The triglyceride-cholesterol-body weight index is positively associated with kidney stones and their recurrence: A cross-sectional study followed by external validation

BACKGROUND: Kidney stones represent a prevalent and economically burdensome urinary system disorder with rising global incidence. Although dyslipidemia is a recognized risk factor for nephrolithiasis, the association of the Triglyceride-Cholesterol-Body Weight Index (TCBI)-a novel measure integrating lipid metabolism and body weight-with both incident and recurrent kidney stones has not been investigated in the general population. METHODS: Data from the 2007-2016 cycles of the National Health and Nutrition Examination Survey (NHANES) formed the basis of this cross-sectional analysis. Analyses included 9929 participants for kidney stone risk evaluation and 724 for assessing recurrence risk. We employed multivariable logistic regression, extensively controlling for demographic, socioeconomic, and clinical factors, to assess associations. The dose-response relationship and effect consistency were then examined using restricted cubic splines (RCS) and subgroup analyses. We further analyzed an independent external validation dataset of 201 participants to validate the results. RESULTS: A positive association was observed between TCBI and kidney stone prevalence after full adjustment: each 1-unit increase in log-transformed TCBI (Lg TCBI) was associated with a 50.3% higher risk. A strong association was found between the highest Lg TCBI quartile and increased prevalence of both incident and recurrent kidney stones, relative to the lowest quartile. This positive association followed a monotonic dose-response pattern (P for nonlinearity >0.05), as confirmed by RCS, and was upheld across subgroups. External validation reinforced the positive link between Lg TCBI and kidney stone development and recurrence. CONCLUSIONS: TCBI was demonstrated to be independently associated with the presence of both new-onset and recurrent kidney stones. Given its ease of calculation, TCBI holds value as a clinical indicator for assessing associated risk and identifying individuals who may benefit from evaluation, notably those with underlying metabolic abnormalities.