Association between frailty and kidney stone among U.S. adults using data from NHANES

This study aimed to investigate the association between frailty and kidney stone prevalence among U.S. adults. We conducted a cross-sectional analysis using data from National Health and Nutrition Examination Survey 2017 to 2020. Frailty was assessed using a 49-item frailty index (FI) based on the cumulative deficit model and categorized into robust (FI ≤ 0.10), pre-frail (0.10 < FI < 0.25), and frail (FI ≥ 0.25). Kidney stone history was self-reported. Weighted logistic regression models were used to estimate the association between frailty and kidney stones, with adjustments for demographic, socioeconomic, lifestyle, comorbidity, and biochemical covariates. A total of 26,454 participants were included, with 2530 (9.6%) reporting a history of kidney stones. The FI was positively associated with kidney stone risk (OR per 0.01 increase = 1.024; 95% CI: 1.016-1.032; P < .0001). Compared with robust individuals, the adjusted odds ratios for kidney stones were 1.509 (95% CI: 1.310-1.740) for the pre-frail group and 1.852 (95% CI: 1.472-2.331) for the frail group (P for trend <.0001). RCS analysis confirmed a nonlinear dose-response relationship. Subgroup analyses revealed stronger associations in individuals <60 years, females, and those with lower socioeconomic status, with a significant interaction by age (P for interaction <.0001). Frailty is independently associated with an increased risk of kidney stones in U.S. adults, particularly among younger and socioeconomically vulnerable populations. However, due to the cross-sectional nature of this study, causality cannot be inferred. These findings highlight the potential value of frailty screening in kidney stone prevention strategies and warrant further prospective and mechanistic research.