Gamma-glutamyltransferase, general and cause-specific mortality in 19,000 construction workers followed over 20 years

Background: Associations of serum gamma-glutamyltransferase levels (g-GT) with a variety of incident diseases and mortality have been suggested. The present study attempted to expand the body of evidence to especially relevant occupational cohorts in which exposure to established g-GT determinants may greatly differ from the general population. Methods: The study was based on occupational health examinations conducted from 1986 to 1992 in 19,090 German male workers from the construction industry, aged 25–64 years. Sociodemographics and other health-related information were collected during the exam. Vital status follow-up was conducted through 2008. Associations of baseline g-GT levels (measurements at 25°C) with all-cause and cause-specific mortality were examined by Kaplan-Meier plotting and adjusted Cox regression models. Adjustment included potential confounders such as age, prevalent diseases, body mass index, and smoking. Additional models were further adjusted for alcohol consumption. Results: A total of 2,170 deaths occurred during 303,252 person-years of follow-up. The risk of death due to any cause was 2.5-fold increased in subjects in the highest (≥39 U/L) versus lowest (<11 U/L) g-GT quintile. To varying extent, elevated g-GT was associated with higher mortality due to cancer, circulatory, respiratory, and digestive causes, as well as accidents/poisoning. The associations were largely independent of alcohol consumption. Conclusions: The findings in this cohort provide evidence for g-GT being associated with a broad range of causes of death, including less investigated outcomes. Some characteristics of the observed patterns need to be seen in the context of our cohort featuring particularly high g-GT levels.