.The original contributions presented in the study are included in the article/FG conceived and designed the study, conducted systematic search, screened and selected eligible articles, data interpretation, and manuscript drafting. SN performed analyses and interpreted results, data interpretation, and manuscript drafting. MS and NR screened and selected eligible articles and extracted information. KM is the guarantor. All authors contributed to writing, reviewing or revising the paper and have approved it for publication.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.


I2 = 92.0%, Egger’s test P = 0.001, N = 13) for per 1 °C increase and 1.0244  for per 1 °C decrease. As to relative humidity, only high effect of relative humidity was slightly significant (for per 1 unit increase with RR of 1.0088 (95% CI: 1.0027–1.0150), I2 = 72.6%, Egger’s test P = 0.159, N = 9). Subgroup analysis showed that regional climate with temperate areas may have a higher risk of incidence of mumps than areas with subtropical climate in cold effect of ambient temperature and low effect of relative humidity. In addition, meta-regression analysis showed that regional climate may affect the association between incidence of mumps and cold effect of ambient temperature. Our results suggest ambient temperature could affect the incidence of mumps significantly, of which both hot and cold effect of ambient temperature may increase the incidence of mumps. Further studies are still needed to clarify the relationship between the incidence of mumps and ambient temperature outside of east Asia, and many other meteorological factors. These results of ambient temperature are important for establishing preventive measures on mumps, especially in temperate areas. The policy-makers should pay more attention to ambient temperature changes and take protective measures in advance.Many studies have shown that the relationship between ambient temperature, relative humidity and mumps has been highlighted. However, these studies showed inconsistent results. Therefore, the goal of our study is to conduct a meta-analysis to clarify this relationship and to quantify the size of these effects as well as the potential factors. Systematic literature researches on PubMed, Embase.com, Web of Science Core Collection, Cochrane library, Chinese BioMedical Literature Database (CBM) and China National Knowledge Infrastructure (CNKI) were performed up to February 7, 2022 for articles analyzing the relationships between ambient temperature, relative humidity and incidence of mumps. Eligibility assessment and data extraction were conducted independently by two researchers, and meta-analysis was performed to synthesize these data. We also assessed sources of heterogeneity by study region, regional climate, study population. Finally, a total of 14 studies were screened out from 1154 records and identified to estimate the relationship between ambient temperature, relative humidity and incidence of mumps. It was found that per 1 °C increase and decrease in the ambient temperature were significantly associated with increased incidence of mumps with RR of 1.0191 (95% CI: 1.0129–1.0252,  Mumps is usually a self-limiting disease, and often occurs in children and adolescents. However, mumps virus can invade other organs and the central nervous system through blood circulation, resulting in up to 10% with severe complications, such as meningoencephalitis, meningitis, orchitis, pancreatitis, ovarian inflammation, and inflammation of many other organs2. In general, mumps is transmitted by droplets and direct contact, which are infectious in seven days before and nine days after parotid gland enlargement3. Moreover, the susceptible population is children under 15, especially those aged between five and nine years old4.Mumps, also known as epidemic parotitis, which is an acute respiratory infectious disease caused by mumps virus belonging to the Paramyxovirus family, is characterized by unilateral or bilateral swollen and painful parotid gland with precursory fever5. By the end of 2016, a total of 121 countries nationwide belonging to the WHO have adopted the mumps vaccine6, and 123 countries by the end of 20207. However, the effect of mumps vaccination is determined by many factors, such as age, coverage, the potential evolution of mumps virus, and inoculation times8. Mumps outbreaks have recently reemerged in some areas and countries with high mumps immunization rates, which have caused wide concerns regarding its re-outbreak12. In most parts of the world, the annual incidence of mumps in the absence of immunization is in the range of 100–1000 cases/100 000 population, with epidemic peaks every two to five years, and natural infection with this virus is thought to confer lifelong protection14. In China mainland, despite the use of mumps virus (MuV) vaccination since 2008, 194 MuV strains were also isolated from 10 of 31 provinces in China mainland in the MuV virology surveillance during 2013–20154. Therefore, the mumps is still a serious public health issue in China.Mumps is an infectious disease that can be prevented effectively by vaccination, which is most often incorporated into national immunization programs in a combined measles-mumps-rubella (MMR) vaccine. Since the mumps vaccine was approved for use in 1967, the incidence of mumps decreased dramatically in countries where large-scale immunization against mumps has been implemented15, suicide16, stroke occurrence17, and infectious diseases, such as hand, foot, and mouth disease (HFMD)18, influenza20, tuberculosis23 and so on. Many articles have tried to clarify the mechanisms between mumps and meteorological factors. The potential biological mechanisms of the relationship between ambient temperature, humidity and incidence of mumps can be explained by survival and reproduction of pathogens, host population, and environmental factors. Several means may be used by meteorological factors to affect the incidence of infectious disease. First, environmental factors such as warm climate and high humidity may promote the survival of the virus in the humid environment24. Then, the host population behavior pattern may be affected by the ambient temperature. Many studies have found that there was significant association between weather conditions and physical activity in outdoor environments25, while the physical activity of adolescent would be less in winter and would be more during warm months26, thereby increasing the chance of contact with pathogens in warm months27. In addition, the low air circulation of indoor environment makes the air-borne infectious disease communicate more easily in winter, especially crowded area, such as school. Many researches have attempted to explore the relationship with meteorological factors, especially ambient temperature and relative humidity30, but the results are inconsistent quantitatively or qualitatively. Therefore, the aim of this study is to systematically identify and review epidemiological evidence related to ambient temperature, relative humidity and the incidence of mumps, as well as to quantify the size of these effects and to identify potential factors.Meteorological factors have been considered as important influencing factors to many disease, including non-infectious diseases, such as blood pressure31.We carried out this meta-analysis in accordance with the Preferred Reporting Items for Systematic review and Meta-Analysis (PRISMA) statement18, was listed as follows:  AND (mumps OR epidemic parotitis).Systematic research was performed in both English and Chinese database, including PubMed, Embase.com, Web of Science Core Collection, Cochrane library, Chinese Biomedical Literature Database (CBM) and the China National Knowledge Infrastructure (CNKI) for relevant studies up to February 7, 2022. Medical Subject Headings (MeSH) Term and free words strategy were applied to maximize the output. The search strategy, which was referenced to Qiang Cheng et al.After deleting duplicates, all abstracts and titles were filtered independently by two reviewers to remove the irrelevant articles (T.W. Wang and J.J. Wang). Two authors evaluated potential publications by checking their titles and abstracts and then procured the most relevant publications for further full-text examination. Bibliographies section of retrieved articles were also reviewed for additional pertinent studies that were possibly missed in the initial search. If any agreement can’t be solved by discussion, a third reviewer (J.H. Zhang) was requested to make arbitration.32: 33, or RR = 1 + PC17; and (iv) provided the corresponding 95% confidence interval(CI); (v) the study incorporated at least 4 year of continuous data and controlled for potential confounding factors.Studies included for further analysis should fulfill the rules as follows: (i) the outcome measure was incidence of mumps at a monthly, weekly or daily resolution; (ii) the exposure of interest was mean ambient temperature and/or relative humidity; (iii) the estimated parameter was the rate of incidence (RR) of mumps associated with each 1 °C increase/decrease in ambient temperature and each 1% increase/decrease in relative humidity, or which can be converted to standardized RR using the following formulaThe exclusion criteria of our literature were listed as follows: (i) the full text of the article could not be found; (ii) the format of the paper is not a research article; (iii) articles do not contain data for meta-analysis; and (iv) duplicate publication, or the data was covered by another study included completely.The following information was extracted from the studies that met the inclusion criteria: first author, publication year; location, study period; population, ages, exposure meteorological factor, data sources, measures of exposure (95% CI) and outcome, statistical model and so on.18, such as single-day hysteresis and cumulative hysteresis34, we chose the estimate effect with the following rules. If only one lag estimate was provided , this estimate was recorded. If multiple lags were reported, we chose one based on the following criteria: (1) the lag that the investigators focused on or stated as a priority, (2) the lag that was statistically significant, (3) the lag with the largest effect estimate35.Due to some studies providing different hysteresis patterns to estimate the delayed effects of ambient temperature and relative humidity36. If more than one place were reported in one study, we selected the overall effect or pooled it as one single study to avoid over weight any one study.In addition, if the threshold effect existed in the studies, and two effect values be given, we pooled them separately, such as ambient temperature with hot effect and cold effect. Where multiple estimates were reported, we selected the final model as specified by the authors or, if a final model was not specified, the model with the greatest number of relevant covariates based on the Cochrane Collaboration guidelines37. This tool provides a description of the instrument devised to assess the risk of bias in the individual studies included in the systematic reviews of adverse health effects informing the guidelines. A total of 13 items are grouped into six domains, which include confounding, selection bias, exposure assessment, outcome measurement, missing data, and selective reporting in the instrument. Each item could be evaluated as low, moderate, and high risk of bias. The results for each domain were analyzed separately, without considering a single result for the whole article. If only one item of the same domain was judged as having high RoB, the entire domain was classified as having “High Risk”. If all domains in one study were low risk of bias, the study could be classified as “Low Risk” study; if at least two domains were high risk of bias, the study would be classified as “High Risk” study; Otherwise, the study was classified as “Moderate Risk”. Further