title: Serum cotinine predicts bronchial obstruction regardless of self-reported smoking history.
abstract: BACKGROUND
  We studied ability of serum cotinine and detailed history of smoking to predict bronchial obstruction.
  
  
  METHODS
  The baseline study was done during the Mini-Finland Health Survey in 1980 and the follow-up study during the Health 2000 Survey in 2000 for a total of 662 persons free from bronchial obstruction at baseline. Spirometric values of the ratio of forced expiratory volume in one second to forced vital capacity (FEV%) <80% were defined as moderate and <70% as severe bronchial obstruction at follow-up. Cotinine was determined from frozen serum samples collected at baseline.
  
  
  RESULTS
  For those who reported at baseline not to smoke currently but whose serum cotinine (≥100 μg/l) indicated active smoking, the age- and sex-adjusted odds ratio of bronchial obstruction at follow-up was 2.55 (95% CI 1.26-5.19) compared with the ''true non-smokers'' (<100 μg/l). Among current smokers, after adjustment for age, sex, pack years, daily consumption of cigarettes, and inhalation of smoke, the odds ratio of moderate and severe bronchial obstruction was 1.61 (95% CI 1.12- 2.32) and 1.97 (95% CI 1.10-3.54) per an increment of one standard deviation (367 μg/l) in serum cotinine. The predictive value of all the interview measures of past or current smoking was clearly lower.
  
  
  CONCLUSIONS
  Serum cotinine concentration is a useful predictor for development of obstruction. Smoking history alone may be insufficient in risk factor studies focusing on smoking-related diseases.
authors.affiliation: Department of Respiratory Medicine, Turku University Hospital, PL 52, FI 20521 Turku, Finland. tuula.vasankari@utu.fi
authors.forename: Tuula
authors.initials: T
authors.lastname: Vasankari
authors.forename: Pekka
authors.initials: P
authors.lastname: Jousilahti
authors.forename: Paul
authors.initials: P
authors.lastname: Knekt
authors.forename: Jukka
authors.initials: J
authors.lastname: Marniemi
authors.forename: Sami
authors.initials: S
authors.lastname: Heistaro
authors.forename: Kari
authors.initials: K
authors.lastname: Lppo
authors.forename: Markku
authors.initials: M
authors.lastname: Heliovaara
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D003367:Cotinine / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000209:etiology*; D012307:Risk Factors; D057566:Self Report; D012907:Smoking / Q000009:adverse effects / Q000097:blood*; D013147:Spirometry; D014797:Vital Capacity
chemical_list: D015415:Biomarkers; D003367:Cotinine