Exhaled carbon monoxide as a marker for evaluating smoking abstinence in a Brazilian population sample

Abstract

Background: Exhaled carbon monoxide (CO Exh ) measurement is used to confirm smoking status in smoking cessation programs, but the cut-off level is still a matter for discussion. The objective of this study was to compare CO Exh levels in smokers and non-smokers to validate the method in a Brazilian population and to estimate the probability of the patient still smoking according to different cut-off points. Methods: In this cross-sectional study we studied non-atopic Caucasian volunteers with no respiratory infection or steroid therapy in the preceding four weeks. Exclusion criteria were: pregnancy; breast feeding; age<18 and >65 years old; and subjects not signing informed consent. Participants filled out a questionnaire and had their CO Exh levels measured. Bayes' theorem was used to calculate the posttest probabilities. Results: We included 393 subjects of whom 239 (61%) were smokers. The mean CO Exh was 14.7 +/-9.4ppm and 4.3 +/-2.5ppm (p<0.001) in smokers and nonsmokers, respectively. Patients with CO Exh below 8ppm had a likelihood ratio below 1 of still smoking. The levels 9ppm and 10ppm provided likelihood ratios of 1.50 and 1.93, respectively. Better discriminant power was obtained at >11ppm, when the likelihood ratio became 63.80 (95%CI 16.1-253.1). Conclusions: In smoking cessation practice, a likelihood ratio approach may be useful to determine the probability that an individual is still smoking according to various CO Exh cut-off points instead of using a fixed value for all patients.

Carbon monoxide in exhaled breath testing and therapeutics

“…eCO has been proposed as a practical, non-invasive diagnostic tool for health professionals to assess and monitor smoking status, in particular, in patients who deny or underestimate smoking status in self-evaluation [32, 35, 48, 86-87]. Recent studies suggest that eCO measurements may represent a reliable and cost-effective alternative to testing of urinary cotinine, as a method for monitoring smoking cessation [88].…”

Withdrawal Symptoms and Nicotine Dependence Severity Predict Virtual Reality Craving in Cigarette-Deprived Smokers

“…This number was selected as a cut-off as it has been shown to provide high confidence intervals for abstinence without being so low that it could yield false positives. 28 Self-report assessments were completed immediately after consenting on Day 1, and as soon as the participant arrived on Day 2, before they completed the VR session.…”

Assessing smoking behaviour among medical students by the measurement of expired carbon monoxide (CO)

“…A few studies used expired carbon monoxide to investigate the smoking status [7,8,[16][17][18], but they were all done among the general population. CO-measurement (and other biomedical markers like urine cotinine) will complement and at some stage replace the usual question regarding the number of cigarettes consumed, as CO-measurement is an objective, noninvasive, inexpensive and simple to carry out method to get data about smoking habits.…”