detailed assessments were referred to in similar articles40.A new domain-based risk of bias (RoB) assessment tool was adopted to assess the RoB of included studies, which was developed by experts convened by the WHO36. Statistical heterogeneity was evaluated by Cochran’s Q test  and the I2 statistic41. An I2 from 0 to 40% was treated as an unimportant heterogeneity, I2 from 30 to 60% was treated as moderate heterogeneity, I2 from 50 to 90% was treated as substantial heterogeneity and I2 from 75 to 100% was treated as considerable heterogeneity42. A pooled model was chosen based on the heterogeneity: if obvious heterogeneity existed, a random effects model was adopted; otherwise, a fixed effects model was adopted. In addition, subgroup analysis and meta-regression were also performed to explore the potential source of heterogeneity if obvious heterogeneity was found. Furthermore, sensitivity analysis was performed by two means, (i) by converting the pooled results from a random effects model to a fixed effects model or from a fixed effects model to a random effects model; (ii) “leave-one-out” analyses, which was performed by sequentially removing individual studies and evaluating the effect on the overall estimate. Publication bias was tested by funnel plot, Begg’s and Egger’s test43. All statistical tests for the meta-analysis were carried out using R software version 4.1.244 (with the package “meta” version 4.18–045). A P value of ≤ 0.05 was considered to indicate statistical significance for all tests and models.For standardized results obtained from each study included, we assessed the heterogeneity of the relationship between ambient temperature, relative humidity and incidence of mumps before got the pooled results56 , regional climate , study population (All vs Children only).As shown in Tables To better understand the influence of factors, we also performed meta-regression analysis based on the information we obtained. As shown in Table 55, the result become significant with RR (95%) of 1.0054  in low relative humidity. Secondly, sensitivity analysis was performed by changing the pooled results by converting the pooled model (from random effects model to fixed effects model). The results exhibited no big differences before and after pooling of ambient temperature effect, indicating stability in the pooled results. However, similar results were not found in the low effect of relative humidity. Overall, the results of low effects of relative humidity were not stable.Two types of sensitivity analyses were performed. Firstly, we removed any single study to verify whether the overall effect was affected. The results showed that no significant difference was found except for the effect of relative humidity. After removing the study of YangWe plotted the funnel plot and performed Begg’s and Egger’s tests to check whether publication bias exists. As shown in Fig. 57. China, as one of the countries including the MMR into the immunization programs, also has a relative high morbidity of mumps among adolescents58. To date, this study was the first meta-analysis to examine the relationship between ambient temperature, relative humidity and incidence of mumps. In the 14 articles included in this paper, we identified significant positive relationship between ambient temperature and incidence of mumps, and high relative humidity, while no relationship was found between low relative humidity and incidence of mumps. We also found that there was also significant heterogeneity in the estimated association, and subgroup analysis also showed that people living in temperate regions had a higher risk of incidence of mumps than in subtropical regions in cold effect of ambient temperature and low effect of relative humidity, which was also confirmed by meta-regression in cold effect of ambient temperature.Although vaccination was widely used in mumps prevention, dramatic increases in mumps cases have received much attention in recent years60, dengue outbreaks61, COVID-1962, et al. Many reasons may be used to explain this phenomenon. First, compared with the other pathogen, the pathogenicity of mumps virus may have different effect on humidity. The effect of mumps may not be affected by humidity significantly. Second, as to humidity, the publication bias was found, leading to that the pooled results may be affected by unpublished studies. Third, obvious heterogeneity also existed. Compared with ambient temperature, the effect of humidity is relative smaller per 1 unit, and could be affected by many factors. Fourth, even some factors were adjusted, such as school holidays, long-term trend, and seasonality, the confounding factor may not be fully explained, and the number of studies included for humidity is not large enough, only 11 studies. In addition, sensitivity analysis showed that the results of relative humidity were not stable. Therefore, the results may be unstable, indicating further exploring may be still needed.To our surprise, relative humidity is found to be slightly associated with mumps in our study, only high relative humidity with RR of 1.0088 (1.0027–1.0150). In previous study, humidity was found to be associated with many diseases, such as hand, foot, and mouth disease47. The pathogen of mumps has clear tolerance of ambient temperature in biological mechanism, which had bad tolerance of high ambient temperature and relative better tolerance of low tolerance. However, as the difference in environmental and climate factors, which led to the different thresholds of meteorological factors, such as threshold of ambient temperature in our study, ranging from about 10 °C and 25  °C, mainly focusing on 20 °C to 25 °C, which may also contribute to the heterogeneity. What's more, the non-linear relationships were also complex. In our studies included, several types were found, such as inverse “S”46, inverse “V”51, “V”50, and even “M”50, et al. However, in our study, based on the information provided in the included studies, we only obtained the main part result, such as only “V” part of “M” shape.In detail, the ambient temperature affected the incidence of mumps in both hot and cold effect, indicating hotter and colder ambient temperature had higher risk than the thresholds, which was corresponding to the fact that non-linear relationships of meteorological factors with morbidity and mortality18. In our studies, 12 studies reported cases with resolution of daily, 3 of weekly and 1 of monthly. As only 3 with weekly data and 1 with monthly data, we didn’t perform subgroup analysis based on time resolution. As mumps is an acute infectious disease, research based on daily data may be more suitable for disease control and prevention by providing more timely information. In the future, similar studies may perform sensitivity analysis by changing the resolution to confirm the effect of resolution and the stability of overall and specific results.Previous studies indicated a slightly lower pooled value and narrower confidence interval than the studies of weekly resolution, suggesting it may be more reasonable to use the daily exposure measures in future research designs, especially for those diseases with shorter incubation period25, especially for children and adolescents. Mumps is a disease mainly happens in younger people, which also increase the risk for children and adolescents from temperate region. It is reported that a total of about 500 thousand cases was reported in 201863, and half of them happened in China64. However, in our study, all studies are from Chinese mainland, China Taiwan and Japan, which may not represent other places, such as tropical and frigid. Therefore, researchers may pay more attention to other climate regions in the future.In our subgroup analysis, only the regional climate was found to affect the relationship between meteorological factors and mumps. Human activities may be one of the most important reasons. Temperate climate may be more suitable for outdoor activities65 within the statistical environment R, provided much convenience for analysis between meteorological factors and disease. In the meta-analysis, most of include studies were performed with this package. However, due to complexity between meteorological factors and disease, and no standard report guideline, all of these led to the difficulty for meta-analysis. To solve this situation, the author has built a package “mvmeta” within the statistical environment R to pool the results from multiple cities68. However, this two-stage analysis is based on the individual data, which is hard to obtain for meta-analysis. Therefore, if the authors provided the RR  per 1 unit in each line trend range in both single lag day and accumulative lagged effect, meta-analysis of this type analysis may be easier in the future.Distributed Lag Non-linear Models, which was achieved with “dlnm” package constructed by Gasparrini AAlthough this was the first meta-analysis with 16 studies to examine the relationship between ambient temperature, relative humidity and incidence of mumps, our meta-analysis has several limitations that should be recognized when interpreting the results. Firstly, the heterogeneity is obvious. Although we have performed subgroup and meta-regression analysis, and found the great importance of climate, obvious heterogeneity still existed. In addition, when available, adjusted estimates were used in preference to unadjusted estimates. Even though the adjusted estimates may be closer to the true effect for adjusted results could control confounding factors, the different adjusted factors in different studies may also contribute to the heterogeneity. Secondly, publication bias may exist in both ambient temperature and relative humidity. Researchers were more trend to publish statistically significant findings, which may lead to the ignorance of negative results. Thirdly, all studies for meta-analysis were from East Asian , with limited adjustment for confounders, which may limit the extension to other places. Fourthly, most of the included studies tend to report the largest effect estimates, and the effect estimates of different lag days is not fully available for analysis, we ignored the lag effect and chose the largest effect estimates for meta-analysis, which also contributed to heterogeneity. Fifthly, although our study was performed with strict inclusion and exclusion criteria, a total of 14 studies were excluded for no relevant data, which may also affect our results. Sixthly, in China, the mumps vaccine has been used since 2008 and its efficacy is a function of age, coverage, and timing of the inoculation. All Chinese studies included were conducted after 2008. Thus, even by controlling for confounding, it is very difficult to disentangle the contribution of meteorological factors from vaccination efficacy on mumps incidence. However, as the widely use of mumps vaccine, our results may be more suitable for current preventive measures. Finally, different confounding factors were adjusted in different studies, which may also lead to heterogeneity and bias of risk. Nevertheless, our study is still the most comprehensive about the association between incidence of mumps and ambient temperature/relative humidity.Overall, the pooled results of our meta-analysis provide systematic evidence that ambient temperature may increase the incidence of mumps, especially in east Asia regions. As limitation of the number of studies for relative humidity and the significant effect of relative humidity on other air-borne diseases, the effect of relative humidity on mumps needs further exploring. Further studies are still needed to clarify the relationship between ambient temperature and mumps in areas outside of east Asia regions, and many other meteorological factors. These results of ambient temperature are important for establishing preventive measures on mumps, especially in temperate regions.Supplementary Information 1.Supplementary Information 2.


