Clinical and Radiological Characteristics of 2009 H1N1 Influenza Associated Pneumonia in Young Male Adults

Purpose: Pneumonia was an important cause of death in 2009 H1N1 influenza pandemic (pH1N1). Clinical characteristics of pH1N1 have been described well, but discriminative characteristics suggesting pH1N1 infection in pneumonia patients are not evident today. We evaluated differences between clinical and radiologic characteristics for those associated and not associated with pH IN 1 influenza during the pandemic period. Materials and Methods: We reviewed all patients with pneumonia who visited the Armed Forces Capital Hospital between July 2009 and February 2010. During this period, all pneumonia patients were tested for pH1N1 by reverse transcription-polymerase chain reaction (RT-PCR) using nasopharyogeal specimens. Results: In total, 98 patients with pneumonia were enrolled. Their median age was 20 years and all patients were males. Forty-nine (50%) of patients had pH1N1 infection and the others (50%) had negative results in pH1N1 RT-PCR. Patients with pH1N1 infection complained of dyspnea more commonly (83.3% vs. 29.0%; p<0.001), had higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores [5 (range, 0-12) vs. 3 (range, 0-11); p<0.01], fewer days of prehospital illness [2 (range, 0-10) vs. 4 (range, 0-14); p=0.001], and a higher chance of bilateral infiltrates on chest X-ray (CXR) (67.3% vs. 14.3%; p<0.001) and ground-glass opacity (GGO) lesions on computed tomography (CT; 48.9% vs. 22.0%; p<0.001) than patients without pH1N1 infection. Conclusion: Dyspnea, bilateral infiltrates on cm., and GGO on CT were dominant features in pH1N1-associated pneumonia. Understanding these characteristics can help selection of patients who require prompt antiviral therapy.