Serum Transaminases and Older Adults: Distribution and Associations With All-Cause Mortality.

Background: Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are commonly ordered tests in general medical practice. However, their distribution and significance in older adults are understudied. As such, we aimed to evaluate sex-stratified distribution of both ALT and AST in older adults (≥70 years) and assess for associations with mortality.

Methods: Post-hoc analysis of the ASPirin in Reducing Events in the Elderly (ASPREE) randomized, placebo-controlled trial of daily low-dose aspirin for initially relatively healthy older persons. Univariate analysis and multiple logistic regression were used to explore baseline characteristics. Cox regression and restricted cubic splines were used to examine links between transaminase levels and mortality.

Results: Of the 11 853 participants with ALT and AST levels, 1 054 (8.9%) deaths were recorded over a median of 6.4 (interquartile range [IQR] 5.4-7.6) years. For ALT, the lowest quintiles for males and females were 6-15 and 5-13 U/L, respectively; for AST, the lowest quintiles were 8-18 and 7-17 U/L, respectively. On both univariate and models adjusted for covariates including age, body mass index, frailty, diabetes, and kidney disease, males and females in the lowest quintile of ALT had an increased hazard of mortality (aHR 1.51 [95% confidence interval {CI} 1.14-1.99] and aHR 1.39 [95% CI 1.03-1.88], respectively). For the lowest quintile of AST, only males were at increased risk (aHR 1.33 [95% CI 1.04-1.70]). Associations remained significant when removing outliers.

Conclusions: Low ALT levels independently confer an increased hazard of mortality for older males and females; low AST only affected older male survival. Further evaluation of mechanisms would be worthwhile, and re-evaluating the lower limit of normal for ALT in older adults should be considered.