Las Vegas – A fibromyalgia survey may provide important information about the degree to which patients with rheumatic disease experience centralized pain. This information may guide treatment decisions, said , professor of anesthesiology, rheumatology, and psychiatry and director of the Chronic Pain and Fatigue Research Center at the University of Michigan in Ann Arbor.
The questionnaire that Dr. Clauw uses is a patient self-report survey for the assessment of fibromyalgia based on criteria in the 2011 modification of the American College of Rheumatology preliminary diagnostic criteria for fibromyalgia. In it, he asks patients to report where they experience pain throughout the body and symptoms such as fatigue, sleep problems, and memory problems. The survey predicts outcomes of surgery for osteoarthritis better than x-rays, MRI scans, or psychological factors do, he said.
Physicians should ask every patient with chronic pain, including patients with OA, rheumatoid arthritis, or lupus, to complete the survey, Dr. Clauw said at the annual Perspectives in Rheumatic Diseases held by Global Academy for Medical Education. “This score will tell you the degree to which their central nervous system is augmenting or amplifying what is going on in their body,” he said. “And the higher their score is, the more you should treat them like you would someone with fibromyalgia, even if their underlying disease might be an autoimmune disease.”
Physicians should not use a cutoff of 13 points on the fibromyalgia measure to define whether a patient has the disease, as has been done in the past, he said. The threshold is arbitrary, he said. “We should not think about fibromyalgia as ‘yes’ or ‘no.’ We should think of the degree of fibromyalgia that people have.”
A poor relationship between pain and imaging
Some patients who have severe knee OA on imaging walk without pain. Other patients have normal x-rays, but severe pain. “There is a terrible relationship between what you see on a knee x-ray or an MRI and whether someone has pain,” Dr. Clauw said. Furthermore, the poor relationship between imaging and pain is common across chronic pain conditions, he said.
This phenomenon may occur because pain manifests in different ways, similar to there being multiple ways to adjust the volume of an electric guitar, he said. How hard the strings are strummed affects the volume. But so does the amplifier setting. “In these centralized pain conditions, the problem is an amplifier problem, not a guitar problem,” he said. “The amplifier, i.e., the central nervous system, is set too high.”
Researchers have found that people who have severe OA of the knee on x-ray but do not experience pain “have a very low amplifier setting,” he said. That is, they are nontender and less sensitive to pain. Most of these patients are men. “On average, men have a much lower amplifier setting than women,” he said. “This is also why ... women have 1.5 to 2 times the rate of any type of chronic pain than men, because on average women have a higher amplifier setting. ... In OA, at any given age, men and women have the exact same percentage of radiographic OA. But if you look at the clinical condition of OA, it is always two-thirds women, one-third men.”