Residual Disease Activity and Associated Factors in Psoriatic Arthritis

Abstract

Objective: Remission or low disease activity should be the treatment target of psoriatic arthritis (PsA). However, residual disease activity (RDA) in some domains could persist. The aim of this study was to assess RDA and its associated factors in a group of patients with PsA.

Methods: Patients with PsA were enrolled if they satisfied ClASsification for Psoriatic ARthritis (CASPAR) criteria with > 6 months' followup and achieved a status of low disease activity (LDA), minimal disease activity (MDA), or remission [Disease Activity Index for PsA (DAPSA) remission or very low disease activity (VLDA)]. RDA was assessed by the percentage of patients who had, although in LDA or remission, tender and/or swollen joints > 1, Leeds Enthesitis Index > 1, Health Assessment Questionnaire > 0.5, Psoriasis Area Severity Index (PASI) > 1, patient's global assessment > 20, physician visual analog scale (VAS) > 20, and VAS pain > 15. Associated factors of RDA were also assessed.

Results: Of 113 enrolled patients, 78 (69%) were in MDA. Moreover, DAPSA remission was observed in 46 (40.7%) while VLDA only in 32 (28.3%) of patients with PsA. VLDA seems to be the most stringent criterion, with a minimal RDA only in the VAS physician in 1 patient (3.1%) and none in the different domains, while patients in MDA had RDA in tender joints (14.1%), VAS pain (29.4%) and PASI > 1 or body surface area (BSA) > 3% (17.9%). Of note, although patients in DAPSA remission show a very low rate of RDA in almost all domains, 12 (26%) of them show a PASI > 1 or BSA > 3%. Finally, LDA shows RDA in higher percentages, mainly in patient-reported outcomes, tender joints, and skin domain.

Conclusion: RDA can be recognized in patients with PsA. VLDA seems to be the most stringent composite index to identify patients in the absence of RDA.

Keywords: composite indices; psoriatic arthritis; remission; residual disease activity.