Yonsei Med J.  2012 Jan;53(1):213-220. 10.3349/ymj.2012.53.1.213.

Characteristics of Outpatients with Pandemic H1N1/09 Influenza in a Tertiary Care University Hospital in Korea

• Park KS
• Park TS
• Suh JT
• Nam YS
• Lee MS
• Lee HJ

• KMID: 1779709
• DOI: http://doi.org/10.3349/ymj.2012.53.1.213

Abstract

The pandemic H1N1/09 emerged rapidly in Korea. Here, we describe the clinical characteristics of outpatients in Seoul, Korea who were infected in the 2009 H1N1 pandemic. We reviewed the cases of outpatients with pandemic H1N1/09 who visited a tertiary care teaching hospital between September 1 and December 31, 2009. Infection with pandemic H1N1/09 was confirmed by molecular tests. Of a total of 7,182 tests, 3,020 (42.0%) were positive. Compared with 473 cases of influenza-like illness (ILI), the 586 confirmed cases of pandemic H1N1/09 differed in age [odds ratio (OR) 0.975] and fulfilling at least one of the following factors: age <5 or > or =65 years, history of contact with other pandemic H1N1/09-infected individuals (OR 0.611), fever > or =37.8degrees C (OR 3.567), cough (OR 2.290), and myalgia (OR 1.559). The sensitivity of the best criteria, "fever (> or =37.8degrees C) plus cough" (41.03%) in this study was lower than that of the Korea Centers for Disease Control and Prevention (KCDC) criteria (47.95%), whereas the positive likelihood ratio (3.55) and positive predictive value (81.6) of this criteria was higher than those of the KCDC criteria (2.98 and 78.7, respectively). The clinical characteristics of pandemic H1N1/09 are, in many regards, indistinguishable from those of ILI. Moreover, the accuracy and predictability of criteria which include only symptoms or signs were not sufficient to diagnose pandemic H1N1/09 infection. Therefore, use of a combination of symptoms with confirmatory laboratory testing is necessary for accurate diagnosis of pandemic H1N1/09.

Keyword

Influenza A virus; H1N1 subtype; pandemic H1N1/09; outpatients; characteristics

MeSH Terms

Adolescent
Adult
Child
Comorbidity
Female
Hospitals, University/statistics & numerical data
Humans
*Influenza A Virus, H1N1 Subtype
Influenza, Human/*diagnosis/*epidemiology/physiopathology
Male
Multivariate Analysis
Outpatients/*statistics & numerical data
Pandemics/*statistics & numerical data
Republic of Korea/epidemiology
Risk Factors
Young Adult

Figure

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  Fig. 1 Laboratory-confirmed cases of pandemic H1N1/09 influenza reported at Kyung Hee University Hospital between September 1 and December 31, 2009.

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  Fig. 2 Age distribution of numbers of infections (columns) and positivity rate (line) during the 2009 H1N1 influenza pandemic.

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