Validation of a risk factor in a multifactorial disease like ischemic stroke is necessary to practice precision medicine. Many risk factors have been attributed to causing ischemic stroke but contribute very little to it. There are many risk factors that need to be validated, and fibrinogen is one such risk factor. Using a meta-analysis technique, we investigated fibrinogen as a risk factor for ischemic stroke.We searched the computerized databases such as PubMed, Google Scholar, and Cochrane to explore articles on ischemic stroke. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random effects model.2 = 78.3%, P = 0.000).A total of 10 case-control studies with 6877 cases and 7219 controls were included in the study that match inclusion and exclusion criteria. The Asiatic population was portrayed in four studies, whereas the Caucasian population was portrayed in six studies. Under the recessive model, an elevated level of serum fibrinogen is linked to an increased risk of ischemic stroke as shown by pooled odds ratio (OR: 1.47, 95% CI: 1.19-1.76, IOur meta-analysis concluded that a high level of fibrinogen is associated with an increased risk of ischemic stroke. Ischemic stroke is a condition due to sudden deprivation of blood supply to a part of the brain leading to a focal neurological deficit. It is caused by thrombotic or embolic occlusion of cerebral arteries and is more common than hemorrhagic stroke. Looking at the worldwide scenario, it is the second major cause of demise and disability, of which most of the cases are from low- and average-income countries . About 6There are many inflammatory markers whose levels tend to increase after an acute attack of ischemic stroke. Fibrinogen is one such important inflammatory marker. It is an acute-phase protein that is seen to rise after stroke and myocardial infarction . An earlThe rationale behind taking up this study is that there has been no isolated systematic review and meta-analysis in the literature so far considering the association of fibrinogen with an increased risk of ischemic stroke. One meta-analysis has been done considering fibrinogen as a risk factor in cardiovascular disease, in which pooled odds ratio (OR) of 2.3 (CI: 1.9 to 2.8) was found . One of MethodsSearch StrategyThe relevant studies were searched individually by MKP and SM on PubMed, Cochrane database, and Google Scholar from 1991 to April 2022. The search strategy consisted of the following search term: Blood OR serum OR plasma AND Fibrinogen AND ischemic stroke. The search was performed by two independent reviewers. During the search, any discrepancies were resolved by mutual discussion among us and with other authors involved in this meta-analysis. Studies reporting the association of fibrinogen with ischemic stroke were identified, and their references were also screened.Inclusion and Exclusion CriteriaStudies reporting the association of fibrinogen as a risk factor for ischemic stroke, studies reporting sufficient data to pooled OR, adult patients aged more than 18 years, and full-text articles published in English were included. Articles not in English language, editorials, letters to editors, conference proceedings, and abstracts were excluded.Study SelectionEach article was scrutinized individually by two authors to determine whether they meet the incorporating criteria. The differences in opinion were resolved by mutual discussion among us and with other authors.Data ExtractionRelevant quantitative data were drawn out by two writers (MKP and SM) in the form of first author name, year of publication, the cut-off for fibrinogen value, OR with lower and upper confidence intervals (CIs), the number of cases and the number of controls, mean age, sex, ethnicity, type of blood sample for fibrinogen (serum/plasma), methods used to test for fibrinogen, and other variables mentioned in the demographic profile of each study .Assessment of the Quality of StudyAs all the selected studies are of case-control study type, the standard of the different studies was assessed individually by MKP and SM using the Newcastle-Ottawa scale. Each study was assessed for the adequacy of case definition, the representativeness of cases, the selection of control, the definition of control, the ascertainment of exposure, the same method of ascertainment for cases and control, the non-response rate, and the assessment of outcome. Each end result was further classified as good, fair, or poor as per Agency for Health Care Research and Quality (AHRQ) standards.Statistical Analysis2 test was used to look for the heterogeneity among the studies. A forest plot was computed to find out the pooled OR. Meta-regression analysis was done for each variable  to look for the cause of heterogeneity. Publication bias of the studies was assessed by drawing a funnel plot of studies included in this meta-analysis. The unavailable data were marked as NA (not available).The software STATA version 13  was used for the analysis of data. Z-test was done to find out the pooled effect size using the random effect model, and the IResultStudy SelectionUpon preliminary search, a total of 18,860 studies were retrieved through a computerized database. Irrelevant articles were excluded by going through the titles and abstracts, and 315 studies were sought for retrieval out of which 96 studies could not be retrieved. A total of 219 studies were assessed for eligibility, and 209 studies were excluded; finally, 10 studies that fulfilled the inclusion criteria were included in our meta-analysis -16. All Characteristics of the StudyA total number of 6877 cases and 7239 controls were incorporated into this study. The general characteristics of the study subjects are tabulated in Tables Six studies -10,12,13Methodological Quality of StudyThe quality of these included studies was assessed by the Newcastle-Ottawa scale criteria Table . Among tDiagnostic Accuracy2) was 78.3% with a p-value of 0.00. As the heterogeneity was more than 50%, the random effect model was used.Outcomes of the studies were recorded in the form of pooled OR with upper and lower CIs as shown in the forest plot Figure . The pooPublication Bias A funnel plot was drawn to search for publication bias Figure , and it Meta-regression AnalysisImportant variables were also recorded in the studies, which can influence the study outcome. These variables were age, gender, diabetes, hypertension, smoking, alcohol, total cholesterol, serum triglyceride, fibrinogen cut-off level, sample size, ethnicity, BMI, HDL, and LDL Table . FollowiDiscussionThere are many risk factors like diabetes, hypertension, smoking, and old age, which attribute to stroke. Fibrinogen is one such risk factor. A meta-analysis was done on fibrinogen as a risk factor for myocardial infarction in the cardiovascular system. In this meta-analysis, the OR found was 2.3 (CI: 1.9 to 2.8); this indicates that serum fibrinogen level is associated with an increased risk of cardiovascular events . The fib2) in our study is 78.3% (p = 0.00), which is significant and may be due to the publication bias as shown by the funnel plot  gives an inference that patients with raised fibrinogen levels are 1.47 times more likely to have an increased risk of ischemic stroke. The heterogeneity  in our meta-analysis, none of these variables had influenced the effect size. Hence, fibrinogen may be a predictor for an increased risk of ischemic stroke.The strength of our study is that it is supposed to be the first meta-analysis that has individually looked for the association of fibrinogen as a risk factor for ischemic stroke. We have reported our meta-analysis as per the latest PRISMA protocol 2020. This systematic review and meta-analysis are very much in line with the contemporaneous literature of interest.However, there are certain limitations to our study. Only one of our studies had more than 10,000 study participants, and the remaining nine studies had study participants ranging from 100 to 1200. All of these studies were case-control studies, so in the future, we will need cohort studies with larger sample sizes and a greater number of studies to validate the association of fibrinogen as a risk factor for ischemic stroke. Different studies included in our meta-analysis have reported serum/plasma fibrinogen levels in different types of ischemic stroke ranging from minor to major ischemic stroke, so it is difficult to say whether the increased level of fibrinogen is associated more with minor or major ischemic stroke. As we have included different studies published in the English language only, there can be language bias. Another limitation is that we have not seen the correlation between fibrinogen level and the incidence of ischemic stroke.Our meta-analysis concluded that increased fibrinogen levels are associated with an increased risk of ischemic stroke. However, the role of fibrinogen as a risk factor for ischemic stroke is ambiguous due to the presence of significant heterogeneity and publication bias. But, it may be used to identify those at serious risk for ischemic stroke and then to initiate ischemic stroke intervention.So, we conclude this discussion with the hope that, in the future, a greater number of high-quality studies, including individual participant meta-analyses with larger sample sizes, will be conducted in order to accept increased fibrinogen levels as a risk factor for ischemic stroke.


