Concordance between clinician- and 2016 criteria-based diagnoses of fibromyalgia.

Objectives: The Fibromyalgia Survey Diagnostic Criteria-2016 (FSD-2016 criteria) were recently recommended for both clinical and research purposes. The present study aims to examine whether there is concordance between clinician-based and FSD-2016 criteria-based diagnoses of FM, and secondly, to examine how the illness severity and physical function relate to the criteria-based diagnosis among patients referred to a rheumatism hospital.

Methods: Participants with a clinician-based diagnosis of FM were included consecutively when referred to a patient education programme for patients with FM. Illness severity was assessed with the Fibromyalgia Survey Questionnaire (FSQ). Based on the FSQ, the fulfilment of the FSD-2016 criteria was evaluated. Physical function was assessed using the Fibromyalgia Impact Questionnaire (FIQ) function scale and self-reported employment status.

Results: The sample included 130 patients (84% women) from 20 to 66 years of age. Eighty-nine per cent met the FSD-2016 criteria, and 44% of the patients were fully or partially employed. Great variability in illness severity was seen irrespective of employment status. There was an association between illness severity and physical function (r=0.4, p<0.001). For 95% of the patients, the FSQ illness severity scores classify as severe or very severe, and even for those not fulfilling the diagnostic criteria the scores were moderate and severe.

Conclusions: There was relatively high agreement between clinician- and criteria-based diagnoses. The illness severity overlapped irrespective of different employment status and fulfilment of FSD-2016 criteria.