Affiliation:
1. Radiology Department, University of Montreal Medical Center (CHUM), Montreal, Québec, Canada
2. Microbiology Department, University of Montreal Medical Center, Montreal, Québec, Canada
Abstract
Objective To describe chest radiographic findings in patients with isolated and complicated acute novel influenza A (H1N1) virus infection. Methods Retrospective study of 147 patients (64 men, mean age 41) with reverse-transcriptase polymerase chain reaction confirmed acute influenza A (H1N1) infection, who also had a chest radiograph <72 hours of viral specimen collection. Radiographs were analysed for acute findings. A correlation with bacterial cultures results was performed. The unpaired 2-sample equal-variance Student t test was applied to continuous variables and the Pearson χ2 test of association to discrete variables. Results In 71% of cases, chest radiograph was normal. The presence of acute imaging findings was associated with older age ( P < .05), increased number of comorbidities (most commonly, chronic obstructive pulmonary disease, diabetes, asthma) ( P < .05), higher rate of hospitalization ( P < .05) and intensive care unit admission, and increased mortality. Predominant acute radiographic finding in isolated influenza A (H1N1) was alveolar opacity (88%), either unifocal or multifocal, most often in the lower lobes. In the subgroup of patients with positive imaging findings and for whom nonviral microbiologic data was available, 62% had superimposed bacterial or fungal infection. Conclusion In the majority of patients with acute influenza A (H1N1) infection, the chest radiograph is normal. Acute imaging findings are associated with older age, an increased number of comorbidities, and a higher rate of complications and mortality. The predominant radiographic finding of isolated primary influenza A (H1N1) infection is alveolar opacity. Superimposed bacterial infection is frequent and must be excluded in patients with abnormal imaging.
Subject
Radiology Nuclear Medicine and imaging,General Medicine
Cited by
7 articles.
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