Abstract: Objective To investigate the incidence of frailty in community-dwelling Chinese elderly population and explore the risk factors and protective factors of frailty in the elderly. Methods This study was conducted based on the 2011-2015 survey data provided by the China Health and Retirement Longitudinal Study (CHARLS). A research cohort was established consisting of non-debilitated elderly individuals aged 60 years and above at the 2011 baseline survey to assess the incidence of debilitation in the cohort population followed up till 2015. A nested case-control study was conducted to analyze the contributing factors to frailty in the elderly. Results In this study, the cohort population was followed up for a total of 14351 person-years. A total of 248 individuals had newly developed frailty during the follow-up period, resulting in an incidence of 17.28/1000 person-years; the incidence was lower in elderly men than in elderly women (14.63/1000 vs 20.14/1000 person-years). The incidence of debilitation increased progressively with ageing: 8.90/1000 person-years in 60-64 years group, 16.77/1000 person-years in 65-69 years group, 24.04/1000 person-years in 70-74 years group, and 64.67/1000 person-years in 80 years or older group. Multivariate conditional logistic regression analysis showed that depressive symptoms (OR=2.534, 95% CI: 1.714-3.748), smoking (OR=1.713, 95% CI: 1.081-2.715) and self-care difficulties (OR=1.684, 95% CI: 1.155-2.456) were the risk factors contributing to frailty in the elderly; the marital status (unmarried, divorced and widowed) (OR=0.432, 95%CI: 0.278- 0.673), a high cognitive function score (OR=0.919, 95%CI: 0.870-0.970), a primary school education (OR=0.453, 95%CI: 0.254-0.806) and drinking (OR=0.520, 95%CI: 0.323-0.837) were the protective factors against frailty in the elderly. Conclusions The incidence of frailty in community-dwelling Chinese elderly population is lower than the average incidence globally. The incidence of frailty in the elderly differs with gender and age, and depressive symptoms, smoking, and self-care difficulties are the main risk factors for frailty in the community-dwelling elderly

Key words: frailty; incidence density; nested case-control study; influencing factors