Relationship Between Body Mass Index and Kidney Stones Based on Dose–Response Analyses Using Restricted Cubic Splines Applied to NHANES 2011–2016 Data

The objective of the study was to estimate the dose-response relationship between body mass index (BMI) and the self-reported prevalence of kidney stones based on a restricted cubic spline (RCS) method.This cross-sectional study analyzed 13,223 adults aged ≥20 years who had participated in the National Health and Nutrition Examination Survey performed during 2011-2016. Kidney stones were identified using a standard questionnaire, and physical examinations were used to determine BMI. Logistic regression was used to assess the relationship between BMI and the prevalence of kidney stones, with the dose-response relationship explored using RCSs.The overall prevalence of kidney stones was 9.7%: 10.6% in males and 8.9% in females. After adjusting for potential confounders, compared with those with a BMI in quartile 1, the odds ratios of kidney stones among those with BMIs in quartiles 2, 3, and 4 were 1.45, 1.60, and 2.00, respectively (95% confidence interval = 1.21-1.75, 1.33-1.92, and 1.67-2.39; all P < .001). Multivariate RCS regression revealed that BMI was related to kidney stones in a nonlinear manner (P for nonlinearity <0.001). There was a significant positive relationship, with the curves being steeper when BMI was <28 kg/m2.This analysis of National Health and Nutrition Examination Survey data has demonstrated that BMI is significantly associated with the prevalence of kidney stones.