Twenty years have gone by since the American College of Rheumatology (ACR) published its criteria for the classification of fibromyalgia. The criteria required pain throughout the body and a certain intensity of pain in at least 11 of 18 soft tissue tender points. Over these twenty years a series of objections to these criteria developed, and now the ACR has given us its Preliminary Diagnostic Criteria for Fibromyalgia, as published earlier this year in "Arthritis Care & Research".
It is well known that many fibromyalgia patients are not given that diagnosis based on tender point counts, but rather on complaints of generalized pain in the setting of an absence of any other explanation for that pain, and in the accompaniment of complaints of fatigue, sleep and cognitive difficulties ("fibro fog"). Fibromyalgia has become a symptom-based diagnosis, and one for which a sense of the severity required a lot of subjective musing on the part of the care providers of the fibromyalgia patient.
Therefore, the authors of the new criteria made certain that the old problems would be addressed with new diagnostic tools, so that non-tender point diagnostic criteria could be identified and the severity of symptoms objectified. This was accomplished by collecting an extensive set of patient and physician variables from over 500 patients and controls, including an index of pain extent (the widespread pain index (WPI)) and characteristic fibromyalgia symptoms. It was from this data that models were developed for diagnostic criteria and a severity scale. Next, another 315 patients and controls were assessed by physicians with a reduced set of variables in a physician questionnaire format.