RÉSUMÉ
Objective: To examine the associations between metabolic syndrome (MS) and the risks for impaired activities of daily living (ADL) in the middle-aged and elderly population in China and provide basis for improving healthy life expectancy. Methods: Prospective cohort study design was used in this study. Based the data of China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2018 and the baseline data in 2011, the follow up for ADL outcomes was conducted in 2013, 2015 and 2018 respectively, and the participants recruited in 2013 and 2015 were new baseline populations. The participants with impaired ADL in three baseline populations were excluded. Cox proportional hazard model was used to estimate the effect of different components and number of MS components on the risk for ADL impairment in the middle-aged and elderly population in China. Results: In 59 795 person-years of follow-up, a total of 1 011 cases of ADL impairments were recorded. The incidence density of ADL impairment was 16.91 per 1 000 person-year; The findings of Cox regression analysis showed that compared with the middle aged and elderly people without MS, the risk for ADL impairments was 1.29 times higher (95%CI: 1.12-1.50) for those with one component of MS, 1.32 times higher (95%CI:1.07-1.64) for those with hyperlipemia complicated with diabetes, 1.78 times higher (95%CI: 1.22-2.59) for those with obesity and one component of MS, 2.48 times higher (95%CI:1.59-3.85) for those with hypertension complicated with hyperlipemia, 3.51 times higher (95%CI:1.66-7.43) for those with hypertension complicated with diabetes, 1.80 times higher (95%CI: 1.40-2.32) for those with ≥3 MS, respectively. Compared with the middle-aged and elderly population without MS, the risk for impaired ADL increased by 30% (HR=1.30, 95%CI: 1.13-1.51), 54% (HR=1.54, 95%CI: 1.28-1.85) and 87% (HR=1.87, 95%CI:1.45-2.41), respectively, in the middle-aged and elderly with one, two, and more than three components of MS, with a significant dose-response relationship that ADL impaired risks increased as the number of MS components increased (P<0.001). Conclusions: Our findings suggested that MS is a risk factor for ADL impairment in middle-aged and elderly population in China. Prevention and early intervention of obesity, hypertension, hyperlipemia, diabetes and metabolic syndrome could help to reduce or delay the incidence of ADL impairment.