Dietary diversity, frailty transitions, and frailty-state life expectancy in Chinese older adults: a 10-year multistate analysis of the CLHLS

Background Dietary diversity has been linked to incident frailty, but it remains unclear whether it is associated with specific transitions along the frailty continuum and with the number of later-life years spent in healthier states. We examined dietary diversity in relation to frailty transitions and frailty-state life expectancy in Chinese older adults. Methods We analyzed 2008–2018 data from the Chinese Longitudinal Healthy Longevity Survey. Frailty was classified as robust, prefrail, or frail using a graded deficit-accumulation frailty index (FI), and dietary diversity was assessed with a repeated 0–18 dietary diversity score (DDS). Multistate models estimated transition intensity ratios (IRs) with 95% confidence intervals (CIs) for transitions among frailty states and death, and a previous-wave analysis separated dietary assessment from subsequent transitions. Frailty-state life expectancy was estimated at ages 65, 70, 75, and 80 years. Results The primary analysis included 22,804 person-period observations from 13,427 individuals. In the previous-wave analysis, each 2-point higher DDS was associated with lower robust-to-prefrail transition intensity (IR 0.892, 95% CI 0.835–0.953), whereas the interval-start DDS estimate within the same 9,464 intervals was 0.982 (0.922–1.046). The lagged association was similar under FI threshold and dietary-component sensitivity analyses. Under model-standardized age-65 scenarios, DDS 11 versus DDS 7 corresponded to +0.45 robust years (95% uncertainty interval [UI] + 0.23 to +0.70), whereas the +0.23 non-frail and +0.20 total-year contrasts had UIs including zero. Life-expectancy contrasts depended on the fitted model and standardization assumptions. Conclusion Higher DDS recorded at the preceding wave was associated with a lower subsequent intensity of early frailty deterioration. Model-standardized higher-DDS scenarios showed more years in the robust state; at age 65, uncertainty intervals for differences in total and non-frail years included zero. The observational results do not establish that dietary changes prevent frailty or preferentially affect deterioration over recovery.