Patterns of Systemic Treatment for Psoriatic Arthritis in the US: 2004-2015

To examine trends in the use of systemic disease-modifying antirheumatic drugs (DMARDs) among patients with psoriatic arthritis (PsA) in the US.

Using claims data (2004-2015) from a large US commercial health plan, we identified patients with PsA who initiated DMARD therapy. We examined baseline patient characteristics and initial treatment patterns. We then assessed changes in the DMARD regimen over the 12-month period after the first DMARD initiation date. Using Poisson regression, we estimated age- and sex-adjusted incidence rates of treatment changes in each calendar year.

We identified 9,222 PsA patients who initiated DMARD therapy (42.8% biologic DMARDs [bDMARDs] and 57.2% conventional synthetic DMARDs [csDMARDs]). Initiators of bDMARDs were younger than those initiating csDMARDs (mean ± SD age 48 ± 13 versus 52 ± 14 years) and generally had fewer comorbidities, but a higher proportion of bDMARD initiators received nonsystemic treatments for psoriasis at baseline. Methotrexate was the most frequently used DMARD, constituting 80.6% of csDMARD initiations. Etanercept (49.1%) was the most commonly prescribed bDMARD, followed by adalimumab (34.4%). During the 12-month followup after the first DMARD initiation, 20.1% of bDMARD initiators and 31.1% of csDMARD initiators had their initial DMARD regimen modified, with an increasing trend in treatment modifications over the 11-year study period (P = 0.03). Overall, 5.3% of patients discontinued treatment, but the rates of discontinuation decreased over time (P < 0.001).

In this large cohort of PsA patients with DMARD initiation, more than 40% were treated with a bDMARD. We found an increasing trend in treatment modification after use of the initial DMARD and a decreasing trend in complete DMARD discontinuation over the past decade.