DISCUSSION
In line with our hypothesis, patients beginning combination therapy differed from patients on monotherapy in their medical history, demographics, and PROs. Our most salient finding was that the combination therapy group was more likely to have concomitant PsA. This is not surprising, as combinations of TNFalpha inhibitors and agents such as MTX have been extensively studied in PsA patients relative to those with isolated dermatologic disease.11-13 Indeed, a study from the Corrona Psoriatic Arthritis and Spondyloarthritis Registry found that a greater percentage of PsA patients were on combination therapy than monotherapy (61.3% vs 38.7%).9 While many patients with PsA are well controlled on biologic monotherapy, these data may allow clinicians to anticipate the possible need for adjuvant systemic agents in this population and counsel patients accordingly.
