Recently, several genome-wide association studies have demonstrated a cumulative association of 17q24 rs1859962 gene variants with prostate cancer (PCa) risk, but conflicting results on this issue have been reported. Hence, we performed a systematic literature review and meta-analysis to assess the association between 17q24 rs1859962 gene and PCa risk.Systematic literature searches were conducted with PubMed, EMBASE, Science Direct/Elsevier, CNKI, and the Cochrane Library up to January 2019 for studies focusing on the association of 17q24 rs1859962 gene polymorphism with PCa risk. Meta-analysis was performed with Review Manager and stata software. Combined OR were identified with 95% confidence intervals (95% CI) in a random or fixed effects model.P < 0.05). The combined odds ratios and 95% confidence intervals were as follows: Additive model ; Codominant model ; Dominant model ; recessive model ; allele model .Eight studies were identified, including 7863 cases of PCa patients and 17122 normal controls. Our results revealed significant associations between the 17q24 rs1859962 gene polymorphism and PCa in all genetic models (The present study supports the proposed association between the 17q24 gene rs1859962 and PCa progression. Specifically, this polymorphism is suggested to be a risk factor of PCa. However, studies with larger sample sizes are needed to better illuminate the correlation between 17q24 rs1859962 gene polymorphism and PCa. A genome-wide association study (GWAS) found at least 35 loci related to PCa.,7 Testing of these risk alleles across populations is important. Approximately 42% of the risk of PCa can be explained by heritable genetic factors.Risk factors for PCa increase with age, ethnic background, and familial history of PCa.Chromosome 17q24 belongs to the non-coding pathogenic gene located in the long arm region 2 and 4 of chromosome 17 with a total length of about 600 kb Genes, its biological expression mechanism is not yet clear. SOX9 (SRY (sex determining region Y)-box 9), which is located in relatively close proximity (1 Mb) to the 17q24 rs1859962 risk variant. It is an important gene associated with early embryonic development, it does not directly regulate testicular development, but occurs through the combined action of the SRY gene on the male Y chromosome.–14 several large-scale GWASs have reported these SNP variants and PCa risk correlation, but conflicting results on this issue have been reported. Some studies reported that such a polymorphism may increase the risk of PCa, but others did not.–22 Therefore, we systematically reviewed the available literature and performed a meta-analysis to evaluate the association of the 17q24 rs1859962 gene polymorphism with PCa risk, which might provide valuable insights on the biology of PCa.The long arm of chromosome 17 has been reported in several linkage studies of PCa,22.1This meta-analysis was restricted to published studies that investigated the association between the 17q24 rs1859962 gene polymorphism and PCa risk. Two independent reviewers searched PubMed, EMBASE, Science Direct/Elsevier, MEDLINE CNKI, and the Cochrane Library from their inception until January 2019; no restrictions were placed on the language of the report or the study type. The search terms combined text words and MeSH terms. For example, the search terms for the 17q24 rs1859962 gene were “17q24 rs1859962 gene,” “chromosome 17,” “17q24 gene,” “rs1859962,” or “17q gene,” “17q rs1859962 gene,” those for prostate cancer were “prostate cancer,“ “prostatic neoplasms,” “cancer of prostate,” “cancer of the prostate,” “neoplasms, prostate,” “neoplasms, prostatic,” “prostate neoplasms,” “prostatic cancer,” or “PCa”; and those for the polymorphism were “SNP,” “single-nucleotide polymorphism,” “polymorphism,” “variation,” or “mutation.” All related articles and abstracts were retrieved. In addition, references cited within relevant reviews were retrieved manually; the search only focused on full articles.2.2Inclusion criteria: Studies were included if they tested the association of 17q24 rs1859962 gene variants with PCa. The case groups were PCa patients, while the controls were male, no family history of PCa, negative digital rectal examination, and PSA level <4 ng/mL. Genotyping for the 17q24 rs1859962 gene SNP was conducted using polymerase chain reaction-restriction fragment length polymorphism. Available data were extracted from the article, including eligible and genotyped cases and controls, and the numbers of cases and controls for each 17q24 rs1859962 genotype.Exclusion criteria: Studies were excluded if they involved case reports; were only published as abstracts, reports from meetings, or review articles; lacked a control population; lacked data on genotype frequencies; or duplicated previous publications.2.3Two independent reviewers screened the titles and abstracts of all citations obtained from the literature search. All relevant studies that appeared to meet the eligibility criteria were retrieved. If an ambiguous decision was made based on the title and abstract, the full text was analyzed. The final decision regarding the eligibility of studies was made by reviewing the articles. Disagreements were resolved by consensus or a third reviewer. Two reviewers completed the quality assessment according to the primary criteria for nonrandomized and observational studies of the Newcastle–Ottawa quality assessment scale in meta-analyses.2.4The following data were extracted from the papers by 3 reviewers: authors, year of publication, country, number, and genotyping methods, outcomes of eligible and genotyped cases and controls, and the numbers of cases and controls for each 17q24 rs1859962 genotype. Disagreements were resolved by consensus. Quantitative meta-analysis was performed by 2 reviewers using Review Manager (RevMan) software  and Stata software . Available data were analyzed in the meta-analysis.P-value and the I-square statistic (I2) in the pooled analyses, which represents the percentage of total variation across studies. If the P-value was less than .1 or the I2-value was greater than 50%, the summary estimate was analyzed in a random-effects model. Otherwise, a fixed-effects model was applied. To reduce I error probability, using 5 genetic models for each genotype repeat the comparison several times in pairs. Allele model was calculated for wild type homozygotes versus heterozygotes and mutant type homozygotes, wild type homozygotes versus mutant type homozygotes, wild type homozygotes and heterozygote versus mutant type homozygote. Additive mode was calculated for wild type homozygotes versus mutant type homozygotes. Dominant model was calculated for mutant type homozygote versus wild type homozygotes and heterozygote. Recessive model was calculated for heterozygotes and mutant type homozygotes versus wild type homozygotes. Codominant model was calculated for mutant type versus mutant type homozygotes. The association between 17q24 rs1859962 polymorphism in the 17q24 rs1859962 gene and PCa risk was investigated in an allelic model (T vs G), additive model (TT vs GG), dominant model (TT and TG vs GG), recessive model (TT vs TG and GG), and codominant model (TG vs GG), In addition, publication bias was detected by visual symmetry of funnel plots, with asymmetry suggesting possible publication bias. It was also assessed by Begg and Egger test in the meta-analysis. A P-value of less than .05 was considered to indicate publication bias. We also conducted a sensitivity analysis of the meta-analysis.The combined odds ratio (OR) and its 95% confidence interval (CI) were calculated. Heterogeneity was assessed using the 33.1–22 In addition, all of these studies tested for the 17q24 rs1859962 polymorphism by using restriction fragment length polymorphism analysis after polymerase chain reaction amplification.Figure 3.2P < .05). The combined ORs and 95% CIs were as follows: Additive model    7]) Fig. A, 11A, s5) Table B, 11B.4This study focused on 8 reports in the literature to clarify the association of the 17q24 rs1859962 gene polymorphism with the risk of PCa. For the additive model, dominant model, recessive model, codominant model, and allele model, 7, 3, 2, 2, and 6 studies reported a significant association between the 17q24 rs1859962 gene polymorphism and PCa, respectively, while the others did not. Our results reveal that, overall, significant associations between the 17q24 rs1859962 gene polymorphism and PCa were found in all genetic models. Specifically, the data indicate that 17q24 rs1859962 gene polymorphism might a risk factor of PCa.17q24 SNPrs1859962 belongs to the noncoding pathogenic gene located in the long arm region 2 and 4 of chromosome 17, with a total length of about 600 kb Genes, its biological expression mechanism is not yet clear. SOX9 (SRY (sex determining region Y)-box 9), which is located in relatively close proximity (1 Mb) to the 17q24 rs1859962 risk variant. It is an important gene associated with early embryonic development, it does not directly regulate testicular development, but occurs through the combined action of the SRY gene on the male Y chromosome.–26 Heterozygous SOX9 mutation is the cause of campomelic dysplasia, a severe form of human dwarfism characterized by extreme cartilage and bone malformation, which is frequently associated with XY sex reversal. The identified major targets of SOX9 are collagens (such as type II collagen [Col2a1] and type XI collagen [Col11a2]) during chondrogenesis and the Mullerian inhibiting substance during male sex differentiation. In adult tissues, SOX9 is expressed in intestinal crypts and hair follicles, where it is regulated by the Wnt/h-catenin or Sonic hedgehog signaling pathways and seems to be necessary to maintain stem cell/progenitor cell populations.,30SOX9 belongs to the SOX (Sry-related high mobility group box) family of transcription factors and is a key regulator of developmental processes including male sex determination, chondrogenesis, neurogenesis, and neural crest development. reported that SOX9 can interact with and regulate AR expression in PCa cells, which express high levels of AR in PCa cells indicates that SOX9-regulated genes may similarly play critical roles in supporting PCa growth. SOX9 also acts as a transcription factor in the development of prostate epithelia and its overexpression evidently plays a role in PCa tumorigenesis,34 by the Wnt/h-catenin pathway, which has been implicated in the initiation and progression of many types of cancer. Manuel et al reported that SOX9 has also been identified as a downstream target of oncogene ERG and a recent large histopathological study found a strong correlation between positive ERG status and moderate and high levels of SOX9 in PCa tumor tissues.Recently studies In this meta-analysis the G/G genotype is significantly associated with PCa risk. The transformation from codon T to G at this site, may influenced the biological function express of normal prostate cells, resulting in the increase risk of PCa. However, studies with larger sample sizes are needed to better illuminate the mechanisms of the 17q24 rs1859962 in the PCa tumorigenesis.Our findings suggest that 17q24 rs1859962 gene polymorphism is a risk factor of PCa. The possible mechanisms may the target genes regulated by SOX9, and through stimulate androgen receptor, prostate-specific antigen expression, transcriptional regulation in PCa tumorigenesis, when over expressed.There are some limitations in our study, which need to be taken into consideration when interpreting the results of this meta-analysis. First, the sample size of each study was relatively small, and a total of 7863 PCa patients and 17122 normal controls were investigated in the 8 studies. Second, several studies on this issue were excluded owing to a lack of control data. Furthermore, because of the limited amount of original research, a subgroup of 17q24 rs1859962 gene polymorphism in different race was not conducted. As such, it is difficult to draw definitive conclusions about the clinical value of 17q24 rs1859962 gene variants in PCa.In summary, the results of this meta-analysis suggests that 17q24  is possibly a risk factor of PCa. The possible mechanism behind this may be as follows: the target genes regulated by SOX9, the transformation from codon T to G at this site, may influenced the biological function express of normal prostate cells, and it through stimulate androgen receptor, prostate-specific antigen expression, transcriptional regulation resulting in the increase risk of PCa. However, many important questions remain unanswered, including a more detailed analysis of the interactions between 17q sequence variants with PCa risk variants elsewhere in the genome and whether such modulation reflects SOX9 direct or indirect effects. In any case, SOX9-regulated genes may participate in important processes such as tumor angiogenesis, growth, or invasion. So studies with larger sample sizes are needed to shed more light on the correlation between 17q24 rs1859962 gene variants and PCa.Conceptualization: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Data curation: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Formal analysis: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Funding acquisition: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Investigation: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Methodology: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Project administration: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Resources: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Software: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Supervision: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Validation: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Visualization: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Writing – original draft: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.Writing – review and editing: Feiqiang Ren, Peihai Zhang, Ziyang Ma, Ling Zhang, Guangsen Li, Xiaopeng Huang, Degui Chang, Xunjun Yu.


