Diagnosing swine flu: The inaccuracy of case definitions during the 2009 pandemic, an attempt at refinement, and the implications for future planning

Abstract

Background At the onset of the pandemic H1N1/09 influenza A outbreak in Australia, health authorities devised official clinical case definitions to guide testing and access to antiviral therapy. Objectives To assess the diagnostic accuracy of these case definitions and to attempt to improve on them using a scoring system based on clinical findings at presentation. Patients/Methods This study is a retrospective case-control study across three metropolitan Melbourne hospitals and one associated community-based clinic during the influenza season, 2009. Patients presenting with influenza-like illness who were tested for H1N1/09 influenza A were administered a standard questionnaire of symptomato..