Combination Therapy Comes at a Cost in Patients with Psoriatic Arthritis

Combination therapy in patients with psoriatic arthritis has a lower discontinuation rate than that of patients on monotherapy, but comes with a higher price tag.

Psoriatic arthritis (PsA) patients using disease-modifying antirheumatic drugs (DMARDs) in conjunction with biologic therapy have lower discontinuation rates than patients on biologic therapy alone, but saw higher pharmacy costs, the results of a study published in the September 2013 edition of Clinical Therapeutics suggest.

The rates of therapy continuation and therapy switches were relatively consistent between patient groups receiving both therapy regimens, the researchers determined. Despite this, researches did find a statistically significant difference in the proportion of patients discontinuing biologic monotherapy—34.5% of the group discontinued their index biologic therapy—compared with patients receiving biologic therapy and DMARDs.

“In multiple studies, the use of a conventional DMARD, such as methotrexate or azathioprine, in combination with a biologic was associated with prolonged remission in PsA patients, even after therapy interruption, and lower rates of developing antidrug antibodies, compared with biologic monotherapy,” the researchers wrote. “The results of this study suggest that the addition of conventional DMARD therapy in patients who likely have more severe disease activity could confer a potentially beneficial effect in reducing the discontinuation rates of biologic therapy.”

The study also confirmed the high costs associated with PsA, which have been observed in prior studies. The data surveyed showed an average annual medical expenditure of $26,138 for patients receiving biologic monotherapy, and an average annual medical expenditure of $27,368 for patients receiving a biologic therapy and a DMARD.

Within both cohorts, pharmacy expenditures accounted for the largest portion of the overall medical cost. Pharmacy payments accounted for approximately half of the overall medical expenditures and more than half of PsA-related expenditures, the research revealed.

“In this study, conventional DMARDs, when used adjunctively with biologic agents, reduced the rate of discontinuation but added pharmacy costs while not affecting overall medical expenditures in patients with psoriatic arthritis,” the researchers wrote.

Researchers surveyed patient data from the Truven Health Analytics MarketScan database, covering the period from January 1, 2005, to December 31, 2009. The data included 3164 participants with PsA who initiated biologic treatment for the condition during the study time period. They then identified patients receiving biologic monotherapy and those receiving biologic therapy in conjunction with a conventional DMARD, such as auranofin, aurothioglucose, azathioprine, chlorambucil, chloroquine, cyclophosphamide, cyclosporine, gold sodium thiomalate, hydroxychloroquine, leflunomide, minocycline, methotrexate, pencillamine/pencillamine-d, and sulfasalazine.

In addition to observing, the researchers also investigated concurrent medication use and the frequency of concurrent conditions, including rheumatoid arthritis, psoriasis, diabetes, hypertension, and hyper- or dyslipidemia. Although concurrent medication use was similar in both cohorts prior to and after therapy initiation, the researchers observed greater concurrent use of antihypertensive, antidepressant, statin, and antidiabetic medications during the post-therapy period.

The researchers also noted that the use of pain medications was significantly reduced in the year after patients initiated biologic therapy, suggesting that biologic therapy helps reduce therapy-related pain.

“The results of this study add more evidence that biologic therapy may play a role in reducing the pain for patients with PsA; after initiation of biologic therapy, a decrease in the use of pain medication was observed in both cohorts,” the researchers noted.