The ability of ultrasound (US) to identify subclinical joint inflammation in rheumatoid arthritis (RA) patients in remission has been already reported. Nonetheless, current studies present a lack of homogeneity in patient's characteristics and number of joints assessed by US. The aim of this study was to identify a reduced set of target joints to be scanned in RA patients in clinical remission in order to detect subclinical synovitis.
Forty RA patients in clinical remission (DAS28 ≤2.6) for at least 3 months underwent an US examination of 18 joints: wrist, II-III-IV-V metacarpophalangeal (MCP) and II-III-IV-V metatarsophalangeal joints bilaterally. The presence of synovial hypertrophy (SH) and power-Doppler (PD) signal was registered following the OMERACT definitions and was graded according to a 4-point scale (0-3). Then, by applying a process of data reduction based on the frequency of joint involvement, a reduced assessment was obtained.
Twenty (50%) subjects had at least one joint affected by active synovitis; 17.5% presented grade 1 PD and 32.5% grade 2 PD. The joints most frequently affected by active synovitis were the wrists (75%) and the II MCP joints (55%). After data reduction, the evaluation of 3 joints (both wrists and the II MCP of the dominant hand) obtained a sensitivity of 90% for the detection of subclinical synovitis.
The US scan of 3 target joints showed a high sensitivity in detecting subclinical active synovitis in RA patients in clinical remission and can be feasible in the routine assessment of these patients.