Augmentation of smoking cessation education by urinary cotinine measurement.

Monitoring the current smoking status by an objective method may augment the effects of smoking cessation instruction. To quantitatively evaluate smoking status and its modification by smoking cessation instruction, urinary cotinine, a major metabolite of nicotine, was measured by radioimmunoassay in 64 patients with a smoking habit before and during smoking cessation instruction. Urinary cotinine levels were used to discriminate between smokers and nonsmokers (with 50 ng/ml used as a threshold). In 49 patients who claimed to have stopped smoking, urinary cotinine concentrations 1 month after instruction indicated that only 30 (61%) of them had actually stopped (before: 243 +/- 104, after: 1 +/- 3 ng/ml) (mean +/- standard deviation). In the remaining 15 patients who failed to stop smoking while reporting a reduction of cigarette consumption (before: 27 +/- 12, after: 7 +/- 5/day), there was no appreciable reduction in urinary cotinine levels (before: 298 +/- 140, after: 229 +/- 171 ng/ml). When the patients who had failed to stop smoking again received intensive smoking cessation instruction, the success rate increased from 47% (30/64) to 69% (44/64) (p < 0.05). Thus, urinary cotinine measurement may provide a useful and quantitative method for monitoring actual smoking habits and thus augment the efficacy of smoking cessation educational programs.