Background: To explore to what extent synovial hypertrophy in joints without Doppler activity is a sign of active disease, we investigated the sensitivity to change of synovial hypertrophy without Doppler activity during biological disease-modifying antirheumatic drug (bDMARD) treatment in rheumatoid arthritis (RA) patients.
Method: RA patients initiating or switching bDMARD treatment had ultrasound (US) performed on 36 joints at baseline, and at 3 and 6 months. Synovial hypertrophy by grayscale US and Doppler activity were graded separately from 0 to 3 at the joint level for all time points. Changes in synovial hypertrophy in joints without Doppler activity during treatment were assessed and compared with changes in synovial hypertrophy in joints with Doppler activity.
Results: We included 151 patients (82.8% women, 80.1% seropositive for anticyclic citrullinated peptide) with a mean ± standard deviation age of 51.4 ± 13.2 years, a disease duration of 9.9 ± 7.9 years, and baseline Disease Activity Score 28-joint count C-reactive peptide (DAS28-CRP) of 4.14 ± 1.32. At baseline, 44.8% of all joints examined (n = 5225) had synovial hypertrophy ≥ 1 and 50.7% of these had synovial hypertrophy without Doppler activity. The improvement in synovial hypertrophy was similar in joints with and without Doppler activity but, when adjusting for the baseline score of synovial hypertrophy, joints with synovial hypertrophy without Doppler had a higher tendency towards a decrease than joints with synovial hypertrophy with Doppler activity independent of grade (3 months: p < 0.0001; 6 months: p = 0.0003).
Conclusion: Joints with synovial hypertrophy without Doppler activity improve during treatment, independent of the grade. Thus, SH without Doppler activity is not a sign of inactive disease. These findings indicate that joints with synovial hypertrophy without Doppler activity should also be taken in to account when assessing disease activity by US.
Keywords: Doppler; Rheumatoid arthritis; Sensitivity-to-change; Synovitis; Ultrasound.