medwireNews: Patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), or ankylosing spondylitis (AS) who receive concomitant methotrexate treatment have lower rates of tumor necrosis factor (TNF) inhibitor discontinuation than those not taking methotrexate, researchers report.
Michael George, from the University of Pennsylvania in Philadelphia, USA, and colleagues used a US administrative claims database to evaluate rates of treatment discontinuation in a cohort of approximately 65,000 patients with inflammatory arthritis initiating methotrexate or TNF inhibitors between 2000 and 2014.
The most commonly used TNF inhibitor in the study was etanercept (47%), followed by adalimumab (28%) and infliximab (19%), and the median duration of TNF inhibitor treatment was 1.31 years.
George and team report in The Journal of Rheumatology that among patients who remained on TNF inhibitors for 90 days or longer, 65% of the 19,903 patients with RA, 41% of the 5604 with PsA, and 29% of the 3079 with AS also received a conventional DMARD in the 90 days after initiating their TNF inhibitor, most commonly methotrexate.
After adjusting for a number of factors including age, sex, TNF inhibitor type, and comorbidities, RA patients taking concomitant methotrexate had a significantly 15% lower likelihood of discontinuing their TNF inhibitor than those not using methotrexate, while methotrexate was associated with a significant 19% and 21% lower odds of TNF discontinuation among people with PsA and AS, respectively.
The researchers found less clear associations for the other conventional DMARDs used; sulfasalazine was associated with lower rates of TNF inhibitor discontinuation in people with RA or PsA, while hydroxychloroquine use was associated with lower discontinuation rates only in those with RA, and there was no link between leflunomide use and discontinuation rates for any of the patient groups.
These findings suggest “that [methotrexate] may help prolong the efficacy of TNF [inhibitors] in both RA and spondyloarthritis,” say the study authors.
They caution, however, that their study was “unable to determine reasons for medication discontinuation,” and “did not have laboratory data or drug-antibody levels,” meaning that it was not possible to establish whether associations between methotrexate use and TNF inhibitor discontinuation “are mediated by prevention of anti-drug antibodies, synergistic effects with the TNF [inhibitors] on disease control, or confounding factors.”
George and colleagues also compared overall treatment discontinuation rates among patients with the different types of inflammatory arthritis, finding that methotrexate was discontinued significantly earlier among patients with PsA or AS compared with RA, while TNF inhibitors were discontinued “slightly later” among people with PsA relative to those with RA.
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