Triaging pandemic flu: pneumonia severity scores are not the answer

SETTING: The 2009 H1N1 influenza pandemic caused significant strain on health systems worldwide. A tool to triage patients at low risk of requiring intensive care services would assist practitioners in safely reducing hospital admission rates during pandemic influenza outbreaks. Community-acquired pneumonia severity scores have not been validated for use in pandemic influenza. OBJECTIVE: To assess the accuracy of the pneumonia severity index (PSI), CURB-65 and SMRT-CO severity scores in predicting patients at low risk of requiring intensive care services. DESIGN: Between May and July 2009, 105 patients admitted with laboratory-confirmed pandemic (H1N1) 2009 influenza to Melbourne public hospitals were assessed on admission to determine their pneumonia severity scores and subsequent need for intensive care unit (ICU) support and length of stay. RESULTS: SMRT-CO was the most accurate score at predicting ICU admission, with an area under the curve of the receiver operating characteristic of 0.826. No score provided good discrimination of low-risk patients, with respectively 19%, 21% and 12% requiring ICU admission as predicted by PSI, CURB-65 and SMRT-CO. CONCLUSION: Current pneumonia severity scores have insufficient predictive ability to safely identify low-risk patients with pandemic (H1N1) 2009 influenza.