Treatment Patterns and Costs for Anti-TNFα Therapy in Patients with Ankylosing Spondylitis

Objective: Limited information exists on real-world use of anti-tumor necrosis factor-α (TNFα) biologic agents in ankylosing spondylitis (AS). This study evaluated the treatment patterns and costs of anti-TNFα biologic therapy and disease-modifying antirheumatic drugs (DMARDs) in patients with AS. Methods: MarketScan claim databases were used to identify anti-TNFα biologic treatment-naïve AS patients (aged ≥ 18 years that had not undergone anti-TNFα biologic therapy in the previous 6 months) who initiated antiTNFα biologic treatment between October 1, 2009 and September 30, 2010. Frequency of anti-TNFα biologic switching, duration, treatment modification, and medical and pharmacy drug costs for each line of anti-TNFα biologic therapy was analyzed during the 3-year follow-up. Results: We identified 337 eligible patients with AS. First-line anti-TNFα biologics were: etanercept (n=115), adalimumab (n=129), infliximab (n=38), and golimumab (n=15). Patients who did not switch were persistent with their first-line agent for a longer duration (505 days) than those who switched to a second-line (336 days) or thirdline (325 days) anti-TNFα biologic agent. Time to first treatment modification was shorter for those who switched to second-line (88 days) and third-line (6 days) therapy versus those who remained on first-line therapy (160 days). Monthly per member medical costs were greatest for nonswitchers ($354) than for patients who received secondline ($225) or third-line ($112) anti-TNFα biologic treatment. Overall pharmacy drug costs were similar for patients with first-line ($1899), second-line ($1955) or third-line and further ($1890) therapy. Conclusion: Patients with AS who switched anti-TNFα biologic therapy had more modifications to their treatment during the follow-up period. Those who switched to secondor third-line anti-TNFα biologic therapy had lower medical costs compared with those who remained with first-line treatment; however, pharmacy costs were similar among all.