Effectiveness of Oseltamivir in reducing 30-day readmissions and mortality among patients with severe seasonal influenza in Australian hospitalized patients

Background: Worldwide, seasonal influenza causes significant mortality and poses a significant economic burden. Oseltamivir is an effective treatment, but benefits beyond immediate hospitalization are unknown. Methods: This retrospective multicenter study included adult hospitalized influenza patients from two major teaching hospitals in Australia. Patients who received Oseltamivir < 48 h of admission (prompt-treatment group) were compared with those who either did not receive treatment or if treatment was delayed by > 48 h (delayed/no-treatment group). Propensity-score matching was used to balance confounders between two groups. Primary outcomes included 30-day readmissions, 30-day mortality, composite-outcome (30-day mortality and readmissions), in-hospital mortality, and hospital length of stay (LOS). Results: Between January 2016-March 2020,1828 adult patients mean (SD) age 66.4 (20.1), 52.9% females, were hospitalized with influenza. Four hundred and forty-eight (24.5%) received prompt-treatment with Oseltamivir, while 1380 (75.5%) patients were in the delayed/no-treatment group. The median (IQR) time from onset of symptoms to the administration of Oseltamivir was three (1-5) days. The propensity-score model included 245 matched patients in each group (standardized mean difference of < 10%). Both 30 -day readmissions and the composite-outcome were, respectively, 5.7% (P = 0.03) and 6.5% (P = 0.02) lower in patients who received prompt-treatment with Oseltamivir when compared to the delayed/no-treatment group. LOS showed a significant reduction, and in-hospital mortality showed a trend towards improvement among patients who received prompt-treatment when compared to the other group. Conclusions: Early administration of Oseltamivir was associated with a reduction in 30-days readmissions and composite-outcome of 30-day readmissions and mortality in adult hospitalized influenza patients when compared to delayed/no-treatment. (c) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).