Background The objective was to compare different definitions of remission and low disease activity (LDA) in patients with psoriatic arthritis (PsA), based on both patients’ and physicians’ perspectives.

Methods In ReFlap (Remission/Flare in PsA; NCT03119805), adults with physician-confirmed PsA and >2 years of disease duration in 14 countries were included. Remission was defined as very low disease activity (VLDA), Disease Activity index for PSoriatic Arthritis (DAPSA) ≤4, and physician-perceived and patient-perceived remission (specific question yes/no), and LDA as minimal disease activity (MDA), DAPSA <14, and physician-perceived and patient-perceived LDA. Frequencies of these definitions, their agreement (prevalence-adjusted kappa), and sensitivity and specificity versus patient-defined status were assessed cross-sectionally.

Results Of 410 patients, the mean age (SD) was 53.9 (12.5) years, 50.7% were male, disease duration was 11.2 (8.2) years, 56.8% were on biologics, and remission/LDA was frequently attained: respectively, for remission from 12.4% (VLDA) to 36.1% (physician-perceived remission), and for LDA from 25.4% (MDA) to 43.9% (patient-perceived LDA). Thus, patient-perceived remission/LDA was frequent (65.4%). Agreement between patient-perceived remission/LDA and composite scores was moderate to good (kappa range, 0.12–0.65). When patient-perceived remission or LDA status is used as reference, DAPSA-defined remission/LDA and VLDA/MDA had a sensitivity of 73.1% and 51.5%, respectively, and a specificity of 76.8% and 88.0%, respectively. Physician-perceived remission/LDA using a single question was frequent (67.6%) but performed poorly against other definitions.

Conclusion In this unselected population, remission/LDA was frequently attained. VLDA/MDA was a more stringent definition than DAPSA-based remission/LDA. DAPSA-based remission/LDA performed better than VLDA/MDA to detect patient-defined remission or remission/LDA. Further studies of long-term outcomes are needed.