A Deficit Accumulation-Based Lower Extremity Function Index and Subsequent Falls in Chinese Community-Dwelling Older Adults: A Prospective CHARLS Cohort Study

Abstract Background. Falls are a leading cause of injury and lost independence in older people. Weak lower-limb function is a consistent risk factor but is usually assessed one item at a time. We applied the deficit-accumulation framework to the lower-extremity domain and examined whether the resulting index was associated with subsequent falls. Methods. In the China Health and Retirement Longitudinal Study (CHARLS), community-dwelling adults aged 50 years or older at the 2015 wave were followed to 2018. A Lower Extremity Function Index (LEFI) was constructed as the proportion of deficits across 15 lower-extremity-related items spanning mobility, transfers and lower-limb-dependent activities of daily living (range 0–1). The outcome was self-reported falls at follow-up. Multivariable logistic regression, restricted cubic splines, receiver operating characteristic analysis and seven sensitivity analyses were used. Results. Among 11,430 participants (mean age 64.0 years; 55% women), 2,568 (22.5%) reported a fall. In the fully adjusted model including baseline fall history, each 0.1-unit higher LEFI was associated with higher fall odds (odds ratio 1.13, 95% confidence interval 1.10–1.16). The association was non-linear and robust across sensitivity analyses, including a core 7-item index (odds ratio per 0.1 unit 1.09). Discrimination was modest (area under the curve 0.61) and improved only slightly over age, sex and fall history (0.65 to 0.67). Conclusions . A deficit-accumulation LEFI was independently associated with subsequent falls but had limited absolute discrimination; it may serve as a low-cost first-stage screen, identifying lower-risk individuals for triage, rather than as a standalone predictor.