Transitions between states of disability and independence among older persons.

The objectives of this prospective cohort study, conducted in New Haven, Connecticut, from 1998 to 2004, were to describe disability states experienced by older persons, to evaluate the rate of transitions between states and the duration of disability episodes, and to determine whether these findings differ on the basis of physical frailty--a condition of low physical capacity and vulnerability to adverse functional outcomes. Participants included 754 persons aged 70 years or older who were initially independent in four key activities of daily living: bathing, dressing, walking, or transferring. Disability was assessed during monthly telephone interviews for a median of 60 months, and participants were classified each month according to the following four states: no disability, mild disability (one or two activities), severe disability (three or four activities), and death. Transitions between states of disability and independence were common, with a majority of both frail and nonfrail participants experiencing at least one transition. The rate of transitions varied greatly among individuals. Nonfrail participants had lower rates of transition from less to more disability, higher rates of transition from more to less disability, and slightly shorter durations of disability. To fully understand the disabling process, investigators and clinicians must consider the episodic and recurrent nature of disability.