title: A comparison of the clinical and epidemiological characteristics of adult patients with laboratory-confirmed influenza A or B during the 2011-2012 influenza season in Korea: a multi-center study.
abstract: BACKGROUND
  During the 2011/2012 winter influenza season in the Republic of Korea, influenza A (H3N2) was the predominant virus in the first peak period of influenza activity during the second half of January 2012. On the other hand, influenza B was the predominant virus in the second peak period of influenza activity during the second half of March 2012. The objectives of this study were to compare the clinical and epidemiological characteristics of patients with laboratory-confirmed influenza A or influenza B.
  
  
  RESULTS
  We analyzed data from 2,129 adult patients with influenza-like illnesses who visited the emergency rooms of seven university hospitals in Korea from October 2011 to May 2012. Of 850 patients with laboratory-confirmed influenza, 656 (77.2%) had influenza A (H3N2), and 194 (22.8%) influenza B. Age, and the frequencies of cardiovascular disorders, diabetes, hypertension were significantly higher in patients with influenza A (H3N2) (P<0.05). The frequencies of leukopenia or thrombocytopenia in patients with influenza B at initial presentation were statistically higher than those in patients with influenza A (H3N2) (P<0.05). The rate of hospitalization, and length of hospital stay were statistically higher in patients with influenza A (H3N2) (P<0.05), and of the 79 hospitalized patients, the frequency of diabetes, hypertension, cases having at least one of the comorbid conditions, and the proportion of elderly were significantly higher in patients with influenza A (H3N2) (P<0.05).
  
  
  CONCLUSIONS
  The proportion of males to females and elderly population were significantly higher for influenza A (H3N2) patients group compared with influenza B group. Hypertension, diabetes, chronic lung diseases, cardiovascular disorders, and neuromuscular diseases were independently associated with hospitalization due to influenza. Physicians should assess and treat the underlying comorbid conditions as well as influenza viral infections for the appropriate management of patients with influenza.
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Seong-Heon
authors.initials: SH
authors.lastname: Wie
authors.forename: Byung Hak
authors.initials: BH
authors.lastname: So
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Song
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Cheong
authors.forename: Yu Bin
authors.initials: YB
authors.lastname: Seo
authors.forename: Sung Hyuk
authors.initials: SH
authors.lastname: Choi
authors.forename: Ji Yun
authors.initials: JY
authors.lastname: Noh
authors.forename: Ji Hyeon
authors.initials: JH
authors.lastname: Baek
authors.forename: Jin Soo
authors.initials: JS
authors.lastname: Lee
authors.forename: Hyo Youl
authors.initials: HY
authors.lastname: Kim
authors.forename: Young Keun
authors.initials: YK
authors.lastname: Kim
authors.forename: Won Suk
authors.initials: WS
authors.lastname: Choi
authors.forename: Jacob
authors.initials: J
authors.lastname: Lee
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Jeong
authors.forename: Woo Joo
authors.initials: WJ
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D009980:Influenza A virus / Q000276:immunology*; D009981:Influenza B virus / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000401:mortality* / Q000628:therapy / Q000821:virology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D056910:Republic of Korea / Q000453:epidemiology; D016896:Treatment Outcome; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult