Abstract
Introduction In this investigation, the focus was on exploring the connection between serum gamma-glutamyl transferase (GGT), a vital element that influences health and mortality in relation to aging, and all-cause mortality. The study was conducted using a follow-up approach at eight- and 20-year intervals. Methods The study involved 1,101 female participants, with an average age of 69 years (± 9), and 916 male participants, with an average age of 67 years (± 11), who were all diagnosed with hypertension. These individuals were drawn from the Nomura cohort study, which consisted of two separate cohorts: the initial cohort established in 2002 and the subsequent cohort in 2014. We used a Cox proportional hazards model to calculate the hazard ratios (HRs), adjusted for multiple variables, for mortality risk from the initial health examination until the conclusion of the follow-up periods. Results The study followed the participants for a median period of 13.9 years (interquartile range: 8.5-20.2 years). During this follow-up period, 716 deaths were recorded in this population (360 in men and 356 in women), resulting in a mortality rate of 25.5 deaths per 1,000 person-years. Male participants categorized with serum GGT levels ranging from 42 to 86 IU/L showed a 64% increased risk of all-cause mortality (HR: 1.64; 95% confidence interval (CI): 1.11-2.40), while those with GGT levels of 87 IU/L or higher exhibited a 93% elevated risk (HR: 1.93; 95% CI: 1.18-3.16) compared to individuals with GGT levels below 19 IU/L. The association between higher GGT levels and increased all-cause mortality was more evident in men than in women, with a significant interaction between gender and baseline serum GGT (p = 0.020). Conclusions Our findings suggest a notable correlation between irregular GGT levels and the overall mortality rate among Japanese individuals with hypertension living in community settings. Notably, especially in older males, GGT activity turns out to be a critical biomarker for predicting long-term survival.