The association between serum uric acid to creatinine ratio and gallstones: National Health and Nutrition Examination Survey 2017–2020

Objective This cross-sectional study investigates the association between the serum uric acid-to-creatinine (UA/Cr) ratio and gallstone risk using NHANES 2017–2020 data, while exploring modifying effects of demographic and metabolic factors. Methods A total of 5450 adult participants were included after excluding individuals with missing gallstone diagnoses or incomplete UA/Cr data. UA/Cr was calculated as uric acid (mg/dL)/creatinine (mg/dL). Gallstone diagnosis relied on self-reported questionnaires. Weighted logistic regression models (unadjusted, partially adjusted, fully adjusted) assessed associations, with covariates including demographic (age, sex, race/ethnicity, education), lifestyle (smoking, alcohol use), and metabolic factors (BMI, hypertension, total bilirubin, diabetes). A restricted cubic spline analysis was further employed to visualize potential nonlinear relationships. Additionally, subgroup analyses were conducted to evaluate the association between the UA/Cr and gallstone risk across various subgroups. Results Gallstone prevalence was 9.85% (537/5450), with higher UA/Cr in affected individuals (7.29 vs. 6.16, p = 0.034). Fully adjusted models demonstrated a 17% increased gallstone risk per UA/Cr unit (Odds ratio (OR) = 1.17, 95% confidence interval: 1.09–1.38, p = 0.021). The highest UA/Cr quartile (≥7.234) showed a 41% elevated risk (OR = 1.41, p = 0.017). Restricted cubic spline analysis revealed a non-linear dose–response relationship (inflection point: UA/Cr = 6.4). Subgroup analyses identified stronger associations in females (OR = 1.23, p = 0.012), obese individuals (OR = 1.24, p = 0.016), and divorced participants (OR = 1.21, p = 0.009). Conclusions Elevated UA/Cr ratio was independently associated with an increased risk of gallstone disease in this nationally representative sample. Future prospective and mechanistic studies are warranted to clarify the temporal relationship and the underlying pathways linking purine metabolism to biliary pathology.