Among psoriatic arthritis (PsA) patients who started a systemic disease-modifying antirheumatic drug (DMARD) in the United States during 2004-2015, treatment modification rates went up and discontinuation rates decreased over the 11-year period, according to results from a large study of national claims data.

The increased rate of treatment modification may not be surprising given the “significant advancement in PsA treatment and expanding pharmacotherapy options in the past decade,” wrote researchers led by Moa P. Lee, PharmD, of the division of pharmacoepidemiology and pharmacoeconomics in the department of medicine at Brigham and Women’s Hospital and Harvard Medical School, Boston (Arthritis Care Res. 2017 Aug 13. doi: 10.1002/acr.23337 ).

The researchers reviewed records between July 1, 2004, and Sept. 30, 2015, from the Clinformatics Datamart data set, which contains demographic and longitudinal claims information for all United Healthcare beneficiaries. They observed an increasing trend in treatment modifications over the 11-year study period (P = .03) and found that 5% of all patients discontinued treatment, with the discontinuation rates decreasing over time (P less than .001).

Of the 9,222 PsA patients who initiated DMARDs, 43% received a biologic agent (bDMARD) and 57% received a conventional synthetic agent (csDMARD). Patients who were initiated on bDMARDs had an average age of 48 years, compared with 52 years in csDMARD initiators. Biologic DMARD initiators also had generally fewer comorbidities.

The most frequently used DMARD overall was methotrexate, which constituted 81% of csDMARD initiations. The most commonly prescribed bDMARDs were etanercept and adalimumab (49% vs. 34%, respectively).

When the researchers evaluated 12-month follow-up data after the first DMARD initiation, they found that 20% of bDMARD initiators had their initial DMARD regimen modified, compared with 31% of csDMARD initiators. Treatment modifications occurred more quickly after starting a csDMARD (median of 102 days) when compared against bDMARD initiators (148 days), and the rate of modification was also higher for patients who first started a csDMARD (adjusted incidence rate of 39.3 cases per 100 patient-years vs. 21.1 cases per 100 person-years for bDMARDs).

The most common modification made by csDMARD initiators was the addition of a bDMARD to methotrexate, particularly etanercept or adalimumab, in 16%. For bDMARD initiators, the most common modification was adding methotrexate in 7%, followed by switches between etanercept and adalimumab in 6%.

“In a rapidly evolving field of PsA treatment, further studies that elucidate more comprehensive real-world trends in the use of available treatment, including more recent novel therapies for PsA, may be needed,” the researchers concluded.

There was no specific funding source for the study. The researchers reported having no financial disclosures relevant to the study.