Remifentanil patient-controlled analgesia (rPCA) and epidural analgesia (EA) has been used for pain relief in labor. We aimed to evaluate the efficacy and safety of rPCA versus EA in labor, to provide evidence support for clinical analgesia and pain care.We searched PubMed, EMBASE, ScienceDirect, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang and Weipu databases for RCTs comparing rPCA and EA in labor until February 15, 2022. Two researchers independently screened literature and extracted data. RevMan 5.3 software was used for data analysis.A total of 10 RCTs involving 3086 parturients were enrolled, 1549 parturients received rPCA and 1537 received EA. Meta-analysis indicated that the incidence of intrapartum maternal fever within 1 hour of labor analgesia , after 1 hour of labor analgesia  in the rPCA was significantly less than that of EA . The incidence of respiratory depression  in the rPCA was significantly higher than that of EA. There were no significant differences in the incidence of Apgar scores<7 at 5 minutes , the patients’ satisfaction of pain relief during labor analgesia  between rPCA and EA .rPCA can be an optional alternative to EA with similar pain relief and less risk of intrapartum maternal fever. However, rPCA was associated with increased risk of respiratory depression. Future studies with rigorous design and larger sample size are needed to provide more reliable evidences for clinical rPCA and EA use. With the rapid development of medical science, and the increasing demands of modern people on the pain relief and quality of life, labor analgesia has been paid more and more attention by mothers and medical workers . At presEpidural anesthesia (EA), as one of the most common methods of labor analgesia, has the advantages of strong analgesic effect, fixed analgesic plane, long duration, and easy control of drug dosage , 6. It cThis present meta-analysis and systematic review was performed and reported in accordance to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement . Ethics The inclusion criteria of RCT for this meta-analysis were as follows (1) study design: RCT comparing the effects of rPCA and EA in labor; (2) Research population: healthy nulliparous or parous women with single or multiple gestations; (3) The RCT reported the corresponding outcome data such as the incidence of intrapartum maternal fever(body temperature≥38.5°), patients’ satisfaction of pain relief, fetal respiratory depression, and the data can be extracted; (4) The RCT was published and reported in the language of English or Chinese.The literature exclusion criteria for this meta-analysis were as follows: (1) RCTs focused on alternate use of two or more analgesic methods; (2) Duplicate publications; (3) Reviews, editorials, letters or case reports.Two investigators performed a scientific literature search on PubMed, EMBASE, ScienceDirect, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang and Weipu databases. The following keywords o and corresponding Medical Subject Headings (MeSH) were used for search in every database:  AND , we analyzed the reasons for the heterogeneity, and random effects model was used for data synthesis; Continuous variable effect indicators were expressed by standard mean difference (SMD) and its 95% confidence interval (CI), and dichotomous variable effect indicators were expressed by odd ratio (OR) and its 95% CI. In this meta-analysis, P<0.05 was considered as a statistically significant difference between groups.We used the RevMan 5.3 evaluation software provided by the Cochrane Collaboration for analysis. The heterogeneity among the studies was analyzed by the Q test. If IThe process of RCT selection is presented in Of the included 10 RCTs –24, a toAll domains were evaluated at low or unclear risk of bias, except the domains of blinding outcome assessment. Generally the methodological quality of included RCTs was moderate and acceptable. The quality grading of the risk of bias is presented in Figs The incidence of intrapartum maternal fever within 1 hour of labor analgesia 7 RCTs [2 = 39%, P = 0.16) then fixed model was applied. Meta-analysis indicated that the incidence of intrapartum maternal fever within 1 hour of labor analgesia in the rPCA was significantly less than that of EA  then random model was applied. Meta-analysis indicated that the incidence of intrapartum maternal fever after 1 hour of labor analgesia in the rPCA was significantly less than that of EA  then fixed model was applied Meta-analysis indicated that there was no significant difference in the incidence of Apgar scores<7 at 5 minutes between rPCA and EA  then fixed model was applied Meta-analysis indicated that the incidence of respiratory depression in the rPCA was significantly higher than that of EA  then random model was applied. Meta-analysis indicated that there was no significant difference in the patients’ satisfaction of pain relief during labor analgesia between rPCA and EA .Sensitivity analyses, which evaluate the influence of one single study on the overall risk estimate by removing RCTs one by one, showed that the overall risk estimates were not substantially changed by any single RCT.Remifentanil was used in obstetrics in the 1980s due to its unique pharmacological effects, and was first used for labor analgesia by PCA in 2000 . RemifenRemifentanil is hydrolyzed by non-specific cholinesterase, its volume of distribution is small, the onset time is 30s, the peak effect time is 1min, the action time is 5-10min, the plasma time-dependent half-life is 3-5min, and it is rapidly cleared after drug withdrawal , 28. TheRemifentanil is a synthetic new type of piperidine opioid μ receptor agonist, which has high-efficiency analgesia and can improve the onset speed and hydrolysis speed of anesthesia , 36. TheThe clinical use of rPCA in labor must be cautioned with respiratory monitoring. Severe pain during labor can cause changes in maternal function and metabolism, reduce placental blood flow, and cause fetal hypoxia and other neonatal complications . PreviouThere are some limitations of this meta-analysis worth considering. Firstly, the included RCTs in his meta-analysis were all derived from published literature, and gray literatures were not searched and considered, which may have potential publication bias. Secondly, the data reported for some outcomes in the included RCTs are very limited, we could not conduct subgroup analysis to analyze the reasons for heterogeneity. Besides, the included studies did not report the important outcomes including duration of labor, which need further investigated in the future studies. Thirdly, the blinding design in the patients, intervention and evaluator is still difficult to achieve, which can lead to certain biases to the results. Future studies with larger sample size and rigorous design in different area and populations are needed to elucidate the effects and safety of rPCA.A and EA in labor.In conclusion, rPCA can be used as an optional alternative to EA for pain relief with similar analgesic effects without reducing maternal satisfaction with pain relief and increase adverse neonatal events. However, rPCA is associated with higher risk of maternal respiratory depression during labor. Routine use of rPCA during labor must be accompanied by close respiratory monitoring. Future well-designed studies are needed to provide stronger evidence to explore the efficacy and safety of rPCA and EA in clinical labor analgesia.S1 Table(DOCX)Click here for additional data file.


