Asking knee osteoarthritis patients a simple question – do you have difficulty climbing stairs? – may predict the risk of future functional limitation, according to research presented at the annual meeting of the American College of Rheumatology. Finding out that the patient has difficulty also opens avenues for further evaluation and intervention, said Jason Jakiela, a PhD candidate at the University of Delaware, Newark, who led the study. “We like to view it as a kind of yellow flag,” Mr. Jakiela said in an interview.
Another expert agreed. “I think this is useful for clinical rheumatologists,” said C. Kent Kwoh, MD, professor of medicine and medical imaging at the University of Arizona, Tucson, and director of the University of Arizona Arthritis Center. He commented on the study findings but was not involved in the study. Another common question asked of OA patients, about pain, may not be as useful as asking about difficulty climbing stairs, he said. “Their pain level can go up and down and can be quite varied.”
Osteoarthritis affects more than 32.5 million adults, according to the CDC, and the knee is a common site.
Study details, results
Mr. Jakiela and his team, including Daniel White, PT, ScD, MSC, associate professor of physical therapy at the University of Delaware, Newark, used data from the Osteoarthritis Initiative (OAI). They assessed stair climbing difficulty at baseline with the question: Does your health now limit you in climbing several flights of stairs? Respondents could answer that they were limited a lot, a little, or not at all.
The researchers evaluated functional limitation using two measures: Walking speed and Western Ontario and McMaster Universities Osteoarthritis Index physical function (WOMAC-PF) scores. A walking speed of < 1.22 m/s over 20 meters, the speed needed to safely cross a timed intersection, represented poor function. A WOMAC-PF score of 28/68 or more was also used to define low functioning.
The analyses included only people free of functional limitations at baseline. Each measure was conducted at the start and then at 12, 24, 36, 48, 72, and 96 months’ follow-up visits.
While 2,952 participants (mean age 60.1, 54% female, mean body mass index 27.9) were in the walking speed sample, 3,983 participants (mean age 61.2, 57% female, mean BMI 28.2) were in the WOMAC-PF sample.
When compared with people who had no limitations, those limited a little had a 47% greater risk of gait speed functional limitation and those limited a lot had a 61% greater risk at follow-up. There was a 70% greater risk for functional limitation defined by WOMAC-PF score at follow-up among people who were limited a little in stair climbing when compared with those not limited at all, and people with a lot of limitations had 161% greater risk. Slow gait speed has been linked with mortality.
Over the 8-year follow-up, 973 in the walking speed sample and 578 in the WOMAC-PF sample developed functional limitation.