Real-World Treatment Patterns and Healthcare Costs in Patients with Psoriatic Arthritis Treated with Ixekizumab: A Retrospective Study

Objective To describe adherence, persistence, discontinuation, restarting, switching, dosing, and health care costs among patients with psoriatic arthritis (PsA) treated with ixekizumab (IXE). Methods MarketScan administrative claims databases were used to select adults (>= 18 years) initiating IXE between January 1, 2016, and June 30, 2019, for this retrospective study (earliest IXE claim = index). Eligible patients had one or more PsA diagnoses during the 12 months preceding the index and had 12 months of follow-up time after the index. Adherence (measured by proportion of days covered [PDC]) persistence (<60-day gap), discontinuation (>= 90-day gap), switching, and dosing patterns were reported. Health care costs were reported per patient per month (PPPM) during follow-up and were assessed after adjusting PsA treatment costs for discount rates reported by the Institute for Clinical and Economic Review (ICER). Results A total of 496 patients met the selection criteria (mean age, 51.1 years; 50.4% female). Over the 12-month follow-up, 52.8% remained persistent, 38.7% discontinued, 13.5% had no other treatment, 4.6% restarted, and 20.6% switched to a new biologic/traditional synthetic disease-modifying antirheumatic drug. 70.6%of patients were identified as highly adherent (i.e. PDC > 0.80)to IXE prior to discontinuation. Dose values were consistent with prescribing information for patients with and without comorbid psoriasis. Although IXE costs ($5233 [SD = $2497]) accounted for 85.6% of PsA-related health care costs, only 3.5% of IXE costs were patient out-of-pocket expenses. Adjusting for the ICER discounts decreased all-cause and PsA-related costs by $2509 PPPM. Conclusion Results from this real-world analysis suggest that treatment patterns and costs among patients with PsA initiating IXE are consistent with prior literature for other biologics.