IL-12B rs3212227 and IL-6 rs1800795 polymorphisms are associated with an increased risk of cervical cancer. However, conflicting results warrant a meta-analysis to obtain more precise estimates. Primary studies have shown that the A comprehensive literate search on PubMed, Web of Science, Scopus, CNKI, and SciELO was performed to collect all eligible studies up to November 10, 2019. The pooled odds ratios (OR) and 95% confidence intervals (CI) were used to calculate the risk. This meta-analysis was carried out by utilizing CMA software. IL-12B rs3212227 and seven studies on IL-6rs1800795 were selected. Pooled ORs revealed that the IL-6 rs1800795 polymorphism was significantly associated with an increased risk of cervical cancer , but not IL-12B rs3212227 polymorphism. Stratified analysis by ethnicity revealed that both IL-12B rs3212227 and IL-6 rs1800795 polymorphisms were associated with risk of cervical cancer in Asian women. A total of eleven case-control studies including four studies on  IL-12B rs3212227 and IL-6 rs1800795 polymorphisms may be used to identify individuals at high risk of cervical cancer in Asian women.Our pooled data revealed that the IL-12 and IL-6 with an increased risk of cervical cancer.Cervical cancer is the second most commonly diagnosed malignancy and third leading cause of cancer-related mortality among women in less developed countries . According to GLOBOCAN, cervical cancer accounts for 528,000 new cases and 266,000 deaths worldwide in 2012 . Although, it has been widely accepted for several decades that Human papillomavirus (HPV) is the main risk factor for development of cervical cancer , HPV infections have developed to persistent infection in only a very few cases and it is sufficient to induce cervical cancer in an even smaller proportion . Thus, many scientists acknowledge that etiology of cervical cancer is multifactorial and several factors such as sexually transmitted infections, reproductive factors, hormonal influences, genetics and host factors are responsible for development of cervical cancer . However, studies revealed a preventive role for antiretroviral therapy (ART) on cervical lesion incidence and progression and promotion of regression . In the recent years, several number of genome-wide association studies (GWAS) have been performed to evaluate the effects of different cytokines in development of cervical cancer, and many case-control studies have reported the association of IL-12 is a potent pro-inflammatory cytokine that plays a central role in cellular immunity which is mainly produced by phagocytic cells, such as dendritic cells, monocytes, macrophages, neutrophils, and microglia in response to antigenic stimulation. IL-12 has a number of proinflammatory biological functions and its pleiotropic functions which drive cellular immunity support its exploration as an antitumor agent. Therefore, in clinical studies it has been evaluated as an experimental agent for treatment of numerous tumours . The IL-12B gene is mapped to chromosome 5q31-33 and encodes the p40 subunit of interleukin 12 . Moreover, IL-6 is a multipotent cytokine that regulates immune and inflammatory responses . Moreover, IL-6 has been considered as a “metabolic hormone” which affects metabolism of glucose, protein and lipids . The human IL-6 gene is localized to chromosome 7p21-24, consists of seven exons and spanning 12.8 kb .IL-12 rs3212227 and IL-6 rs1800795 polymorphisms with risk of cervical cancer. Some epidemiological studies suggested that IL-12B rs3212227 and IL-6 rs1800795 polymorphisms are associated with an increased risk of cervical cancer. However, two recent meta-analyses were performed to evaluate IL-12B rs3212227 and IL-6 rs1800795 polymorphisms with cervical cancer risk and their results indicated that no significant association was found among all ethnicities . Therefore, controversy and inconformity still remained about IL-12B rs3212227 and IL-6 rs1800795 polymorphisms and most of studies recruited a limited sample capacity, which is insufficient to get a firm conclusion about the associations of these polymorphisms with development of cervical cancer. Thus, we systematically reviewed previous publications and a meta-analysis was conducted to evaluate the associations of IL-12B rs3212227 and IL-6 rs1800795 polymorphisms with risk of cervical cancer.Up to now, many related articles have evaluated the association of Primary Search StrategyIL-12B rs3212227 and IL-6 rs1800795 polymorphisms and cervical cancer risk up to November 10, 2019. The combination of following keywords and terms were used:  AND (‘’Interleukin 12’’ OR ‘’IL-12’’ OR ‘’1188A>C’’ OR ‘’rs3212227’’) AND (‘Interleukin 6’’ OR ‘’ -174G>C’’ OR ‘’rs1800795’’) AND (‘‘Polymorphism’’ OR ‘‘Mutation’’ OR ‘‘Genotype’’ OR ‘‘Allele’’ OR ‘‘Variation’’ OR ‘‘Variant’’). Meanwhile, hand searching of the references in retrieved reviews and eligible articles were performed as sources to find other relevant publications. Languages were limited to English, Portuguese, Farsi and Chinese.Ethical approval was not necessary for the present meta-analysis. We systematically searched PubMed, EMBASE, Wed of Science, Elsevier, Google Scholar, Cochrane Library, SciELO, SID, WanFang, VIP, Chinese Biomedical Database (CBD) and Chinese National Knowledge Infrastructure (CNKI) comprehensively for all publications regarding the association Including and Excluding CriteriaIL-12B rs3212227 and IL-6 rs1800795 polymorphisms with risk of cervical cancer; and 4) enough and available data to figure out odds ratios (ORs) and 95% confidence intervals (CIs). In addition, we also restricted these exclusive criteria: 1) studies without control group (case only studies); 2) insufficient data offered to analyze or unavailable data; 3) studies were carried out based on animals and in vitro studies; 4) studies evaluated the association of other polymorphisms at IL-12 and IL-6 genes with cervical cancer; 5) case reports, case series, letters, comments, reviews, and previous meta-analyses 6) overlapped data or duplication.We set these inclusive criteria for recruited publications: a) studies with case-control or cohort design; 2) published studies in English, Chinese and Farsi; 3) studies evaluated the association of Data extractionAll recruited studies had to be seriously scanned by two individual researchers separately. If there was a dispute between the two researchers, they would reach a consensus by discussing or a third researcher. We extracted the following information from eligible studies: name of the first author, year of publication, country of origin, ethnicity of participants, genotyping methods, source of controls, total numbers of cases and controls, genotyping method, genotypes frequencies of cases and controls, minor allele frequencies (MAFs) and Hardy-Weinberg equilibrium test in control subjects.Statistical AnalysisIL-12B rs3212227 and IL-6 rs1800795 polymorphisms with risk of cervical cancer was measured by odds ratios (ORs) with 95% confidence intervals (CIs). The statistical significance of the pooled OR was determined using the Z-test. Pooled estimates of the OR were obtained by calculating a weighted average of OR from each study. The pooled ORs was calculated under all five genetic models, i.e., allele (B vs. A), homozygote (BB vs. AA), heterozygote (BA vs. AA), dominant (BB+BA vs. AA) and recessive (BB vs. BA+AA). A χ2-based Q test was calculated for assessing the heterogeneity among recruited investigations and if the P-value of Q test exceeded 0.05 that meant there was no obvious heterogeneity. In addition, I2-value was used to quantify the proportion of the between study heterogeneity . Random-effect models (DerSimonian-Laird method) would be adopted for analyses if I2 was >50%. Otherwise, analyses would be conducted with fixed-effect models (Mantel- Haenszel method). Genotype frequencies of controls for each study using goodness-of-fit test (chi-square) and a p-value less than 0.05 was considered as significant disequilibrium (HWE-violating). Sensitivity analysis was conducted by excluding one study at a time to examine the stability of the pooled results. Begg’s funnel plot and Egger’s linear regression test were applied to assess potential publication bias, in which P<0.05 was considered statistically significant. All of the statistical calculations were performed using Comprehensive Meta-Analysis (CMA) software version 2.0 . Two-sided P-values < 0.05 were considered statistically significant.An ethical approval was not necessary as this study was a meta-analysis based on previous studies. The strength of association of Characteristics of Included StudiesIL-12B rs3212227 and IL-6 rs1800795 polymorphisms and cervical cancer risk, 297 relevant studies up to November 05, 2019 were identified. After reading titles and abstracts, 139 irrelevant and duplicate articles were excluded. Another 95 articles were subsequently excluded because not reporting useful data for meta-analysis, review, case only study, and not being case-control studies. Finally, a total of eleven case-control studies including four studies on IL-12B rs3212227  and seven studies on IL-6 rs1800795  were selected. Characteristics of included studies are shown in By electronic and manual searches concerning the association of Quantitative Data SynthesisIL-12B rs3212227 PolymorphismIL-12B rs3212227 polymorphism and cervical cancer risk are shown in IL-12B rs3212227 polymorphism and cervical cancer risk under all five genetic models genetic models, i.e., allele , but not among Brazilian women  and IL-6 rs1800795 polymorphism .Begg’s funnel plot and Egger’s test were inspected to evaluate the possible publication bias in this meta-analysis. The shape of the funnel did not show any obvious asymmetry under all five genetic