title: Urine Cotinine for Assessing Tobacco Smoke Exposure in Korean: Analysis of the Korea National Health and Nutrition Examination Survey (KNHANES).
abstract: BACKGROUND
  The level of urine cotinine is an indicator of tobacco smoke exposure. The purpose of this study is to investigate urine cotinine for the purpose of assessing the smoking status of Korean smokers and non-smokers exposed to tobacco smoke.
  
  
  METHODS
  The subjects were identified from the 2007-2009 and the 2010 data sets of the Korea National Health and Nutrition Examination Survey (KNHANES). They were assigned as non-smokers, current smokers and ex-smokers. Non-smokers were also divided into three subset groups according to the duration of smoke exposure. Each group was stratified by gender prior to analysis.
  
  
  RESULTS
  The median value of urine cotinine in the male current smokers was 1,221.93 ng/mL which was the highest among all groups. The difference between levels of urine cotinine for male and the female groups was statistically significant (p<0.01). In the female group, passive smoke exposure groups reported higher urine cotinine levels than non-exposure groups (p=0.01). The cutoff point for the discrimination of current smokers from non-smokers was 95.6 ng/mL in males and 96.8 ng/mL in females. The sensitivity and specificity were 95.2% and 97.1%, respectively, in males, 96.1% and 96.5% in females. However, the determination of urine cotinine level was not useful in distinguishing between passive smoke exposure groups and non-exposure groups.
  
  
  CONCLUSIONS
  Urine cotinine concentration is a useful biomarker for discriminating non-smokers from current smokers. However, careful interpretation is necessary for assessing passive smoke exposure by urine cotinine concentration.
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sungmo
authors.initials: S
authors.lastname: Jung
authors.forename: In Seon
authors.initials: IS
authors.lastname: Lee
authors.forename: Sae Byol
authors.initials: SB
authors.lastname: Kim
authors.forename: Chan Soo
authors.initials: CS
authors.lastname: Moon
authors.forename: Ji Ye
authors.initials: JY
authors.lastname: Jung
authors.forename: Young Ae
authors.initials: YA
authors.lastname: Kang
authors.forename: Moo Suk
authors.initials: MS
authors.lastname: Park
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Kim
authors.forename: Se Kyu
authors.initials: SK
authors.lastname: Kim
authors.forename: Joon
authors.initials: J
authors.lastname: Chang
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Kim