Effectiveness of Disease-Modifying Antirheumatic Drugs for Enthesitis in a Prospective Longitudinal Psoriatic Arthritis Cohort

OBJECTIVE: Our objective was to assess the effectiveness of conventional and targeted disease-modifying antirheumatic drugs (cDMARDs and tDMARDs, respectively) in treating enthesitis in psoriatic arthritis (PsA). METHODS: Patients with active enthesitis, defined as ≥ 1 tender entheses (of the 29 enthesis sites included in the Spondyloarthritis Research Consortium of Canada Enthesitis Index, the Leeds Enthesitis Index, and the Maastricht Ankylosing Spondylitis Enthesitis Score), who were enrolled in a large PsA cohort were included. Medications at baseline were classified into 3 mutually exclusive categories: (1) no treatment or nonsteroidal antiinflammatory drugs (NSAIDs) only; (2) cDMARDs ± NSAIDs; and (3) tDMARDs ± cDMARDs/NSAIDs. Complete resolution of enthesitis (no tender enthesis) at 12 months was the primary outcome. Logistic regression models were developed to determine the association between medication category and enthesitis resolution. RESULTS: Of the 1270 patients studied, 628 (49.44%) had enthesitis. Of these, 526 patients (51.71% males; mean [SD] age 49.02 [13.12] years; mean enthesitis score 2.13 [2.16]; median enthesitis score 2 [IQR 1-2]), with adequate follow-up were analyzed. Complete resolution of enthesitis was noted in 453 (86.12%) patients, within a mean period of 8.73 (3.48) months from baseline. In the regression analysis, though not significant, DMARDs (categories II and III) had higher odds ratios (ORs) compared to category 1 for resolution of enthesitis. Enthesitis resolution was associated with lower joint activity (OR 0.97, 95% CI 0.95-0.99; P = 0.01) and male sex (OR 1.66, 95% CI 0.97-2.84; P = 0.06). CONCLUSION: Resolution of enthesitis was observed in 86% of patients in an observational setting regardless of the medication used. Future effectiveness studies may warrant evaluation of enthesitis using advanced imaging.