We know that functional disability increases with age, but the magnitude of specific limitations is still largely unknown in the oldest old (those aged 90 years or older). The 90+ Study, a population-based study of aging, examined disability in activities of daily living (ADLs; defined as bathing, dressing, feeding, toileting, walking, and transferring in and out of a bed or chair),1 in the oldest old, the fastest growing age group in the United States. By examining the incidence of individual ADL disability, The 90+ Study determined the ADLs for which the most individuals were impaired; in addition, it sought to determine which ADLs make the best targets for potential therapeutics.
To determine incident disability in each ADL, participants in the study were asked to identify an informant who could best provide researchers with information about their functional abilities via postal mail. A questionnaire was mailed annually to this informant asking about the participant's abilities for each ADL.
We examined the incidence rates for each ADL using a person-years analysis. We defined disability in an ADL as requiring help from another person to perform it. At baseline, the mean age of the 216 nondisabled participants was 93.7 years; 56.9% still lived alone. Mean follow-up time was 2.7 years.
The incidence of bathing disability was 14.9% per year (95% confidence interval[CI] = 12.0, 18.2), which was significantly higher than any other ADL (Figure 1). The ADL with the lowest incidence rate of disability was walking (6.9% per year, 95% CI = 5.2, 9.0).
FIGURE 1.
Incidence of problems with the activities of daily living among those aged 90 years or older: The 90+ Study.
According to The 90+ Study, bathing is the ADL with the highest disability incidence in the oldest old. We are not the first to show that problems with bathing are especially detrimental to the elderly. Bathing is described as a “sentinel event in the disabling process,”2 and those unable to bathe themselves without help are more likely to need long-term care.3
In the United States, there are more than 22 million unpaid informal caregivers for seniors, a number that is projected to double over the next 30 years.4 Given that more than 51% of the oldest-old still require help from another person to bathe,5 caregivers will be most often assisting with bathing despite the fact that bathing assistive devices are the most frequently used assistive devices in the oldest-old.6 These current bathing assistive devices then appear to be ineffective at preventing dependency in the oldest-old. Developing effective assistive devices for bathing—like those available for walking—would likely have the greatest benefit in reducing caregiver need, and should be a focus of health care research. If these devices are effective, health care costs for the elderly may decline dramatically.
Acknowledgments
This letter was funded by a grant from the National Institutes of Health (R01AG21055) and the Al and Trish Nichols Chair in Clinical Neuroscience. We thank all participants, their relatives, and the testers and examiners of The 90+ Study.
References
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