Performance of Fibromyalgia Rapid Screening Tool (FiRST) to detect fibromyalgia syndrome in rheumatic diseases.

OBJECTIVE: To evaluate the performance of the Fibromyalgia Rapid Screening Tool (FiRST) self-questionnaire for the detection of FM associated with inflammatory rheumatic diseases.

METHODS: This cross-sectional, French single-centre study was carried out between September 2014 and April 2015 in all patients who consulted for RA, SpA or CTD. Diagnosis of FM was based on ACR 90 criteria and rheumatologist opinion.

RESULTS: The self-questionnaire was completed by 605 patients (279 RA, 271 SpA, 57 CTD). It detected 143 concomitant FMs (24.4%). When assessed against ACR 90 criteria, FiRST had a sensitivity of 74.5%, a specificity of 80.4%, a positive predictive value of 26.6% and a negative predictive value (NPV) of 97.1%. Specificity was lower in the CTD group (RA: 84.4%, SpA: 80.2%, CTD: 59.6%) (P = 0.001). When assessed against the rheumatologist's opinion, FiRST had a sensitivity of 75.8%, a specificity of 85.1%, a positive predictive value of 48.3% and an NPV of 95%. Sensitivity was lower in the SpA group than in the CTD group (66% vs 94.4%) (P = 0.004). Performance varied according to self-questionnaire items.

CONCLUSION: Although it performs less well in inflammatory rheumatic disease, FiRST's opinion is close to that of the rheumatologist. It can be used by the rheumatologist in clinical practice for patients facing an apparent treatment failure and to rule out a potential FM diagnosis which could interfere with the treatment response.