Breath Carbon Monoxide Samples Research Articles

Mobile, Remote, and Individual Focused: Comparing Breath Carbon Monoxide Readings and Abstinence Between Smartphone-Enabled and Stand-Alone Monitors.

Newly available, smartphone-enabled carbon monoxide (CO) monitors are lower in cost than traditional stand-alone monitors and represent a marked advancement for smoking research. New products are promising, but data are needed to compare breath CO readings between smartphone-enabled and stand-alone monitors. The purpose of this study was to (1) determine the agreement between the mobile iCO (Bedfont Scientific Ltd) with two other monitors from the same manufacturer (Micro+ pro and Micro+ basic) and (2) determine optimal, monitor-specific, cotinine-confirmed abstinence cutoff values. Adult (≥18) smokers (n = 26) and nonsmokers (n = 21) provided three breath CO samples (using three different monitors) in each of 10 sessions, and urine cotinine was measured for gold standard determination of abstinence. CO comparisons (N = 437) were analyzed using regression-based Bland-Altman Analysis of Agreement; receiver operating characteristics curves were used to determine optimal abstinence cutoffs. Bland-Altman analyses indicated that the iCO monitor provided higher CO results than both Micro+ monitors. Sensitivity and specificity analyses showed that the optimal CO cutoff for determining abstinence was <3 ppm for the Micro+ pro (88% sensitivity, 93% specificity) and Micro+ basic (83% sensitivity, 98% specificity), but was higher for the iCO (<6 ppm; 73% sensitivity, 100% specificity). Relative to both Micro+ monitors, the smartphone-enabled iCO provided systematically higher CO values and required a higher cutoff to reliably determine smoking abstinence. This does not indicate that CO values obtained using the iCO are not valid; instead, these results suggest that monitor-specific abstinence cutoffs are needed to ensure accurate bioverification of smoking status. Results from this study indicate that CO values from the smartphone-enabled iCO should not be used interchangeably with the stand-alone Micro+ pro and Micro+ basic, particularly when lower CO values (<10 ppm) are critical (ie, determination of abstinence vs confirming smoking status for study inclusion). Optimal CO cutoffs recommended for determining abstinence on Micro+ and iCO monitors are at <3 and <6 ppm, respectively.

The effects of fixed versus escalating reinforcement schedules on smoking abstinence.

Studies indicate that when abstinence is initiated, escalating reinforcement schedules maintain continuous abstinence longer than fixed reinforcement schedules. However, these studies were conducted for shorter durations than most clinical trials and also resulted in larger reinforcer value for escalating participants during the 1st week of the experiment. We tested whether escalating reinforcement schedules maintained abstinence longer than fixed reinforcement schedules in a 12-week clinical trial. Smokers (146) were randomized to an escalating reinforcement schedule, a fixed reinforcement schedule, or a control condition. Escalating reinforcement participants received $5.00 for their first breath carbon monoxide (CO) sample <3 ppm, with a $0.50 increase for each consecutive sample. Fixed reinforcement participants received $19.75 for each breath CO sample <3 ppm. Control participants received payments only for delivering a breath CO sample. Similar proportions of escalating and fixed reinforcement participants met the breath CO criterion at least once. Escalating reinforcement participants maintained criterion breath CO levels longer than fixed reinforcement and control participants. Similar to previous short-term studies, escalating reinforcement schedules maintained longer durations of abstinence than fixed reinforcement schedules during a clinical trial.

The effects of percentile versus fixed criterion schedules on smoking with equal incentive magnitude for initial abstinence.

Incentives have been successfully used to reduce smoking in hard-to-treat (HTT) smokers by progressively reinforcing lower levels of breath carbon monoxide (CO). When compared with schedules only providing incentives for smoking abstinence, using a progressive (percentile) criterion facilitates longer periods of smoking abstinence. However, participants receiving incentives for lower breath CO levels on percentile schedules typically earn more for their first abstinent breath CO sample relative to participants receiving incentives only for smoking abstinence. Many studies show that larger incentive magnitude increases abstinence rates. The present study tested the effects of different incentive schedules on rates of abstinence maintenance while holding the initial incentive magnitude constant for 93 HTT smokers to eliminate initial abstinence incentive magnitude as a potential confound. Smokers were randomized to percentile, fixed criterion, or random incentive schedules. The incentive magnitude for the first abstinent breath CO sample (<3 ppm) was $5 for percentile and fixed criterion incentive participants, and then increased by $0.50 for each consecutive abstinent breath CO sample. All groups had similar patterns of meeting the abstinence criterion for at least 1 visit. However, once this abstinence criterion was met, abstinence was more likely to be maintained by fixed criterion incentive participants. Unlike previous studies comparing percentile and fixed criterion schedules, percentile incentive schedules were not associated with longer periods of abstinence relative to fixed criterion incentive schedules. Further studies that manipulate initial incentive magnitude are needed to test whether the difference between the current and previous studies was due to initial incentive magnitude.