models for bothorphisms . MoreoveIL-12B rs3212227 polymorphism was not significantly associated with an increased risk of cervical cancer. However, our subgroup analysis revealed that IL-12B rs3212227 polymorphism was significantly associated with risk of cervical cancer in Asians. Roszak et al., in a case-control study reported that the IL-12B rs3212227 might be contributed to an increased risk of cervical cancer in Polish population. However, de Carvalho et al., (2012) reported that IL-12B rs3212227 polymorphism has a protective effect in development of cervical cancer among Brazil women. Moreover, Han et al., (2008) in an earlier study identified that there was no relationship between cervical cancer and IL-12B rs3212227 in Korean population. In 2017, Zheng et al., (2017) in a meta-analysis of 33 studies with 10,587 cancer cases and 12,040 cancer-free controls evaluated association of IL-12B rs3212227 with cancer risk. Their pooled data showed a significant association between IL-12B rs3212227 polymorphisms and overall cancer risk, especially in hepatocellular carcinoma, nasopharyngeal cancer, and among Asians. However, their stratification analyses demonstrated that IL-12B rs3212227 was not associated with cervical cancer. In 2015, Chang et al., (2015) in a meta-analysis of five case-control studies with 2,552 cases and 2,232 controls were evaluated association of IL-12B rs3212227 with cervical cancer. Their results revealed that rs3212227 polymorphism in IL-12 gene may not be the risk factor to cervical cancer.Our pooled data showed that IL-6 rs1800795 polymorphism was associated with an increased risk of cervical cancer in the overall population. Similarly, Duan et al., (2018) in a meta-analysis of seven publications found that IL-6 rs1800795 polymorphism was associated with cervical cancer risk. In 2017, Zidi et al., (2017) in a case-control study evaluated the effects of IL-6 rs2069845, rs2069840, rs1474348, rs1800795, rs1800797, and rs2069827 polymorphisms with risk of cervical cancer among Tunisian women. Their results revealed high linkage disequilibrium (LD) between rs2069845, rs2069840, rs1474348, and rs1800795 polymorphism. Moreover, their 6-locus haplotype analysis have identified that GACCCA haplotype to be positively associated with an increased risk of cervical cancer, while GAGGGG haplotype was negatively associated with occurrence of cervical cancer, thus suggesting a protective role for this haplotype in development of this disease. They have reported that IL-6 rs1800795 polymorphism might be has a protective role in development of cervical cancer. In 2016, Pu et al., (2016) in a case-control study of 360 cervical cancer cases and 728 controls evaluated the relationship between rs1800795 and rs2069837 polymorphisms at IL-6 and cervical cancer among Chinese women. Their results revealed that mutant alleles of rs1800795 and rs2069837 polymorphisms were associated with an increased risk cervical cancer. de Lima et al., (2016) revealed that there was no significant association between the IL-6 rs1800795 polymorphism and HPV infected women or uninfected controls. Moreover, they have not found any significant association between TGF-β1 +869T>C and +915G>C polymorphisms and the risk of HPV infection in the patients. Thus, they have hypothesized that the IL-6 rs1800795 polymorphism did not play a role in the risk of HPV infection in the Brazilian population .In 2006, Nogueira De Souza et al., (2006) for first time in a case-control study with 56 cases and 253 controls evaluated the association of IL-6 rs1800795 polymorphism with cervical cancer in a Brazilian population. Since a few studies evaluated the association in different population. Our pooled data revealed that Between-study Heterogeneity in a meta-analysis refers to the variation in study outcomes between studies . Moreover, the extent to which effect sizes vary within a meta-analysis is called heterogeneity. Heterogeneity is to be expected in a meta-analysis and assessment of heterogeneity. Thus, the proportion of between-study heterogeneity is one of the major concerns in meta-analysis because nonhomogeneous study has high possibility to mislead results . Therefore, the assessment of heterogeneity is necessary, as high heterogeneity could be caused by the fact that there are actually two or more subgroups of studies present in the data, which have a different true effect. According to our previous meta-analyses, we suggested that heterogeneity might be due to differences in study design, sample size, genotyping methods, disease heterogeneity, and to the different roles played by gene-gene and gene-environment interactions . Moreover, after subgroup an analysis, heterogeneity was obviously decreased in Asians; however, the corresponding pooled ORs were not materially altered after deleting these studies, indicating that our results were statistically robust. Publication bias is another key factor that might affect the quality of a meta-analysis . Both Begg’s and Egger’s test were used to assess publication bias in this study. No significant publication bias was observed when all studies were included.IL-12B rs3212227 and IL-6 rs1800795 polymorphisms was relatively small, with limited statistical power to explore the associations. Third, included studies are still so limited that we cannot perform subgroup analysis by ethnicity, genotyping methods and source of controls. Accordingly, it is required that a more precise analysis could be performed if sufficient individual study in globally populations were available. Fourth, there was heterogeneity between studies for both IL-12B rs3212227 and IL-6 rs1800795 polymorphisms which could distort our pooled data. Fifth, due to lack of original data in the selected studies restricted us to continue investigating some potential interactions, such as age, HPV infection, reproductive factors, hormonal influences, family history, environmental factors, and lifestyle. Hence, our pooled ORs might have some bias to a certain degree. Finally, cervical cancer is a complex disease with etiological factors that can be subdivided into extrinsic and intrinsic factors, whereas, in the current meta-analysis, the effects of these factors were not performed due to the insufficient data. Furthermore, plausible effects of gene-gene and gene-environment interactions on development of cervical cancer risk were not taken into account because of limited data as well.Several limitations should be acknowledged for interpretation of our pooled ORs. First, in the current meta-analysis we have selected only eligible published articles, so some relevant unpublished studies might be missed, generating certain publication bias, though not detected even with funnel plot or Egger test. Second, the sample size for both  IL-12B rs3212227 and IL-6 rs1800795 polymorphisms could be used to identify individuals at high risk of cervical cancer in Asian women. In view of the above mentioned restrictions, high-quality researches with larger sample sizes are needed to assess the effect among different ethnicities and to validate our results.In summary, our pooled data revealed that


The link between food insecurity and depression in people living with HIV/AIDS (PLWHA) has been explored in numerous studies; however, the existing evidence is inconclusive due to inconsistent results. Therefore, the objective of this systematic review and meta-analysis is to examine the relationship between food insecurity and depression in PLWHA.We systematically searched PubMed, EMBASE, and Scopus to identify relevant studies. A random-effect model was used for conducting the meta-analysis. We assessed the risk of publication bias by funnel plot and Egger’s regression asymmetry test.In this review, seven studies were included in the final analysis. Our meta-analysis revealed that food insecurity significantly increased the risk of depression in PLWHA [RR 2.28 (95% CI 1.56–3.32)]. This association remained significant after adjusting for the confounding effects of drug use [RR 1.63 (95% CI 1.27–2.10)], social support [RR 2.21 (95% CI 1.18–4.16)] as well as ART drugs [RR 1.96 (95% CI 1.17–3.28)]. Our subgroup and sensitivity confirmed the robustness of the main analysis.This systematic review and meta-analysis suggest a significant association between food insecurity and increased risk of depression PLWHA. Therefore, early screening and management of food insecurity in PLWHA seem to be necessary. According to the U.S. Department of Agriculture, food insecurity refers to “a lack of consistent access to food for an active, healthy life” . Food inEpidemiologic evidence also showed that the reported prevalence of food insecurity is remarkably high in people living with HIV/AIDS (PLWHA) and is associated with poor HIV health outcomes , 8. For A substantial body of evidence has linked food insecurity in PLWHA to an increased risk of depression , 12. ForAlthough the above epidemiologic studies found a greater risk of depression in PLWHA who were food insecure, these results are not constant all over the available studies; there are also articles that reported no significant risk of depression in PLWHA . Thus, tWe conduct this systematic review and meta-analysis in accordance with the preferred reporting items for systematic review and meta-analysis guidelines (PRISMA) . We utilThree authoritative electronic databases  were systematically searched for pertinent studies. We searched without restriction on the date of publication. The systematic literature search was conducted in May 2019. The search terms and keywords included (Food insecurity OR food insufficiency) AND (HIV OR Human immune deficiency Virus OR AIDS OR Acquired immune deficiency syndrome) AND (depression OR depressive symptom OR depressive disorder). We also