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.”
To examine whether fibromyalgia survey results correlate with outcomes after knee and hip arthroplasty, Dr. Clauw and colleagues conducted a prospective, observational cohort study that included approximately 500 people. Patients completed the questionnaire on the day of surgery.
Patients with higher levels of fibromyalgia were less responsive to opioids. “For each 1-point increase in the fibromyalgia score, people needed about one more hydrocodone tablet in the first 24-48 hours to control their pain,” he said (Anesthesiology. 2013 Dec;119:1434-43). In addition, each 1-point increase in the fibromyalgia score made people about 25% less likely to have a 50% improvement in knee pain level after 6 months (Arthritis Rheumatol. 2015 May;67:1386-94). The correlations were independent of psychological factors. In addition, the associations were linear. “There was nothing magical about a fibromyalgia score of 13,” Dr. Clauw said.
Dr. Clauw is a coauthor of ato be presented at the 2019 American College of Rheumatology/Association of Rheumatology Professionals annual meeting that found pain centralization in patients with RA is associated with poor response to disease-modifying antirheumatic drugs (DMARDs).
Prior studies in patients with RA have found that the degree of fibromyalgia is a better predictor of pain and disability than erythrocyte sedimentation rate or the number of swollen joints.
Diagnosed cases are the “tip of the iceberg”
Researchers at Dr. Clauw’s institution have identified dozens of patients undergoing knee surgery who met criteria for fibromyalgia but had not received the diagnosis. “This is at the University of Michigan, which is the epicenter for fibromyalgia research. If we are not seeing fibromyalgia superimposed on OA in our patients, no one is seeing it,” he said.
Patients with diagnosed fibromyalgia are “the tip of the iceberg,” he said. “There are far greater numbers of individuals whose primary diagnosis is OA, RA, lupus, ankylosing spondylitis, cancer pain, or sickle cell disease that have the same fundamental problem as fibromyalgia patients. But you do not see it because you label them as having an autoimmune disease or osteoarthritis. And that is at your peril and at their peril. Because treating that individual as if all of their pain and other symptoms are due to a problem out on the periphery will not make that person better.”
Patients with high levels of centralized pain may be less responsive to peripherally directed therapies such as surgery or injections, Dr. Clauw said. Pharmacologic options for patients with centralized pain include gabapentinoids (e.g., pregabalin and gabapentin), serotonin-norepinephrine reuptake inhibitors (e.g., duloxetine and milnacipran), and tricyclic compounds (e.g., amitriptyline and cyclobenzaprine), he said. “Opioids are going to be quite unlikely to help these individuals,” he said. “In fact, it is likely that opioids will make this kind of pain worse.”
Dr. Clauw is a consultant for Aptinyx, Daiichi Sankyo, Eli Lilly, Intec Pharma, Pfizer, Samumed, Theravance, Tonix, and Zynerba Pharma. He has received grant or research support from Aptinyx and Pfizer and is an expert witness.
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