Treatment with anti-tumor necrosis factor alpha inhibitor (TNFi) therapy was successful in reducing long-term disease activity of ankylosing spondylitis (AS) and psoriatic arthritis (PsA), with a 60% retention rate, in a trial including TNFi-naive patients with spondyloarthritis (SpA) in Thailand. The study was published in the Journal of Clinical Rheumatology.

TNFi therapy is generally reserved for patients who are unresponsive to treatment with conventional synthetic disease-modifying antirheumatic drugs (DMARDs). Unfortunately, conventional synthetic DMARDs are not usually efficacious for the treatment of axial SpA.

This retrospective cohort study identified 138 patients with SpA (97 with AS; 41 with PsA) who were prescribed their first TNFi medication between 2009 and 2014. TNFi efficacy was assessed using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) for axial improvement, and by means of joint count reductions for peripheral improvement. Patients were treated with either etanercept or infliximab.

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At 4 months after therapy initiation, 74.7% of patients with AS demonstrated a decrease of at least 2 points on the BASDAI, 58.6% saw at least a 50% reduction in BASDAI score, and 27.6% achieved a BASDAI under 2. At 3 years, for those still on TNFi therapy, these rates increased to 88.5%, 75.0% and 51.0%, respectively. Drug survival was 63% at 3 years for patients with AS.

Among patients with PsA, joint count reductions of 20%, 50%, and 70% at 4 months were seen in 85.3%, 61.8%, and 34.0% of patients, respectively. At 3 years, these rates increased to 100%, 100%, and 91.4%, respectively. Among those with PsA and axial arthritis, 80.6% demonstrated a decrease of at least 2 points on the BASDAI, 54.8% saw at least a 50% reduction in BASDAI score, and 35.5% achieved a BASDAI under 2 at 4 months. At 3-year follow-up, these figures had improved to 100%, 96.8%, and 58.1%, respectively. Drug survival at 3 years was 56% for patients with PsA.

TNFi therapy was generally discontinued because of a good clinical response (38.5%), serious adverse effects/drug toxicity (28.2%), nonadherence (20.5%), or lack of efficacy (12.8%). Of the 11 patients who experienced serious adverse events, 7 had infections, including 4 who contracted tuberculosis. Higher baseline BASDAI scores were also associated with increased rates of discontinuation (hazard ratio 1.8; 95% CI, 1.1-2.9).

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Study limitations included incomplete clinical data that prevented the calculation of frequently used composite scores for disease activity and a smaller sample than those found in other SpA investigations.

TNFi therapy yielded favorable results in patients with AS or PsA, with progressively better responses between 4 months and 3 years, as measured by BASDAI scores and joint count reductions. These results could prove especially useful in other developing countries with similar populations and healthcare systems.

This work was supported by the Thai Rheumatism Association. The grant had no role in any part of this work. The authors declare no conflict of interest.

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Chiowchanwisawakit P, Katchamart W, Osiri M, et al. Effectiveness and drug survival of anti-tumor necrosis factor α therapies in patients with spondyloarthritis: analysis from the Thai Rheumatic Disease Prior Authorization Registry [published online March 7, 2018]. J Clin Rheumatol. doi:10.1097/RHU.0000000000000741