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

• Published in: Preventive medicine Vol. 38; no. 4; pp. 492 - 497
• Main Authors: Martı́nez, Marı́a Elena, Reid, Mary, Jiang, Ruiyun, Einspahr, Janine, Alberts, David S
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-04-2004
• Subjects: Adenoma - blood; Adenoma - prevention & control; Adult; Aged; Aged, 80 and over; Antineoplastic Agents - therapeutic use; Colorectal Neoplasms - blood; Colorectal Neoplasms - prevention & control; Cotinine; Cotinine - blood; Deception; Female; Humans; Male; Middle Aged; Reproducibility of Results; Sensitivity; Sensitivity and Specificity; Smoking; Smoking Cessation; Specificity; Surveys and Questionnaires; Tobacco; Sensitivity; Specificity; Tobacco; Cotinine; Smoking
• ISSN: 0091-7435; 1096-0260
• 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.