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.