Aspartate Aminotransferase/Alanine Aminotransferase Ratio: A Predictor of All-Cause Mortality Rate Among Japanese Community-Dwelling Individuals

Introduction An elevated ratio of aspartate aminotransferase (AST) to alanine aminotransferase (ALT) not only independently affects aging-related health but also plays a critical role in mortality. However, there is limited predictive data on all-cause mortality, particularly in the context of community-dwelling individuals in Japan. This study examined the association between the AST/ALT ratio and survival prognosis in a cohort study using two follow-up studies based on 19-year and 7-year intervals. Methods The study included 1,573 male (63 +/- 14 years; range, 20-90 years) and 1,980 female participants (65 +/- 12 years; range, 19-89 years). The participants were those involved in a Nomura cohort study conducted in 2002 (first cohort) and 2014 (second cohort) that continued to participate throughout the follow-up periods (follow-up rates were 90.3% and 97.4% for each cohort). A Cox proportional hazards model was adopted to calculate the multivariate-adjusted hazard ratios (HRs) of death from the baseline health check-up to the follow-up periods while controlling for potential confounding factors. Results The follow-up survey revealed that there were 473 male deaths (30.1% of total male participants) and 432 female deaths (21.8% of total female participants). The univariate Cox regression analysis showed that HRs for all-cause mortality were greater for participants in higher AST/ALT ratio quartiles (p < 0.001). The multivariate Cox regression analysis with adjusted variables showed a significant association between those in the fourth AST/ALT ratio quartile (HR: 1.83, 95% confidence interval, 1.46-2.29) and the risk of all-cause mortality. This association holds irrespective of gender, age, and elevated gamma-glutamyl transpeptidase, particularly in the case of participants with a body mass index < 25 kg/m(2) without a history of cardiovascular disease or diabetes. Conclusions Our results reveal that an elevated AST/ALT ratio is an independent factor that can predict the risk of all-cause mortality among community-dwelling individuals.