Capturing transitions and trajectories: the role of socioeconomic status in later life disability.

OBJECTIVES: Disability is conceptualized as a life course process and measured using either transitions or trajectories. Previous research does not simultaneously explore both aspects of disablement, accounting for timing and trajectory. The role of education is noted in disability research, but its independent effects over time have not been fully examined. I investigate the effects of education and income on disability onset and progression over a decade.
METHODS: I use a latent curve modeling approach with four waves of the Duke Established Populations for Epidemiologic Studies of the Elderly data to independently test the preventive and mediating effects education and income provide for disability.
RESULTS: Education has a preventive effect for disability onset but no significant effect on progression once income is held constant. Income has both a preventive and mediating effect on disability, although preventive effects are stronger for education. DISCUSSION: Later life disability is measured here using both onset and trajectory. Findings are consistent with health research suggesting that education and income work through shared and independent mechanisms to affect disability over time. These findings also highlight the importance of modeling timing when studying health trajectories.