Association between alanine aminotransferase-to-aspartate aminotransferase ratio and obstructive sleep apnea: A cross-sectional study of NHANES.

Obstructive sleep apnea (OSA) has been associated with abnormal liver enzyme levels. However, the association between the alanine aminotransferase-to-aspartate aminotransferase (ALT/AST) ratio and OSA remains understudied in large, nationally representative samples. This study examined the relationship between ALT/AST ratio and OSA among adults in the United States. We conducted a cross-sectional analysis of 7371 participants aged ≥20 years, pooling data from 4 National Health and Nutrition Examination Survey cycles (2005-2006, 2007-2008, 2015-2016, and 2017-2018). Weighted multivariate logistic regression was used to assess the relationship between the ALT/AST ratio and OSA, complemented by dose-response curve fitting, stratified subgroup analyses, and sensitivity analyses. Among 7371 participants (mean age 47.07 years; 48.50% male), 3672 reported OSA symptoms. A key finding was a significant inverted L-shaped nonlinear relationship between the ALT/AST ratio and OSA risk (P for nonlinearity = 0.021), with a threshold identified at a ratio of 1.08. Below this threshold, each unit increase in the ALT/AST ratio was associated with an 84% increase in the odds of OSA (odds ratio = 1.84, 95% confidence interval: 1.03-3.32, P = .041). Above 1.08, no significant association was observed. In a traditional quartile analysis, participants in the highest quartile of the ALT/AST ratio had 55% higher odds of OSA compared to those in the lowest quartile (odds ratio = 1.55, 95% confidence interval: 1.26-1.89, P < .001). The findings were robust across subgroup and sensitivity analyses. The ALT/AST ratio shows an association with self-reported OSA in cross-sectional data. These findings should be confirmed in longitudinal studies before considering clinical application. Additionally, prospective cohort or interventional studies are required to validate the observed threshold effect.