Real benefits of ultrasound evaluation of hand and foot synovitis for better characterisation of the disease activity in rheumatoid arthritis

OBJECTIVES: Optimal management of rheumatoid arthritis (RA) depends on accurate evaluation of disease activity. Foot synovitis is not included in the most used RA outcome measure (DAS-28 score). The aim of this study was to investigate how musculoskeletal ultrasound (MSK-US) examination of hand and feet correlate with the disease activity score (DAS-28 score). We also explored whether performing MSK-US assessments of hands alone compared with hands and feet underestimates the disease activity in RA. METHODS: This is a real-life cross-sectional study of 101 patients (51 with RA and 50 with other musculoskeletal conditions) with inflammatory small joint pain, who underwent MSK-US examination of hands and feet. RESULTS: MSK-US-detected hand synovitis was found in 18/51 (35.3%) RA patients and 16/50 (32%) of those with other musculoskeletal conditions (p = 0.96), while foot synovitis was detected in 18/51 (35.3%) and 12/50 (24%) patients, respectively (p = 0.78). DAS-28 did not correlate with any of the US outcome measures in patients with RA. Six out of 13 (46.1%) RA patients in remission, 7/14 (50%) with low disease activity and 18/32 (56.2%) with moderate disease activity (according to DAS-28 definition) had active synovitis as assessed by the MSK-US examination of their hands and feet. MSK-US-detected synovitis led to treatment escalation in 26/51 (51%) RA patients. CONCLUSION: This study emphasises that MSK-US examination of hands and feet has led to optimised management of the majority of RA patients, which would have not been possible otherwise, because of the lack of correlation between DAS-28 assessment and MSK-US outcomes. KEY POINTS: • The most used disease activity score in rheumatoid arthritis (DAS-28) did not correlate with US outcome measures derived from hands and feet examination. • DAS-28 did not differentiate between RA patients with subclinical active synovitis versus well-controlled disease on US. • As a result of US examination of the hands and feet, 51% RA patients had their immunosuppressive treatment optimised. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00330-019-06187-8) contains supplementary material, which is available to authorized users.