The results of subgroup analyses demonstrate that (1) there was a significant decrease in IL-6 for studies that were equal to or <8 weeks in duration vs. more than 8 weeks in duration, and (2) IL-6 was significantly reduced in the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnosis  of MDD, but not for the subgroup without DSM diagnosis. Publication year was identified as a potential contributor to heterogeneity of the results from our analysis. Taken together, our findings support the notion that CBT influences peripheral IL-6 in individuals with depression and represents a point of commonality with other antidepressant treatment modalities .There is interest in the role of peripheral interleukin-6 (IL-6) in depression and the effect of treatment . However, the relationship between cognitive behavioral therapy (CBT), IL-6 and depression has not yet been established. We conducted a meta-analysis to explore the association between CBT and change of peripheral IL-6 levels in depressive symptoms or major depressive disorder (MDD). A systematic search of online databases  was completed from inception to May 2021. In total, 10 eligible papers with 940 participants reporting peripheral IL-6 levels before and after CBT were included in the analysis. The main result indicates that peripheral levels of IL-6 were significantly lower after CBT intervention in individuals with depression, with a small effect (SMD = 0.38, 95% CI: 0.07, 0.69, https://doi.org/10.17605/osf.io/tr9yh, identifier: 10.17605/osf.io/tr9yh. Major depression is a major public health issue implicating significant economic and psychosocial burden . CurrentIt is separately reported that disparate antidepressant modalities influence peripheral cytokine concentrations in adults with depression . MoreoveCognitive behavioral therapy (CBT) is a structured, short-term and targeted psychotherapy with replicated evidence of acute antidepressant and recurrence prevention effects in adults with MDD. Cognitive behavioral therapy is one of the most common psychosocial interventions for mental disorders , 20. CogThe mechanism of action of CBT is unknown and its effect on neurobiological systems implicated in depression are not well-characterized. The latest meta-analysis paper revealed that psychosocial interventions including CBT were significantly associated with levels of proinflammatory cytokines or markers . HoweverAgainst a background of inconsistent findings in the extant literature, the aim of the study herein was to use a meta-analysis to comprehensively and systematically evaluate the impact of CBT on changes of peripheral IL-6 levels in individuals with depression. The results of this analysis are intended to guide further mechanistic research and inform conceptual frameworks.Two investigators (HJM and JTX) independently conducted the literature search to identify studies reporting IL-6 levels of subjects with depression before and after CBT intervention. The information in this review was compiled by searching online databases: PubMed, Web of Science, Google Scholar, PsycINFO, Cochrane Library databases, and by searching the reference lists of relevant papers to locate additional studies that were not identified by the database searches. The databases were scanned from inception to May 2021. Systematic searches were completed using terms including “cognitive behavioral therapy,” “CBT,” “psychotherapy,” “inflammation,” “IL-6,” “interleukin,” and “immunity,” “MDD,” “major depressive disorder,” “depressive.”The inclusion criteria were as follows: (1) The study subjects were adults (≥18 years old) with a diagnosis of major depressive disorder (MDD) based on Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria , or MDD with other chronic diseases; Or had a verified scale to assess depressive symptoms ; (2) Follow-up results after CBT intervention were reported (baseline assessment scores vs. post-treatment scores); (3) The peripheral IL-6 levels were evaluated before and after CBT; (4) identified random controlled trials (RCT), open-label studies, and longitudinal studies with pre-test-post-test design were included in our analysis.Exclusion criteria included: (1) Non-original studies  Non-research articles ; (3) Conference abstracts and unpublished literature; (4) case reports, case studies, case series studies, case control studies; (5) Basic experimental research studies ; (6) studies including subjects that did not have a DSM-defined diagnosis of MDD, and/or included case groups with comorbid mental disorder diagnoses  without depressive symptoms; (7) studies without follow-up results (8) studies including healthy individuals or individuals with other diseases analyzed as the control group; (9) studies that did not report on peripheral IL-6 levels as part of the study outcome.N at baseline, clinical diagnosis, comorbidity, IL-6 measure method, diagnostic criteria, study design and duration of intervention were recorded for each eligible study for analysis. All eligible studies were screened and evaluated by two independent investigators. We also carefully verified data from each included article to ensure the accuracy of the extracted data. Any discrepancies were resolved by discussion among all of the authors.The purpose for the meta-analysis was to examine the relationship between CBT and the change of peripheral IL-6 levels in individuals with depression from baseline to endpoint. First author, published year, country, sex , mean age (age range), total I2) test was used to evaluate the heterogeneity across the studies. It has been suggested that the adjectives low, moderate, and high (heterogeneity) be assigned to I2 values of 25, 50, and 75%. If P <0.10 or I2>50%, there would be a high degree of heterogeneity with statistical differences  within a 95% confidence interval (CI). According to the statistical power analysis for the behavioral sciences (2nd edition), the effect size of SMD is judged using the following rules: trivial (SMD < 0.20), small (0.20 ≤ SMD < 0.50), medium (0.50 ≤ SMD <0.80), and a large effect (SMD ≥ 0.80). The chi-square and I-Squared  to assess the quality of included studies . The assThe summary of the article extraction process for this meta-analysis is shown in n = 3); Germany (n = 2); Brazil (n = 2); and China (n = 1), Sweden (n = 1), Hungary (n = 1). Six studies used Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) as diagnostic criteria for depression; two implemented the Center for Epidemiological Survey (CES-D) and one study each used the Positive and Negative Affect Schedule, Hospital Anxiety, and Depression Scale (HADS), respectively. Eight studies had more females than males, among them, one had only female; one study had less females than males; and one did not include the sex. According to the GRADE system, four studies are rated moderate and six are rated HIGH. The main characteristics of the included studies and quality assessments are shown in Ten studies were identified comprising 940 participants were conducted in six countries: USA , the random effects model was adopted for the analysis. Since the scales are consistent across studies, we used SMD for data processing. The results indicate that there was a statistically significant difference in the peripheral levels of IL-6 before and after CBT intervention, with a small effect . In order to explore the potential sources of heterogeneity, subgroup analysis, regression analysis, and sensitivity analysis were carried out in the following studies.Overall meta-analysis results are shown in p = 0.04), but the data heterogeneity remained medium . In the subgroup of developed countries, IL-6 levels do not have a significant overall comprehensive effect (p = 0.11), and its heterogeneity is also large , indicating that subgroup analysis of the classification of developed and developing countries cannot explain the heterogeneity sources of IL-6 levels in all included studies.We performed the subgroup analyses to identify the sources of the literature heterogeneity. For the classification of developed and developing countries, we found that the overall combined change of peripheral IL-6 levels was statistically significant in developing countries , whereas there was no significant difference in subgroup >8 weeks (p > 0.05). Moreover, the heterogeneity was lower in both of the two subgroups. There was strong heterogeneity and significant difference among subgroups .According to the treatment duration of the studies included in our analysis, we used 8 weeks as a cut-off point to conduct subgroup analysis. Four original studies reported a treatment duration ≤ 8 weeks, five studies reported a treatment duration of more than 8 weeks, and one study did not report the treatment duration. As shown in p = 0.05), whereas there was no significant difference in subgroup without DSM diagnosis (p > 0.05). The heterogeneity was high in both of the two subgroups. There was low heterogeneity and significant difference among subgroups .According to the diagnosis method, we used diagnosis of depression as a cut-off point to conduct subgroup analysis. Six original studies reported depression diagnosed method is DSM, four reported others. As shown in t = −2.86, p = 0.02], and the goodness-of-fit of the model was good (Tau2 = 1.423). The estimation of variation among studies was relatively high (Adjusted R-squared = 52.91%).We conducted univariate meta-regression analysis for the year of publication, average age and sex ratio  of the included studies . Among tt = 1.37, p = 0.208. In addition, the results of Begg's test did not show publication bias with z = 1.34, p = 0.180.In order to test the stability of the results, we conducted sensitivity analysis to test the stability of the combined effect sizes, and their 95% CI. As shown in The results of our analysis indicate that CBT is associated with significant decreases of peripheral IL-6 levels with small effect in persons with depressive symptoms or MDD. Due to the potential heterogeneity of main outcome, subgroup analysis and meta-regression analysis were used to identify probable sources of heterogeneity. Subgroup analysis revealed a significant decrease in peripheral IL-6 in studies of 8 weeks duration or less, with no effect noted in studies of >8 weeks duration. The association between CBT