Assessment of Response to Treatment, Remission, and Minimal Disease Activity in Axial Psoriatic Arthritis Treated with Tumor Necrosis Factor Inhibitors.

Objective: To assess the response to treatment, remission, and minimal disease activity (MDA) in a group of patients with predominant axial psoriatic arthritis (axPsA). Predictors of response were also evaluated.
Methods: Patients fulfilling the ClASsification of Psoriatic ARthritis (CASPAR) criteria and treated with anti-tumor necrosis factor (anti-TNF) agents adalimumab, etanercept, and golimumab were enrolled and prospectively followed every 4 months for 1 year in a clinical practice setting. Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 50 was assessed as a set of response criteria to treatment; Composite Psoriatic Disease Activity Index (CPDAI) < 4, Disease Activity Index for Psoriatic Arthritis (DAPSA) score ≤ 3.3, and partial remission (PR) were also evaluated as remission criteria. Patients were considered in MDA when they met at least 5/7 of the criteria previously defined. Patients achieving BASDAI 50, PR, and MDA were compared to identify outcome predictor factors. Concordance between the outcome measures was also performed.
Results: Of the 58 patients treated with anti-TNF, at baseline no patients were in PR or MDA. No patients had a CPDAI < 4 or a DAPSA score ≤ 3.3. After 12 months, BASDAI 50 was achieved in 15/48 patients (31.2%). CPDAI < 4, DAPSA score ≤ 3.3, PR, and MDA were achieved, respectively, in 17/48 (35.4%), 11/48 (22.9%), 11/48 (22.9%), and 24/48 (50%) patients. No difference was found among the 3 anti-TNF. Predictors for MDA were male sex, young age, low disease duration, low Health Assessment Questionnaire score, and absence of enthesitis.
Conclusion: This longitudinal observational study, based on a clinical practice setting, showed that remission and MDA are achievable targets in axPsA treated with anti-TNF. Predictors of remission and MDA were also identified.