Validation of the 2010 American College of Rheumatology preliminary diagnostic criteria for fibromyalgia in an Iranian population

The aim of this study was to validate the 2010 American College of Rheumatology (ACR) preliminary criteria for fibromyalgia (FM) in an Iranian population. In this multicenter prospective study, we enrolled 168 FM patients and 110 controls. All participants underwent dolorimetry examination by study assessors and completed a questionnaire containing variables of both the ACR 2010 preliminary and ACR 1990 criteria. We compared the performance of the ACR 2010 criteria with the expert diagnosis as well as the ACR 1990 criteria. Receiver operator characteristic analyses and Youden index were used to evaluate the test characteristics of a set of different cutoff points for two subcomponents of ACR 2010 criteria including widespread pain index (WPI) and symptom severity (SS) scale. Considering expert diagnosis as the gold standard, the ACR 2010 criteria showed comparable specificity with ACR 1990 (92.8 vs. 88.3 %, P = 0.073), but lower sensitivity (58.9 vs. 71.4 %, P = 0.003) and a tendency for lower accuracy (72.4 vs. 78.4 %, P = 0.105). Applying the ACR 1990 criteria as the gold standard, we observed a trend toward an increase in overall accuracy (72.4 vs. 79.1 %, P = 0.064). Optimal test characteristics were achieved for WPI ≥6 and SS scale score ≥4 and improved sensitivity and accuracy of ACR 2010 criteria when compared to expert, 76.1 and 81.7, respectively. The preliminary ACR 2010 criteria performed less desirably in terms of sensitivity in our set of Iranian patients. Selecting lower cutoff points as WPI ≥6 and SS scale score ≥4 improved the diagnostic values of the criteria.