title: Optimal carbon monoxide criteria to confirm 24-hr smoking abstinence.
abstract: BACKGROUND
  Smoking cessation is typically verified biochemically by expired-air carbon monoxide (CO) levels below 9 ppm (i.e., ≤8 ppm), but this CO criterion may lead many who have smoked within 24hr to be misclassified as abstinent.
  
  
  METHODS
  Adult dependent smokers (N = 261; 124 men, 137 women) prospectively recorded each cigarette smoked and provided CO on five consecutive days during each of two short-term attempts to quit smoking. Participants were those recruited for crossover tests of the effects of placebo versus medication (nicotine patch or varenicline) on the ability to initiate 24-hr abstinence. All had either a high or low interest in permanently quitting smoking soon (within 3 months) and were randomized to the presence or absence of daily ($12) monetary reinforcement of abstinence.
  
  
  RESULTS
  Total accuracy of sensitivity to detect smoking (83%) plus specificity to verify abstinence (87%) was optimal at a CO criterion for abstinence below 5 ppm (≤4 ppm), compared with below 9 ppm (sensitivity of 60%, specificity of 97%). Overall CO detection of sensitivity and specificity was higher in those with high versus low quit interest, but reinforcement of abstinence made no difference.
  
  
  CONCLUSIONS
  Results indicate a CO criterion half that used in most clinical research may optimally validate 24-hr cessation and reduce misclassification of smokers as "abstinent."
authors.affiliation: Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA. perkinska@upmc.edu
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Perkins
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Karelitz
authors.forename: Nancy C
authors.initials: NC
authors.lastname: Jao
mesh_terms: D000328:Adult; D001552:Benzazepines / Q000627:therapeutic use*; D002248:Carbon Monoxide / Q000032:analysis*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D018722:Nicotinic Agonists / Q000627:therapeutic use*; D011446:Prospective Studies; D011810:Quinoxalines / Q000627:therapeutic use*; D012201:Reward; D012680:Sensitivity and Specificity; D016540:Smoking Cessation / Q000379:methods*; D000074606:Smoking Prevention; D013997:Time Factors; D062789:Tobacco Products; D014029:Tobacco Use Disorder; D016896:Treatment Outcome; D000068580:Varenicline; D055815:Young Adult
chemical_list: D001552:Benzazepines; D018722:Nicotinic Agonists; D011810:Quinoxalines; D002248:Carbon Monoxide; D000068580:Varenicline