As per the American College of Rheumatology (ACR) 2010 preliminary diagnostic criteria and its 2011 modification, the widespread pain is no longer required for fibromyalgia (FM) diagnosis although its absence may be of concern. A study report explored whether the widespread pain definition was satisfactory and the outcomes of having a small number of painful regions or of not fulfilling the widespread pain criterion.

A total of 5011 patients were found to satisfy the 2011 criteria. FM was detected using the Widespread Pain Index (WPI) and the Symptom Severity Scale (SSS): WPI ≥ 7 and SSS ≥ 5 or WPI 3–6 and SSS ≥ 9. According to the 1990 ACR FM criteria, widespread pain was 4 quadrants plus axial pain. As per the ACR 1990 widespread pain criterion, 4700 patients (93.8%) were included. A 98.8% of criteria-positive patients were detected using a new strict definition for 5 pain regions situated on the WPI sites, a modified widespread pain criterion requiring 4 of 5 regions. The patients without widespread pain or those in the low WPI/high SSS group had milder FM and no confirmation of increased psychological or physical distress.

The 2010 and 2011 criteria work quite efficiently in usual clinical and epidemiological studies, but are not as effective in patients with asymmetrical or regional pain who do not satisfy a widespread pain criterion. A ≥ 4-pain region widespread pain definition will abolish regional pain false-positives and will recognize 98.8% of current 2011 cases. To avoid the misclassification, future revisions of the 2010/2011 criteria should take into account incorporating the ≥ 4-region requirement.