Background/Purpose: Ultrasound has been shown to detect subclinical synovitis in in rheumatoid arthritis and psoriatic arthritis (PsA in clinical remission.). The value of power Doppler ultrasound (PDUS) to predict flares in patients with PsA in remission or minimal disease activity has not been fully studied.

Objective: To determine whether PDUS assessment of synovitis predicts short term relapse in patients with PsA in clinical remission or minimal disease activity.

Methods: consecutive PsA patients in clinical minimal disease activity (MDA) and/or remission (fulfillment MDA criteria or Disease Activity Score in 28 joints [DAS28] <2.6, respectively) underwent PDUS examination of 18 joints (second and third metacarpophalangeal joints, second and third proximal interphalangeal joints, wrist, knee, ankle and second and fifth metatarsophalangeal joints).  US assessment were performed by the same rheumatologist, blinded to clinical data, usig a MyLab 70 machine (Esaote) provided with a 6-18 MHz multifrequency broad band linear transducer. PD signal was graded on a semi-quantitative scale from 0 to 3. PD synovitis was defined as the presence of intraarticular PD signal ≥1, and was treated as a dichotomous variable. On the same day a complete clinical assessment was performed by another rheumatologist. All patients were followed-up for 6 months. Flare was defined as the requirement of a change in disease modifying antirheumatic drugs (DMARDs) (increasing dose, adding or changing DMARDs or biologics therapy) by the treating rheumatologist, who was blinded to the US findings.  Relative risks (RR) with their 95% CI for flare among patients with and without PD signal were calculated. Multivariable analysis using logistic regression with flare as the outcome variable, and PD signal, demographic characteristics, and baseline disease activity as independent variables were also calculated.

Results: Fifty four patients were included: 47 patients fulfilling MDA criteria, 36 DAS28 remission criteria (DAS28<2.6) (29 patients fulfilled both criteria). Baseline patients’ characteristics are shown in the table. Among the 54 patients on MDA or DAS28 remission, 15 (28 %) experienced a flare within the next 6 months,15/47 (32%) of patients in MDA,  10/36 (28%) of patients in DAS28 remission, and 10/29 (35%) patients fulfilling both criteria. Thirteen (87%) of the 15 patients with flares had baseline PD synovitis, compared with 7/39 (35%) patients without flares (RR= 11; 95% CI: 2.8-44; p<0.0001).). On logistic regression analysis the only variables associated with short term flares were baseline positive PD signal (OR: 119;p=0.001), and baseline use of non-biologics DMARDs (OR: 5.9; p=0.038).

Conclusion: Among PsA patients on clinical remission and/or MDA, synovial inflammation determined by the presence of a positive PD signal, was a strong predictor of short term flare. 

Table: Patients’ characteristics.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/utility-of-power-doppler-ultrasound-detected-synovitis-for-the-prediction-of-short-term-flare-in-psoriatic-arthritis-patients-in-clinical-remission/