ObjectiveTo evaluate the association between tumor necrosis factor alpha (TNF-α) gene -308G/A polymorphism and the risk of endometriosis (EM). MethodsDatabases including PubMed, EMbase, CBM, CNKI, VIP, and WanFang Data were searched to collect case-control studies about the association between TNF-α gene -308G/A polymorphism and the risk of EM from inception to October 2014. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies. Then Meta-analysis was performed by using Stata 12.0 software. ResultsA total of seven case-control studies were included, which involved 687 patients and 877 controls. The results of meta-analysis showed that, AA genotype carriers presented 2.06-fold (OR=2.06, 95%CI 1.10 to 3.83, P=0.02) and 1.94-fold (OR=1.94, 95%CI 1.18 to 3.18, P<0.01) higher risk of EM than GG genotype carriers and AG+GG genotype carriers, respectively; but sensitivity analysis showed that the robustness of these results was unstable. No statistical significance was found in the allele model, co-dominant model, and dominant model (A vs. G: OR=1.37, 95%CI 0.87 to 2.17, P=0.18; AG vs. GG: OR=1.09, 95%CI 0.77 to 1.53, P=0.63; AA+AG vs. GG: OR=1.29, 95%CI 0.95 to 1.77, P=0.11). While excluding studies that controls were not in HWE, no significant association was observed in these five genetic models; and no significant association was found in the results of subgroup analysis by ethnicity. ConclusionThe AA genotype of TNF-α gene -308G/A polymorphism might contribute to the risk of EM, but the association between other genotypes and EM susceptibility is unclear. In addition, due to the limited quantity and quality of included studies, more high quality studies are needed to verify the above conclusion.
ObjectiveTo evaluate the relationship between tumor necrosis factor-α (TNF-α) gene promoter-308 G/A polymorphism and ankylosing spondylitis (AS) in Chinese population by meta-analysis. MethodsThe casecontrol studies about the correlation between TNF-α gene polymorphism and AS in Chinese population were retrieved from PubMed, EMbase, CNKI, CBM, WanFang Data and VIP database by two researchers. The retrieval time was from their establishment to December, 2015. After the paper screening, data extraction, and assessment of bias risk, the metaanalysis was conducted by Stata 12.0 software. ResultsA total of 11 case-control studies involving 1 154 AS patients and 1 458 controls were included. The results of meta-analysis showed that, for Chinese population, there was no significant association between TNF-α-308 G/A polymorphism and AS susceptibility (A vs. G: OR=0.96, 95% CI 0.63 to 1.47, P=0.86; AA vs. AG: OR=0.97, 95% CI 0.51 to 1.84, P=0.93; AA vs. GG: OR=0.92, 95% CI 0.32 to 2.61, P=0.87; AA+AG vs. GG; OR=1.04, 95% CI 0.60 to 1.80, P=0.89; AA vs. AG+GG: OR=1.03, 95% CI 0.58 to 1.82, P=0.92). ConclusionTo date, it has not found the relationship between TNF-α gene promoter-308 G/A polymorphism and AS in Chinese population. For the quantity and quality limitation of the included studies, the conclusion has to be verified by more large-scale highquality studies.
