Fibromyalgia (FM) is one of the most controversial diagnoses in the field of pain management. Some experts believe that it does not exist and actually represents an accidental or purposeful misdiagnosis of other conditions, while others believe that it is badly underdiagnosed. (1)
The truth likely falls somewhere between these 2 extremes. FM is certainly a real syndrome, but it is also perhaps overdiagnosed, both because many physicians are unaware of the actual diagnostic criteria, and because there may be a desire to avoid diagnosing patients with other conditions that could explain the symptoms of FM--most notably mental disorders.
Fibromyalgia Diagnosis Through the Years
Over the years, the medical understanding of FM has evolved. It has gone from being viewed as a pain disorder to being considered a multisymptom syndrome that falls on a continuum, depending on the number and severity of the symptoms. (2)
There are no universally agreed-upon definition diagnostic criteria for FM. At minimum, it is generally agreed that there is chronic pain spread throughout the body. However, even here there is some ambiguity. For example, the current International Statistical Classification of Diseases and Related Health Problems (ICD-10) diagnosis for FM says it can be "an acute, subacute, or chronic" painful state, although it also describes FM as "a chronic disorder." (3)
What appears to have been the first attempt to develop formal diagnostic criteria was presented by Smythe and Moldofsky in 1977. (4 Because of the many competing definitions of FM that emerged over time, the American College of Rheumatology (ACR) sought to develop a clear set of diagnostic criteria, which it issued in 1990. (5) The most significant criteria were that 1) generalized pain was present for at least 3 months; 2) the pain was present in at least 3 of 4 body quadrants; and 3) the patient had pain to pressure of up to 4 kg/[cm.sup.2] as measured by an algometer at more than 11 of 18 points throughout the body.
The establishment of formal criteria resulted in FM being included as a diagnosis in the ICD in 1992. However, over the years, concerns grew about using these criteria, especially the identification of tender points, because it appeared that many physicians did not know how to accurately determine their presence or how much pressure to apply to elicit pain.
To address these concerns, the ACR revised its criteria in 2010. (6) The requirement for tender points was eliminated, and the ACR instead based the diagnosis primarily on 2 scales: The Widespread Pain Index (WPI) and the Symptom Severity scale (SS).
The WPI asks whether pain has been present during the previous week in 1 of 19 locations in the body (Table 1). (6) The SS scale consists of 2 parts: 1) asking about the presence and severity of fatigue, waking feeling unrefreshed, and cognitive symptoms during the past week and scoring them on a 0 to 3 scale; and 2) asking about the presence of any of 41 potential symptoms, including depression, fatigue, constipation,...