Liver enzymes and stroke risk in middle-aged German adults

Objective: To investigate the association between the liver enzymes gamma-glutamyltransferase (GGT) and (alanine aminotransferase) ALT and risk of stroke, its subtypes including TIA as well as fatal and non-fatal events. Methods: A case-cohort study within the European Prospective Investigation into Cancer and Nutrition-Potsdam Study comprising 27548 middle-aged subjects was designed. GGT and ALT were measured in plasma of 353 individuals who developed a stroke and in 2110 individuals who remained free of cardiovascular events during a mean follow-up of 8.2 +/- 2.2 years. Cox proportional-hazard models were applied to evaluate the association between liver enzymes and stroke risk. Results: After adjustment for established clinical and lifestyle factors, a 1 unit change in naturally logged GGT was related to a 1.20 (95%CI: 1.03-1.40) increased stroke risk. Risk estimates did not significantly differ between fatal (Relative Risk (RR) = 1.35, 95%CI: 1.14-1.61) and non-fatal events (RR = 1.15; 95%CI: 0.97-1.36). ALT was not associated with overall stroke risk (RR = 0.95; 95%CI: 0.71-1.26). However, in subtype analyses we observed in multivariable adjusted models a significant increased risk of hemorrhagic stroke (RR = 2.00; 95%CI: 1.01-3.96), but decreased risk of ischemic stroke (RR = 0.66; 95%CI: 0.44-0.998). Conclusions: Our data provide further evidence for a link between GGT, but not ALT and overall stroke suggesting that these biomarkers are involved in different pathways of disease development. Further studies are needed to clarify the putative relationships between ALT and subtypes of stroke. (C) 2013 Elsevier Ireland Ltd. All rights reserved.