ObjectiveTo systematically review the correlation between apolipoprotein E (ApoE) polymorphism and sporadic Alzheimer's disease (SAD) in Chinese population. MethodsThe case-control studies about the relationship between ApoE polymorphism and SAD in Chinese population were electronically retrieved in PubMed, EMbase, CBM, The Cochrane Library (Issue 8, 2013), CNKI, VIP, and WanFang Data from the date of their establishment to August 2013. Literature screening according to the inclusion and exclusion criteria, data extraction and methodological quality assessment of the included stuides were completed by two reviewers independently. Meta-analysis was then conducted using Stata 12.0 software. ResultsA total of 50 case-control studies invovling 3 396 cases and 4 917 controls were finally included. The results of meta-analysis showed that, in Chinese, the risk of SAD was 2.89 times higher in population with allele ε4 than in population with allele ε3 (OR=2.89, 95%CI 2.61 to 3.19, P < 0.001); 7.24 times higher in those with ε4/ε4 genotype than in those with ε3/ε3 genotype (OR=7.24, 95%CI 5.11 to 10.24, P < 0.001); 2.90 times higher in ε3/ε4 genotype than in ε3/ε3 genotype (OR=2.90, 95%CI 2.56 to 3.29, P < 0.001); 2.11 times higher in ε2/ε4 genotype than in ε3/ε3 genotype (OR=2.11, 95%CI 1.64 to 2.72, P < 0.001); and no statistic significance was found in the risk of SAD compared ε2/ε3, ε2/ε2 genotypes and ε2 allele with ε3/ε3 genotype and ε3 allele. ConclusionFor Chinese population, ApoE allele ε4 is significantly associated with the onset of SAD, and genotype ε4/ε4 is a high risk factor of SAD. While allele ε2 is not associated with the onset of SAD. Since a great deal of current studies failed to conduct stratified analysis, it is suggested to further conduct relevant relevant studies according to clinical classification of SAD and patients' characteristics.
ObjectiveTo systematically review the correlation between E-cadherin expression and prostate cancer, as well as its clinicopathologic features in Chinese population. MethodsSuch databases as PubMed, EMbase, CBM, CNKI, VIP and WanFang Data were electronically searched from their inception to December, 2015 to collect case-control studies about the correlation between E-cadherin expression and prostate cancer, as well as its clinically pathologic features in Chinese population. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed using RevMan 5.3 software. ResultsA total of 21 studies were included, involving 920 prostate cancer cases, 415 benign prostatic hyperplasia cases, and 48 controls. The results of meta-analysis showed that the prostate cancer group had a lower E-cadherin expression level when compared with the benign prostatic hyperplasia group (OR=0.07, 95%CI 0.05 to 0.11, P<0.00001) or the control group (OR=0.04, 95%CI 0.01 to 0.18, P<0.00001). Moreover, the expression level of E-cadherin was lower in the low and medium differentiation group than in the high differentiation group (OR=0.13, 95%CI 0.08 to 0.23, P<0.00001), lower in the stage of C+D than in the stage of A+B (OR=0.23, 95%CI 0.15 to 0.34, P<0.00001), and lower in the prostate cancer with metastasis (OR=0.46, 95%CI 0.27 to 0.79, P=0.005) and it was decreased gradually with the increment of pathological differentiation and clinical stage of prostate cancer and with the decrement of lymph node or bone metastasis and serum PSA level. ConclusionCurrent evidence indicates that the expression level of E-cadherin is significantly correlated with prostate cancer and its clinicopathologic features in Chinese population. Due to limited sample size and quality of included studies, the conclusion needs to be verified by conducting more high quality studies.
ObjectiveTo systematically evaluate the association between 936C/T polymorphism in vascular endothelial growth factor (VEGF) gene and the risk of preeclampsia (PE). MethodsSuch databases as PubMed, EMbase, The Cochrane Library (Issue 11, 2014), CBM, CNKI, VIP, and WanFang Data were searched up to November 2014, to collect case-control studies of the association between 936C/T polymorphism in VEGF gene and the risk of PE. Two reveiwers independently screened studies according to the inclusion and exclusion criteria, extracted data, and assessed the risk of bias of included studies. And then, meta-analysis was conducted using RevMan 5.3 software. ResultsA total of nine case-control studies involving 904 PE patients and 1 113 controls were included. The results of meta-analysis showed that, significant association was found between VEGF gene 936C/T polymorphism and the risk of PE in the total analysis (T vs. C:OR=1.61, 95%CI 1.17 to 2.22, P=0.003; TT vs. CC:OR=2.65, 95%CI 1.37 to 5.11, P=0.004; CT vs. CC:OR=1.55, 95%CI 1.09 to 2.22, P=0.02; TT+CT vs. CC:OR=1.68, 95%CI 1.15 to 2.45, P=0.007; TT vs. CT+CC:OR=2.19, 95%CI 1.31 to 3.68, P=0.003). In the subgroup analysis, significant association of the polymorphism was found in Asians but not in Caucasians. ConclusionVEGF gene 936C/T polymorphism may be associated with PE risk in Asians. Due to limited quantity and quality of the included studies, the conclusion should be assessed in further studies.
