Consistency and change in functional status among older adults over time.

Consistency and change between 1984 and the last reinterview (either two, four, or six years later) on 22 individual functional status markers and the five summary scales that they form are examined among the 5,986 members of the Longitudinal Study on Aging who were reinterviewed at least once. At baseline, at least three-fifths of the respondents are without limitations on any individual marker. At the last reinterview, at least 43.4% of the respondents are without such limitations. Among those who had limitations at baseline, at least one-fifth get better. For those without limitations at baseline, one-seventeenth to two-fifths get worse. Difficulties in walking and doing heavy housework were the most common, most likely to develop, and least likely to resolve of any of the ADL or IADL items, and lower body limitations were more common, more likely to develop, and less likely to resolve than upper body limitations. Linear panel analysis of the five summary scales indicates that the top predictors of increased functional limitation are baseline levels of functional limitation, older age, decedent status, and poorer perceived health (in that order). Other less consistent and less robust predictors include the length of the exposure window, being female, having a history of arthritis, lower educational attainment, having fewer nonkin social supports, higher prior physician visit levels, and not living alone.