The mobile-phone-based iCOTM Smokerlyzer®: Comparison with the piCO+ Smokerlyzer® among smokers undergoing methadone-maintained therapy

Hsui Yang Wong; Muniswary Subramaniyan; Chris Bullen; A N Amer Siddiq; Mahmoud Danaee; Anne Yee

doi:10.18332/tid/111355

The mobile-phone-based iCO^TM Smokerlyzer^®: Comparison with the piCO⁺ Smokerlyzer^® among smokers undergoing methadone-maintained therapy

Tob Induc Dis. 2019 Sep 9:17:65. doi: 10.18332/tid/111355. eCollection 2019.

Authors

Hsui Yang Wong¹, Muniswary Subramaniyan¹, Chris Bullen², A N Amer Siddiq¹, Mahmoud Danaee³, Anne Yee¹

Affiliations

¹ Department of Psychological Medicine, University of Malaya Center of Addiction Sciences (UMCAS), Kuala Lumpur, Malaysia.
² National Institute for Health Innovation, The University of Auckland, Auckland, New Zealand.
³ Department of Social and Preventive Medicine, University of Malaya, Kuala Lumpur, Malaysia.

Abstract

Introduction: The mobile-phone-based Bedfont iCO^TM Smokerlyzer^® is of unknown validity and reproducibility compared to the widely-used piCO⁺ Smokerlyzer^®. We aimed to compare the validity and reproducibility of the iCO^TM Smokerlyzer^® with the piCO⁺ Smokerlyzer^® among patients reducing or quitting tobacco smoking.

Methods: Methadone-maintained therapy (MMT) users from three centers in Malaysia had their exhaled carbon monoxide (eCO) levels recorded via the piCO⁺ and iCO^TM Smokerlyzers^®, their nicotine dependence assessed with the Malay version of the Fagerström Test for Nicotine Dependence (FTND-M), and daily tobacco intake measured via the Opiate Treatment Index (OTI) Tobacco Q-score. Pearson partial correlations were used to compare the eCO results of both devices, as well as the corresponding FTND-M scores.

Results: Among the 146 participants (mean age 47.9 years, 92.5% male, and 73.3% Malay ethnic group) most (55.5%) were moderate smokers (6-19 cigarettes/day). Mean eCO categories were significantly correlated between both devices (r=0.861, p<0.001), and the first and second readings were significantly correlated for each device (r=0.94 for the piCO⁺ Smokerlyzer^®, p<0.001; r=0.91 for the iCO^TM Smokerlyzer^®, p<0.001). Exhaled CO correlated positively with FTND-M scores for both devices. The post hoc analysis revealed a significantly lower iCO^TM Smokerlyzer^® reading of 0.82 (95% CI: 0.69-0.94, p<0.001) compared to that of the piCO⁺ Smokerlyzer^®, and a significant intercept of -0.34 (95% CI: -0.61 - -0.07, p=0.016) on linear regression analysis, suggesting that there may be a calibration error in one or more of the iCO^TM Smokerlyzer^® devices.

Conclusions: The iCO^TM Smokerlyzer^® readings are highly reproducible compared to those of the piCO⁺ Smokerlyzer^®, but calibration guidelines are required for the mobile-phone-based device. Further research is required to assess interchangeability.

Keywords: cessation; nicotine; nicotine dependence; smoking/harm reduction.