and change in peripheral IL-6 was delimited to those studies that codified the diagnosis of MDD using the DSM . It was also revealed that publication year might be a potential contributor to heterogeneity in the findings. Moreover, no potential publication bias was identified in the studies in our analysis.In general, our meta-analysis identified the potential modulating effect of CBT on IL-6. Cognitive behavioral therapy covers a range of strategies that could account for its potential anti-inflammatory effects. Cognitive behavioral therapy can trigger positive lifestyle changes that in turn reduce inflammation . CognitiOur results only identified the changes of peripheral IL-6 in individuals with DSM diagnosed MDD, no statistical changes were reported in individuals with depressive symptoms assessed by other scales. Major depressive disorder is heterogenous in phenomenology, illness trajectory, and pathoetiology . AccordiAccording to Lanquillon , there wOur subgroup analysis showed that only the studies with intervention of less than 8w had a significant decrease in peripheral IL-6, but the changes of peripheral IL-6 in studies with more than 8w had no statistical difference. It has been proposed that IL-6 hyperproduction may play a pathogenetic role in the immunological pathophysiology of major depression due to its critical involvement in the early phase of the immune response cascade. Increased IL-6 activity in severe depression may be linked to hypotransferrinemia, hyperhaptoglobinemia, and hyperactivity of the HPA axis, according to the findings . Thus, oIt is also worth noting that we identified publication year as a source of heterogeneity in our analysis. It is a testable hypothesis that changes in diagnostic criteria and treatments over the past two decades accounts for this variability. It is also possible that refinement of the CBT model and its implementation over the past several decades may be contributing to the observed heterogeneity . Our curMoreover, evidence indicated that women are 1.5 to two times more likely than males to develop depression, and the onset of depression increases during the childbearing years. This female preponderance has been observed to last into elderly life. Patients above the age of 75 had a lower prevalence of depression, which did not appear to be connected to their socioeconomic level. Comorbid diseases, serum IL-6, albumin, and age may all have a role in determining which patients are more likely to develop depression symptoms . TherefoThere are several limitations that affect interpretations and inferences of our study. Firstly, the sample size of this meta-analysis was relatively small . Secondly, studies included in our analysis had varying definitions of depression and five studies included individuals with subthreshold depression. Moreover, the sensitivity analysis indicated that our results had insufficient stability. Additionally, limited information in the included studies betrayed a thorough analysis of the sources of heterogeneity. As with all studies, we could not control for residual confounding effects. Finally, previous antidepressant treatment may also affect the levels of inflammatory factors such as IL-6, but we could not distinguish participants with prescribed medications or medication-free in the original studies.Our results indicate that individuals with MDD or depressive symptoms receiving CBT have lower peripheral IL-6 concentrations. It is unknown whether the change on peripheral IL-6 levels is simply an association or whether the relationship observed has predictive and/or moderational effects. We did not evaluate CBT-IL-6 association from the point of view of dimension-based outcomes. Future studies will need to determine whether elevated IL-6 levels identify a biotype more likely (or less likely) to respond to CBT treatment .The original contributions presented in the study are included in the article/BC and FY conceived and designed the study. HM and JX performed the data extraction and statistical analysis. RM, BC, FY, and KT contributed to the discussion. HM, JX, and RL took the lead in writing the manuscript. All authors discussed the results and commented on the manuscript. All authors contributed to the article and approved the submitted version.This work was sponsored by the MOE (Ministry of Education in China) Project of Humanities and Social Sciences (Project No. 21YJCZH004) and Ph.D. Research Startup Fund of Southwest University (Project No. SWU019039). The funding agents had no role in the design and conduct of the study; collection, management, analysis, interpretation of the data; preparation, review, or approval of the manuscript. The authors alone are responsible for the content and writing of the paper.RM has received research grant support from CIHR/GACD/Chinese National Natural Research Foundation; speaker/consultation fees from Lundbeck, Janssen, Purdue, Pfizer, Otsuka, Takeda, Neurocrine, Sunovion, Bausch Health, Novo Nordisk, Kris, Sanofi, Eisai, Intra-Cellular, NewBridge Pharmaceuticals, Abbvie. RM is a CEO of Braxia Scientific Corp. KT receives personal fees from Braxia Scientific Corp. The remaining 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.


Several studies have explored the relationship between intratumoral microvessel density (MVD) and the risk of postoperative biochemical recurrence (BCR) in prostate cancer (PCa), although the results are contradictory. Therefore, we conducted a meta‐analysis to investigate the effect of MVD on BCR in PCa.We searched PubMed, MEDLINE, Science Direct/Elsevier, the Cochrane Library, CNKI, and EMBase databases from inception through January 2022, with no year or language restrictions, and used NOS guidelines to evaluate the quality of the 19 eligible studies. The derived hazard ratio (HR) and 95% confidence interval (95%CI) were used to assess each endpoint. Data synthesis was performed with RevMan to assess the prognostic value of MVD in PCa and its heterogeneity, while the publication bias was examined using STATA 16.0.p = 0.03; I2 = 83%), T1‐3 , T1‐4 .The subgroup analyses based on European and immunohistochemical antibody none‐factor VII were consistent with primary one. Sensitivity analysis excluding those studies judged to be at high risk of bias in T1‐2 showed a HR of 2.99 , demonstrating the robustness of risk estimates of MVD for the assessment of biochemical recurrence.Our meta‐analysis included 19 articles  on postoperative biochemical recurrence of PCa, among which, 3933 patients were pooled. The predictive ability of intratumoral MVD for different stages of PCa on BCR was T1‐2 (HR, 2.46; 95% CI, 1.08–5.58; Microvessel density is a predictor of BCR among patients with PCa, and earlier T stage PCa with a stronger MVD is associated with BCR. Further studies are needed to investigate neoangiogenesis in different T stages of PCa and whether MVD will be of benefit to the EAU‐recommended tool for biochemical recurrence risk assessment. Microvessel density is a predictor of biochemical recurrence among prostate cancer patients.Moreover,in earlier T stage PCa is, a stronger microvessel density is associated with biochemical recurrence. The three keywords used were PCa, microvessel density, and prognosis. PCa included “PCa,” “prostate tumor,” “prostate neoplasm,” and “prostate carcinoma”; for prognosis, “Prognos*,” “prognostic factor,” “outcome,” “survival” “PSA recurrence,” “PSA failure,” “predictor,” and “predict” were used; and for microvessel density, “mvd,” “microvessel densit*,” “microvessel count,” “neovascularization,” “microvascular densit*,” “vascularity,” “CD34,” “CD31,” “vwf,” and “vascular density” were used. We also retrieved citations from a manual search.2.2To access eligible articles, studies were required to meet certain inclusion and exclusion criteria.2.2.1Exploring the relationship between MVD and the risk of biochemical recurrence.Patients with PCa had not received neoadjuvant therapy or invasive biopsy before tumor resection.Classification of patients with PCa was based on TNM staging.MVD visualized by CD31, CD34, and Factor VII.MVD located in the primary tumor tissue .Evaluation of outcomes on MVD including BCR.Include cohort studies and randomized controlled studies.2.2.2Meeting abstracts, reviews, descriptive studies, case reports, commentaries.Sample size <20.Inadequate information on HR calculations and data synthesis.Non‐English language2.3The information for each study was extracted independently by two investigators (Jinze Li and Xingyu Xiong) with a standardized data form including the following items: first author, publication year, patient source, age, follow‐up, disease stage, specimen acquisition, and results. Among these articles, HR from multivariate analysis was preferred, followed by univariate analysis and Kaplan–Meier survival curve. The primary endpoint was biochemical recurrence, and the secondary endpoint was tumor progression. For studies lacking HR, we calculated the HR using survival curves as described by Tierney.2.4The RoB in the selected studies was assessed by two authors using the Newcastle‐Ottawa Scale (NOS) tool, which assesses selection, performance, detection, attrition, reporting, and other sources of bias (Supplementary Table 2.5p < 0.05 (two‐sided).In assessing the BCR for PCa of T1‐2, T1‐3, and T1‐4, the log HR and the standard error calculated from the published HR and confidence interval (CI) were retrieved. A meta‐analysis was conducted for each outcome using a random effect models for the predictive value of MVD. The relative predictive effects are presented as the HR and 95% CI.We planned to perform a subgroup analysis based on (1) ethnicity and (2) immunohistochemical antibodies none‐Factor VII. STATA 16.0 was employed to assess publication bias via a funnel graph and Egger's test. When publication bias existed, we used trim and fill method via STATA 16.0 to examine the stability of the findings. All statistical analyses were performed using Review Manager 5.4 software and STATA 16.0 software. Statistical significance was defined as 33.1We searched 72 articles, of which 34 were excluded during abstract reading. Thirty‐eight articles were full‐text reviews, of which 19 met our requirements, and each study source was extracted for data synthesis. The reasons for