Gamma-glutamyltransferase is associated with cardiovascular and all-cause mortality: a meta-analysis of prospective cohort studies.

OBJECTIVE: The purpose of the present study was to investigate whether gamma-glutamyltransferase (GGT) is an independent predictor for future cardiovascular (CV) and all-cause mortality with prospective observational studies by meta-analysis.
METHODS: Electronic literature databases (Cochrane Library, Medline, and Embase) were searched for relevant prospective observational studies on the association between baseline GGT and CV and all-cause mortality published prior to June 2012. Pooled adjust relative risk (RR) and corresponding 95% confidence intervals(CI) were calculated separately for categorical risk estimates(highest vs. lowest GGT quartile) and continuous risk estimates (per unit-log GGT increment).
RESULTS: Seven studies with 273,141 participants were identified and analyzed. The pooled RR of CV mortality for highest vs. lowest GGT quartile was 1.52 (95% CI 1.36-1.70). The pooled RR of CV mortality for per unit-log (GGT) increment was 1.76 (95% CI 1.60-1.94). The pooled RR for all-cause mortality for highest vs. low GGT quartile was 1.56 (95% CI 1.34-1.83). Subgroup analyses based on region, gender, follow-up duration, and sample size showed that the positive association between GGT and risk of CV mortality was consistently observed in each subgroup except for the Asia subgroup (RR=1.59, 95% CI 0.76-3.30).
CONCLUSIONS: GGT is an independent predictor for future CV mortality and all-cause mortality, and might be independent of alcohol intake.