Comparison of health care costs among patients with psoriasis initiating ixekizumab, secukinumab, or adalimumab

Abstract

BACKGROUND: As more biologics become available for the treatment of psoriasis (PsO), there is a lack of direct comparisons of health care costs between patients who are treated by different medications, including ixekizumab (IXE), secukinumab (SEC), and adalimumab (ADA). OBJECTIVE: To compare the real-world health care costs of patients with PsO initiating IXE with those of patients initiating either SEC or ADA. METHODS: Patients diagnosed with PsO between July 1, 2015, and May 31, 2018, were identified from the IBM MarketScan commercial and Medicare databases. Two weighted patient sample sets were constructed based on drug claims between March 1, 2016, and May 31, 2018: IXE versus SEC and IXE versus ADA. Within each sample, the first claim of eligible drugs was set as the index date. Patients were aged ≥ 18 years and had ≥ 12 months of continuous eligibility before and after the index date. Patients with other indications for the index drug in the preperiod or with use of the index drug within 90 days before the index date were excluded. Inverse probability of treatment weighting (IPTW) was employed to balance cohorts. All-cause and PsO-related health care costs per member per month (PMPM) incurred during the 12-month follow-up period were assessed. Monthly PsO-related pharmacy costs were adjusted using drug discount rates published by the Institute for Clinical and Economic Review (ICER). Annual index drug costs were estimated by adjusting for medication possession ratio and ICER discount rates. All costs were weighted by IPTW. RESULTS: Two study samples were identified: 357 IXE users were compared with 763 SEC users, and 388 IXE users were separately compared with 2,578 ADA users. Before weighting, IXE users were demographically and clinically similar to SEC users but were older and had worse health status than ADA users. Cohorts were balanced postweighting. After weighting, mean monthly all-cause health care costs were $7,313 and $6,477 (P = 0.002) and mean PsO-related costs were $6,303 and $5,437 (P < 0.001), for IXE and SEC users, respectively. Similarly, mean monthly all-cause health care costs were $6,535 and $5,557 (P = 0.026) and mean PsO-related costs were $5,792 and $4,754 (P = 0.017), for IXE and ADA users, respectively. After applying ICER adjustments, mean monthly PsO-related costs were comparable between groups: $3,637/IXE versus $3,443/SEC (P = 0.132) and $3,320/IXE versus $3,287/ADA (P = 0.907). CONCLUSIONS: After adjusting for drug discount programs (through application of ICER discount rate), this real-world study estimated that average monthly PsO-related costs during the first year of treatment were similar between patients treated with IXE compared with those treated with SEC or ADA.