Ultrasound-detected tenosynovitis independently associates with patient-reported flare in patients with rheumatoid arthritis in clinical remission: results from the observational study STARTER of the Italian Society for Rheumatology.

Objectives: This study aimed to estimate the prevalence of US-detected tenosynovitis in RA patients in clinical remission and to explore its clinical correlates.

Methods: A total of 427 RA patients in clinical remission were consecutively enrolled from 25 Italian rheumatology centres. Tenosynovitis and synovitis were scored by US grey scale (GS) and power Doppler (PD) semi-quantitative scoring systems at wrist and hand joints. Complete clinical assessment was performed by rheumatologists blinded to the US results. A flare questionnaire was used to assess unstable remission (primary outcome), HAQ for functional disability and radiographic erosions for damage (secondary outcomes). Cross-sectional relationships between the presence of each US finding and outcome variables are presented as odds ratios (ORs) and 95% CIs, both crude and adjusted for pre-specified confounders.

Results: The prevalence of tenosynovitis in clinical remission was 52.5% (95% CI 0.48, 0.57) for GS and 22.7% (95% CI 0.19, 0.27) for PD, while the prevalence of synovitis was 71.6% (95% CI 0.67, 0.76) for GS and 42% (95% CI 0.37, 0.47) for PD. Among clinical correlates, PD tenosynovitis associated with lower remission duration and morning stiffness while PD synovitis did not. Only PD tenosynovitis showed a significant association with the flare questionnaire [OR 1.95 (95% CI 1.17, 3.26)]. No cross-sectional associations were found with the HAQ. The presence of radiographic erosions associated with GS and PD synovitis but not with tenosynovitis.

Conclusions: US-detected tenosynovitis is a frequent finding in RA patients in clinical remission and associates with unstable remission.