Ultrasound-detected tenosynovitis as a risk factor for flares in rheumatoid arthritis patients in clinical remission

Background Our objective was to investigate the value of ultrasound (US) detected synovitis and tenosynovitis as risk factors for short term flare in rheumatoid arthritis (RA) patients in clinical remission. Methods Consecutive RA patients in clinical remission (DAS28 ERS < 2.6) for at least 3 months underwent Power Doppler ultrasound (PDUS) examination of 1st to 6th extensor compartments at the wrist, 2nd to 5th finger flexor, posterior tibial tendon, and peroneal tendons. To assess synovitis, carpal joints, 1st to 5th metacarpophalangeal (MCP) joints, and 2nd to 5th interphalangeal proximal (IPP) joints were bilaterally examined. Synovitis and tenosynovitis were defined according to OMERACT. Patients were followed for 1 year. Disease flare was defined as an increase in disease activity generating the need for a change in therapy by the attending rheumatologist. Results Ninety patients were included. After 1 year of follow-up, 26 patients (29%) experienced a flare. At baseline 39%, 23% and 8% had US-detected synovitis, tenosynovitis or both, respectively. In the 1-year period after the baseline US examination, US-detected tenosynovitis (RR: 4.9; 95% CI: 2.2-10.8) was associated with an increased risk of exacerbation. This association was not shown with US-detected synovitis (RR: 1.3; 95% CI: 0.76-2.2). In the multivariate analysis, only subclinical tenosynovitis (OR: 9.8; 95% CI: 2.5-39.1; p = 0.001) and baseline DAS28 (OR: 5.7; 95% CI: 1.1-31.6; p = 0.047) were significantly associated with an increased risk of having a flare. Conclusion In our study, subclinical tenosynovitis was associated with disease flare in patients with RA in clinical remission.