Retention of triple therapy with methotrexate, sulfasalazine, and hydroxychloroquine compared to combination methotrexate and leflunomide in rheumatoid arthritis

Objective: There are various combination conventional synthetic disease-modifying-anti-rheumatic drug (csDMARD) treatment strategies used in rheumatoid arthritis (RA). A commonly used csDMARD combination is triple therapy with methotrexate (MTX), sulfasalazine (SSZ) and hydroxychloroquine (HCQ). Another approach is double therapy with MTX and leflunomide (LEF). We compared the real-world retention of these two treatment combinations. Methods: Patients with RA from the Ontario Best Practices Research Initiative (OBRI) who received triple or double therapy on or after OBRI enrolment were included. Retention rates were compared between these two groups. We also analyzed which medication in the combination was discontinued and the reasons for treatment discontinuation. Disease activity was assessed at baseline, 6 and 12 months after treatment initiation as well as at time of discontinuation. Risk factors for treatment discontinuation were also examined. Results: 692 patients were included (258 triple and 434 double therapy). There were 175 (67.8%) discontinuations in the triple therapy group and 287 (66.1%) discontinuations in patients on double therapy. The median survival for triple therapy was longer (15.1 months; 95% CI: 11.2-21.2) compared to double therapy (9.6 months; 95%CI: 7.03-12.2). However, this was not statistically significant. Disease activity at 6 and 12 months, measured by 28-joint count Disease Activity Score based on erythrocyte sedimentation rate (DAS28-ESR) was lower with triple therapy (mean DAS28 at 6 months 3.4 vs. 3.9, p<0.0001 and at 12 months 3.2 vs. 3.5, p=0.0005). Conclusion: Patients on triple therapy remained on treatment longer than patients on double therapy. However, this difference was not statistically significant.