Clin Infect Dis . Inhaled Zanamivir versus Oral Oseltamivir to Prevent Influenza-related Hospitalization or Death: a Nationwide Population-based Quasi-experimental Study

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Clin Infect Dis


. 2022 Mar 17;ciac217.
doi: 10.1093/cid/ciac217. Online ahead of print.
Inhaled Zanamivir versus Oral Oseltamivir to Prevent Influenza-related Hospitalization or Death: a Nationwide Population-based Quasi-experimental Study


Chia-Ping Su ^{1 2} , K Arnold Chan ³ , Ching-Tai Huang ⁴ , Chi-Tai Fang ^{2 5}



Affiliations

• PMID: 35299245
• DOI: 10.1093/cid/ciac217

Abstract

Background: Individual patient data meta-analyses of randomized controlled trials show that early oseltamivir treatment for influenza cut risk of pneumonia and hospitalization by 44% and 63%, respectively. However, data are lacking for inhaled zanamivir on its effectiveness to prevent hospitalization and death.
Methods: This nationwide, population-based cohort study included all outpatients treated with inhaled zanamivir or oral oseltamivir, within 48 hours after a clinical diagnosis of influenza, before and after the rollout of inhaled zanamivir as the first-line antiviral in Taiwan. The main outcome is influenza-related hospitalization or death within 14 days, ascertained using Taiwan national health insurance database and national death registry, respectively. Those developed the outcome within 2 days were excluded from analyses. Propensity score stratification was used to control confounding from covariates.
Results: A total of 865,032 eligible influenza outpatients were included in the analysis. The risk of developing the main outcome (adjusted hazard ratio [aHR]: 1.01, 95% confidence interval [CI]: 0.96 to 1.06) did not differ between inhaled zanamivir group (n = 595,897, 68.9%, the reference) and oral oseltamivir group (n = 269,135, 31.1%). Prespecified analysis on high-risk subgroups further showed that inhaled zanamivir is not inferior to oral oseltamivir in either >65 years elderly patients (aHR: 1.14, 95% CI: 1.05 to 1.25) or patients with chronic lung diseases (aHR: 1.23, 95% CI: 1.08 to 1.41).
Conclusion: Inhaled zanamivir is not inferior to oral oseltamivir as outpatient treatment to prevent influenza-related hospitalization or death, for patients whose conditions do not require hospitalization within 2 days.

Keywords: Complications; Effectiveness; Hospitalization; Influenza; Oseltamivir; Zanamivir.