γ-Glutamyltransferase and risk of stroke: The EUROSTROKE project

Background: Alcohol consumption has been implicated in the aetiology of stroke. As data on alcohol consumption obtained by questionnaire are susceptible to missclassification, this study evaluated the assocation between γ-glutamyltransferase (γ-GT), as a marker for alcohol consumption, and fatal, non-fatal, haemorrhagic and ischaemic stroke in three European cohort studies, participating in EUROSTROKE. Methods: EUROSTROKE is a collaborative project among ongoing European cohort studies on incidence and risk factors of stroke. EUROSTROKE is designed as a nested case-control study. For each stroke case, two controls were sampled. Strokes were classified according to MONICA criteria or reviewed by a panel of four neurologists. At present, data on stroke and γ-GT were available from cohorts in Cardiff (57 cases), Kuopio (66 cases), and Rotterdam (108 cases). Results: An increase in γ-GT of one standard deviation (28.7 IU/ml) was associated with an age and sex adjusted 26% (95% Cl 5 to 53) increase in risk of stroke. Adjustment for confounding variables such as drug use, history of myocardial infarction, total cholesterol, and diabetes mellitus did not materially attenuate the association. The risk of haemorrhagic stroke increased linearly with increase in γ-GT. The association for cerebral infarction was not graded: the risk increased beyond the first quartile, and remained increased. The association of γ-GT with stroke was significantly stronger among subjects without diabetes mellitus compared with subjects with diabetes mellitus (no association observed). Conclusion: This EUROSTROKE analysis showed that an increased γ-GT, as a marker of alcohol consumption, is associated with icreased risk of stroke, in particular haemorrhagic stroke.