The bidirectional relationship between sarcopenia and disability in China: a longitudinal study from CHARLS

Objectives Sarcopenia and disability represent significant concerns impacting the health of older people. This study aimed to explore the bidirectional relationship between sarcopenia and disability in Chinese older people. Methods This study recruited older people >= 60 years old from the China Health and Retirement Longitudinal Study. In phase I, the study analyzed the relation between disability and subsequent sarcopenia using multinomial logistic regression models. Conversely, in phase II, the study assessed whether sarcopenia was associated with future disability using binary logistic regression models. Results In phase I, 65 (16.80%) new cases of possible sarcopenia, 18 (4.65%) cases of sarcopenia, and 9 (2.33%) cases of severe sarcopenia were observed in the disabled older people and 282 (10.96%) new cases of possible sarcopenia, 97 (3.77%) cases of sarcopenia, 35 (1.36%) cases of severe sarcopenia were observed in the older people without disability. The OR (95% CI) for sarcopenia in older disabled individuals compared to those without disability was 1.61 (1.25-2.07). Adjusting for all covariates in 2011, the OR (95% CI) value for disabled individuals vs. those without disability was 1.35 (1.02-1.79). Subgroup analyses showed that disabled participants aged < 80 years were more likely to have sarcopenia (OR = 1.42, 95% CI: 1.07-1.89), and the risk of sarcopenia did not differ significantly between sex subgroups. In phase II, 114 cases (33.83%) in the possible sarcopenia patients, 85 cases (28.91%) in the sarcopenia patients, 23 cases (35.94%) in the severe sarcopenia patients, and 501 cases (16.10%) in the individuals without sarcopenia showed symptoms of disability. The OR (95% CI) for disability was 2.66 (2.08-3.40) in the possible sarcopenia patients, 2.12 (1.62-2.77) in the sarcopenia patients, and 2.92 (1.74-4.91) in the severe sarcopenia patients compared with the no sarcopenia patients. After adjusting for all covariates in 2011, the OR (95% CI) values were 2.21 (1.70-2.85) in the possible sarcopenia patients, 1.58 (1.14-2.19) in the sarcopenia patients, and 1.99 (1.14-3.49) in the severe sarcopenia patients, as compared to the older people without sarcopenia. Subgroup analyses showed that compared with men, women with possible sarcopenia had a higher risk of disability (OR = 2.80, 95% CI: 1.98-3.97). In addition, participants aged < 80 years with sarcopenia or severe sarcopenia s were more likely to have disability (OR = 2.13, 95% CI: 1.52-2.98; OR = 2.98, 95% CI: 1.60-5.54). Conclusion The occurrence of disability increase the risk of sarcopenia in the older people, and baseline sarcopenia predicts the future disability in older people.