Methotrexate treatment in early psoriatic arthritis in comparison to rheumatoid arthritis: an observational nationwide study

Abstract

Introduction: We aimed to compare the proportions of patients with newly diagnosed psoriatic arthritis (PsA) and rheumatoid arthritis (RA) remaining on methotrexate (regardless of other disease-modifying antirheumatic drug (DMARD)-changes), and proportions not having started another DMARD (regardless of methotrexate discontinuation), within 2 years of starting methotrexate, as well as methotrexate effectiveness.

Methods: Patients with DMARD-naïve, newly diagnosed PsA, starting methotrexate 2011-2019, were identified from high-quality national Swedish registers and matched 1:1 to comparable patients with RA. Proportions remaining on methotrexate and not starting another DMARD were calculated. For patients with disease activity data at baseline and 6 months, response to methotrexate monotherapy was compared through logistic regression, applying non-responder imputation.

Results: In total, 3642/3642 patients with PsA/RA were included. Baseline patient-reported pain and global health were similar, whereas patients with RA had higher 28-joint scores and evaluator-assessed disease activity. Two years after methotrexate start, 71% of PsA vs 76% of patients with RA remained on methotrexate, 66% vs 60% had not started any other DMARD, and 77% vs 74% had not started specifically a biological or targeted synthetic DMARD. At 6 months, the proportions of patients with PsA versus RA achieving pain-scores ≤15 mm were 26% vs 36%; global health ≤20 mm: 32% vs 42%; evaluator-assessed 'remission': 20% vs 27%, with corresponding adjusted ORs (PsA vs RA) of 0.63 (95% CI 0.47 to 0.85); 0.57 (95% CI 0.42 to 0.76) and 0.54 (95% CI 0.39 to 0.75).

Discussion: In Swedish clinical practice, methotrexate use is similar in PsA and RA, both regarding initiation of other DMARDs and methotrexate retention. On a group level, disease activity improved during methotrexate monotherapy in both diseases, although more so in RA.

Keywords: Arthritis, Psoriatic; Arthritis, Rheumatoid; Methotrexate.

Figure 1

Kaplan-Meier curves indicating time from start of methotrexate until start of another DMARD. Time to starting any other DMARD: Person-years at risk for patients wih PsA/RA for the whole follow-up period, 13 985/12 792 years; for the first 2 years, 5639/5422 years. (B) Time to starting a b/tsDMARD: Person-years at risk for patients with PsA/RA for the whole follow-up period, 16 339/15 874 years; for the first 2 years, 6175/6157 years. b/tsDMARD, biological or targeted synthetic DMARD; DMARD, disease-modifying antirheumatic drugs; PsA, psoriatic arthritis; RA, rheumatoid arthritis.

Figure 2

Kaplan-Meier curve indicating time from start of methotrexate until discontinuation. Person-years at risk for patients with PsA/RAs for the whole follow-up period, 14 159/14 701 years; for the first 2 years, 6231/6342 years. PsA, psoriatic arthritis; RA, rheumatoid arthritis.

Figure 3

Proportions of patients with favourable patient-reported and evaluator-reported disease measures at baseline and after 6 months of methotrexate monotherapy. Error bars indicate 95% CIs. The numbers of PsA cases and RA comparator-subjects, respectively, included in these complete case analyses were 707 and 1496 for VAS pain; 716 and 1527 for VAS global health; 759 and 1532 for evaluator’s assessment of disease activity. PsA, psoriatic arthritis; RA, rheumatoid arthritis; VAS, Visual Analogue Scale.