Diagnosis of fibromyalgia: comparison of the 2011/2016 ACR and AAPT criteria and validation of the modified Fibromyalgia Assessment Status.

OBJECTIVE: To compare the concordance of the three diagnostic criteria, respectively the 2011 ACR criteria (ACR 2011 Cr), the ACR 2016 criteria (ACR 2016 Cr) and the Analgesic, Anesthetic, and Addiction Clinical Trial Translations Innovations Opportunities and Networks (ACTTION)-APS Pain Taxonomy criteria (AAPT Cr), and to explore the performance of an additional set of criteria, the modified Fibromyalgia Assessment Status (FAS 2019 modCr), in the diagnosis of FM syndrome.

METHODS: Consecutive patients with chronic widespread pain, referred by the primary care setting, underwent rheumatologic assessment that established the presence or not of FM and were investigated through the four sets of proposed criteria. For the FAS 2019 modCr, discriminant validity to distinguish patients with FM and non-FM was assessed with receiver operating characteristic curve analysis.

RESULTS: A total of 732 (405 with FM and 327 with other common chronic pain problems) patients were evaluated. Against the clinical diagnosis of FM, the sensitivity, specificity and correct classification were, respectively: 79.8, 91.7 and 85.1% for ACR 2011 Cr; 78, 90.5 and 83.6% for the ACR 2016 Cr; and 73.8, 91.7 and 81.8% for the AAPT Cr. The alternative set, proposed on the FAS 2019 modCr, provided a maximal diagnostic accuracy with a score ≥20 (Youden's index), with a sensitivity of 84.2%, specificity 89.0% and positive likelihood ratio 7.65.

CONCLUSION: There is a considerable agreement between criteria-based diagnoses of FM, although the AAPT Cr perform least well in terms of percentage of correct classification. The FAS 2019 modCr had comparable characteristics.