The role of serum uric acid in frailty among individuals with reduced renal function: a cross-sectional study base on CHARLS.

Frailty is a common geriatric syndrome associated with adverse health outcomes, particularly in individuals with chronic kidney disease (CKD). However, the relationship between Serum uric acid (SUA) and frailty in individuals with reduced renal function remains unclear. This cross-sectional study utilized data from the 2015 wave of the China Health and Retirement Longitudinal Study. Participants with self-reported CKD or an estimated glomerular filtration rate < 60 mL/min/1.73 m² were included (N = 1,809). SUA levels were measured and categorized into tertiles (< 4.70 mg/dL, 4.70-6.03 mg/dL, and ≥ 6.03 mg/dL). Frailty status was assessed using a validated frailty index based on 30 health-related variables. Ordinal logistic regression and restricted cubic spline analysis were used to examine the association between SUA and frailty, adjusting for demographic, clinical, and lifestyle factors. Higher SUA levels were significantly associated with frailty. In multivariable models, participants in the highest SUA tertile had increased odds of frailty compared to the lowest tertile (odd ratio [OR] = 1.354, 95% confidence interval [95% CI]: 1.028-1.783, P = 0.031). Restricted cubic spline analysis indicated a linear relationship between SUA and frailty index (P for overall = 0.037). Subgroup analysis showed a stronger association in participants aged < 65 years (highest vs. lowest tertile: OR = 1.872, 95% CI: 1.185-2.966, P = 0.007), while no significant association was observed in those aged ≥ 65 years (highest vs. lowest tertile: OR = 1.029, 95% CI: 0.719-1.473, P = 0.877). Elevated SUA levels are independently associated with frailty in individuals with reduced renal function, particularly among younger participants. These findings suggest that SUA may serve as a potential biomarker and therapeutic target for frailty prevention in this population.