manually searched to identify additional relevant studies.Articles satisfying the following criteria were included in this study: First, all observational study . Second, the exposure of interest was food insecurity. Third, the outcome was depression. Fourth, the study population was PLWHA. Fifth, studies that reported relative risks (RR) or odds ratio, estimates with the respective 95% confidence intervals (CIs), or studies that reported data to calculate these. In this review, we excluded editorials, comments, case reports, reviews, letters, abstracts presentations, as well as studies published in a non-English language.Two reviewers (MS and LT), in an independent manner, used a predesigned standard form to extract the data, which included the first author’s name, publication year, the study design, country, confounders adjusted for, risk estimate (OR/RR) and their 95% CI as suggested by PRISMA guidelines . We resoThe Newcastle–Ottawa quality evaluation scale (NOS)  was used2 statistics were used to assess heterogeneity .Figure I2 = 87.62%; Q = 42.30; df = 4; p < 0.0001), but not for cross-sectional studies  ), whereas based on cross-sectional studies was 3.24 (95% CI 1.85–5.68). The heterogeneity was significant for cohort studies (6–3.12), In our stratified analysis by the level of food insecurity, the risk of depression was 1.83 (95% CI 1.09–3.07)), 1.95 (95% CI 0.85–4.52)), 2.59 (95% CI 1.03–6.48)) respectively for mild, moderate and severe food insecurity. The observed differences in risk estimates between the groups were not statistically significant (P = 0.813)  provided evidence of substantial publication bias for the association between food insecurity and the risk of depression in PLWHA  but it was significant in those that did not adjust for the effects of drug use  ] as it was in the studies with no adjustment [RR 2.71 (95% CI 1.46–5.00)]. In this analysis, the observed difference in risk estimates of depression (RR) between the groups was not significant (P = 0.134). The reported heterogeneity across the studies was also not significant in studies that adjusted for the confounding effects of drug use  but it was significant in those that did not adjust for social support  ] as well as in studies that did not account for confounding effects of social support [RR 2.32 (95% CI 1.48–3.63)]. This analysis resulted in no significant heterogeneity between studies that adjusted for social support  but it was significant in those studies that did not adjust ART drugs   ranging between 1.88 (95% CI 1.41–1.70) and 2.58 (95% CI 2.52–4.29) after the deletion of a single study. This finding indicates that our findings were robust and not dependent on a single study  that was unaffected by the level of adjustment for ART drug use, the degree of social support, as well as substance use (drug use). When we limit the analysis by the level of food insecurity, the risk was higher for severe food insecurity (RR = 2.59) followed by moderate (RR = 1.95) and mild food insecurity (R = 1.83), which supports the robustness of the main analysis. This finding suggests the necessity of the application of early screening and intervention strategies of food insecurity in PLWHA.However, the included cross-sectional studies, the sample sizes, and the level of adjustment for the potential confounding factors must be considered. The level of adjustment factors was inconsistent in the included seven studies. Drug use (2 studies), age of participants (4 studies), on ART (2 studies), and social support (2 studies) were the most common potential confounders taken into account in the included studies. Only one study accounted for the possible confounding effects of the previous history of depression . This stIn fact, the robustness of an increased risk of depression in PLWHA with food insecurity was supported by our s analysis that we conduct in the current study: Firstly, the robustness of the observed association between food insecurity and depression was supported by our dose–response analysis. In this analysis, we found a greater risk of developing depression in those participants with severe food insecurity followed by moderate and mild food insecurity. These findings suggest the possible causal association between food insecurity and depression. Secondly, the robustness of the association observed in the current study was also supported by the sensitivity analyses that we conducted restricting the analysis to studies that controlled the confounding effects of drug use, ART drugs, and social support. In this analysis, we found the increased risk of depression in those PLWHA studies which accounted for the possible effects of drug use [RR 1.63 (95% CI 1.27–2.10)] social support [RR 2.21 (95% CI 1.18–4.16)] as well as those studies that adjusted for effects of ART drugs [RR 1.96 (95% CI 1.17–3.28)].Even though our meta-analysis resulted in a significant association between food insecurity and depression in PLWHA, the observed differences across the seven studies led to a significant level of between-study heterogeneity in our final analysis. The stage of the disease, the country, and the exposed population differed on a number of characteristics which may have contributed to the variance in the risk of depression in those PLWHA who were food insecure. Nevertheless, our leave-one-out sensitivity analysis indicated that the risk of developing depression remained virtually unchanged from the main analysis. This finding suggests that our findings were strong and not significantly influenced by a single study. Additionally, our subgroup analysis and sensitivity analysis by the degree of food insecurity as well as the level of adjustment to a range of confounding factors supported the robustness of our findings. Moreover, in order to make the finding of the current meta-analysis meaningful, we have used a random-effects model to pool risk estimates from the individual studies. It is widely held that the summary effect estimates in the random effect model meta-analysis are more conservative than fixed effect summaries in the epidemiological meta-analysis, suggesting the robustness of our findings .In our study, two of the evidence came from cross-sectional studies therefore the possibility that depression in PLWHA may lead to rather than precede the diagnosis of food insecurity might be considered. This is because epidemiologic evidence reported a reciprocal relationship between food insecurity and depressive symptoms . SupportThere is a range of explanations for the associations between food insecurity and increased risk of depression in PLWHA. Firstly, food insecurity is linked with incomplete HIV viral load suppression and less immune reconstitution in PLWHA, which in turn linked with a higher risk of depression –39. SecoThis systematic review and meta-analysis have several strengths: Firstly. First, we utilized a predesigned search strategy, data abstraction, quality assessments, analysis, data extraction, and quality assessment to minimize the reviewer’s bias. Secondly, we performed a sensitivity and subgroup analysis based on drug use, level of social support, and use of ART drugs to identify the small study effect and the risk of heterogeneity in analyses of the risk of depression and those with food insecurity. Thirdly, we use a standard tool to evaluate the quality of the included studies (NOS) and our evaluations showed that the methodologic qualities of the included studies were good.However, the current review also has some limitations: (1) our meta-analysis resulted in significant associations between food insecurity and depression, but the degree of adjustments was inconsistent across the studies and important confounding variables including the effects of drug use, social support, previous history of depression, as well as ART drugs, were not adjusted in most studies. (2) Our final analysis showed significant heterogeneity between the studies. However, the observed variations between the studies may not be a major issue because our sensitivity and subgroup analysis resulted in a greater risk of depression in those food-insecure participants in both cohort 2.06 (95% CI 1.36–3.12)) and cross-sectional 3.24 (95% CI 1.85–5.68) studies. (3) The inclusion of a relatively low number of studies in our subgroup and sensitivity analysis is the other limitation of this review, which might reduce the precision of the reported estimate. (4) Pertinent studies published in a language other than English may have been missed. Finally, we found a significant publication bias the possibility of publication bias indicating the possibilities of remained studies due they may not be reported or published based on their findings or other factors. (5) We have not conducted the literature search in PsycINFO to identify studies relevant to the current review, which is one of the authoritative databases in mental health. In fact, we have conducted our systematic search for relevant studies in the three commonly used databases in mental health such as EMBASE, PubMed, and Scopus. We have also tried to include all the potential articles relevant to the review by our manual search and we believe that we have included the required important articles to estimate the pooled relative risk for the association between food insecurity and the risk of depression in people living with HIV/AIDS.This systematic review and meta-analysis suggest food insecurity is associated with an increased risk of depression in PLWHA. Early screening for food insecurity and depression is warranted in PLWHA.Additional file 1: Table S1. The quality of the included studies based on NOS score (9 point score).Additional file 2: Table S2. The sensitivity analysis of food insecurity and the risk of depression in PLWHA after each study removed.


