Illnesses and injuries requiring hospitalization of elderly people usually increase the patient’s level of disability, regardless of what that level was prior to the event, according to a report in the Nov. 3 issue of JAMA.
Similarly, an illness or injury requiring that an elderly patient restrict his or her activity for at least half a day also tends to increase the level of disability. "These results provide strong evidence that intervening events have an important role in precipitating and, subsequently, perpetuating the disabling process," said Dr. Thomas M. Gill of Yale University, New Haven, Conn., and his associates.
"The dynamic nature of disability has only recently been elucidated," they noted. "We have previously shown that illnesses and injuries leading to either hospitalization or restricted activity are strongly associated with the initial onset of disability. The current study extends this earlier work by demonstrating that exposure to these intervening illnesses and injuries also is associated with the subsequent course of disability."
To characterize the nature of disability in the population, Dr. Gill and his colleagues examined data from an ongoing longitudinal study of 754 community-living people who were aged 70 and older and were not disabled at enrollment in 1998-1999. Researchers had followed the study subjects by monthly telephone interviews and in-home assessments of physical and cognitive status every 18 months until 2008 or when a participant died (median, 9 years).
A total of 117 subjects (16%) survived and remained nondisabled through the follow-up. The remaining 637 subjects became disabled to some degree at some time during the study.
"Intervening events" prompting hospitalization were classified into nine categories: cardiac, infection, fall-related injury, stroke, arthritis, cancer, gastrointestinal bleeding, other medical causes, and other surgical causes. Fall-related injury was by far the intervening event most strongly associated with worsening disability.
Hospitalization for an illness or injury was particularly strongly associated with the onset of new disability or the worsening of existing disability. This is probably due in part to the potent disabling effects of serious illness and of hospitalization itself, the investigators said.
Of the 637 subjects who became disabled at some time, 91% had at least one hospital admission and 94% had at least one spell of restricted activity. In contrast, people who did not incur an injury or illness requiring hospitalization or restricted activity were at extremely low risk of becoming disabled.
"Our results support the hypothesis that illnesses and injuries leading to hospitalization act not only to precipitate and worsen disability but also to hasten death and to impede recovery from disability, thereby prolonging the disabling process," Dr. Gill and his associates said (JAMA 2010;304:1919-28).
Periods of restricted activity were not as strongly associated with disability as was hospitalization. However, restricted activity is still an important trigger of worsening disability because it is much more common than hospitalization, said the researchers.
All the associations found in this study were accentuated by the presence of physical frailty, as measured by diminished walking speed.
"Given the central role of intervening illnesses and injuries on the disabling process, more aggressive efforts are warranted to prevent their occurrence; to manage them more effectively and reduce subsequent complications, especially in the hospital setting; and, after an event, to enhance restorative interventions in the subacute, home care, and outpatient settings," the investigators said.
The study was funded by the National Institute on Aging. The investigators reported no financial conflict of interest.