Sarcopenia and the frailty progression among Chinese: a longitudinal study.

Introduction: Previous studies primarily focused on baseline sarcopenia status, neglecting changes over time. This study aims to explore the association between changes in sarcopenia status and frailty progression, hypothesizing that transitions to possible sarcopenia or sarcopenia increase frailty risk, while recovery to non-sarcopenia reduces this risk. Methods: Using data from the China Health and Retirement Longitudinal Study (CHARLS), sarcopenia was evaluated at baseline and after 2 years using the AWGS 2019 criteria. Frailty was assessed with a 32-item frailty index. Cox regression and linear mixed models analyzed the association between sarcopenia transitions and frailty progression. Results: Participants who developed possible sarcopenia or sarcopenia faced a 56% higher frailty risk (HR 1.56, 95% CI 1.21-2.01) and a faster frailty index increase (β = 0.007/year, 95% CI 0.005-0.010) compared to those remaining non-sarcopenic. In contrast, those recovering from sarcopenia to non-sarcopenia or possible sarcopenia had a 46% lower frailty risk (HR 0.54, 95% CI 0.32-0.89) and a slower frailty index rise (β = -0.008/year, 95% CI -0.015 to -0.002). Among individuals with possible sarcopenia at baseline, recovery to non-sarcopenia reduced frailty risk by 48% (HR 0.52, 95% CI 0.39-0.68), while progression to sarcopenia increased it by 77% (HR 1.77, 95% CI 1.07-2.94). Conclusion: Transitions in sarcopenia status significantly affect frailty risk and progression. Worsening sarcopenia heightens frailty risk, whereas recovery diminishes it. These findings highlight the value of monitoring and addressing sarcopenia in middle-aged and older adults, offering potential to enhance quality of life and lower healthcare costs through targeted interventions.