The aim of this study is to evaluate the impact of diabetes, hypertension, cardiovascular disease and the use of angiotensin converting enzyme inhibitors/angiotensin II receptor blockers (ACEI/ARB) with severity  and mortality of COVID-19 cases.Systematic review of the PubMed, Cochrane Library and SciELO databases was performed to identify relevant articles published from December 2019 to 6th May 2020. Forty articles were included involving 18.012 COVID-19 patients.The random-effect meta-analysis showed that diabetes mellitus and hypertension were moderately associated respectively with severity and mortality for COVID-19: Diabetes [OR 2.35 95% CI 1.80–3.06 and OR 2.50 95% CI 1.74–3.59] Hypertension: [OR 2.98 95% CI 2.37–3.75 and OR 2.88 (2.22–3.74)]. Cardiovascular disease was strongly associated with both severity and mortality, respectively [OR 4.02 (2.76–5.86) and OR 6.34 (3.71–10.84)]. On the contrary, the use of ACEI/ARB, was not associate with severity of COVID-19.In conclusion, diabetes, hypertension and especially cardiovascular disease, are important risk factors for severity and mortality in COVID-19 infected people and are targets that must be intensively addressed in the management of this infection. The World Health Organization declared the SARS-CoV-2 outbreak, the Coronavirus Disease–COVID-19, as pandemic on 11th of March of 2020. At that time, it affected 114 different countries, being responsible for about 4 thousand deaths around the world. Until the end of May, SARS-CoV-2 infection had already affected more than 200 countries/regions and accounted for more than 360 thousand deaths worldwide [Considering the prognosis of the COVID-19, approximately 80% of patients have mild illness, 14% have severe illness and 5% critical illness , 3. CurrSince the first reports of COVID-19 in Wuhan, China, high frequencies of diabetes, hypertension and cardiovascular disease among hospitalized patients and in those with fatal outcome have shown the importance of these co-morbidities as a risk factor for serious outcomes and lethality . MoreoveAs the pandemic advanced to other continents, data from Europe and Americas have confirmed the disturbing relationship between diabetes, hypertension and cardiovascular disease and COVID-19 outcomes , 9. ThesWe conducted this study in accordance with the PRISMA Checklist   and it wA comprehensive search of the PubMed, Cochrane Library and SciELO databases was performed to identify relevant articles published in English and Chinese from December 2019 to 6th May 2020. The search terms were as follows: “ COVID19 disease-CoV-2 infection” (COVID-19 virus disease OR 2019 novel coronavirus infection OR 2019-nCoV infection OR coronavirus disease 2019 OR coronavirus disease-19 OR 2019-nCoV disease OR COVID-19 virus infection) AND severity outcomes terms, that includes “Intensive Care Unit” , “Need for Mechanical Ventilation”  or “Death”  AND Comorbidities Including “Hypertension and cardiovascular disease” , “Diabetes Mellitus” . Additionally, references cited in the retrieved articles were also examined to find relevant studies that had not been identified by database searches.Observational studies that met the following criteria were included: 1) study design ; (2) presence of the following comorbidities ; (3) use of ACE inhibitors and/or ARB. Only adult patients aged 18 years or older were included. We excluded reviews, case report, editorials, letters, expert opinions, animal and experimental studies. We also did not include studies that did not report the interest outcomes  (see below). Articles in English and Chinese were included. The inclusion process followed the PRISMA flow-chart and is depicted in detail in Fig.  study deThe primary outcomes were (1) Severity of COVID-19 including: (Intensive Care Unit (ICU) admission or need for mechanical ventilation or low O2 saturation (< 90%) and (2) mortality due to confirmed COVID-19. Only intra-hospital mortality was considered.The systematic search was performed by 3 pairs of reviewers who extracted data in a double-blinded manner. Disagreements were solved by discussion within the pair of delegated authors and then confirmed by the whole group.Critical Appraisal Checklist for Cohort Studies and Critical Appraisal Checklist for Analytical Cross Sectional Studies [Data were extracted from the 40 studies selected and recorded using standardized forms. It included authors’ first names, study location, type of study, numbers of participants, the exposition factors  and the outcomes Table . The qua Studies .Table 1C2 test and the I2 statistic. A p value < 0.05 for the Q-statistic was considered to indicate substantial heterogeneity. Random-effects model was used for comparison to address heterogeneity. To assess publication bias, through the qualitative assessment, we performed Funnel Plots and evaluated the distribution visually and by performing the Egger’s regression test  version 3.0. To provide a quantitative estimate of the association of the morbidities of interest  with severity outcomes  or death in COVID-19 patients, adjusted ORs with corresponding 95% confidence intervals (CIs) , with no significant publication bias .For the analysis of severity, 18 studies were included, with a total of 4.305 patients with 564 diabetes analyzed. A random-effect meta-analysis estimated a pooled odds-ratio (OR) of 2.35 (95% CI 1.80–3.06) . A random-effects analysis showed a pooled OR of 2.50 (95% CI 1.74–3.59). There was a moderate heterogeneity I2 = 49.89 p = 0.009. There was no publication bias: Eggers test: – 0.4887; p = 0.48. In the analysis of mortality, 13 studies were included, with a total of 3.822 patients, being 1007 with hypertension. The random-effect analysis indicated an OR 2.88 (95% CI 2.22–3.74)    Fig. g. There This is one of the largest meta-analysis, to our knowledge, associating cardiovascular disease, diabetes and hypertension with COVID-19 outcomes. It was able to analyze 40 papers, with 18.012 confirmed COVID-19 patients, including 564 with diabetes, 1315 with hypertension and 505 with cardiovascular disease. We identified a moderate positive association between diabetes mellitus and hypertension with COVID-19 severity and mortality, and a strong positive association with the report of previous cardiovascular disease with both outcomes. On the other hand, no association was found between the use of ACE/ARBs with severity.2: 72%) and severity of the COVID-19 infection  [The link between diabetes and COVID-19 outcomes was previously detected in meta-analyses with a smaller number of studies –58. In aI2: 45%) . PatientI2: 45%) , 63.Multiple pathophysiological mechanisms can support the association between DM and COVID-19 severity; however, much of knowledge is derived from SARS-COV infection rather than COVID-19. Compromised innate immune system due to chronic hyperglycemia, pro-inflammatory state characterized by inappropriate and exaggerated cytokine response and underlying pro-thrombotic hypercoagulable have been implicated in this association , 63.Regarding hypertension, Pranata et al. have performed a meta-analysis, searching for the association including solely hypertension and COVID-19 severity/mortality, with 6.560 patients from 30 studies published in PUBMED and in other databases. The authors found that a diagnosis of hypertension was associated with increased mortality , p < 0.001) and COVID-19 severity , p < 0.001) . HoweverWe found that the highest effect size for severity and mortality was related to cardiovascular disease . This corresponds about the double of the risk attributed to diabetes and hypertension for mortality alone, indicating that pre-existing cardiovascular disease is the greatest risk factor to be addressed. Although cardiovascular disease was recognized as an important risk factor for these outcomes in most studies, the intensity of association is variable, possibly due to different definitions and severity of cardiovascular disease. While some authors included cerebrovascular diseases, others included only those with coronary heart disease and/or heart failure.The mechanism associated for the development of atherosclerotic cardiovascular disease is complex and involves a pathological process associated with oxidative stress, inflammation and a prothrombotic status . These sIt is possible that mechanism mediated by ACE2 receptor links type 2 diabetes, hypertension and cardiovascular disease with a higher risk of severe manifestations of COVID-19 infection. It was also documented that some medications can increase ACE2 expression, such as ACE inhibitors (ACEI) and angiotensin 2 receptor blockers (ARBs). In this study, however, the association between the use ACE or ARB and severity or mortality of COVID-19 was not conclusive. We found a remarkably high heterogeneity even after random-effects analysis. We identified the source of heterogeneity in the 9 studies included in this analysis. There were 3 studies , 48, 50 This study has several limitations. First, it included cross-sectional, retrospective cohort and series of cases, with a lack of prospective studies in the field. Second, most of the studies were performed exclusively in China. As the pandemic is advanced through different countries, more data will become available to understand if these results are also valid for other populations. Third, although we have observed a higher intensity in the association between mortality and severity of COVID-19 with cardiovascular disease in comparison to hypertension and diabetes, all three diseases commonly coexist in the same individuals and it is likely that one might have influenced the risk attributed to the others. As the number of patients with an overlap of these conditions was not reported in most studies, it was not possible to determine the independent risk for each of these factors. Finally, since information was scarce in the studies, we were not able to investigate the interference of age, type of diabetes, glycemic control and obesity, a significant risk factor for COVID-19 severity and/or mortality , 72. TheIn conclusion, diabetes, hypertension and especially cardiovascular disease, are important risk factors for severity and mortality in COVID-19 infected people and are targets that must be intensively addressed in the management of COVID-19.Additional file 1. Funnel Plot of each of the morbidities and severity or mortality in COVID-19.


