Accuracy of self-reported smoking status among participants in a chemoprevention trial

Prev Med. 2004 Apr;38(4):492-7. doi: 10.1016/j.ypmed.2003.12.006.


Background: Exposure to tobacco products is readily assessed through self- or interview-administered questionnaires. Degree of misreporting among participants in chemoprevention trials is unknown. We assessed the level of discrepancy between self-reported smoking exposure and plasma cotinine among participants in a chemoprevention trial.

Methods: Analyses were conducted among 824 men and women who participated in a dietary trial of adenoma recurrence. Smoking exposure was ascertained through self-administered questionnaires at three time-points. Plasma cotinine was measured by gas chromatography among 283 never, 446 former and 95 current self-reported smokers. Sensitivity and specificity were assessed using various plasma cotinine cut-points.

Results: Degree of misclassification for self-reported current smokers was minor (0-3%), regardless of cotinine cut-point used. Using a cut-point of 20 ng/ml, which takes into account exposure to environmental tobacco smoke among nonsmokers, sensitivity and specificity were 98.9% and 80.2%, respectively.

Conclusions: These data indicate that degree of misreport for current smokers is extremely low; however, approximately 20% of self-reported never smokers misreport their exposure, suggesting that validation of self-report is needed for these individuals.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoma / blood*
  • Adenoma / prevention & control
  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents / therapeutic use
  • Colorectal Neoplasms / blood*
  • Colorectal Neoplasms / prevention & control
  • Cotinine / blood*
  • Deception
  • Female
  • Humans
  • Male
  • Middle Aged
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Smoking Cessation
  • Smoking*
  • Surveys and Questionnaires*


  • Antineoplastic Agents
  • Cotinine