Abstract
BackgroundMost illnesses caused by pandemic influenza A (H1N1) pdm09 virus (A/H1N1) infection are acute and self-limiting among children. However, in some children, disease progression is rapid and may require hospitalization and transfer to a pediatric intensive care unit (PICU). We investigated factors associated with rapid disease progression among children admitted to hospital for A/H1N1 infection, particularly findings on initial chest radiographs.MethodsIn this retrospective study, we investigated the records of children who had received a laboratory or clinical diagnosis of A/H1N1 infection and were admitted to the largest children’s hospital in Japan between May 2009 and March 2010. The medical records were reviewed for age, underlying diseases, vital signs on admission, initial chest radiographic findings, and clinical outcomes. According to chest radiographic findings, patients were classified into 4 groups, as follows: [1] normal (n = 46), [2] hilar and/or peribronchial markings alone (n = 64), [3] consolidation (n = 64), and [4] other findings (n = 29). Factors associated with clinical outcomes were analyzed using logistic regression.ResultsTwo hundreds and three patients (median 6.8 years) were enrolled in this study. Fifteen percent (31/203) of patients were admitted to PICU. Among 31 patients, 39% (12/31) of patients required mechanical ventilation (MV). When the initial chest radiographic findings were compared between patients with consolidation (n = 64) and those without consolidation (n = 139), a higher percentage of patients with consolidation were admitted to PICU (29.7% vs.8.6%, P < 0.001) and required MV (17.2% vs. 0.7%, P < 0.001). These findings remain significant when the data were analyzed with the logistic regression (P < 0.001, P < 0.001, respectively).ConclusionsConsolidation on initial chest radiographs was the most significant factor to predict clinical course of hospitalized children with the 2009 A/H1N1 infection.
Highlights
Most illnesses caused by pandemic influenza A (H1N1) pdm09 virus (A/H1N1) infection are acute and self-limiting among children
A few studies have described findings on chest radiographs were associated with disease progression of A/H1N1 infection in adults and children [17,18,19]; these studies did not include the information regarding the use of antivirals
217 inpatients received a diagnosis of A/H1N1 infection, but 14 (6%) were excluded from the study because A/H1N1 infection occurred during hospitalization for a condition other than influenza (n = 7) or because a chest radiograph was not obtained on admission (n = 7), ie, the diagnosis of A/H1N1 infection was confirmed by laboratory testing, but a chest radiograph was not obtained
Summary
Most illnesses caused by pandemic influenza A (H1N1) pdm virus (A/H1N1) infection are acute and self-limiting among children. We investigated factors associated with rapid disease progression among children admitted to hospital for A/H1N1 infection, findings on initial chest radiographs. The novel swine-origin influenza A virus first circulated in Mexico in late March 2009 [1] and was confirmed in the United States [2]. Most illnesses caused by A/H1N1 infection have been acute and self-limited with the highest attack rates, some children demonstrated rapid disease progression, required hospitalization, and had to be transferred to pediatric intensive care units (PICUs), and some required mechanical ventilation (MV) [10,11,12,13,14]. We investigated factors associated with rapid disease progression among children admitted for A/H1N1 infections using logistic regression analysis, and focused on initial chest radiographic findings in the context of NI use
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