Yonsei Med J.  2013 Jul;54(4):927-934. 10.3349/ymj.2013.54.4.927.

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

• Lee JE
• Choe KW
• Lee SW

• KMID: 2158228
• DOI: http://doi.org/10.3349/ymj.2013.54.4.927

Abstract

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 pH1N1 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 nasopharyngeal 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 CXR, and GGO on CT were dominant features in pH1N1-associated pneumonia. Understanding these characteristics can help selection of patients who require prompt antiviral therapy.

Keyword

Pneumonia; influenza A virus H1N1 subtypes; viral pneumonia

MeSH Terms

Adolescent
Adult
Antiviral Agents/therapeutic use
Dyspnea/virology
Humans
Influenza A Virus, H1N1 Subtype/genetics/*pathogenicity
Influenza, Human/*complications/radiography/virology
Male
Middle Aged
Pneumonia/etiology/radiography
Pneumonia, Viral/drug therapy/etiology/*radiography/*virology
Radiography, Thoracic
Tomography, X-Ray Computed
Young Adult
Antiviral Agents

Figure

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  Fig. 1 Number of total and pH1N1-associated pneumonia cases between July 2009 and February 2010.

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  Fig. 2 Typical radiographic findings of pneumonia with and without pH1N1 influenza infection. (A) CXR (a) and CT (b) findings of 21-year-old (A-1) and 23-year-old man (A-2) with pH1N1 influenza infection. CXR and CT showed bilateral infiltrates and GGO-dominant infiltrations in multiple lobes. (B) CXR (a) and CT (b) findings of the 21-year-old (B-1) and 20-years-old man (B-2) without pH1N1 influenza infection. CXR and CT showed unilateral consolidation and unilobar consolidation. CXR, chest X-ray; CT, computed tomography; GGO, ground-glass opacity.

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