Gamma-glutamyl transferase as a risk factor for mortality and cardiovascular events in older adults - results from a prospective cohort study in a primary care setting (getABI).

Background: In primary care, the gamma-glutamyl transferase (GGT) activity is used for assessing hepatobiliary dysfunction, but is also known to be associated with the risk of cardiovascular events as well as overall mortality. As this knowledge is mainly based on cohorts with middle-aged participants, we aim to assess these associations in elderly patients in a primary care setting. Patients and methods: 6,880 unselected primary care patients, aged 65 years or older, were enrolled by 344 general practitioners all over Germany (getABI study). During seven years of follow-up, coronary heart disease (CHD) events (myocardial infarction or coronary revascularization), cerebrovascular events (stroke or carotid revascularization) and deaths were recorded. Event rates were calculated and Cox regression analysis with adjustment for age, gender, GGT, classical and other risk factors (e.g. education, homocysteine, C-reactive protein, vitamin D) was performed. Results: 1,243 patients died. 27.8 deaths per 1,000 patient years (0.95 confidence interval [0.95 CI]: 26.2-29.3) occurred in the whole cohort. 605 participants had a CHD event, i.e. 16.1 per 1,000 patient years (0.95 CI: 14.8-17.4). 296 cerebrovascular events were observed, i.e. 7.7 per 1,000 patient years (0.95 CI: 6.9-8.6). Cox regression analysis with adjustment for the above-mentioned risk factors showed a significant impact of baseline elevation of GGT above the 3rd quartile (women > 18 U/L, men > 26 U/L) compared to the rest on mortality (hazard ratio [HR] 1.38, 95% CI 1.22-1.56, p < 0.001) and cerebrovascular events (1.39, 95% CI: 1.08-1.79), p = 0.010), whereas the association with CHD events (HR: 1.16, 95% CI: 0.97-1.39, p = 0.103) showed no significance. Conclusions: In a primary care setting, GGT values have a significant association with overall mortality and cerebrovascular events, but not with CHD events in elderly patients.