ObjectiveTo systematically review the correlation between Survivin expression and prostate cancer, as well as its clinicopathologic features in Chinese population. MethodsSuch databases as PubMed, EMbase, CBM, CNKI, VIP and WanFang Data were electronically searched from inception to November, 2015 to collect case-control studies about the correlation between Survivin expression and prostate cancer, as well as its clinically pathologic characteristics in Chinese population. Two reviewers independently screened literature, extracted data and assessed the methodological quality of included studies. Then, meta-analysis was performed using RevMan 5.3 software. ResultsA total of 32 case-control studies were included, involving 1613 prostate cancer cases, 708 benign prostatic hyperplasia cases, and 93 controls. The results of meta-analysis showed that the prostate cancer group had a higher Survivin expression level when compared with the benign prostatic hyperplasia group (OR=32.95, 95% CI 19.88 to 54.63, P<0.00001) or the control group (OR=75.78, 95% CI 26.97 to 212.98, P<0.00001). Moreover, the expression level of Survivin was higher in the low and medium differentiation group than in the high differentiation group (OR=4.45, 95% CI 3.13 to 6.32, P<0.00001), higher in the stage of C+D than in the stage of A+B (OR 5.42, 95% CI 2.91 to10.10, P<0.00001), and higher in the prostate cancer with lymph node metastasis than in the prostate cancer without lymph node metastasis (OR 4.07, 95% CI 2.91 to 10.10, P<0.00001). ConclusionCurrent evidence indicates that the expression level of Survivin is significantly correlated with prostate cancer and its clinicopathologic features in Chinese population. Due to the limited quantity and quality of included studies, above conclusions need to be verified by conducting more high quality studies.
When investing the relationship between independent and dependent variables in dose-response meta-analysis, the common method is to fit a regression function. A well-established model should take both linear and non-linear relationship into consideration. Traditional linear dose-response meta-analysis model showed poor applicability since it was based on simple linear function. We introduced a piecewise linear function into dose-response meta-analysis model which overcame this problem. In this paper, we will give a detailed discussion on traditional linear and piecewise linear regression model in dose-response meta-analysis.
Cumulative meta-analysis could help researchers to justify the effectiveness of the intervention and whether the obtained evidence is sufficient. However, the process of the meta-analysis does not adjust the repeated testing of the null hypothesis and neither quantifies the statistical power. The sequential meta-analysis has solved the aforementioned problems and has been widely used in the clinical practice and decision-making. Currently several methods of sequential meta-analysis have been proposed and these methods differ from each other. Of which, the methodology of trial sequential (TSA) is well developed and corresponding performance is relatively easy; the methodology of double-triangular test of Whitehead is lagged than TSA and its performance is relatively difficult; the approach of semi-Bayes refers to the theory of Bayes and it's very difficult to generalize. Our paper aimed to give a brief introduction of the methodology of the sequential meta-analysis.
As a valid method in systematic review, dose-response meta-analysis is widely used in investigating the relationship between independent variable and dependent variable, and which usually based on observational studies. With large sample size, observational studies can provide a reasonable amount of statistical power for meta-analysis. However, due to the design defects of observational studies, they tend to introduce many kinds of biases, which may influence the final results that make them deviation from the truth. Given the dead zone of methodology, there is no any bias adjusting method in dose-response meta-analysis. In this article, we will introduce some bias adjusting methods from other observational-study-based meta-analysis and make them suit for dose-response meta-analysis, and then compare the advantages and disadvantages of these methods.