Water, sanitation, and hygiene interventions often fail to show long-term impact on diarrhoeal and/or intestinal parasite risk in many low- and middle-income countries. Less attention has been paid to wider contextual factors that may contribute to high levels of contamination in the domestic environment such as household flooring. The purpose of this study will be to assess the association between diarrhoeal and/or intestinal parasite infection status and unimproved/unfinished flooring in low- and middle-income countries.We will conduct a comprehensive search of published studies  that examined the association between unimproved/unfinished household flooring and diarrhoeal and/or intestinal parasite infection status from January 1, 1980, onwards with no language restriction. The primary outcome will include diarrhoeal and/or intestinal parasite infection status. Databases to be searched include EMBASE, MEDLINE, Web of Science, and Google Scholar. The secondary outcome will be the association between specific pathogens (laboratory confirmed) and unimproved/unfinished household flooring. Independent screening for eligible studies using defined criteria and data extraction will be completed in duplicate and independently. Any discrepancies between the two reviewers will be resolved by consensus and/or arbitration by a third researcher. If data permits, random effects models will be used where appropriate. Subgroup and additional analyses will be conducted to explore the potential sources of heterogeneity  and potential risk of bias of included studies.This review will provide a comprehensive examination of a possible association between suboptimal household flooring and increased risk of enteric pathogen infection, highlight gaps for future research in high risk areas, and inform intervention design for future planned studies in Kenya and/or elsewhere in the region.PROSPERO registration number: CRD42019156437 Enteric parasites and diarrhoeal disease are amongst the most widespread diseases in low- and middle-income settings –3, with The relationship between water, sanitation, and hygiene (WASH) and enteric/parasitic disease is complex. Global estimates suggest that improvements in water and sanitation have contributed to reductions in enteric disease burden . HoweverThere is increasing interest in ‘healthy homes’ and infectious disease, which at this stage has been primarily focused on vector control; however, there is an urgent need to assess the relationship between the built environment and its impact on enteric infection risk. While some observational studies have suggested no association between unimproved flooring and enteric pathogen risk, multiple observational studies have shown associations between unimproved flooring and diarrhoeal risk  as well To foster the design of more effective integrated control strategies, the main aim of this systematic review and meta-analysis will be to assess the association between enteric pathogen infection and sub-optimal or unimproved household flooring (adjusted for other key risk factors) through pooled risk estimates using all available evidence from LMIC.Patients were not involved in the development of this protocol.The present protocol has been registered within the PROSPERO database (registration number CRD42019156437) and is being reported in accordance with the reporting guidance provided in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement , which iThe following minimal set of electronic databases of peer-reviewed literature as suggested by Bramer et al.  will be Study authors will be contacted where relevant for clarification or for additional missing key meta-data.Google Scholar will be used to search for grey literature including relevant unpublished data and relevant websites such as randomized controlled trial registries, Global NTD database, and conference proceedings quantifying the association between unimproved/unfinished household flooring and diarrhoea/intestinal parasitic infection status.Studies conducted from January 01, 1980-onwards, with no language restriction, will be eligible for inclusion. Furthermore, only studies conducted in a low- and middle-income setting will be eligible for further screening.When searching PubMed/Medline, Medical Subject Headings (MESH) search terms will be used. Search terms to be used will include keywords referring to ‘household flooring’, ‘floor’, ‘dirt’, ‘earthen’, ‘cement’, ‘wood’, ‘tile’, ‘concrete’, ‘hard’, ‘solid’, ‘enteric’, ‘diarrhea’, ‘diarrhoea’, ‘soil-transmitted’, ‘helminth’, ‘worm’, ‘intestinal parasite’, ‘giardia’, ‘entamoeba’.The following proposed search term will be used: “(soil OR dirt OR earth* OR cement OR wood OR tile OR concrete OR hard OR solid) AND floor* AND  AND (infection OR helminth* OR worm OR parasit*)”. A draft search for PubMed/MEDLINE is available in Supplementary Material Studies will be selected or excluded for inclusion based on the criteria proposed in Table The PICO  classification approach is widely used as a strategy for formulating search strategies and characterizing meta-analyses. We have utilised this framework to explicitly define the criteria for eligibility Table . StudiesRetrieved citations from the various search engines will be imported into EndNote and checked for duplicates, i.e. de-duplicated. Eligibility of the studies will be ascertained by two independent researchers who will screen the titles and abstracts (phase 1). Full articles of potentially eligible titles/abstracts will be independently assessed by two researchers (BS and HL) for inclusion in the review (phase 2). In case of disagreement about the eligibility, a third investigator (RP) will be consulted. Articles will be archived in a data extraction spreadsheet that will be pilot-tested to evaluate its appropriateness.The data capture sheet will consist of a screening checklist consisting of study details , study characteristics , measures of exposure  and outcome/disease status  Table , and meaThe primary outcome to be analysed will be any diarrheal/intestinal parasite infection. As a secondary outcome, we will also attempt to assess the association between specific pathogens and unimproved/unfinished household flooring for the subset of studies for which this was laboratory confirmed (if numbers of eligible studies are sufficient).To accurately report on the content of individual eligible papers and to explore relationships between the outcome(s) and risk factor(s), data will be summarised in tabular format presenting the main findings of each paper individually, including population under study, region or continent , outcomes , exposures (specific household flooring type), and main results . A qualitative or narrative summary of the key characteristics and quality of the papers will also be included, and in addition, we will also present the risk of bias summary for each paper (please see ‘Risk of bias assessment for eligible studies’ section).2 statistic [2 statistic is the proportion of variation in prevalence estimates that is due to genuine variation in treatment effects rather than sampling (random) error. I2 statistic ranges between 0 and 100%  [2 [P value of < 0.05 considered statistically significant (heterogeneity).As epidemiological and clinical heterogeneity is expected, all meta-analyses in this study will be conducted using the random effects model. We will employ random effects modelling as the effect(s) underlying the different studies are assumed to be drawn from a normal distribution, considering both within- and between-study variation. Forest plots will be used to visually assess pooled estimates and ascertain the extent of heterogeneity between studies. We will quantify statistical heterogeneity by estimating the variance between studies using Itatistic . The I2 ctively) . We willvely) [2  and Cochvely) [2  with a PIf the selected studies are deemed suitable for quantitative synthesis, data will be pooled in a meta-analysis approach combining the primary exposure (unimproved household flooring) across studies and presented as a summary of effects based on study design/measure of effect, e.g. odds ratios versus relative risk.http://www.R-project.org/) or STATA/IC V 16 .If a meta-analysis approach is justified, we will likely employ random effects models with inverse variance weighing to estimate the pooled/meta-weighted effect size for unimproved/unfinished household flooring versus diarrheal/intestinal parasite status across eligible studies with 95% CI. If there are sufficient studies/data, we may also conduct a meta-regression analysis utilising various other meta-covariates extracted from the eligible. The analysis will be conducted using the R statistical software (R core team (2019). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL Where possible, we will also perform subgroup analysis by age group, study design , and/or geographical region , in order to assess differences between the strength of association by geography and potential impact of contextual confounders which may vary by geography. This will also be extended to a subgroup analysis across specific pathogen species if there are a sufficient number of studies.This systematic review can be categorised under aetiology and risk (exposure and outcome). We will use the Cochrane Risk of Bias (RoB) 2.0 Tool for assessing risk of bias for randomised controlled trials . We willFunnel plots  will be WASH interventions often fail to show long-term impact on diarrhoeal and/or intestinal parasite risk in many LMIC. Less attention has been paid to wider contextual factors that may contribute to high levels of contamination in the domestic environment such as household flooring. It has been hypothesized that unimproved/unfinished household flooring may be an important contextual risk factor in these settings. This systematic review aims to assess whether there is a significant association between unimproved/unfinished household flooring and the risk of diarrhoea and/or intestinal parasite infection in low- and middle-income settings. We anticipate that differences in floor type classification across different settings and variation in confounder measurement/classification as well as lack of multivariable adjustment may be potential limitations.The findings of this review will augment current knowledge and add to the evidence base regarding risk factors for diarrhoea and intestinal parasites in low- and middle-income countries (LMIC). If this is found to be the case, it would help identify children at greater risk based on household living conditions that would have important implications for interventional packages and will help inform future interventions and establish whether more research is warranted, and potentially highlight additional intervention measures required to reduce this burden in LMIC.We do not envisage any amendments to the present protocol. However, should any essential amendments be found to be necessary, they will be reported in the published review.The results will be disseminated in the form of a peer-reviewed journal article and also be shared with relevant health authorities such as WHO.Additional file 1: Supplementary Material 1. PRISMA-P 2015 Checklist.Additional file 2: Supplementary material 2. Draft search using PubMed/MEDLINE, including planned temporal limits.


