Modifiable healthy behaviours and incident disability in older adults: Analysis of combined data from two cohort studies in Japan

Healthy behaviours reduce the risk of incident disability; however, their components require further consideration. Specifically, little evidence exists on healthy behaviours that comprise modifiable factors, including social aspects, and their effects on those who do not engage in them. This study aimed to examine the association between engaging in healthy behaviours with modifiable factors and incident disability among community-dwelling older adults; as well as identify factors associated with nonengagement in healthy behaviours. We analysed data obtained from 1357 older adults aged 65 years and more without disabilities at baseline. The outcome was incident disability, which was defined based on the long-term care insurance certification in Japan. This study included regular exercise (≥1 day/week), favourable eating habits (≥4 dietary variety score), and social participation (engaging in two or more social activities) as components of healthy behaviours. We used the Cox proportional hazards model to calculate hazard ratios (HR) for incident disabilities. The proportion of those who satisfied all healthy behaviours was 21 %. During the follow-up period (median: 6.3 years), 282 incident disabilities were confirmed. Compared to those who engaged in one healthy behaviour, those who satisfied all healthy behaviours showed a 31 % (95 % confidence interval: 0.48, 0.98) lower HR of incident disability after adjusting for covariates. Current smoking and depressive mood were associated with non-engagement in healthy behaviours. This study found that having physically and socially active lifestyles and favourable eating habits are effective in reducing the risk of incident disability. Meanwhile, several older adults lack the components of a healthy lifestyle. Approaches that focus on multiple healthy behaviours are necessary to enhance the benefits of healthy lifestyles.