exclusion of articles are presented in Figure 3.2p = 0.0005), for T1‐3 were 2.38 , and the pooled HR (95% CI) for T1‐4 was 1.61 . The results are shown in Figure We performed statistical calculations among the 19 eligible studies associated with biochemical recurrence, including four studies for T1‐2 PCa, six for T1‐3 PCa, and nine for T1‐4 PCa. Individually, the pooled HR and its 95% CI for T1‐2 were 2.46  and 1.66  in T1‐3 and T1‐4, respectively. As shown in Figure We performed subgroup analysis with the following items: the patients' origin (European) and the antibody used to detect MVD (none‐Factor VII) in immunohistochemical staining. We aggregated the studies from three groups T1‐2, T1‐3, T1‐4) based on angiogenic markers (none‐Factor VII) to predict the BCR within HRs. As shown in Figure , T1‐4 ba3.3p = 0.002), which was consistent with the primary one, indicating that publication bias in T1‐3 did not generally change results.Publication bias was assessed using funnel plots and Egger's test with STATA 16.0. However, total number of articles of T1‐2 PCa was 4, there was a risk of overestimating the validity of the results of pubication bias in T1‐2 PCa. We only performed publication bias on T1‐3 and T1‐4. The funnel plots revealing evidence of potential publication bias are displayed in Figures 3.4I2 = 38%, p = 0.0001) in the T1‐2 group.Overall, a sensitivity analysis was conducted, in which one study was removed at a time, and the results are presented in Figures 4Until now, predictors related to BCR can be roughly divided into two categories: tumor biology including the pathological Gleason score and clinical variables including preoperative PSA level, tumor stage, seminal vesicle invasion, lymph node, and surgical margin status, and are widely used as risk factors for BCR, most of which are incorporated through the nomogram. Raisa et al. reported that their BCR nomogram, which included easily applicable variables, could be used to predict BCR within 12 and 24 months of RP in European patients who received RP.We performed a meta‐analysis to explore the ability of MVD to predict the risk of BCR in different stages of PCa. The results of the meta‐analysis demonstrate that, in general, MVD in cancer tissues is associated with postoperative BCR of PCa, but the value of risk prediction differs when considering patients at different clinical stages. For PCa in the T1‐4 population, MVD was associated with poor prognosis, with an HR of 1.61 (1.19–2.19). While only clinically localized prostate was included, the HR for BCR was 2.46 . Interestingly, the risk of PSA recurrence changed when patients were included in different clinical stages. As more higher‐stage patients are included, the HR for predicting BCR in PCa decreases; however, patients diagnosed with pathological stage T3‐4 are prone to undergo more aggressive treatment, such as chemical therapy and anti‐androgen therapy (ADT), after surgery. In contrast, most of the T1‐2 patient population merely undergo surgical resection or radiotherapy and rarely receive additional treatment after surgery, resulting in the patients with PCa in the T1‐2 population being at a higher risk of BCR.Elżbieta Łuczyńska observed that the expression of VEGF in pTNM3 and pTNM4 is significantly higher than that in pTNM1.However, from the perspective of tumor progression, angiogenesis is more intensive in early stage PCa confined to the fibrous capsule than in patients with locally advanced PCa, in which the cancer has breached the fibrous capsule and invaded surrounding tissues. The process of tumor vascularization is vital for the early stage of tumor growth and remains vulnerable to inhibitors. Weidner found that PCa tumor cells rarely enter the blood circulation and undergo micrometastasis before the primary tumor is fully vascularized, and tumor progression and metastasis require tumor cells to enter the bloodstream.Bevacizumab is a monoclonal drug targeting VEGF‐A, which is the main regulator of angiogenesis. Theoretically, bevacizumab can bind to VEGF‐A and interfere with the combination of VEGF‐A and its receptors, blocking the process of tumor angiogenesis and consequently delaying or even inhibiting tumor growth, invasion, metastasis, and other malignant behaviors. Bevacizumab has achieved good performance in the treatment of non‐small cell lung cancer, metastatic colorectal cancer, and breast cancer.Unlike the poor outcome of mCRPC treated with bevacizumab, bevacizumab achieved satisfactory results in clinically localized PCa. In a phase II clinical trial of neoadjuvant docetaxel plus bevacizumab in high‐risk localized patients with PCa, 29% of patients achieved a >50% reduction in tumor volume. It is encouraging that bevacizumab combined with neoadjuvant chemotherapy can reduce the tumor volume and decrease the difficulty of cancer resection.The discrepancy in the predictive value and efficacy of anti‐angiogenesis therapy in different stages of PCa suggests that tumor vascular development and response to antivascular therapy are highly associated with tumor progression. In addition to VEGF, PDGF, FGF, and other typical angiogenesis molecules, Boddy et al. claimed that androgens may regulate VEGF levels by activating HIF in androgen‐sensitive tumors.Currently, with numerous drugs targeting angiogenesis molecules, whether an angiogenesis‐targeted regimen can be a promising choice for PCa requires further exploration among different stages of PCa. The underlying mechanism may involve a complex interaction of angiogenesis‐related molecules and androgens in PCa at different clinical stages, resulting in different predictive values of MVD and discrepancies in the efficacy of angiogenesis‐targeted therapy.The conventional BCR stratification tool proposed by the EAU was based on the GS score, clinical stage, and preoperative PSA. Cooperberg5I2 = 0.0001) among T1‐2 group. Overall, after confirming no extra missing study, performing sensitivity analysis, the original results were considered to be convincing.We failed to perform publication on T1‐2 PCa. Only 4 studies on clinically localized PCa (T1‐2) were included, for publication bias, there is a risk of overestimating the validity of the results of publication bias.We were unable to conclude a quantitative relationship between MVD and PSA relapse time because the median MVD and follow‐up duration were highly heterogeneous among the included studies.6Microvessel density can predict postoperative BCR in different stages of PCa, and as tumor stage increases, the risk of BCR decreases. Whether MVD prediction can supplement existing EAU BCR risk stratification tools requires further research.Jinjiang Jiang contributed to choose research directions. Jinze Li,Xingyu Xiong, Lu Yang were responsible for literature retrieval. Jinze Li, Qiang Wei and Xingyu Xiong contributed to literature inclusion. Shiyu Zhang and Daqing Tan assessed the level of evidence. Jinjiang Jiang and Jinze Li finished the manuscript. All authors read and approved the publication of final manuscript.The authors declare that there are no conflicts of interest.The data that support the findings of this study are available from the corresponding author upon reasonable request.Not applicable.Figure S1Figure S2Figure S3Figure S4Figure S5Click here for additional data file.


Several systematic reviews and meta-analyses have been carried out to assess the impact of synbiotics on lipid profiles and anthropometric parameters. In this regard, an umbrella meta-analysis was performed to provide a more accurate view of the overall impacts of synbiotic supplementation on lipid profile and anthropometric parameters.Databases such as PubMed, Scopus, Embase, Web of Science, and Google Scholar were searched for this study from inception to January 2022. A random-effects model was applied to evaluate the effects of synbiotic supplementation on lipid profile and anthropometric parameters. The methodological quality of eligible articles was evaluated using the AMSTAR2 questionnaire. The GRADE approach was used to evaluate the overall certainty of the evidence in the meta-analyses.p < 0.001, I2 = 0.0%, p = 0.870), BW , waist circumference (WC) , low-density lipoprotein cholesterol (LDL-C) , total cholesterol (TC) , and triglyceride (TG)  but not high-density lipoprotein cholesterol (HDL-C)  following synbiotic supplementation.Meta-analyses of 17 studies revealed significant decreases in body mass index (BMI) (ES: −0.13 kg/m2; 95% CI: −0.19, −0.06, The present umbrella meta-analysis suggests synbiotic supplementation can slightly improve lipid profile and anthropometric indices and might be a therapeutic option for obesity and its related disorders.www.crd.york.ac.uk/prospero, identifier CRD42022304376. It is established that obesity is a multi-factorial, chronic, treatable, and neurobehavioral condition in which excess body fat mass results in adipose tissue dysfunction and abnormal physical forces of fat mass that lead to a variety of metabolic diseases . The incSeveral studies have revealed that overweight and obesity by 2030 in women and men will reach 85 and 89%, respectively . This inThe research protocol has been registered on PROSPERO (registration number: CRD42022304376). We conducted the current investigation in accordance with the PRISMA  .International scientific databases, such as Web of Science, Embase, PubMed, Scopus, and Google Scholar, were searched for relevant published papers till January 2022. The search technique for MeSH and the keywords utilized in this research are as follows: [(“Synbiotics” OR “Symbiotics” OR “Synbiotic”) AND  AND ]. The “*” keyword was used to improve the sensitivity of our study methodology. Also, to prevent the loss of research, a thorough search of references to relevant studies was conducted.in vivo, in vitro, and ex vivo studies, observational studies, case reports, controlled clinical trials, and quasi-experimental studies were excluded from the present study.We followed these PICO criteria: Population/Patients (P: adults aged 18>), Intervention (I: treated with synbiotic), Comparison (C: control group), Outcome (O: anthropometric and lipid profile parameters), and Study design . The previous meta-analyses, reviewed in the present study, investigated the effects of synbiotic supplementation on