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OBJECTIVES: To characterize distinct and clinically meaningful subtypes of disability, defined based on the number and duration of disability episodes, and to determine whether the incidence of these disability subtypes differ according to age, sex, or physical frailty. DESIGN: Prospective cohort study. SETTING: Greater New Haven, Connecticut. PARTICIPANTS: Seven hundred fifty-four community-living residents aged 70 and older and initially nondisabled in four essential activities of daily living. MEASUREMENTS: Disability was assessed during monthly telephone interviews for nearly 8 years; physical frailty was assessed during comprehensive home-based assessments at 18-month intervals. The incidence of five disability subtypes was determined within the context of the 18-month intervals in participants who were nondisabled at the start of the interval: transient, short-term, long-term, recurrent, and unstable. RESULTS: Incident disability was observed in 29.8% of the 18-month intervals. The most common subtypes were transient disability (9.7% of all intervals), defined as a single disability episode lasting only 1 month, and long-term disability (6.9%), defined as one or more disability episodes, with at least one lasting 6 or more months. Approximately one-quarter (24.7%) of all participants had two or more intervals with an incident disability subtype. Although there were no sex differences in the incidence rates for any of the subtypes, differences in rates were observed for each subtype according to age and physical frailty, with only one exception, and were especially large for long-term disability. CONCLUSION: The mechanisms underlying the different disability subtypes may differ. Additional research is warranted to evaluate the natural history, risk factors, and prognosis of the five disability subtypes. [ABSTRACT FROM AUTHOR]

Background. Many older persons experience multiple transitions between states of disability and independence, but little is known about the effect of prior disability history on subsequent functional transitions. Our objective was to determine the effect of prior disability on subsequent transitions between no disability, mild disability, severe disability, and death. Methods. For 60 months, 754 persons aged 70 or older underwent monthly assessments of disability in basic activities of daily living. We used a multistate extension of the proportional hazards model to determine the effects of amount, defined as cumulative duration, and distribution, defined as number of episodes, of prior disability on subsequent functional transitions, adjusted for age, gender, cognitive status, timed gait, and habitual physical activity. Results. For each additional month of prior disability, participants were more likely to make transitions representing new or worsening disability and were less likely to make transitions from disability to independence or from severe disability to death. Adjusting for the cumulative duration of prior disability, more episodes of prior disability were associated with a higher likelihood of most transitions, representing both increasing and decreasing disability, but had no effect on transitions to death. Conclusions. Both the amount and distribution of prior disability are important determinants of the likelihood of subsequent functional transitions. Analytic methods that account for prior disability history should be used in studies of functional transitions, and new measures of disability burden are needed that incorporate distribution as well as amount of disability. [ABSTRACT FROM AUTHOR]

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... [ABSTRACT FROM AUTHOR]