Association Between Healthy Lifestyle Index Trajectories and Functional Disability in Middle-Aged and Older Adults: A Longitudinal Cohort Study

OBJECTIVE: To explore the trajectories of combined healthy lifestyle index (HLI), and to examine the association between HLI at a single point, HLI trajectories, and new-onset functional disability among middle-aged and older adults. DESIGN: A longitudinal cohort study. Group-based trajectory modeling and binomial logistic regression analysis were used to explore HLI trajectories and their associations with functional disability. SETTING: Data were obtained from the China Health and Retirement Longitudinal Survey (2011-2020), a nationally representative assessment of community-dwelling middle-aged and older adults spanning 150 counties across 28 provinces. PARTICIPANTS: A total of 5985 community-dwelling individuals aged ≥45 years were included for cross-sectional analysis, 3213 of whom were women. In addition, 3888 individuals without functional disability at baseline were eligible for the longitudinal analysis. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Activities of daily living (ADLs) disability and instrumental activities of daily living (IADLs) disability. RESULTS: Three distinct HLI trajectories were identified: persistently high-level then declining group (n=742, 19.08%), persistently moderate-level then declining group (n=2416, 62.14%), and persistently low-level group (n=730, 18.78%). In comparison with persistently low-level group, persistently high-level then declining group was associated with a lower risk of ADL disability (odds ratio [OR], 0.40; 95% confidence interval [CI], 0.23-0.67) and IADLs disability (OR, 0.51; 95% CI, 0.36-0.73), whereas persistently moderate-level then declining group only had a lower risk of ADL disability (OR, 0.70; 95% CI, 0.50-1.00). CONCLUSIONS: The healthy lifestyle was stable and not susceptible to prolonged change without external influences. Sustaining the high level of healthy lifestyle benefited functional capacity in middle-aged and older adults. Future research needs to focus on improving the overall lifestyle intervention to maximize the effectiveness of the intervention.