Effectiveness of oseltamivir in reduction of complications and 30-day mortality in severe seasonal influenza infection

Objectives: The benefit of oseltamivir treatment in patients admitted with influenza virus infection and the design of studies addressing this issue have been questioned extensively. As the burden of influenza disease is substantial and oseltamivir treatment is biologically plausible, this study assessed the clinical benefit of oseltamivir treatment in adult patients admitted with severe seasonal influenza virus infection in daily practice. Patients and methods: A multi-centre, retrospective cohort study was conducted to compare the effectiveness of treatment with and without oseltamivir <48 h after admission in patients admitted with laboratory-confirmed influenza virus infection in three large hospitals in the Netherlands. Propensity score matching was used to compare clinically relevant outcome variables. Results: In total, 390 patients were included in this study, of whom 80% had comorbidities. Thirty-day mortality, as well as the composite endpoint of 30-day mortality or intensive care unit admission >48 h after admission, were reduced by 9% (P = 0.04) and 11% (P = 0.02), respectively. Length of hospital stay and in-hospital mortality rates all showed a trend towards reduction. The median duration between symptom onset and initiation of treatment was 3 days. Conclusions: This study supports that, in daily practice, patients admitted with influenza virus infection should be treated with oseltamivir within 48 h of admission, even if they have had complaints for >48 h. (C) 2020 The Author(s). Published by Elsevier Ltd.