Utility of Power Doppler Ultrasound-detected Synovitis for the Prediction of Short-term Flare in Psoriatic Patients with Arthritis in Clinical Remission

Objective. Power Doppler ultrasound (PDUS) has been shown to detect subclinical synovitis in psoriatic arthritis (PsA), but its value is not yet fully understood. The aim of this study was to evaluate PDUS features at joint level in patients with PsA in clinical remission and to investigate its value for predicting short-term flares. Methods. Consecutive patients with PsA in clinical remission according to the attending rheumatologist and who fulfill minimal disease activity criteria and/or 28-joint Disease Activity Score in remission criteria underwent PDUS examination of 18 joints. All patients were followed up for 6 months. Disease flare was defined as any increase of disease activity generating the need of any of the following changes in therapy with disease-modifying antirheumatic drugs (DMARD) by the attending rheumatologist: dose increase, switch or addition of a different DMARD, and/or switch or addition of biological therapies. Results. Among 54 patients with PsA in clinical remission, 15 (27.8%) experienced a flare within the next 6 months. Twenty patients had at least 1 joint with PDUS synovitis at baseline, and 13 (65%) of these had a disease flare during the followup period compared with only 2 of the 34 patients (5.9%) without baseline PDUS synovitis (relative risk = 11, 95% CI 2.8-44, p < 0.001). On logistic regression analysis, the only variables associated with short-term flares were baseline PDUS synovitis and the use of nonbiologic DMARD. Conclusion. Among patients with PsA in clinical remission, PDUS-detected synovitis was a strong predictor of short-term flare of the disease.