| Background: Stroke is often regulated by a number of modifiable and nonmodifiable risk factors.Recently,studies suggested that high gamma glutamyltransferase level will increase the risk of stroke,but draw inconsistent conclusions.So,we conducted a meta-analysis to evaluate the relationship between gamma-glutamyltransferase level and risk of stroke.Methods: We systematically searched Pub Med,EMBASE,Science Citation Index(ISI Web of Science)and Cochrane Library(updated to January 2015)for prospective cohort studies.Then,Relative risk with the 95% confidence intervals was used to assess the association.Regression analyses,subgroup analyses,sensitivity analysis were also performed.The Begg test,Egger test,and the trim and fill method were used to assess potential publication bias.Results: A total of 5,707 cases and 926,497 participants in ten prospective studies were included.Overall,high-gamma-glutamyltransferase level has a positive association with increased risk of stroke(RR 1.28,95% CI: 1.16-1.43).The multivariate analysis based on alcohol consumption showed that alcohol intake has little influence on overall results(p =0.151).In subgroup analysis,the estimated RR was 1.17(95% CI: 1.05-1.31)after alcohol consumption was adjusted.In subgroup analysis stratified by gender,the estimated RR was 1.45(95% CI: 0.9-2.34)in women subgroup and 1.36(95% CI: 1.14-1.61)in men subgroup.In subgroup analysis stratified by ethnicity,the estimated RR was 1.37(95% CI: 1.22-1.53)in European subgroup and 1.05(95% CI: 1.03-1.08)in Asian subgroup.In subgroup analysis stratified by number of stroke events,the estimated RR was 1.25(95% CI: 0.85-1.84)in large number of stroke events(? 500)subgroup and 128(95% CI: 1.17-1.41)in small number of stroke events(< 500)subgroup.In sensitivity analysis,there was little influence in the quantitative pooled measure of RR or 95% CI when omission of any studies.In publication bias' test,potential publication bias didn't found in Begg test(P = 0.077)but in Egger test(P < 0.001)and funnel plot.In order to address this we used trim-and-fill method to correct the bias,we showed that if the publicationbias was the only source of the funnel plot asymmetry,it needed seven more studies to balance the funnel plot.The resulting adjusted RR was attenuated but remained significant(RR 1.10,95% CI: 1.00-1.21)in the Random-effects model,suggesting the stability of our results.Conclusion: Our meta-analysis provides evidence that high level of gamma-glutamyltransferase is significantly associated with increased risk of stroke independently of alcohol intake.Gender and ethnicity variations may exist in the relationship between high-gamma-glutamyltransferase level and risk of stroke. |
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