Most patients with psoriatic arthritis fare better when remaining on a single tumor necrosis factor inhibitor than when switching to a second medication, Norwegian researchers have found.
Karen Fagerli, Ph.D., of the department of rheumatology at Diakonhjemmet Hospital in Oslo, and her colleagues found that patients who switched tumor necrosis factor inhibitor (TNFi) medications had significantly poorer responses in factors like American College of Rheumatology-50 (ACR 50) response and Disease Activity Score-28 (DAS28) remission, compared with those who stayed on one TNFi. Drug-survival rates at 3 years also were lower among patients who changed medications (Ann. Rheum. Dis. 2013 April 5 [doi: 10.1136/annrheumdis-2012-203018]).
Dr. Karen M. Fagerli
Because some (20%-40%) patients showed a response to a second TNFi at 3 months, "our results do not imply that a second TNFi should not be attempted in those who fail their first TNFi, but rather highlight the need for treatments with other mechanisms of action for patients with psoriatic arthritis," Dr. Fagerli and her colleagues wrote.
The investigators studied patient data from the observational NOR-DMARD study, a registry at five centers in Norway of all patients with inflammatory arthropathies starting disease-modifying antirheumatic drugs (DMARDs). Patients in the registry were assessed at baseline and 3, 6, and 12 months after starting treatment. They had annual follow-up visits thereafter.
The researchers included 439 patients with psoriatic arthritis who started their first TNFi between February 2001 and October 2011. They labeled the 95 patients who started a second TNFi as the "switchers," and the remaining 344 patients who stayed on one TNFi as the "nonswitchers." Researchers compared 3-month responses and 3-year drug-survival between switchers and nonswitchers, and within switchers. Among switchers, etanercept (Enbrel) was the most commonly prescribed first TNFi, and adalimumab (Humira) the most commonly prescribed second TNFi.
The switchers receiving their second TNFi had significantly poorer responses by 3 months than the nonswitchers: The ACR 50 response was 22.5% in switchers taking a second TNFi, versus 40% in nonswitchers, and DAS28 remission rates were 28% in switchers taking a second TNFi, versus 54% in nonswitchers.
Researchers also found a trend among the switchers toward poorer responses to the second TNFi, compared with the first. "The estimated 3-year drug-survival was 36% for the second TNFi, compared with 57% for the first TNFi overall," they wrote.
The investigators noted that the comparisons between switchers and nonswitchers could be biased by "some patients still having residual effects of their first TNFi when starting the second, ... but the pattern of poorer response to the second TNFi was consistent for both analytic approaches."
Even though the approach to evaluating effectiveness through the assessment of treatment completers "likely overestimates effectiveness due to discontinuations prior to assessment in poor responders," there was only a small difference in the rate of discontinuation prior to the 3-month assessment between the switchers, who had the poorest response, and the nonswitchers, the investigators said.
The study was supported by the Norwegian South Eastern Health Board. The NOR-DMARD study received funding from Abbott, Amgen, and other companies. Dr. Fagerli reported having received speaker’s honoraria from Abbott and Pfizer. Other authors reported financial ties to manufacturers of TNF inhibitors and other biologics.