Liver enzymes and risk of stroke: The atherosclerosis risk in communities (aric) study

Background and Purpose Liver enzymes (aspartate aminotransferase [AST], alanine aminotrans-ferase [ALT], and gamma-glutamyl transpeptidase [GGT]) are glutamate-regulatory enzymes, and higher glutamate levels correlated with worse prognosis of patients with neurotrauma. However, less is known about the association between liver enzymes and incidence of stroke. We evaluated the association between serum levels of AST, ALT, and GGT and incidence of stroke in the Atherosclerosis Risk in Communities (ARIC) study cohort from 1990 to 1992 through December 31, 2016. Methods We included 12,588 ARIC participants without prevalent stroke and with data on liver enzymes ALT, AST, and GGT at baseline. We used multivariable Cox regression models to examine the associations between liver enzymes levels at baseline and stroke risk (overall, ischemic stroke, and intracerebral hemorrhage [ICH]) through December 31, 2016, adjusting for potential con-founders. Results During a median follow-up time of 24.2 years, we observed 1,012 incident strokes (922 ischemic strokes and 90 ICH). In age, sex, and race-center adjusted models, the hazard ratios (HRs; 95% confidence intervals [CIs]) for the highest compared to lowest GGT quartile were 1.94 (95% CI, 1.64 to 2.30) for all incident stroke and 2.01 (95% CI, 1.68 to 2.41) for ischemic stroke, with the results supporting a dose-response association (P for linear trend <0.001). Levels of AST were associated with increased risk of ICH, but the association was significant only when compar-ing the third quartile with the lowest quartile (adjusted HR, 1.82; 95% CI, 1.06 to 3.13). Conclusions Elevated levels of GGT (within normal levels), independent of liver disease, are associated with higher risk of incident stroke overall and ischemic stroke, but not ICH.