BACKGROUND: Sarcopenia, characterized by loss of muscle mass and strength, has been linked to various health outcomes, including chronic kidney disease (CKD). This study aims to investigate the association of sarcopenia index, based on serum creatinine and cystatin C levels, with incident CKD in middle-aged and older adults. METHODS: This study extracted data from a nation cohort, including age ≥45 years adults without CKD at baseline. Sarcopenia index was calculated based on serum creatinine and cystatin C levels, and incident CKD was assessed through follow-up surveys. Cox proportional hazards regression models were used to analyze the association between sarcopenia index and incident CKD, adjusting for potential confounders, with hazard ratio (HR) with 95% confidence interval (95% CI) reported. RESULTS: A total of 8,618 participants were included in the analysis. The median age was 61.0 years, and 44.7% were male. During a mean follow-up period of 5.0 years, 514 cases of incident CKD were identified. After adjusting for covariates, compared with participants in the lowest tertile, the corresponding CKD HRs (95% CIs) for participants in the medium and highest tertile were 0.701 (95% CI: 0.558-0.880, P=0.002), 0.784 (95% CI: 0.618-0.994
P=0.045). Restricted cubic spline curves revealed that incident rate decreased with increase in sarcopenia index. CONCLUSION: This study provides national longitudinal evidence on the association of higher sarcopenia index with lower incident CKD. Our findings suggest that sarcopenia index may be a useful biomarker for predicting the risk of CKD in this population.