Resisting tempting foods and smoking behavior: Implications from a self-control theory perspective.

Individuals may desire to diet or restrain from eating certain foods while attempting to quit smoking out of concern for weight gain. However, previous research and clinical tobacco treatment guidelines suggest that concurrent dieting may undermine attempts to quit smoking. The current study applied the self-control strength model, which posits that self-regulation relies on a limited strength that is consumed with use, to test whether resisting tempting sweets would lead to a greater likelihood of subsequent smoking. Participants were 101 cigarette smokers randomly assigned to resist eating either from a tempting plate of sweets or from a plate of less tempting vegetables. All participants were then given a 10-min recess. Whether participants smoked during the break, measured with a breath carbon monoxide sample, served as the primary dependent variable. As predicted, participants who resisted sweets were more likely to smoke during the break (53.2%) than those who resisted vegetables (34.0%), chi2(1, N = 101) = 3.65 p < .05. The findings support the tenets of the self-control strength model and suggest the mechanism by which dietary restraint may harm efforts at quitting smoking.

Contingencies for change in complacent smokers.

The majority of smokers have no plans to quit in the near future. These complacent smokers are less likely to quit than other smokers, and few interventions are known to reduce smoking in this population. Although monetary incentives can reduce complacent smokers' breath carbon monoxide (BCO) levels, it is not clear whether these effects can be sustained beyond the several weeks that past studies have examined. The authors compared complacent smokers randomly assigned to receive incentives for BCO reductions (n=18) or noncontingent incentives (n=19) for 3 months. Contingent incentives were associated with (a) reduced BCO; (b) more BCO samples indicative of abstinence; (c) fewer cigarettes smoked and more days abstinent at study end; and (d) lower salivary cotinine. These behaviors can predict future cessation, and 2 of the 18 smokers (11%) receiving BCO-contingent incentives reported quitting as compared with none in the control group. Contingency management procedures, such as those used here, may effectively promote cessation among complacent smokers and provide a model for understanding the possible effects of some environmental interventions (like workplace smoking bans) on the behavior of complacent smokers.

Smoking Topography Predicts Abstinence following Treatment with Nicotine Replacement Therapy

Abstract Objective: Smoking topography refers to how a person smokes a cigarette and includes measures of the number of puffs and puff volume, duration, and velocity. This study examined the relationship between smoking topography and abstinence from cigarettes following nicotine replacement therapy. A secondary objective was to determine the relationship of smoking topography to carbon monoxide (CO) exposure. Method: Participants (n = 113) smoked one of their preferred brands of cigarette through a smoking topography device prior to participating in an open-label trial of transdermal nicotine versus nicotine nasal spray. A subset of participants (n = 50) provided breath CO samples prior to and following smoking the cigarette. Results: Mean Vmax [odds ratio (OR), 1.12; 95% confidence interval (95% CI), 1.02-1.24; P = 0.02], mean puff volume (OR, 0.95; 95% CI, 0.91-0.98; P = 0.01), mean interpuff interval (OR, 1.06; 95% CI, 1.00-1.11; P = 0.03), and cigarette type (full flavor versus light/ultralight; OR, 0.35; 95% CI, 0.14-0.89; P = 0.03) were significant predictors of abstinence in a model controlling for treatment group and nicotine dependence. Controlling for time since last cigarette and initial CO level, mean puff velocity (β = 0.171; P = 0.01) was the only significant predictor of CO boost. Conclusion: These results suggest that smoking topography may be useful to predict abstinence after using nicotine replacement therapy and to assess harm from smoking.