Background Psoriatic arthritis (PsA) is a complex form of arthritis that develops in people with psoriasis. There is no agreement on the optimal criteria to identify remission in patients with PsA and some of them may miss skin lesions.
Objectives To investigate the merits of different potential remission definitions using data from the PRESTA study.1
Methods Remission was investigated for disease activity index for PsA for 3 definitions: very low disease activity (VLDA), Disease Activity in PsA (DAPSA), and clinical (c)DAPSA. VLDA index was defined as 7/7 met criteria of the minimal disease activity (MDA) cut-off points: tender joint count (TJC) ≤1, swollen joint count (SJC) ≤1, psoriasis activity and severity index (PASI) ≤1, patient global visual analog scale (Pt VAS) ≤20mm, Pt pain VAS ≤15mm, health assessment questionnaire (HAQ) ≤0.5, tender entheseal points ≤1. DAPSA remission was defined as DAPSA ≤4 (TJC, SJC, physician global VAS [cm], Pt VAS [cm], C-reactive protein [CRP]) and cDAPSA remission was defined as cDAPSA ≤4 (DAPSA without CRP).
Results At Week 24, the proportion of patients achieving remission was 9.6%, 31.0%, and 34.7% for VLDA, DAPSA, and cDAPSA remission, respectively. Discordance between VLDA and DAPSA or cDAPSA remission was 21.7% or 25.1%, respectively. Only 0.2% of the patients that achieved VLDA did not achieve DAPSA remission and 21.5% vice versa (Kappa coefficient 0.38) and 0.0% in the case of cDAPSA remission and 25.1% vice versa (Kappa coefficient 0.33). At the end of the study, residual levels of dactylitis and enthesitis appeared to be similar among all definitions (all ≤3.0%); however, patients achieving DAPSA and cDAPSA remission had higher proportions of patients with PASI >1 than patients achieving VLDA remission (PASI 2–9: VLDA 0.0% vs DAPSA 46.4% vs cDAPSA 47.2%; PASI ≥10: VLDA 0.0% vs DAPSA 5.8% vs cDAPSA 6.4%). Raised CRP values (upper limit of normal >8.99) were 7.8%, 4.8%, and 7.3% for VLDA, DAPSA, and cDAPSA, respectively.
Conclusions VLDA remission is a more stringent target than DAPSA and cDAPSA remission, with the advantage of including a measurement for psoriasis. Therefore, VLDA is more useful than DAPSA or cDAPSA in assessing a remission state in patients with PsA and extended skin lesions. Measurement of CRP levels does not appear to provide further information on current disease activity level in these patients and exclusion of this laboratory marker should facilitate remission assessment in clinical practice.
Sterry W, et al. BMJ 2010;340:c147.
Disclosure of Interest L. Coates Grant/research support from: Abbvie, Janssen, Consultant for: Abbvie, BMS, Janssen, Lilly, MSD, Novartis, Pfizer, L. Aikman Shareholder of: Pfizer, Employee of: Pfizer, A. Szumski Employee of: InVentiv Health, A. Chhabra Shareholder of: Pfizer, Employee of: Pfizer