PROGRESSIVE VERSUS CATASTROPHIC DISABILITY - A LONGITUDINAL VIEW OF THE DISABLEMENT PROCESS

Background. There is little epidemiologic data on the development of d isability over time in older persons. This study uses prospective data from cohorts followed annually for 6 to 7 years to identify persons w ho developed severe disability and to characterize the: time course of their disabling process and subsequent mortality. Methods. incidence rates of severe disability. defined as need for help in three or more activities of daily living (ADLs), were estimated for 6,640 persons wh o had not reported severe disability Lit baseline and at the first fou r annual follow-up visits. Among persons developing severe disability, those who reported no need for help in ADLs in previous interviews we re defined as cases of catastrophic disability. and those who had prev iously reported some disability in ADLs were defined as cases of progr essive disability. Results. Overall, 212 subjects developed progressiv e and 227 developed catastrophic disability. The rates of progressive disability and catastrophic disability were 11.3 and 12.1 cases per 1, 000 person-years, respectively. For both types of disability. incidenc e rates increased exponentially with age, but the Increase was steeper for progressive disability. At ages 70-74, less than 25% of severe di sability was progressive, while over age 85 progressive disability rep resented more than half of severe disability. Incidence rates of total and both types of severe disability were similar in men and women. Mo rtality after severe disability onset was extremely high. Survival tim e was unrelated to ate at disability onset and type of disability but was significantly longer in women than in men (median 3.44 vs 2.12 yea rs: p < .0001). Conclusion. Tracking the development of disability pro vides new and important insights into the disability experience in old er men and women that are potentially relevant in planning preventive, intervention. and long-term care strategies.