Understanding trends in functional limitations among older Americans.

OBJECTIVES: This report documents trends in functional limitations among older Americans from 1984 to 1993 and investigates reasons for such trends. METHODS: We applied logistic regression to data for noninstitutionalized Americans aged 50 years and older from the Survey of Income and Program Participation. We focused on 4 functional limitation measures unlikely to be affected by changes in role expectations and living environments: reported difficulty seeing words in a newspaper, lifting and carrying 10 pounds, climbing a flight of stairs, and walking a quarter of a mile. RESULTS: We found large declines in the crude prevalence of functional limitations, especially for those 80 years and older. Generally, changes in population composition explained only a small portion of the downward trends. Once changes in population composition and mobility-related device use were considered for difficulty walking, significant improvements in functioning remained for the 65- to 79-year-old group. CONCLUSIONS: Changes in population composition, device use, survey design, role expectations, and living environments do not appear to account completely for improvements in functioning. We infer that changes in under-lying physiological capability--whether real or perceived--likely underlie such trends.