Background: Common functional Val158Met polymorphism in the Catechol-O-methyltransferase(COMT) gene may have an impact on an individual’s susceptibility to suicide, but individually publishedresults are inconclusive. Therefore, we performed this meta-analysis to provide a more preciseestimation of the association between COMT 158G/A  polymorphism and suicidesusceptibility.Study design:  A cross-sectional study.Methods: This systematic review and meta-analysis is a comprehensive literature search of PubMed,Scopus, Web of Science and Google Scholar databases was conducted on case-control studiespublished up to Mar 2017. Crude odds ratios (ORs) with 95% confidence intervals (CIs) werecalculated.Results: We identified 14 eligible case-control studies, including 2353 suicide attempters and 2593controls. The pooled results indicated that COMT 158G/A  polymorphism was notsignificantly associated with increased overall suicide risk. The same results were revealed based onethnicity, Hardy–Weinberg equilibrium (HWE) status and genotyping technique. However, there wassignificant association between COMT Val158Met polymorphism and suicide risk among femalesunder the homozygote  and recessive  models, but not among males.Conclusions: COMT 158G/A  polymorphism was associated with suicidesusceptibility only in females. Approximately, one million people die by suicide each year worldwide. With a prevalence rate of 0.0145% and suicide accounting for 1.5% of death by all causes, it is the 10th leading cause of mortality worldwide2. The etiology of suicide due to a combined effect of genetic and external factors is not known exactly3. Social factors alone cannot fully explain suicidal behavior. However, some studies have indicated a strong genetic component to susceptibility to suicidal behavior4.Suicidal behavioris one of the main public health problems worldwide, which include a wide spectrum of self-destructive actions5. Association studies of dopamine receptor genes and COMT in schizophrenia and/or ADHD subjects report genetic associations with various domains of cognitive function, including executive function, verbal and working memory, attention, and performance monitoring. Therefore, it was suggested that COMT could also play a role in the susceptibility to suicidal behavior7. The COMT gene has a common functional polymorphism, val158met (rs4680) variant9. This polymorphism is due to a G to A transition at codon 158 of the membrane-bound form of COMT, which corresponds to codon 108 of the soluble form of COMT, resulting in a valine  to methionine (Met) substitution9.Catechol-O-methyltransferase (COMT) is an enzyme metabolizing noradrenaline in the synaptic cleft11. A family history of suicide is a strong risk factor for suicide and suicide attempt11. The COMT gene is located on the long arm of chromosome 22 at 22q11; spans 28 kb and contains six exons9. The function of COMT polymorphism in several psychotic conditions, such as schizophrenia, bipolar disorder, major depressive disorder, obsessive-compulsive disorder, and Parkinson’s disease, and the putative effects of COMT on suicide have been proposed13.The genetic component of suicidal behaviorwas originally founded by family, adoption and twin studies. Its heritability is in the range between 30%–55%29, but the results are inconclusive partially because of the possible small effect of the polymorphism on suicide risk and the small sample in some published study. Therefore, we performed a meta-analysis to derive a precise estimate of this association.Several case-control studies have reported the association between COMT polymorphism and suicide susceptibilityWe searched the electronic PubMed, Scopus, Web of Knowledge, and Google scholar database to identify all case–control studies examined the association between COMT Val158Met (158G/A) polymorphism and suicide risk up to Mar 2017. The keywords were as follows: ‘’Catechol-O-methyltransferase’’, ‘’COMT gene’’, ‘’COMT Val158Met’’, ‘’COMT 158G/A’’, ‘’rs4680’’, ‘‘polymorphism’’, ‘‘genotype’’, ‘‘variant’’, ‘’mutation’’, suicide’’, and ‘’suicide behavior’’. Additionally, reference lists of the relevant case-control studies, review, and meta-analysis were reviewed manually to identify additional relevant studies.Studies included in our meta-analysis had to meet all of the following criteria: 1) used case-control study or cohort study; 2) the studies evaluated the associations between the COMT Val158Met (158G/A) polymorphism and suicide risk; 3) studies published in English and Persian; and provided sufficient information for calculation of odds ratio (ORs) with 95% confidence interval (CI). Accordingly, the following exclusion criteria were also considered: 1) those studies that were not designed as case-control or cohort studies; 2) control population including suicide attempter or other similar conditions; 3) there was no available genotype or allele frequency; 4) duplicate of previous publication; and 5) studies not written in English or Persian. Moreover, if multiple studies from the same case series were available, the one including the more individuals was used in the analysis.P-value for Hardy–Weinberg equilibrium (HWE). The countries of origin were categorized as Asian, Caucasian, and African.Information was carefully extracted from all eligible publications independently by two investigators according to the inclusion criteria listed above and data with discrepancies in identification were discussed by all authors. For each included study, the following information was collected: first author’s name, year of publication, country of origin, total number of cases and controls, distribution of genotypes and alleles, minor allele frequencies (MAFs), and P-values < 0.1, and I2 statistics was calculated to quantify the proportion of the total variation across studies due to heterogeneity14. I2 values of 25%, 50%, and 75% were nominally assigned as low, moderate, and high estimates, respectively. When heterogeneity was considered significant, the random-effects model (DerSimonian- Laird approach) was performed. Otherwise, the fixed-effects model (Mantel-Haenszel approach) was used15. The departure from the Hardy–Weinberg equilibrium (HWE) for the control group in each study was tested using an online HWE calculator. The HWE was considered statistically significant when the P-value was less than 0.05. Sensitivity analysis was also tested by removing one study at a time to calculate the overall homogeneity and effect size. Publication bias was evaluated by funnel plots and further assessed by Egger’s linear regression test17. All the statistical analyses were performed by comprehensive meta-analysis (CMA) ver. 2.0  software . All the P values were 2-sided. P-value less than 0.05 was considered statistically significant.The associations between the COMT Val158Met (158G/A) polymorphism and suicide were measured by odds ratios (OR) with 95% confidence intervals (CI) under the allele model (A vs. G), the homozygote model (AA vs. GG), the heterozygote model (AG vs. GG), the dominant model (AA+AG vs. GG), and the recessive model (AA vs. AG +GG). The heterogeneity assumption was checked by the Q-statistics with 29, on COMT genotypes and suicide risk were identified, including a total of 2353 suicide attempters and 2593 controls from 2000 to 2016 (P<0.05)29. Table 2 summarizes the difference of genotypes and alleles frequency between males and females suicide attempters.Thirty-seven publications fulfilled our search criteria were preliminarily were enrolled. After reading the titles and abstracts, 22 studies with duplicate titles, review, meta-analyses or focused on unrelated condition were excluded. One study was excluded because was not case–control. Finally, 14 case-control studies to 2016 . All stuP=0.592; AA vs. GG: OR=1.012; 95% CI: 0.726, 1.411, P= 0.943; AG vs. GG: OR=0.958; 95% CI: 0.762, 1.204, P= 0.714; AA+AG vs. GG: OR=0.889; 95% CI: 0.669, 1.182, P=0.419; and, AA vs. AG +GG: OR=0.980, 95% CI: 0.746, 1.286, P= 0.883).P=0.010) and the recessive model  in females  polymorphism and suicide risk in the Caucasian, Asian and mixed populations. The same results were also revealed by HWE status . Results females . Additio females .To evaluate the robustness of the association results, the meta-analysis was performed repeatedly with each study removed. No individual study significantly affected the pooled ORs. Sensitivity analysis was performed based on HWE, and the corresponding pooled ORs were not materially altered, indicating that our results were statistically robust.Beggs= 0.273, PEggers= 0.696; AA vs. GG: PBeggs= 0.381, PEggers= 0.558; AG vs. GG: PBeggs= 0.443, PEggers= 0.315; AA+AG vs. GG: PBeggs= 0.458, PEggers= 0.722; and AA vs. AG +GG: PBeggs= 0.742, PEggers= 0.784, Publication bias was qualitatively examined using the funnel plots and quantitatively estimated by Begg’s test and Egger’s test. For all genetic models, the shapes of the funnel plots did not reveal any evidence of obvious asymmetry . These r30. Several large studies in the USA, Germany, Slovenia, and Croatia suicide attempter cases found no evidence for an increased risk of suicide26. These epidemiological studies results are inconsistent because this association was found in presence of the COMT Met allele in the male and female suicide attempters and diagnosed with different mental and mood disorders such as schizophrenia and alcohol dependency.. These differences among studies might be explained by the different diagnostic entities used. Therefore, the main limitation could be that the genetic association studies on COMT 158G/A polymorphism have been performed in different ethnicity and may be different criteria have been applied in the studies to define suicidal behavior, which reduces power to find consistent results31.To the best knowledge, the present meta-analysis is the most comprehensive and accurate meta-analysis assessed the association between the COMT 158G/A  polymorphism and suicide risk. Our results did not show any significant association between the COMT Val158Met polymorphism and suicide in overall. Several issues should be further discussed to address the negative results. However, for most 14 studies involved, when they were individually removed from the analysis, the association between COMT Val158Met polymorphism and suicidal behavior was not significant still. Thus, the evidence for an association between COMT and suicidal behavior was robust.To date, the association between COMT Val158Met polymorphism and suicide remains controversial because the reports include both positive and negative findings9. COMT Val158Met polymorphism was not associated with suicidal behavior risk. However, COMT Val158Met and suicide risk essentially remain an open field, as meta-analysis study not selected healthy controls (with only 875 adult suicide attempters). Therefore, their results’ reliability and the number of studies are considerably smaller than that needed to receive the robust conclusions32. Moreover, compared with their meta-analysis, subgroup analysis by ethnicity and gender were also carried out. In our meta-analysis, the COMT Val158Met polymorphism was associated with suicide risk in females.Our results were consistent with a more recent meta-analysis on COMT Val158Met and suicide risk. Eleven case–control studies and one case-only study were included on COMT Val158Met polymorphism34. In addition, gender-related differences in suicide behavior might be due to the fact that COMT 158G/A  polymorphism may differently influence personality traits that presumably affect suicide behavior36. However, we were unable to conduct accurate more analyses of COMT polymorphisms by gender subgroup for insufficient data, thus the existence of gender-specific influences on suicide in this meta-analysis remains unclear. In this meta-analysis the female specificity in effect of the COMT 158G/A  polymorphism on suicide attempt could be a chance finding, this result is inconsistent with gender differences in the dopamine system37. Further examination in the included eligible case-control studies in the gender subgroups showed significant differences between cases and controls numbers in male