FORT LAUDERDALE, FLA. – A new 11-item measure of osteoarthritis pain developed with patient input was validated in a study of 100 people with x-ray-confirmed hip or knee osteoarthritis.
Investigators hope to improve on traditional assessments done with the pain subscale of the Western Ontario and McMaster Universities osteoarthritis index (WOMAC). “We realize it is not getting at the pain of osteoarthritis. It is only five questions relating to pain, and three of them have to do with pain during specific activities,” Dr. Gillian Hawker said in an interview during a poster session at the World Congress of Osteoarthritis.
The Measure of Intermittent and Constant Osteoarthritis Pain “will be much more precise. It really gets at the minutiae of living with pain,” said Dr. Hawker of the department of medicine, Women's College Hospital, Toronto.
Development of this new instrument began with a request from the U.S. Food and Drug Administration. The agency was seeking a good outcome measure for studies to indicate when nonpharmacologic therapy has failed and drug treatment is warranted, said Dr. Hawker, who also is director of the institution's osteoporosis research program and the Canadian osteoarthritis research program.
In clinical settings, physicians can use the measure to monitor response to different therapies–“a tool for the family doc to see if self-management or NSAIDs are making a difference.”
The instrument was developed with patient input. People with osteoarthritis are able to discern two types of pain clearly–intermittent vs. constant pain–according to the focus groups.
“In the beginning, there is intermittent pain. Then it progresses to background pain combined with acute episodes.” Although both types of pain were important to patients, “it was this unpredictable, short-lived pain that curtailed activities,” Dr. Hawker said at the meeting, which was sponsored by the Osteoarthritis Research Society International (OARSI).
For this reason, Dr. Hawker and her associates developed the questionnaire to address both types of pain. “We put it into our osteoarthritis cohort in Toronto, and it looked pretty good.”
The researchers then tested the reliability and validity of the instrument with a telephone survey of 18 people with hip osteoarthritis and 82 with knee osteoarthritis. Researchers also asked three global hip/knee questions, and administered the WOMAC pain subscale, the symptoms subscales of both the Hip Disability and Osteoarthritis Outcome Score (HOOS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS). This preliminary psychometric testing supports the validity and reliability of the Measure of Intermittent and Constant Osteoarthritis Pain, Dr. Hawker said. There was no correlation, however, with the limitation dimension of the Late Life Function and Disability Instrument.
Dr. Hawker and her associates plan to determine the cutoff values for pain and function leading to joint replacement.
The instrument will be online at www.oarsi.orgg.hawker@utoronto.ca