The purpose of this study is to compare and correlate US evaluation with clinical scores of the disease activity in patients with rheumatoid arthritis (RA) and concomitant fibromyalgia (FM).
Ten patients diagnosed with RA according to the 2010 ACR/EULAR classification criteria and associated FM based on the ACR 1990 classification criteria and two control groups, one with RA (10 patients) and one with FM (10 patients), were included. Clinical assessment was performed and the disease activity scores were calculated. Synovial/tenosynovial hypertrophy, fluid collections in grey scale (GS), and Power Doppler (PD) US assessed by US in the 28 joints included in the disease activity score 28 (DAS28).
GS US score and PD US scores were correlated with DAS28 only in patients with RA (Pearson r coefficients 0.3 and 0.5). Mean DAS28 score was significantly higher in the RA/FM group, compared to RA and FM (5.6 versus 4.6 versus 4.5, respectively). Patients with RA/FM had similar median US scores to RA patients, while in FM group significantly lower median US scores were detected (16 versus 9.5 versus 0 for GS US and 3.5 versus 1.5 versus 0 for PD US, respectively).
Disease activity scores should be interpreted with caution in patients with RA and FM. When available, US should be used to guide treatment decisions in patients with RA and FM.