Association of aspartate aminotransferase to alanine aminotransferase ratio with hypertension in Chinese adults: a cross-sectional study

Background Emerging evidence has linked the aspartate aminotransferase to alanine aminotransferase (AST/ALT) ratio to insulin resistance and various metabolic disorders, yet its relationship with hypertension in the Chinese adult population has not been well characterized. The present study was designed to evaluate whether the AST/ALT ratio is independently associated with hypertension risk among Chinese adults. Methods We conducted a cross-sectional analysis using data obtained from the Dryad repository, originally collected through the Rich Healthcare Group Health screening program. A total of 87,869 participants were enrolled. The AST/ALT ratio was derived by dividing serum AST by ALT concentrations. Hypertension was identified when systolic blood pressure reached ≥140 mmHg or diastolic blood pressure reached ≥90 mmHg. Multivariable logistic regression models with progressive covariate adjustment were employed to assess the AST/ALT ratio–hypertension relationship. Smooth curve fitting coupled with threshold analysis was applied to detect nonlinear patterns, while stratified analyses with multiplicative and additive interaction assessments were performed to examine effect modification. A sensitivity analysis excluding renal-function markers was performed to probe robustness. Results A total of 87,869 participants (57.0% male) with a mean age of 42.1 ± 12.8 years were included. In a model adjusted for age, sex, and BMI, each unit increase in the AST/ALT ratio corresponded to a 20% reduction in hypertension odds (OR = 0.80, 95% CI: 0.76–0.84, p < 0.001), and the estimate was essentially unchanged in the fully adjusted model (OR = 0.83, 95% CI: 0.78–0.87, p < 0.001). When stratified by quartiles, participants in higher AST/ALT ratio categories exhibited progressively lower hypertension risk relative to the lowest quartile (Q2: OR = 0.85, 95% CI: 0.81–0.90; Q3: OR = 0.78, 95% CI: 0.73–0.83; Q4: OR = 0.81, 95% CI: 0.75–0.87). A nonlinear dose–response pattern was identified, with the inflection point occurring at an AST/ALT ratio of approximately 1.010. Stratified analyses demonstrated significant effect modification by age (P for interaction < 0.001) and BMI (P for interaction < 0.001), with stronger inverse associations among individuals younger than 60 years and those with BMI ≥ 25 kg/m 2 . Conclusion Among Chinese adults, an elevated AST/ALT ratio is independently and inversely associated with the risk of hypertension, following a nonlinear pattern. Because it is obtainable at no additional cost from routine liver function panels, the AST/ALT ratio may serve as a complementary indicator for flagging individuals who warrant closer blood pressure surveillance; however, the association is modest in size, and the ratio does not replace direct blood pressure measurement.