Nondisease factors affected trajectories of disability in a prospective study

To examine nondisease factors, including sociodemographic variables, health behaviors and psychosocial factors as determinants of trajectories of disability.

We used a classification of 10 trajectories of disability based on a multiround prospective study design; nine trajectories grouped survivors with a similar level and time course of disability, one included all deaths. Multinomial logistic regression was used to assess associations between these trajectories and a wide range of nondisease factors.

Correcting for age, sex, and four chronic diseases, we found that sociodemographic factors (education and income), health behaviors (leisure-time physical activity and BMI), and psychosocial factors (locus of control, neuroticism, and active problem focusing) were significantly associated with the trajectories of disability. Moreover, our results pointed to factors associated with disability trajectories that were characterized by sudden increase (external locus of control and, to a lesser extent, BMI), strong fluctuations (neuroticism, BMI, external locus of control), or high severity (leisure-time physical inactivity) of disability.

A wide range of nondisease factors is associated with the trajectories of disability. Preventing obesity, developing a more internal locus of control, and increasing physical activity could contribute to preventing trajectories characterized by rapid decline, large fluctuations or severe disability. Understanding the role of these factors should receive high priority.