Concordance of self-reported abstinence and measurement of expired air carbon monoxide in a self-help smoking cessation treatment.

Some self-help programmes for smoking cessation obtain abstinence data entirely from participants' self-reports. This may lead to overestimation of efficacy. In the present study, the relationship between self-reported abstinence and expired-air carbon monoxide was evaluated at the 12-mo. follow-up in 200 smokers who had participated in a self-help programme for smoking cessation conducted by mail. Analysis indicated a close relationship between carbon monoxide levels and self-reports of smoking status; concordance was about 90%. Studies of the efficacy of self-help programmes for smoking cessation should include some sort of objective verification of self-reported abstinence.