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Knee News

New Understanding of Disability in Older Adults

Older adults with knee pain can lose independence and function quickly. Joint and mobility problems lead to inactivity and weight gain. Obese older adults are especially at risk for knee pain resulting in disability. And whereas we once thought that disability in older adults was irreversible, studies now show that recovery is possible.

In this study, an effort is made to better understand the progressive transition to disability. By identifying risks for and stages of disability, it may be possible to prevent, shorten, or reverse the process.

Researchers used a model called the Hidden Markov Model (HMM) to show the various changes that occur in activities of daily living that can lead to disability. This model provides a statistical method for analyzing the data collected.

Data was collected using a special tool to assess disability called the Pepper Assessment Tool for Disability. The Pepper Assessment Tool has been tested and found to be reliable and valid. The authors note that they have used this particular self-report survey for over 15 years with the aging adults at their center.

The Pepper Assessment Tool was used with almost 500 men and women 65 and older. Each participant had chronic knee pain that was present almost every day. The pain limited their movement and/or activities. Everyone in the study completed the tool at the start and again 15 months and 30 months later.

The Pepper Assessment Tool looks at three key areas of function and participation in older adults. These include activities of daily living (ADLs), mobility, and Instrumental Activities of Daily Living (IADLs). ADLs measure self-care activities (e.g., bathing, getting out of bed, brushing teeth, eating). Mobility refers to the ability to walk and climb stairs. IADLs describe more complex tasks such as socializing with friends and family, managing money, or preparing meals and keeping the house clean.

The Hidden Markov Model helps the researchers analyze the participants' answers to questions on the Pepper Assessment Tool. Patterns emerge over time that help define states of disability on a continuum (from mild to severe). This concept places disability as a state of being with phases and transitions between phases rather than as a trait used to describe someone.

Using the Hidden Markov Model, the researchers found six separate states of disability (from the least or no disability to severe disability). A distinct pattern or disability profile emerged from the data analysis. The first phase of disability is a decline in mobility such as managing stairs or lifting heavy objects. Loss of activities of daily living (ADLs) occurs next. The last phase is a loss of instrumental (social, financial) activities.

Changes occur over time with a transition phase between states of disability. Adults with greater disability are less likely to recover. Adults in the first three disability states have the best chance of returning to a lower state of disability (and a higher state of function). More obese adults have less of a chance of remaining healthy. Once the obese individual is in a severe state of disability, they are more likely to remain at that level of disability.

This study showed that disability is a dynamic (changing) process. Obesity is a major risk factor in the disablement process. Using the Pepper Assessment Tool and the Hidden Markov Model, the multistate nature of disability became apparent. Using patients with knee pain and observing the process of disability developing and changing over an almost three year period made it clear that there is a pattern of emerging disability.

The most demanding tasks tend to go first. Changing body position (getting in and out of bed, chair, or car) is the first mobility function to be compromised. Physical tasks (cooking, cleaning, self-care) become limited much faster than cognitive function (paying bills, making phone calls).

What is the practical application of this information? First, knee pain is common in older adults and may be a key feature in loss of function. Second, lower-limb strengthening is important in preventing and/or recovering from loss of mobility. Without intervention, decline is much faster than recovery. And once a person starts to transition toward disability, the probability of returning to a previous state of function is less. Obesity stacks the odds against recovery.

The Pepper Assessment Tool is a helpful way to measure a patient's level of disability. It allows the health care provider with a means to track changes over time. A change in function or loss of activities highlighted by this tool can trigger a referral to physical therapy sooner than later. Preventing or regaining loss of function in aging adults is important in avoiding the decline into institutional care (e.g., nursing home or other extended care facility).

W. Jack Rejeski, PhD, et al. Obesity Influences Transitional States of Disability in Older Adults with Knee Pain. In Archives of Physical Medicine and Rehabilitation. November 2008. Vol. 89. No. 11. Pp. 2102-2107.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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