title: The impact of lifestyle behaviors on the acquisition of pandemic (H1N1) influenza infection: a case-control study.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effects of lifestyle behaviors and health habits on the risk for acquiring pandemic influenza (H1N1) virus infection.
  
  
  METHODS
  We conducted a case-control study in a secondary care hospital in South Korea between November 2009 and August 2010. We enrolled patients with H1N1 infection, as confirmed by a positive result of the real-time reverse transcriptase polymerase chain reaction assay; for each patient, we enrolled 4 age- and gender-matched controls with no history of H1N1 infection or severe acute respiratory illness during the H1N1 pandemic in South Korea (1:4 match).
  
  
  RESULTS
  During the study period, 33 cases and 132 age- and gender-matched controls were enrolled. The case group had a higher percentage of current smokers (p<0.01), fewer subjects reporting regular physical activity (p=0.03), or regular vitamin supplementation (p<0.01), and more subjects reporting a higher annual incidence of the common cold (p=0.048) as compared to the control group. In the multivariable analysis, 2 factors were independently associated with the acquisition of H1N1 infection: current smoking [adjusted odds ratio (OR)=5.53; 95% confidence interval (CI), 1.60-19.16; p<0.01] and a higher annual incidence of the common cold (adjusted OR=1.24; 95% CI, 1.002-1.53; p=0.048).
  
  
  CONCLUSIONS
  A current smoking status and a history of frequent colds were associated with an increased risk of acquiring H1N1 infection.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Korea. kauri670@empal.com.
authors.forename: Sun Mi
authors.initials: SM
authors.lastname: Choi
authors.forename: Yun-Jeong
authors.initials: YJ
authors.lastname: Jeong
authors.forename: Jong Sun
authors.initials: JS
authors.lastname: Park
authors.forename: Hyo Jae
authors.initials: HJ
authors.lastname: Kang
authors.forename: Yeon Joo
authors.initials: YJ
authors.lastname: Lee
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Park
authors.forename: Hyo-Jeong
authors.initials: HJ
authors.lastname: Lim
authors.forename: Hee Soon
authors.initials: HS
authors.lastname: Chung
authors.forename: Chang-Hoon
authors.initials: CH
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000472:pathogenicity; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D008019:Life Style; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D058873:Pandemics; D060888:Real-Time Polymerase Chain Reaction; D056910:Republic of Korea; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D012907:Smoking
keywords: H1N1 subtype; Influenza A virus; life style; smoking