Trajectories of ageing well among older Australians: a 16-year longitudinal study

Abstract

In this study we used individual differences concepts and analyses to examine whether older people achieve different ageing-well states universally or whether there are identifiable key groups that achieve them to different extents. The data used in the modelling were from a prospective 16-year longitudinal study of 1,000 older Australians. We examined predictors of trajectories for ageing well using self-rated health, psychological wellbeing and independence in daily living as joint indicators of ageing well in people aged over 65 years at baseline. We used group-trajectory modelling and multivariate regression to identify characteristics predicting ‘ageing well’. The results showed three distinct and sizeable ageing trajectory groups: (a) ‘stable-good ageing well’ (classified as ageing well in all longitudinal study waves; which was achieved by 30.2% of women and 28.0% of men); (b) ‘initially ageing well then deteriorating’ (50.5% women and 47.6% men); and (c) ‘stable-poor’ (not ageing well in any wave; 19.3% women and 24.4% men). Significant gender differences were found in membership in different ageing-well states. In the stable-poor groups there were 103/533 females which was significantly lower than 114/467 men (z-statistic = −2.6, p = 0.005); women had a ‘zero’ probability of progressing to a better ageing-well classification in later years, whilst males had a one-in-five probability of actually improving. Robust final state outcome predictors at baseline were lower age and fewer medical conditions for both genders; restful sleep and Australian-born for women; and good nutrition, decreased strain, non-smoker and good social support for men. These results support that ageing-well trajectories are influenced by modifiable factors. Findings will assist better targeting of health-promoting activities for older people.