A Comparison of Saliva Cotinine, Carbon Monoxide Levels, and Self-Report as Indicators of Smoking Cessation in the Pregnant Adolescent

Cigarette smoking during pregnancy presents significant health risks to both the mother and infant. Among pregnant women, the highest rates of smoking occur among teens 15-19 years old, yet pregnant adolescents are likely to underrepresent their smoking. Self-report, exhaled carbon monoxide, and saliva cotinine levels are all indicators used to determine the status of cigarette smoking in adolescents. The best, yet most cost-effective method to evaluate smoking status in pregnant adolescents needs to be identified. The purpose of the current study was to examine the accuracy of self-report and carbon monoxide levels as compared to saliva cotinine as indicators of smoking cessation in pregnant teenagers. The self-reported smoking behavior, saliva cotinine level, and exhaled breath carbon monoxide of 109 pregnant adolescents who had completed a smoking cessation program were examined. Sensitivity and specificity were calculated to compare the accuracy of self-reported smoking cessation and of the carbon monoxide (CO) measure (using the cut-point of 8 ppm) to the saliva cotinine value of 10 ng/ml or greater at post-intervention. Sensitivity was defined as the proportion of non-smokers detected by self-report or CO measure compared to those detected by the saliva cotinine measures, whereas specificity was the proportion of self-reported smokers and subjects with CO measures of > 8 ppm correctly classified via the cotinine value. The sensitivity of self-reported smoking cessation when compared to saliva cotinine levels was calculated at 62.9%. Specificity was calculated at 86.5%. The sensitivity of carbon monoxide reading compared to saliva cotinine was 93.5%. Specificity was calculated at 38.0%. These findings indicate that self-report is a better indicator of continued smoking (has better specificity), while carbon monoxide is a better indicator of smoking cessation (has better sensitivity). Racial group (African American versus non-African American) and treatment group comparisons were also conducted.