The association between healthy aging index and trajectories of disability: a population-based cohort study

Healthy aging index (HAI) could predict adverse health consequences including mortality and disability independent of age and comorbidity. We investigated the role of HAI on trajectories of disability throughout later life based on a nationally representative sample.

We examined 1733 participants aged over 60 years from the China Health and Retirement Longitudinal Study (CHARLS) followed for 7 years/4 waves repeatedly. Systolic blood pressure [SBP], cognitive function, cystatin C, peak expiratory flow [PEF], and fasting glucose were categorized using tertile or clinical reference range, and scored as 0 (healthiest), 1 (less healthy) and 2 (least healthy) respectively to further generate HAI summary scores (range 0-10). Disability was defined as the sum of impaired activities of daily living (ADL) and instrumental activities of daily living (IADL). We used linear mixed-effects model to study the association between HAI and trajectories of disability.

A total of 10.5% of participants represented in the healthiest group and 22.5% ended up as the least healthy. After adjusting for all potential confounders, disability progression was significantly faster (β = 0.27, 95% CI 0.11-0.42) in the least healthy group when comparing with the healthiest.

Our findings suggest that HAI is associated with disability progression among adults aged over 60 years old. It might be beneficial for future interventions to specifically target older adults with high HAI scores as a means of reducing disability.