Approximately two-thirds of patients with ankylosing spondylitis (AS) newly initiating a tumor necrosis factor inhibitor (TNFi) did not remain on their at index TNFi regimen 2 years after initiation, according to the results of a retrospective analysis published in Rheumatology and Therapy. Data showed that the percentage of women switching to a second TNFi was higher than the percentage of men.

The investigators sought to describe treatment patterns in patients with AS in the 2 years following initiation of TNFi therapy. Treatment patterns included persistence (no gaps in therapy for ≥90 days), discontinuation (≥90-day gap in therapy without initiating a new TNFi), and switching to a new TNFi. Patients with AS who had ≥1 claim for a TNFi (adalimumab, etanercept, infliximab, golimumab, or certolizumab pegol) were included in the cohort analysis. Patients who initiated a TNFi from January 1, 2009 to December 31, 2013 were indexed on their first TNFi, and each patient was followed for 2 years after the index date. Patients needed to have a 1-year pre-index period free of TNFi therapy and continuous enrollment 1 year pre-index and 2 years post-index. All patients who did not have ≥2 years of follow-up were excluded from the study. The final study follow-up could be December 31, 2015.

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A total of 1372 patients with AS were included in the study; 846 men and 526  women. The mean age of men was 44.3 and the mean age of women was 42.3. Adalimumab was the initial biologic prescribed in the majority of participants (44.6% of men and 43.3% of women), followed by etanercept (40.4% of men and 41.6% of women), infliximab (10.4% of men and 10.8% of women), golimumab (4.6% of men and 3.8% of women), and certolizumab pegol (0.0% of men and 0.4% of women).

During the follow-up, 33.1% of patients were persistent on their TNFi, 40.7% discontinued their index TNFi and did not restart another TNFi, and 26.1% switched to a second TNFi. Participants who were prescribed conventional disease-modifying antirheumatic drugs were more likely to be persistent with therapy, whereas women and opioid users were less likely to be persistent on their initial TNFi. In addition, of participants who discontinued their initial TNFi, 32.8% of men and 43.6% of women switched to a second TNFi treatment.

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The investigators concluded that this study implies that approximately 67% of men and 77% of women with AS who newly initiate TNFi treatment do not stay on their index therapy

2 years following treatment initiation. Additional research is warranted to more fully comprehend the reasons for non-persistence and the increasing trend toward the use of second-line TNFi therapy in this patient population.

The study received funding from Eli Lilly and Company.


Hunter T, Schroeder K, Sandoval D, Deodhar A. Persistence, discontinuation, and switching patterns of newly initiated TNF inhibitor therapy in ankylosing spondylitis patients in the United States [published online March 5, 2019]. Rheumatol Ther. doi:10.1007/s40744-019-0148-4