and female subgroups.Interestingly, when all the eligible studies were pooled into male and gender subgroups analysis, only in female subgroup increased risk for suicide was found. However, there was an imbalance in gender distribution, with more males in attempters than females. None of the genetic models showed association with male susceptibility, suggesting that COMT 158G/A  manifest female specific influences on suicide attempt. Estrogen in females modulates neurotransmission and neuronal excitability of catecholaminergic systems and increases the concentration of dopamine in the synaptic gap, leading to the different influence of dopamine on emotion and motivation among male and females In interpreting results of this meta-analysis, some limitations should be acknowledged. First, not all the eligible studies were collected; the sample size of the included studies was large enough by ethnicity, especially in non-Caucasian and Asian populations. Therefore, there was a lack of statistical power to evaluate better the association between COMT 158G/A  polymorphism and suicide, especially in subgroup analysis. Second, due to limited individual data, a more precise analysis on other covariates such as age, number of suicide attempts, and environmental factors were not performed. Third, since the genotypes frequency of COMT 158G/A polymorphism not mentioned by gender of suicide attempters in all studies, we only evaluated the eligible studies for gender subgroups. Finally, as suicide is a complex trait, gene-gene and gene-environment interactions were not analyzed. Specific environmental and lifestyle factors will alter the associations between gene polymorphisms and suicide susceptibility. Therefore, it is necessary to evaluate the roles of lifestyles in suicide.The present meta-analysis is the most comprehensive and accurate meta-analysis assessed the association between the COMT 158G/A  polymorphism and suicide risk. COMT Val158Met polymorphism was not associated with suicide risk in overall population. However, subgroup analysis by gender showed that COMT Val158Met polymorphism was strongly associated with suicide risk in the female subgroup. More comprehensive studies and larger samples are necessary to determine conclusively an association of COMT 158G/A  with suicidal behavior.The authors would like to thank Professor Seyed Mahdi Kalantar and Hasan Sheikhha for impetus to perform this study.We have no conflict of interest to declareNo grants were involved in supporting this work.The COMT Val158Met polymorphism is not significantly associated with suicide risk in overall analysis.Stratified analysis showed no association between COMT Val158Met polymorphism and suicide by ethnicity. The COMT Val158Met polymorphism does appear to be of major importance in the susceptibility of suicide in females


A great deal of evidence has supported that growth differentiation factor 5 (GDF5) is associated with the occurrence of knee osteoarthritis (KOA), while their results are not consistent. In the present study, we aimed to explore the association between GDF5 gene polymorphism and KOA for a more credible conclusion.Comprehensive literature searches were carried out in English databases, including PubMed, Embase, Web of Science (WOS), and Cochrane, and Chinese databases, including China National Knowledge Infrastructure (CNKI), WANFANG, and VIP database. After the data were extracted from the required studies, the odds ratios (ORs) and their 95% confidence intervals (CIs) were determined to assess the correlation between GDF5 gene polymorphism and KOA. The publication bias was evaluated by funnel plot.According to the inclusion and exclusion criteria, 15 studies on the correlation between GDF5 gene polymorphism and KOA occurrence were eligible for meta-analysis. Among these articles, four studies showed no apparent correlation, while the other 11 studies indicated an obvious correlation. Meanwhile, we also carried out a subgroup analysis of the population. Due to the inevitable heterogeneity, three genetic models were finally selected for analysis. With the allele model , recessive model , and homozygous model , GDF5 gene polymorphism decreased the risk of KOA. Besides, a significant association was observed in Caucasians, Asians, and Africans. Meanwhile, the protective effect of genotype C (or CC) in the Asian group was little obvious than that in the Caucasian group and the African group. Although the quality of the included studies was above medium-quality, we obtained results with a low level of evidence.The results of the meta-analysis showed that the genotype C (or CC) of GDF5 protected against KOA occurrence in Caucasian, Asian, and African populations. As the most common degenerative joint disease, osteoarthritis (OA) is the main factor of pain and disability in people aged over 45 years . AlthougSingle nucleotide polymorphism (SNP), which accounts for more than 90% of human gene polymorphism, is the most common and stable gene variation in the human DNA chain . As a meA great deal of previous meta-analysis has supported that there is a correlation between GDF5 and knee osteoarthritis (KOA), while the research results remain contradictory. Some defects exist in the previous meta-analyses, such as the incorrect data extraction and the limitations of population subgroup analysis. On the other hand, there has been an update of the literature. In our present meta-analysis, we systematically and comprehensively evaluated the correlation between the GDF5 gene polymorphism and KOA occurrence.Based on the guidelines for the Preferred Reporting Item of Systematic Review and Meta-Analysis (PRISMA), a comprehensive literature search was conducted in English databases, including PubMed, Embase, Web of Science (WOS), and Cochrane, and Chinese databases, including China National Knowledge Infrastructure (CNKI), WANFANG, and VIP database . We used a combination of medical subject heading terms (“GDF5” or “growth and differentiation factor 5” or “rs143383”) and (“polymorphism” or “SNP”) and (“osteoarthritis” or “OA”). Besides, references that could be included from the reviews and clinical trials were also manually searched.The inclusion criteria in this meta-analysis were set as follows: (1) human studies; (2) studies with a case-control group ; (3) studies on the relationship between GDF5 gene polymorphism and KOA susceptibility; and (4) studies with sufficient specific data to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Meanwhile, the exclusion criteria were set as follows: animal model studies, reviews, case reports, expert opinions, and conference summaries. All the retrieved studies were screened by two reviewers according to the inclusion criteria and exclusion criteria.P value for the Hardy–Weinberg equilibrium (HWE) test in the control group.The following data were extracted from the included studies by two independent reviewers: the first author, the year of publication, the country and population of the subjects, the genotyping method, the number of alleles in the case group and control group, the sample size of the subjects in the case group and control group, and the The Newcastle–Ottawa Scale (NOS)  was usedTo clarify the relationship between GDF5 gene polymorphism and KOA susceptibility, the overall ORs and 95% CIs of the following five models were calculated: allele model (C versus T), dominant model (CC + CT versus TT), recessive model (CC versus CT + TT), heterozygous model (CT versus TT), and homozygous model (CC versus TT).Q statistics and I2 statistics of all studies in each model. If P < 0.1 and I2 ≥ 50%, it was considered that a large heterogeneity existed [The heterogeneity test between studies was performed based on the  existed , and the existed . The soun = 68), Embase (n = 74), WOS (n = 137), Cochrane (n = 5), CNKI (n = 2), WANFANG (n = 5), and VIP database (n = 1), while one study was obtained by manual search. After removing repeated studies, and reading titles and abstracts, 22 studies were obtained. According to the established exclusion and inclusion criteria, eight articles were excluded . Finally, 14 articles (15 studies) [A total of 291 studies were retrieved from the following databases: PubMed (studies) –24 consiTables P<0.00001), dominant model , recessive model , heterozygous model , and homozygous model .During the meta-analysis, we found that there was large heterogeneity in all five genetic models. The random-effects model was selected for analysis, and the source of heterogeneity was further analyzed. The aggregate data of all studies showed that genotype C (or CC) in the GDF5 gene polymorphism had a significant protective effect against KOA. Table I2 > 50% in the subgroups of the dominant model and heterozygous model could not reduce the heterogeneity by excluding each study. Consequently, these two genetic models were not suitable for the evaluation of the correlation between GDF5 gene polymorphism and KOA. In the other three genetic models, the heterogeneity of the Caucasian group  and African group  was low, which could even be 0%, while that of the Asian group  was relatively high. The study of the Asian group could be inferred as the source of heterogeneity. After the studies of Shin et al. [P = 0.18, I2 = 32%; overall: P = 0.15, I2 = 30%). After the study of Zhang et al. [P = 0.52, I2 = 0%; overall: P = 0.73, I2 = 0%. Fig. P = 0.22, I2 = 26%; overall: P = 0.39, I2 = 6%. Fig. P = 0.002, I2 = 69%; overall: P = 0.009, I2 = 54%. Fig. To identify the source of heterogeneity, the subgroup analysis was performed, since previous studies have shown different results in various populations –24. Thren et al.  and ZhanCompared with the original results, there was no obvious difference between the results of sensitivity analysis and the original results, suggesting that the overall results were stable (method: omitting each study in turn).P = 0.386, recessive model: P = 0.776, and homozygous model: P = 0.356).In order to assess the publication bias of the literature, funnel plots, Egger’s test, and Begg’s test were performed. The funnel plots indicated that there was no obvious publication bias Figs. , and 7. This study contains a total of three genetic model analyses. The quality of evidence for each analysis result is low Table .Table 4As a common crippling disease, OA has a great impact on patients and society , 26. AmoIn recent years, a great deal of attention has been paid to the GDF5 gene. GDF5, a member of the bone morphogenetic protein (BMP) family, is involved in a variety of cellular processes related to bone repairs, such as proliferation, differentiation, and angiogenesis, as well as bone and cartilage formation . Like otIn our present meta-analysis, we abandoned the dominant model and heterozygous model because of the irreducible heterogeneity. In the remaining three genetic models, the analysis of overall studies, Caucasian group, Asian group, and African group showed that the GDF5 gene polymorphism was significantly associated with the susceptibility to KOA, suggesting that genotype C (or CC) had a protective effect against KOA. However, in the studies of Cao et al. , Shin etNevertheless, there are some defects in the present analysis. First, the language was restricted to English and Chinese, which might limit the research population and lead to bias. Secondly, there was no more stratified analysis of factors . Although the included studies are all medium- or high-quality studies, the subject of this meta-analysis is different from traditional case-control studies, which made upgrade non-existent. According to the GRADE methodology quality evaluation, the analysis results of the three genetic models are all at low levels of evidence. Further research may have an important impact on the confidence interval of the effect size and may change the effect size. We still need to wait for more well-designed case-control studies to be added to the analysis.Collectively, our current meta-analysis suggested that GDF5 gene polymorphism was associated with KOA susceptibility. In the three genetic models , genotype C (or CC) of GDF5 had a protective effect against KOA in Caucasian, Asian, and African populations.