Association between serum gamma-glutamyltransferase and cardiovascular mortality varies by age: the Minnesota Heart Survey.

BACKGROUND Although serum gamma-glutamyltransferase (GGT) predicted cardiovascular diseases (CVD) in prospective studies and may be useful in risk assessment, prediction in older adults was weaker in several studies. METHODS We performed a nested case-control study with 5-12-year follow-up in 137 CVD deaths and 249 controls (frequency-matched on age, sex, and examination year, age range 26-85 years). RESULTS An age interaction of serum GGT and CVD mortality (P value for interaction=0.02) was observed. After adjusting for known CVD risk factors, compared with the lowest tertile, odds ratios (95% confidence intervals) in participants less than 70 years (half the participants) were: middle tertile: 2.17 (0.68-6.97), top tertile up to GGT less than 50 U/l: 3.54 (1.07-11.7), and GGT >/=50 U/l: 4.69 (1.16-18.9). In participants aged more than or equal to 70 years, GGT was not related to CVD. Well-known demographic and health behavior associations with serum GGT were observed only in controls among participants aged less than 70 years. CONCLUSION Our findings suggest that serum GGT within its normal range can predict CVD mortality in those aged less than 70 years, but may have limited usefulness for risk assessment in older adults.