Disability trajectories and associated disablement process factors among older adults in Taiwan

We aimed to identify disability trajectories and examine whether the predisposing, intra-individual, and extra-individual factors in the disablement process predicted different disability trajectories among older adults in Taiwan.

Data were from the Taiwan Longitudinal Study on Aging (TLSA) Survey in 1996-2007 (n=3186). Disability trajectories for activities of daily living (ADLs) and instrumental activities of daily living (IADLs) were identified by using latent class growth curves modeling. Factors including demographics, health conditions, health behaviors, social relations, and use of assistive devices were significantly predicted different disability trajectories of older adults over the following 11 years by applying hierarchical logistic regression.

Three disability trajectories--maintained function, progressive disability, and consistent disability--were identified. Predisposing factors such as younger age, more educational attainment, and better health conditions had protective effects of leading to a later healthier maintained function trajectory. Intra-individual factors such as engaging in leisure time activities (LTAs) were positively related to the maintained function trajectory but negatively related to the consistent disability trajectory; decreasing social networks was common to those on consistent disability trajectory; dissatisfaction with social support was noted in maintained function trajectory group. An extra-individual factor, using assistive devices, was significantly related to maintaining older adults' disability levels, even for those who started disabled.

The findings suggested that predisposing, intra-individual, and extra-individual factors play different roles in the development of later disability trajectories. More educational attainment, better health conditions, active in LTAs, and using assistive devices might benefit the maintenance of functioning in Taiwanese older adults.