Context: Preventing the development of disability in activities of daily living is an important goal in older adults, yet relatively little is known about the disabling process.
Objectives: To evaluate the relationship between 2 types of intervening events (hospitalization and restricted activity) and the development of disability and to determine whether this relationship is modified by the presence of physical frailty.
Design, setting, and participants: Prospective cohort study, conducted in the general community in greater New Haven, Conn, from March 1998 to March 2003, of 754 persons aged 70 years or older, who were not disabled (ie, required no personal assistance) in 4 essential activities of daily living: bathing, dressing, walking inside the house, and transferring from a chair. Participants were categorized into 2 groups according to the presence of physical frailty (defined on the basis of slow gait speed) and were followed up with monthly telephone interviews for up to 5 years to ascertain exposure to intervening events and determine the occurrence of disability.
Main outcome measure: Disability, defined as the need for personal assistance in bathing, dressing, walking inside the house, or transferring from a chair.
Results: During the 5-year follow-up period, disability developed among 417 (55.3%) participants, 372 (49.3%) were hospitalized and 600 (79.6%) had at least 1 episode of restricted activity. The multivariable hazard ratios for the development of disability were 61.8 (95% confidence interval [CI], 49.0-78.0) within a month of hospitalization and 5.54 (95% CI, 4.27-7.19) within a month of restricted activity. Strong associations were observed for participants who were physically frail and those who were not physically frail. Hospital admissions for falls were most likely to lead to disability. Intervening events occurring more than a month prior to disability onset were not associated with the development of disability. The population-attributable fractions associated with new exposure to hospitalization and restricted activity, respectively, were 0.48 and 0.19; 0.40 and 0.20, respectively, for frail participants and 0.61 and 0.16, respectively, for nonfrail participants.
Conclusions: Illnesses and injuries leading to either hospitalization or restricted activity represent important sources of disability for older persons living in the community, regardless of the presence of physical frailty. These intervening events may be suitable targets for the prevention of disability.