DESTIN, FLA. – The tender point criteria commonly used to diagnose fibromyalgia are not useful and in fact may even explain why the disease appears to disproportionately affect women, Daniel Clauw, M.D., said at a rheumatology meeting sponsored by Virginia Commonwealth University.
According to the American College of Rheumatology's 1990 classification criteria, patients must have both widespread pain and tenderness in 11 of 18 tender points in order to be diagnosed with fibromyalgia.
Yet “tender points merely represent areas of the body where everyone is more tender,” explained Dr. Clauw, the executive director of the Chronic Pain and Fatigue Research Center at the University of Michigan in Ann Arbor.
Fibromyalgia patients and healthy individuals were found to have different thresholds of pain in those tender points. These two groups also had different thresholds of pain in areas not thought to be tender–the forehead and fingernails, for example–as at the recognized tender points. In addition, the cutoff of 11 out of 18 tender points is arbitrary. “We know that tenderness varies a great deal from day to day and week to week, especially in women,” he said.
In clinical practice, many physicians are realizing the arbitrary nature of the diagnostic criteria.
The diminished role of tender points represents a shift in the way that they view the disorder. In the past, the disorder was considered a discrete illness with pain and focal areas of tenderness. In more recent years, fibromyalgia has been appreciated as part of a larger continuum, with many somatic symptoms and diffuse tenderness all over the body–not just at tender points.
Tender points are “not even a good way to measure tenderness,” as study findings suggest that the number of tender points correlates better with a patient's general stress than with pain, Dr. Clauw pointed out.
Women are 10 times more likely to have achy and tender points, so the higher incidence of fibromyalgia among them may be attributable to a selection bias created by the tender point criteria, he continued.
Men who have chronic widespread pain but not many tender points in many cases are given diagnoses other than fibromyalgia, “when in fact they probably have the exact same problem as women, who have a lot of tender points and meet other criteria for fibromyalgia.”