Ultrasound-Detected Synovitis Predicts Short-term PsA Disease Flare

Patients with psoriatic arthritis (PsA) in remission who have synovitis detected by power Doppler ultrasound (PDUS) are 11 times more likely to experience a disease flare within 6 months compared with those who do not have PDUS, according to a study published in the Journal of Rheumatology.

Because current PsA remission criteria rely on clinical findings, underlying inflammatory processes such as synovitis and enthesitis may go undetected. Ultrasound and magnetic resonance imaging can reveal subclinical inflammatory processes that may otherwise be missed relying on clinical exam alone.

In rheumatoid arthritis, subclinical synovitis on ultrasound correlates with worse radiological and clinical outcomes. In PsA, ultrasound findings may disagree with the clinical assessment and lead to reclassification of disease type. However, data are lacking on the link between subclinical, ultrasound-detected inflammatory processes and the risk for disease flare in patients with PsA in remission.

Researchers examined the relationship between PDUS synovitis and the risk for disease flare within 6 months in patients with PsA in clinical remission. Disease flare was defined as an increase in dose of the current therapy, addition of another disease-modifying antirheumatic drug (DMARD) or biologic therapy, or switch to another DMARD or biologic therapy.

Of 54 patients with PsA in remission, 14 (26%) patients had 1 or more swollen joints at baseline. Two-thirds of patients were treated with DMARDs.

By 6 months, 15 (27.8%) patients experienced a disease flare, the majority of which had inflammatory articular involvement. Compared with patients with no flare, those with a disease flare were older and more likely to be treated with DMARDs (P =.011 and P =.037, respectively).

At the time of study enrollment, 37% of all patients had PDUS synovitis (PD grade ≥1) in 1 or more joints. Of these, 65% had a disease flare within 6 months compared with only 5.9% of patients without PDUS synovitis at baseline (relative risk, 11; P <.001).

Patients with PD grade ≥2 were also more likely to experience disease flare within 6 months than those with PD grade <2 (72.7% vs 13.9%; relative risk, 4.5; P <.001).

PDUS synovitis in ≥1 joint and nonbiologic DMARD use were identified as independent predictors of short-term PsA flares in the multivariate analysis.

Summary and Applicability

Imaging modalities, such as ultrasound and magnetic resonance imaging, can detect subclinical inflammatory processes that are not captured in the criteria for clinical remission. Whether imaging-detected inflammation correlates with the risk for increased disease activity was unclear until recently.

“The presence of [ultrasound] synovitis with positive PD signal despite clinical remission suggests that flares may be related to an incomplete suppression of inflammation, undetectable by the clinical indices used in daily rheumatology practice. Therefore, once the patients have achieved clinical remission, an [ultrasound] examination with PD technique could predict the probability of remaining in remission,” the investigators wrote.

Limitations and Disclosures

• The definition of PsA flare in this study was derived from the rheumatoid arthritis definition of flare and has not yet been specifically validated for PsA
• This study used PDUS to evaluate for the presence of synovitis, but not enthesitis or dactylitis, which may have led to underestimation of inflammation at baseline

The researchers report no relevant disclosures.

Reference

Ruta S, Marin J, Acosta Felquer ML, et al. Utility of power Doppler ultrasound-detected synovitis for the prediction of short-term flare in psoriatic patients with arthritis in clinical remission. J Rheumatol. 2017;44(7):1018-1023. doi: 10.3899/jrheum.161347