title: Passive smoking and risk of coronary heart disease and stroke: prospective study with cotinine measurement.
abstract: OBJECTIVE
  To examine the associations between a biomarker of overall passive exposure to tobacco smoke (serum cotinine concentration) and risk of coronary heart disease and stroke.
  
  
  METHODS
  Prospective population based study in general practice (the British regional heart study).
  
  
  METHODS
  4729 men in 18 towns who provided baseline blood samples (for cotinine assay) and a detailed smoking history in 1978-80.
  
  
  METHODS
  Major coronary heart disease and stroke events (fatal and non-fatal) during 20 years of follow up.
  
  
  RESULTS
  2105 men who said they did not smoke and who had cotinine concentrations < 14.1 ng/ml were divided into four equal sized groups on the basis of cotinine concentrations. Relative hazards (95% confidence intervals) for coronary heart disease in the second (0.8-1.4 ng/ml), third (1.5-2.7 ng/ml), and fourth (2.8-14.0 ng/ml) quarters of cotinine concentration compared with the first (> or = 0.7 ng/ml) were 1.45 (1.01 to 2.08), 1.49 (1.03 to 2.14), and 1.57 (1.08 to 2.28), respectively, after adjustment for established risk factors for coronary heart disease. Hazard ratios (for cotinine 0.8-14.0 nu > or = 0.7 ng/ml) were particularly increased during the first (3.73, 1.32 to 10.58) and second five year follow up periods (1.95, 1.09 to 3.48) compared with later periods. There was no consistent association between cotinine concentration and risk of stroke.
  
  
  CONCLUSIONS
  Studies based on reports of smoking in a partner alone seem to underestimate the risks of exposure to passive smoking. Further prospective studies relating biomarkers of passive smoking to risk of coronary heart disease are needed.
authors.affiliation: Department of Community Health Sciences, St George's Hospital Medical School, London SW17 0RE. p.whincup@sghms.ac.uk
authors.forename: Peter H
authors.initials: PH
authors.lastname: Whincup
authors.forename: Julie A
authors.initials: JA
authors.lastname: Gilg
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Emberson
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Jarvis
authors.forename: Colin
authors.initials: C
authors.lastname: Feyerabend
authors.forename: Andrew
authors.initials: A
authors.lastname: Bryant
authors.forename: Mary
authors.initials: M
authors.lastname: Walker
authors.forename: Derek G
authors.initials: DG
authors.lastname: Cook
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D003327:Coronary Disease / Q000097:blood / Q000209:etiology*; D003367:Cotinine / Q000097:blood*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D020521:Stroke / Q000097:blood / Q000209:etiology*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D015415:Biomarkers; D014028:Tobacco Smoke Pollution; D003367:Cotinine