anthropometric and lipid profile parameters by using their effect size (ES) values and their corresponding confidence intervals (CI). In addition, other typologies of research studies including The outcomes that were investigated in this umbrella meta-analysis included the effects of synbiotic supplementation on anthropometric indices and lipid profile. Among the anthropometric indices, BMI, BW, and WC were investigated and regarding the lipid profile, four indices of LDL-c, HDL-c, TG, and TC were investigated.According to the qualifying requirements, two distinct reviewers evaluated the articles (SSA and MMA). We began by reviewing abstracts and titles. To establish if a research was appropriate for a meta-analysis, the entire texts of relevant papers were analyzed. Disputes were resolved by reaching an agreement with the senior reviewer (MV). The following information was retrieved from the chosen papers: the names of the first authors, the sample size, the publication year, dose of synbiotics, gender, health condition, length of the intervention, and ESs and their CIs.Two reviewers (VM and SSA) independently assessed the methodological quality of the qualifying articles using the AMSTAR2 questionnaire . The queI2 statistic and Cochrane’s Q test were used to detect heterogeneity. When the I2 value >50% or the Q-test had p < 0.1, we considered between-study heterogeneity significant. When considerable heterogeneity existed across studies, we adopted the random-effects model. Subgroup analyses were conducted to identify potential sources of heterogeneity according to a number of variables, including dosage of synbiotic, type of ESs, duration of intervention, and the sample size, age of participants, health condition, bacteria strain type. A sensitivity analysis was performed to detect whether the total ES was associated with a single study. Egger  criteria were used to evaluate the overall certainty of the evidence in the meta-analyses. The quality of the evidence was categorized according to four assessment criteria: high, moderate, low, and very low .8 and 1.3 × 1010 CFU. The quality assessment process was performed in almost all meta-analyses included in the present study, except for one study , according to a pooled analysis of 11 meta-analyses . Synbiotic supplementation in subjects with non-alcoholic fatty liver disease (NAFLD) with intervention >10 weeks, in studies with multi strains  and a sample size of 200 individuals or over led to a remarkable reduction in BMI levels . A significant small-study effect was detected using Begg’s (p = 0.002) unlike Egger’s (p = 0.076) tests. Visual inspection of the funnel plot revealed an uneven distribution of meta-analyses (p < 0.05). The BMI quality of evidence was estimated as moderate performing the GRADE system (based on the indirectness)  .p = 0.004) , which was decreased after subgroup analysis based on the dosage of synbiotic, duration of intervention, mean age, gender, and health condition (9 CFU and subjects with a mean age of >45 years in the duration of intervention >10 weeks contributes to a more effective in reducing BW (p = 0.266). The quality of evidence related to BW was downgraded to moderate due to serious limitations in indirectness  . Howeverondition . Subgrouucing BW . The senrectness .p = 0.016) . Dosage, duration of intervention, strains of bacteria, and health conditions were detected as sources of heterogeneity in the subgroup analysis . Based on the GRADE approach, the overall quality of the evidence for WC was considered low due to serious indirectness and imprecision  . There wanalysis . Synbiot strains . Performrecision .p < 0.001) . The dosage of synbiotics, mean age, and health condition were identified as sources of heterogeneity after subgroup analysis  contributes to a greater impact in the lowering LDL-C concentrations , also a visual inspection of the funnel plot revealed the presence of publication bias (p < 0.05). As shown in Synbiotic supplementation meaningfully reduced LDL-C level based on the 10 meta-analyses with 11 ESs  . Signifianalysis . Subgroutrations . The fol strains . A sensiion bias . TherefoES = −2.24 mg/dl, 95% CI: −3.18, −1.30, p < 0.001), with high heterogeneity between-study , which was decreased after subgroup analysis based on the dosage of synbiotic, duration of intervention, strains of bacteria, type of ESs and health condition. Subgroup analysis showed that the impacts of synbiotic reduction on TC were more robust in studies with participants with NAFLD, age ≤50 years, the sample size of ≤200, type of ES (WMD), and multi strains of bacteria  than the entire sample . Also, a visual inspection of the funnel plot found a significant publication bias among included studies . The quality of evidence related to TC was downgraded to moderate due to serious limitations in indirectness (The effect of synbiotics on TC level was reported in 10 studies with 11 ESs . Our anae sample . Sensiti studies . Thereforectness .p = 0.019). However, significant heterogeneity was detected among studies . The dosage of synbiotics, sample size, health status, and type of ES was identified as sources of heterogeneity in the subgroup analysis . After a visual inspection of the funnel plot, publication bias was observed (p < 0.05). According to the GRADE approach, TG was considered to have a moderate quality of evidence due to indirectness  . In addition, a visual inspection of the funnel plot revealed asymmetry (p > 0.05). The HDL-C quality of evidence was rated as moderate using the GRADE system (based on the indirectness)  . Also, i= 0.051) . Performsymmetry . Therefoectness) .The current umbrella review and meta-analysis summarized the results of 17 meta-analyses, involving a total of 7,772 participants, and demonstrated that synbiotic supplementation could lead to a significant decrease in TG, TC, LDL-C, BW, BMI, and WC, nevertheless, no meaningful change was observed in HDL-C levels.Stratifying the studies in different subgroups demonstrates different features of the effects of supplementation with synbiotics on lipid profile and anthropometric parameters and could help with gaining a conclusive result. For instance, stratifying the studies by the mean age of participants revealed that synbiotics had stronger effects on anthropometric parameters and LDL-C among older individuals (>45) in comparison with younger people. In contrast, the supplementation of synbiotics had a weaker impact on TC among individuals ≥50 years old in comparison with young adults, which is in line with a previous umbrella meta-analysis . The incIt should be mentioned that different health conditions could also affect the efficacy of synbiotic supplementation on the studied outcomes substantially. As an example, the administration of synbiotics had more promising impacts on BMI, body weight, TC, and LDL-C in NAFLD patients. On the other hand, among overweight and obese participants, synbiotics had a more substantial lowering effect on WC. Regarding TG levels, type 2 diabetic patients demonstrated more amending change following synbiotic administration. The lipid profile-lowering property of synbiotics could be due to its effect on insulin sensitivity, especially in NAFLD and diabetic patients , 49. As Another possible factor, which might affect the overall findings, is treatment duration. Short-term administration of synbiotics  resulted in smaller effects on BMI, body weight, TC, and LDL-C compared with long-term supplementation. The synbiotic effect on TG was not time-dependent. Also, WC was reduced significantly only in the subgroup of ≤10-week.2, TC by 1.00 mg/dl, and TG by 0.39 mg/dl. Numerous animal and human studies have demonstrated the beneficial effects of different strains of synbiotics, particularly those belonging to lactic acid bacteria and bifidobacteria, on lipid profile and anthropometric indices. In a study on healthy rats, Hosseinfard et al.   and the production of inflammatory cytokines, which consequently leads to a reduction in lipid profile (via producing short-chain fatty acids (SCFAs) resulting in the prevention of the activation of hydroxymethyl glutaryl CoA reductase (HMG-CoA reductase), a rate-limiting enzyme in the cholesterol synthesis pathway /sterol regulatory element-binding protein (SREBP). Synbiotics also could reduce the accumulation of TG in adipose tissues and the liver by increasing the serum levels of the fasting-induced adipose factor (FIAF) following the inhibition of hepatic lipogenic enzymes mediated by ChREBP and SREBP-1c . Moreover, the increased levels of GLP-1 restrain the activity of gut lipases, which in turn leads to a decrease in TG absorption from the intestine  , and inh SREBP-1 , 64. Altle salts –69. Besile salts . Probiot profile . On the  pathway . Other p pathway  and inte pathway . BesidesSREBP-1c . On the ntestine .On the whole, in the present umbrella meta-analysis, all of the performed meta-analyses of RCTs, which addressed the impacts of synbiotics on lipid profile and anthropometric indices were included. The evaluation of possible biases was carried out. The results were assessed based on different subgroups. However, one of the important and instinctive limitations of the umbrella meta-analysis is that some similar RCTs from various meta-analyses would be re-analyzed in the umbrella meta-analysis, and as a result, these similar RCTs experienced an increased weight in the analysis; therefore, actual results may be even weaker than those acquired.According to the results of the current study, synbiotic supplementation can attenuate TG, LDL-C, and TC levels as well as BW, BMI, and WC. Therefore, synbiotics might be a therapeutic option for obesity and its related disorders. However, it must be noted that several factors namely the intervention duration, synbiotic strains, and different health conditions could vary the beneficial effects of synbiotics.The original contributions presented in this study are included in this article/VM, MV, and MMA wrote the original manuscript and contributed to the conception of the manuscript. SSA and VM contributed to data collection, analysis, and manuscript drafting. MV and AK provided the advice and consultation. PD and VM contributed to the final revision of the manuscript. All authors read and approved the final manuscript.