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


METHODS
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.


RESULTS
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.


CONCLUSION
This analysis of National Health and Nutrition Examination Survey data has demonstrated that BMI is significantly associated with the prevalence of kidney stones.