BRUSSELS – Clinical depression plays a significant and potentially important role in the progression of pain and disability in patients with knee osteoarthritis, based on a review of more than 3,000 people who were followed for 2 years.
Based on the 2-year follow-up, patients averaged an annual, independent 0.02-point increase in their Western Ontario and McMaster Universities (WOMAC) pain score for each 1-point increase in their depression score at baseline. At that rate, patients with clearly diagnosed clinical depression would face a meaningful boost in pain after another 2 years (total, 4 years), Daniel L. Riddle, Ph.D., said at the annual World Congress of Osteoarthritis on Sept. 25. The analysis also showed that depression was linked with an independent and statistically significant annual decline in 20-m walk performance that would also be clinically significant when extrapolated to 4 years, said Dr. Riddle, a professor of physical therapy at Virginia Commonwealth University in Richmond.
“Depression is among the most powerful predictors of yearly worsening,” he said. “Pain and depression work in an additive way to reduce function and make the pain worse. Treatment of depression in patients with musculoskeletal complaints is relatively new, and it has not carried over to routine care of patients with knee pain. Our data suggest that in patients with routine knee pain, a work-up for depression may have potential benefits for years down the road.
“Depression is a risk factor for a lot of pain-related problems,” Dr. Riddle said in an interview. “Depression probably leads to a reduced ability for patients to cope with their condition and develop compensatory ways. They reduce their activity and daily function.” He called for routinely screening for depression in patients with osteoarthritis, and starting antidepression treatment for patients with the diagnosis, either directly or by referral.
His study used data collected in the Osteoarthritis Initiative, a federally funded, prospective, longitudinal study of 4,796 people who are at risk for osteoarthritis or who have early-stage disease or advanced disease, and who were enrolled at four U.S. sites starting in 2004. Excluding people with no knee pain at entry and those who underwent surgery during follow-up, the study followed a total of 3,146 people for 1 year and followed 3,007 people for 2 years. The average age of the subgroup was 61 years, 59% were women, 76% were white, and 21% were black.
The primary baseline depression measure used, the CES-D (Centers for Epidemiological Studies–Depression) scale, identifies clinical depression for scores of 16 or greater. The participant records also contained baseline assessment by the mental component summary of the SF-12 (12-item Short Form Health Survey), and also an item on the Knee Injury and Osteoarthritis Outcome Score. By these criteria, 5%-10% of participants analyzed had baseline depression, which was a low rate based on the group’s age and chronic disease.
The outcomes that were assessed at 2 years were WOMAC pain and disability scores and two measures of physical performance (the 20-m walk and repetitive chair stand). All four measures showed statistically significant worsening that was independently linked to baseline depression.
The multivariate analysis adjusted for 17 potential confounding baseline variables, including age, sex, income, body mass index, trauma, and symptom duration.
Dr. Riddle said that he had no disclosures.