BARCELONA – People with knee and hip osteoarthritis tend to overstate their walking disability, but timed walking tests provide an accurate assessment of their lameness, according to a new study.
Dr. Luke Brunton, orthopedic surgeon and researcher at the musculoskeletal research unit at the University of Bristol (England), and his colleagues wanted to find out whether patient self-reports of walking could be used to accurately represent their walking ability. "We found a very poor correlation between self-reports and objective tests," said Dr. Brunton at the World Congress on Osteoarthritis.
Dr. Luke Brunton
He added that "the observers found that patients were performing much more easily than they reported. There was a much better correlation between the observers’ reports and the tests than the patient’s self-reported walking ability."
According to Dr. Brunton, walking impairment in patients with hip and knee OA was particularly important because it was part of the reason for patients’ reduced life span, is linked to social isolation, and has been associated with dementia.
"Questions on walking are very often used to assess function, quality of life, and disability in people with OA. People are commonly asked to self-report on either walking restrictions or distance limitations, however, simply asking patients may not give the whole picture," said Dr. Brunton.
The researchers looked at the correlations between self-reported walking ability and functional tests, and observers’ assessments and the same functional tests of walking ability.
Data from a large U.K. community based cohort study known as the South West and Avon Survey of Health (SASH) cohort were used including demographic and disease-related data.
Self-assessment questions were taken from the commonly used Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Lequesne assessment. WOMAC asked, ‘What degree of difficulty have you experienced walking on flat ground in the last week due to your hips or knees?’ while Lequesne asked, "What is the maximum distance you can walk with pain?"
The study involved 806 participants with a mean age of 68 years and body mass index of 28.6 kg/m2. They were asked to carry out a timed 6-meter walking test and a "get up and go" test. The latter test times how long patients take to stand up from a sitting position, walk 3 meters, turn around, and sit down again.
In particular, research observers looked at whether patients had any difficulties walking and how far they said they could walk. They correlated these findings with the 6-meter walk and the "get-up and go" test results, and compared this to the correlation between patient self-reports and the same objective tests.
"We tell the observers it doesn’t matter how long the person is taking. The important thing is how easy it is for the patient to complete the test or not," explained Dr. Brunton.
A stronger association was found between observer evaluation of walking ability and the timed walk (ANOVA r2 = 0.58; P less than .001) and "get up and go" tests (ANOVA r2= 0.56; P less than .001), than patient self-reports (SF-36; ANOVA r2 = 0.23; P less than .001 and Lequesne ANOVA r2 = 0.27; P less than .001) with the objective tests. ANOVA r2 is a measure of the statistical correlation between the two variables
"It is notable that the observers were watching the patients actually carry out a test whereas patients were asked generally how well they walked," he continued, admitting it was a very different scenario being assessed. "But if you are only asking patients one question on walking you are assuming that their self-assessment and their functional test should be very similar. We have showed this isn’t the case."
The data showed most people did the test with similar times how they rated their own walking ability.
"You can’t just take a questionnaire but you may need to undertake a functional assessment too. Most clinicians would assess patients themselves rather than relying solely on questionnaires. For research, I think we also need a combination of the two methods," he said.
Dr. Brunton has reported no relevant financial disclosures. The meeting was sponsored by the Osteoarthritis Research Society International.