Clinical Features of Hospitalized Patients with Community Acquired Pneumonia during 2009 Influenza A (H1N1) Pandemic

Yun, Myung Jae; Lee, Seong Tae; Oh, Hye Jin; Lee, Seung June; Song, Sook Hee; Sohn, In; Choi, Jae Phil; Kim, Su Hyun

Abstract

BACKGROUND
A new influenza A(H1N1) virus emerged and spread globally in 2009, and the rapid progression of pneumonia often required ICU care. We describe the cause analysis and clinical aspects of community acquired pneumonia during the period of the pandemic H1N1 influenza A.
METHODS
We reviewed the medical records of 48 adult cases of community acquired pneumonia in which patients were admitted to a public health hospital in Seoul from August to November in 2009. The patients had confirmed H1N1 influenza A based on RT-PCR assay.
RESULTS
Thirteen cases of the 48 (27.1%) were 2009 H1N1 RT-PCR positive patients and three (6.3%) of these cases were mixed viral and bacterial pneumonia patients. The mean age was younger and the PSI score was lower in H1N1 patients. Chest radiographic findings of ground glass opacity and interstitial marking were remarkable in H1N1 patients. Major complication events with ICU care or death occurred in 23.1% of the H1N1 positive group and 48.6% of the H1N1 negative group (p=0.202). The major complication group of H1N1 patients had a higher PSI score, lower platelet count, higher CRP and higher mixed bacterial co-infection.
CONCLUSIONS
If patients were younger and showed a radiologic finding of interstitial marking or ground glass opacity, we could consider H1N1 influenza as the cause of community acquired pneumonia. A high PSI score, thrombocytopenia, increased CRP and bacterial co-infection were predictable factors of major complication.