Concomitant fibromyalgia in primary Sjögren's syndrome in the French ASSESS cohort: comparison of the ACR 1990 and ACR 2016 criteria, FiRST questionnaire and physician's opinion.

Objectives: Dryness, fatigue, and pain are classic symptoms in primary Sjögren's syndrome (pSS) but are also common in fibromyalgia (FM). We compared the characteristics of FM assessed by different criteria (American College of Rheumatology (ACR) 2016 and 1990 criteria), physician's opinion and Fibromyalgia Rapid Screening Tool (FiRST) questionnaire) in a cohort of patients with pSS.

Methods: Eight hospital departments tested 134 patients with pSS according to AECG criteria from the Assessment of Systemic Signs and Evolution in Sjögren's Syndrome (ASSESS) cohort.

Resuklts: FM was present in 19%, 18%, 20%, and 29% of cases according to ACR 2016, ACR 1990 criteria, physician's opinion and the FiRST questionnaire, respectively. FM criteria-positive patients had higher EULAR SS Patient-Reported Index (ESSPRI) score, but not higher EULAR SS Disease Activity Index (ESSDAI) score. The objective measurements of dryness and the use of corticosteroids and immunosuppressive drugs did not differ between FM positive and negative patients. Regarding the ESSPRI dryness and fatigue subscale scores, depression and anxiety scores and the use of anxiolytics and antidepressants, the FiRST questionnaire exhibited a higher difference between positive and negative patients than ACR 2016 criteria. ACR 1990 and physician's opinion were somewhere in the middle. ACR 2016 exhibited moderate agreement with ACR 1990 (κ=0.52) and the physician's opinion (κ=0.60) and poor agreement with FiRST (κ=0.39).

Conclusions: The FM criteria identified pSS patients with higher ESSPRI scores but not higher ESSDAI systemic disease scores. Agreement between the different FM criteria was moderate, and the characteristics they described did not fully coincide.