Accuracy of self-reported smoking status among participants in a chemoprevention trial.
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.
Martínez
María Elena
ME
Division of Cancer Prevention and Population Sciences, Roswell Park Cancer Institute, Buffalo, NY 14263, USA. emartinez@azcc.arizona.edu
Reid
Mary
M
Jiang
Ruiyun
R
Einspahr
Janine
J
Alberts
David S
DS
D000236:Adenoma / Q000097:blood* / Q000517:prevention & control; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D015179:Colorectal Neoplasms / Q000097:blood* / Q000517:prevention & control; D003367:Cotinine / Q000097:blood*; D008192:Deception; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012907:Smoking; D016540:Smoking Cessation; D011795:Surveys and Questionnaires
D000970:Antineoplastic Agents; D003367:Cotinine