Gamma-Glutamyltransferase and Future Risk of Pneumonia: A Long-Term Prospective Cohort Study.

Serum gamma-glutamyltransferase (GGT) has been linked with the risk of adverse health outcomes. We aimed to assess the prospective association of GGT activity with pneumonia risk. Serum GGT was measured at baseline in 2400 middle-aged men. Within-person variability in GGT values was corrected for using data from repeat measurements. During a median follow-up of 25.3 years, 409 pneumonia cases were recorded. The age-adjusted regression dilution ratio of GGT was 0.68 (95% CI 0.63-0.73). Gamma-glutamyltransferase was approximately log-linearly associated with pneumonia risk. In analysis adjusted for several major pneumonia risk factors, the hazard ratio (95% CI) for pneumonia per 1 standard deviation increase in GGT was 1.14 (1.02-1.28). The association was however attenuated on additional adjustment for high-sensitivity C-reactive protein (hsCRP) 1.08 (0.96-1.22). There is an approximately log-linear positive association between GGT activity and future risk of pneumonia in a middle-aged male population, which is partly dependent on hsCRP.