Abstract
BackgroundThere are few large-scale, prospective studies of influenza A(H1N1)pdm09 in children that identify predictors of adverse outcomes.ObjectivesWe aimed to examine clinical epidemiology and predictors for adverse outcomes in children hospitalised with influenza A(H1N1)pdm09 in Australia.MethodsActive hospital surveillance in six tertiary paediatric referral centres (June–September, 2009). All children aged <15 years admitted with laboratory-confirmed influenza A(H1N1)pdm09 were studied.ResultsOf 601 children admitted with laboratory-confirmed influenza, 506 (84·2%) had influenza A(H1N1)pdm09. Half (51·0%) of children with influenza A(H1N1)pdm09 were previously healthy. Hospital stay was longer in children with pre-existing condition (mean 6·9 versus 4·9 days; P = 0·02) as was paediatric intensive care unit (PICU) stay (7·0 versus 2·3 days; P = 0·005). Rapid diagnosis decreased both antibiotic use and length of hospital and PICU stay. Fifty (9·9%) children were admitted to a PICU, 30 (5·9%) required mechanical ventilation and 5 (0·9%) died. Laboratory-proven bacterial co-infection and chronic lung disease were significant independent predictors of PICU admission (OR 6·89, 95% CI 3·15–15·06 and OR 3·58, 95% CI 1·41–9·07, respectively) and requirement for ventilation (OR 5·61, 95% CI 2·2–14·28 and OR 5·18, 95% CI 1·8–14·86, respectively). Chronic neurological disease was a predictor of admission to PICU (OR 2·30, 95% CI 1·14–4·61).ConclusionsDuring the 2009 pandemic, influenza was a major cause of hospitalisation in tertiary paediatric hospitals. Co-infection and underlying chronic disease increased risk of PICU admission and/or ventilation. Half the children admitted were previously healthy, supporting a role for universal influenza vaccination in children.
Highlights
There are few large-scale, prospective studies of influenza A(H1N1)pdm[09] in children that identify predictors of adverse outcomes
601 children were admitted to the six hospitals with laboratory-confirmed influenza, of whom 506 (84Á2%) had influenza A(H1N1)pdm[09] (Table 1)
Consistent with other studies, we report a high burden of paediatric hospitalisation due to pandemic influenza in 2009 (33Á9 per 1000 admission in 2009).[4,18]
Summary
There are few large-scale, prospective studies of influenza A(H1N1)pdm[09] in children that identify predictors of adverse outcomes. The WHO declared the first influenza pandemic of the 21st century in June 2009.1 By the end of 2012, 18 449 deaths were reported worldwide due to influenza A(H1N1)pdm[09] this is likely a gross underestimation.[1] Children are vulnerable to seasonal or pandemic influenza, have the highest age-related hospitalisation rates and are the major community reservoir and source of infection.[2] The 2009 pandemic had a significant impact on the a 2014 The Authors. Predictors of pandemic influenza outcome in children paediatric population in terms of disease burden and severity.[3,4]
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