Is the lack of effect of smoking cessation aids in population studies explained by recall bias? Comment on the article by Borland et al. (2012)

Can E-Cigarettes and Pharmaceutical Aids Increase Smoking Cessation and Reduce Cigarette Consumption? Findings From a Nationally Representative Cohort of American Smokers

Many smokers believe that electronic nicotine delivery systems (ENDS) and pharmaceutical cessation aids can help them quit smoking or reduce cigarette consumption, but the evidence for e-cigarettes to aid quitting is limited. Examining 3,093 quit attempters in the nationally representative US Population Assessment of Tobacco and Health (PATH) Study, using data from 2013-2015, we evaluated the influence of ENDS and pharmaceutical cessation aids on persistent abstinence (≥30 days) from cigarettes and reduced cigarette consumption, using propensity score matching to balance comparison groups on potential confounders and multiple imputation to handle missing data. At PATH Wave 2, 25.2% of quit attempters reported using ENDS to quit during the previous year, making it the most popular cessation aid in 2014-2015. More quit attempters were persistently cigarette abstinent than were persistently tobacco abstinent (15.5% (standard error, 0.8) vs. 9.6% (standard error, 0.6)). Using ENDS to quit cigarettes increased the probability of persistent cigarette abstinence at Wave 2 (risk difference (RD) = 6%, 95% confidence interval (CI): 2, 10), but using approved pharmaceutical aids did not (for varenicline, RD = 2%, 95% CI: -6, 13; for bupropion, RD = 4%, 95% CI: -6, 17; for nicotine replacement therapy, RD = -3%, 95% CI: -8, 2). Among quit attempters who relapsed, ENDS did not reduce the average daily cigarette consumption (cigarettes per day, -0.18, 95% CI: -1.87, 1.51).

Nicotine Metabolite Ratio (NMR) Prospectively Predicts Smoking Relapse: Longitudinal Findings From ITC Surveys in Five Countries

INTRODUCTION

The ratio of trans 3'-hydroxycotinine (3HC) to cotinine (nicotine metabolite ratio [NMR]) is a biomarker of the rate of nicotine metabolism, with higher NMR indicating faster metabolism. Higher NMR has been found to be associated with higher daily cigarette consumption and less success stopping smoking in cessation trials. This study examines differences in NMR among population-based samples of smokers in the five countries and explores the relationship between NMR and smoking abstinence.

METHODS

Participants (N = 874) provided saliva samples during International Tobacco Control (ITC) surveys in the United States, United Kingdom, Mauritius, Mexico, and Thailand conducted in 2010/2011 with follow-up surveys in 2012/2013. When all samples were received, they were sent to a common laboratory for analysis using liquid chromatography and tandem mass spectroscopy.

RESULTS

There was significant variation in NMR across countries (F = 15.49, p < .001). Those who reported smoking at follow-up had a mean NMR of 0.32, compared to a mean NMR of 0.42 in participants who reported that they had stopped (F = 8.93; p = .003). Higher mean NMR values were also associated with longer quit duration (p = .007). There was no substantial difference in NMR between current smokers who made a failed quit attempt and those who made no attempt-both had significantly lower NMR compared to those who quit and remained abstinent. Smokers with a higher NMR were more likely to report that they stopped smoking compared to those with a lower NMR (odds ratio = 2.67; 95% confidence interval: 1.25 to 5.68).

CONCLUSIONS

These results suggest faster nicotine metabolizers may be less likely to relapse following a quit attempt. This finding differs from results of clinical trials testing stop smoking medications, where slower metabolizers have been found to be more likely to maintain abstinence from smoking.

IMPLICATIONS

Results of this study suggest faster nicotine metabolizers may be less likely to relapse following a quit attempt. This finding differs from results of clinical trials testing stop smoking medications, where slower metabolizers have been found to be more likely to maintain abstinence from smoking.