AMSTERDAM — The rate of 1-year adherence to tumor necrosis factor-inhibitor therapy was significantly better among patients with ankylosing spondylitis than in those with either rheumatoid arthritis or psoriatic arthritis, judging from the findngs of a large observational registry, Dr. Marte S. Heiberg reported at the annual European Congress of Rheumatology.
Among rheumatoid arthritis patients—and among psoriatic arthritis patients—rates of adherence to anti-tumor necrosis factor (TNF) therapy were significantly greater in those on concomitant methotrexate than with TNF-blocker monotherapy (see chart).
Ankylosing spondylitis patients, however, were different.
Rate of adherence to anti-TNF therapy among patients with ankylosing spondylitis were identically good regardless of whether the treatment was administered as monotherapy or given in combination with methotrexate, noted Dr. Heiberg of the University of Oslo.
She presented an update from the Norwegian Disease-Modifying Anti-Rheumatic Drug (NOR-DMARD) study, a longitudinal observational study that includes consecutive patients with inflammatory arthropathies placed on DMARD therapy in any of five Norwegian rheumatology departments.
NOR-DMARD is designed to provide comparative information regarding the real-world performance of DMARDs outside the restrictive randomized trial setting.
To date 5,281 patients have been enrolled. During her presentation, Dr. Heiberg focused on 1-year treatment adherence rates among patients with ankylosing spondylitis, rheumatoid arthritis, or psoriatic arthritis placed on etanercept, infliximab, or adalimumab.
Unadjusted 1-year adherence to anti-TNF therapy was 82% in ankylosing spondylitis patients, 78% in those with psoriatic arthritis, and 67% in rheumatoid arthritis patients.
Female gender and older age were associated with lower treatment adherence, in a Cox multivariate regression analysis. Concomitant methotrexate was associated with increased adherence—except among patients with ankylosing spondylitis.
One-year adherence wasn't significantly influenced by which TNF inhibitor a patient was being treated with.
The adjusted relative risk of anti-TNF treatment discontinuation for any reason within the first year was 37% less in ankylosing spondylitis patients and 21% less in psoriatic arthritis patients than in those with rheumatoid arthritis.
Women were 63% more likely to stop therapy than were men. Patients on concomitant methotrexate had a 44% reduction in treatment termination.
Psoriatic arthritis patients were more likely than others to discontinue anti-TNF therapy due to adverse events and least likely to do so because of lack of efficacy, Dr. Heiberg noted at the congress sponsored by the European League Against Rheumatism.
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