First-line csDMARD monotherapy drug retention in psoriatic arthritis: methotrexate outperforms sulfasalazine

Objectives: Conventional synthetic DMARDs (csDMARDs) are the first-line treatment for PsA, but there is conflicting data regarding their efficacy and scarce reports describing the duration of use (drug retention) of csDMARD in this population. Their position in treatment recommendations is a matter of growing debate due to the availability of alternative treatment options with higher levels of evidence. We aimed to study drug retention and predictors for drug retention among PsA patients receiving first-line csDMARD monotherapy. Methods: Retrospective cohort study in DMARD-naïve adult PsA patients in whom a first csDMARD was prescribed as monotherapy primarily to treat PsA-related symptoms. The main outcome was time to failure of the csDMARD (i.e. stopping the csDMARD or adding another DMARD). Results: A total of 187 patients were included, who were mainly prescribed MTX (n = 163) or SSZ (n = 21). The pooled median drug retention time was 31.8 months (interquartile range 9.04-110). Drug retention was significantly higher in MTX (median 34.5 months; interquartile range 9.60-123) as compared with SSZ-treated patients (median 12.0 months; interquartile range 4.80-55.7) (P =0.016, log-rank test). In multivariable Cox regression, the use of MTX and older age were associated with increased retention. The main reasons for treatment failure were inefficacy (52%) and side effects (28%). Upon failure, MTX treated patients were more commonly, subsequently treated with a biologic DMARD compared with SSZ (P < 0.05). Conclusion: MTX outperforms SSZ as a first-line csDMARD in DMARD-naïve PsA patients with respect to monotherapy drug retention in daily clinical practice.