Association between sarcopenia and frailty in middle-aged and elder population: Findings from the China health and retirement longitudinal study

Background:<bold> </bold>The relationship between sarcopenia and frailty among middle-aged and elder adults remains unclear. This study conducted a cross-sectional and longitudinal analysis to investigate the association of sarcopenia and frailty in the middle-aged and elder Chinese population. Methods:<bold> </bold>Our data were drawn from the China Health and Retirement Longitudinal Study. Sarcopenia status was assessed according to the Asian Working Group for Sarcopenia 2019 criteria and categorised into: no sarcopenia, possible sarcopenia, sarcopenia, and severe sarcopenia. A 38-item deficit-accumulation frailty index was constructed to assess frailty trajectories at each visit. Generalised linear regression models were performed to analyse the cross-sectional associations between sarcopenia and frailty index. The Group-based trajectory modelling was adopted to identify potential frailty trajectories, and we then examined the associations of sarcopenia and frailty trajectories using logistic regression analysis. Results:<bold> </bold>A total of 13 218 participants were enrolled in the cross-sectional analysis and 4200 individuals were included in the longitudinal study. The cross-sectional study found that possible sarcopenia (regression coefficient (beta) = 0.76; 95% confidence interval (CI) = 0.64-0.87, P < 0.001), sarcopenia (beta = 0.56; 95% CI = 0.37-0.75, P < 0.001) and severe sarcopenia (beta = 1.35; 95% CI = 0.97-1.73, P < 0.001) were significantly associated with higher frailty index. The longitudinal study indicated that participants with possible sarcopenia (odds ratio (OR) = 2.46; 95% CI = 1.77-3.42, P < 0.001), sarcopenia (OR = 1.87; 95% CI = 1.27-2.74, P < 0.001) and severe sarcopenia (OR = 6.57; 95% CI = 3.14-13.77, P < 0.001) had a higher risk of accelerated progression of frailty compared to those with no sarcopenia. Conclusions:<bold> </bold>Possible sarcopenia, sarcopenia, and severe sarcopenia were associated with higher levels of frailty and accelerated progression of frailty. Therefore, clinical medical professionals should pay more attention to frailty status in individuals who have possible sarcopenia and sarcopenia.