1518. Real-World Comparative Effectiveness of Baloxavir Marboxil versus Oseltamivir on Influenza-Related Complication and Resource Utilization

Abstract Background In the 2018-19 season, there were an estimated 490,500 hospitalizations and 24,000 deaths from influenza in the US. Understanding how antiviral use affects rates and severity of complications is crucial to inform clinical practice. The objective of this study was to compare the frequency and costs of complications in influenza patients treated with baloxavir compared with oseltamivir-treated patients. This is one of the first analyses to examine comparative effectiveness of baloxavir in a real-world setting. Methods This retrospective cohort study used IBM MarketScan US administrative claims data from the 2018–19 influenza season. Patients were required to have an outpatient visit for influenza followed by a prescription for baloxavir or oseltamivir within 2 days. Baloxavir- and oseltamivir-treated patients were propensity score matched based on key baseline clinical and demographic characteristics. All-cause, all respiratory-related, and select respiratory-related (infection, asthma, and COPD) HRU in the 15 and 30 days following prescription fill were assessed using chi-square and Fisher’s exact tests for categorical measures and Wilcoxon signed-rank tests for counts and costs. Results We included 5,080 baloxavir-treated patients and 10,160 matched oseltamivir-treated patients in the analysis. Statistically significantly lower HRU was associated with baloxavir compared with oseltamivir therapy (15-day: respiratory-related ED visits, select respiratory-related ED visits and outpatient visits; 30-day: all-cause hospitalization, respiratory-related ED visits, select respiratory-related ED visits and outpatient visits (Table 1). Similarly, associated costs were generally lower in the baloxavir-treated group. Baloxavir-treated patients had lower mean per-patient all-cause 15-day costs (ED visits: $30 [95% CI: $21–$39] vs $42 [95% CI: $32–$51]; hospitalizations: $31 [95% CI: $6–$55] vs $74 [95% CI: $43–$104]) and 30-day costs (ED visits: $46 [95% CI: $35–$57] vs $67 [95% CI: $55–$79]; hospitalizations: $47 [95% CI: $15–$80] vs $119 [95% CI: $78–$161]). Table 1. Proportion of patients with at least one event Conclusion These findings suggest that treatment of influenza with baloxavir may improve outcomes and lower HRU costs compared with oseltamivir treatment. Disclosures Eddie Neuberger, PharmD, Genentech, Inc. (Employee) Chris Wallick, PharmD, MS, Genentech, Inc. (Employee) Devika Chawla, PhD MSPH, Genentech, Inc. (Employee) Rita de Cassia Castro, MD, Genentech, Inc. (Employee)