Association between blood urea nitrogen-to-albumin ratio and kidney stones: A cross-sectional study based on NHANES
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Background
Kidney stones are a disorder in which urinary solutes precipitate to form crystalline aggregates in the urinary space. The blood urea nitrogen-to-albumin ratio (BAR), a nutrition and inflammatory indicator, has an unclear association with kidney stones.
Methods
Using NHANES 2007–2020 data, we compared baseline characteristics between kidney stone formers and controls and evaluated the BAR–stone relationship via weighted multivariate logistic regression (WMLR), restricted cubic splines (RCS), stratification analyses, and XGBoost, and performed an exploratory analysis in an ICU cohort, the Medical Information Mart for Intensive Care IV (MIMIC-IV).
Results
A total of 23,652 participants (2,318 with kidney stones) were included, and 21 baseline features differed significantly between groups (P < 0.05). In WMLR, BAR was positively associated with kidney stone risk in the unadjusted model (OR = 1.15, 95% CI 1.11–1.18) and after adjustment for demographic, lifestyle, dietary, comorbidity and routine laboratory variables (Model 3; OR = 1.05, 95% CI 1.01–1.10, P = 0.012). After further adjustment for body mass index (BMI), diabetes, estimated glomerular filtration rate (eGFR) and poverty income ratio (PIR) in the fully adjusted primary model (Model 4), the association was attenuated to the null (OR = 0.99, 95% CI 0.95–1.04, P = 0.79); restricting the analysis to participants with eGFR ≥ 60 mL/min/1.73 mZ gave consistent results (OR = 1.01, 95% CI 0.95–1.07, P = 0.78). The apparent nonlinear association observed in the unadjusted analysis (inflection point at BAR = 5.4) was not retained after adjustment (P for nonlinearity = 0.87), and subgroup analyses showed no significant effect modification (all P for interaction > 0.05). In XGBoost, BAR ranked seventh of 28 predictors by gain, with modest discrimination (out-of-fold AUC = 0.61). In the exploratory MIMIC-IV analysis, BAR was positively associated with kidney stones (Model 3 of that cohort: OR = 1.029, 95% CI 1.015–1.045), although this cohort was not designed as a validation set.
Conclusions
BAR is not independently associated with kidney stones once renal function and metabolic factors are accounted for, and the previously reported association appears to be largely explained by confounding.
