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

Abstract

Introduction 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 agreement between the mobile iCO TM (Bedfont ® Scientific Ltd.) with two other monitors from the same manufacturer (Micro +TM pro and Micro +TM basic), and 2) determine optimal, monitor-specific, cotinine-confirmed abstinence cut-off values. Methods Adult (≥18) smokers (n=26) and non-smokers (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 cut-offs. Results Bland-Altman analyses indicated that the iCO TM monitor provided higher CO results than both Micro +TM monitors. Sensitivity and specificity analyses showed that the optimal CO cut-off for determining abstinence was <3 ppm for the Micro +TM pro (88% sensitivity, 93% specificity) and Micro +TM basic (83% sensitivity, 98% specificity), but was higher for the iCO TM (<6 ppm; 73% sensitivity, 100% specificity). Conclusions Relative to both Micro +TM monitors, the smartphone-enabled iCO TM provided systematically higher CO values and required a higher cut-off to reliably determine smoking abstinence. This does not indicate that CO values obtained using the iCO TM are not valid, instead these results suggest that monitor-specific abstinence cut-offs are needed to ensure accurate bioverification of smoking status. Implications Results from this study indicate that CO values from the smartphone-enabled iCO TM should not be used interchangeably with the stand-alone Micro +TM pro and Micro +TM basic, particularly when lower CO values (<10 ppm) are critical (i.e., determination of abstinence vs. confirming smoking status for study inclusion). Optimal CO cut-offs for determining abstinence on both Micro +TM monitors is recommended at <3 ppm, and <6 ppm for the iCO TM.

Financial Incentives for Preventing Postpartum return to Smoking (FIPPS): study protocol for a three-arm randomised controlled trial

“…There is recent evidence that the iCO can produce a slightly higher CO reading than more conventional CO monitors [ 20 ]. However, the iCO has not been compared with other monitors during pregnancy; therefore, we retained the cut-off of < 4 ppm for the iCO during testing for eligibility.…”

“…During COVID-19, for the 3- and 12-month postpartum outcomes for smoking cessation, if it is not possible to take an expired CO reading during a face-to-face visit, participants will take a CO reading using a self-administered/single-person use device (iCO TM Smokerlyzer, Bedfont Scientific Ltd.) [ 28 ] and send the CO reading to the stop smoking advisor via an app. There is recent evidence that the iCO can produce a slightly higher CO reading than more conventional CO monitors [ 20 ]. However, the authors of this study recommend an optimal cut-off for the iCO of < 6 ppm; therefore, we decided to retain our more liberal cut-off of < 8 ppm.…”

Financial Incentives for Preventing Postpartum Return to Smoking (Fipps): Study Protocol for a Three-Arm Randomised Controlled Trial

“…During COVID-19, for the three and 12-month postpartum outcomes for smoking cessation, if it is not possible to take an expired CO reading during a face-to-face visit, participants will take a CO reading using a self-administered/single person use device ((iCO TM Smokerlyzer, Bedfont Scientific Ltd.) [27] and send the CO reading to the stop smoking advisor via an app. There is recent evidence that the iCO monitor can produce a slightly higher CO reading than more conventional CO monitors [20]. However, the authors of this study recommend an optimal cut-off for the iCO of <6ppm, therefore we decided to retain our more liberal cut-off of <8ppm.…”

“…There is recent evidence that the iCO monitor can produce a slightly higher CO reading than more conventional CO monitors [20]. However, the iCO has not been compared with other monitors during pregnancy, therefore we retained the cut-off of <4ppm for the iCO during testing for eligibility.…”

Commentary on Graham et al.: Biochemical verification of abstinence in remotely conducted smoking cessation trials should not be a universal design requirement for rigor

“…The latter issues are increasingly being acknowledged among researchers on professional listservs and in other professional discussion forums. The extent of problems with remote testing may well be under‐reported in the literature, although some published studies have reported substantial rates of unusable samples [5] or inconclusive results [6] as well as systematically different readings from a smartphone‐connected remote CO monitor relative to other models made by the same company [7].…”