A randomized, controlled trial of adding expired carbon monoxide feedback to brief stop smoking advice: Evaluation of cognitive and behavioral effects.

OBJECTIVE: To determine the effect of adding biomarker feedback (expired air carbon monoxide) to standard quit advice on cognitive antecedents of behavior change and smoking cessation and to identify potential effect moderators and mediators. DESIGN: Smokers (N = 160) were randomized to a control (quit advice plus leaflet) or an intervention condition (as control group plus carbon-monoxide level feedback). Cognitive measures were assessed immediately after the intervention and behavioral measures at 6 months' follow-up. MAIN OUTCOME MEASURES: Primary outcome measures were threat and efficacy appraisal, fear arousal, and intention to stop smoking. Secondary outcome measures were quit attempts within the last 6 months and 7-day point prevalence abstinence. RESULTS: Threat appraisal was significantly enhanced in the intervention compared with the control group, t(158) = 2.29, p = .023, as was intention to stop smoking in the next month, t(151) = 2.9, p = .004. However, this effect on intention to stop smoking was short-lived. Groups did not differ in terms of quit attempts or abstinence at follow-up, but the intervention increased the likelihood of cessation in smokers with higher self-efficacy, χ2(1) = 5.82, p = .016. CONCLUSIONS: Carbon-monoxide level feedback enhances the effect of brief quit advice on cognitive antecedents of behavior change and smoking cessation rates but further research is required to confirm the longevity of this effect and its applicability to smokers with low self-efficacy.