- Email: [email protected]
E-cigarettes and smoking cessation
Correspondence
E-cigarettes and smoking cessation We congratulate Sara Kalkhoran and Stanton Glantz on their extensive review and meta-analysis on e-cigarettes and smoking cessation.1 However, we are concerned about the variable and heterogeneous group comparisons made in the metaanalysis model. For instance, the odds ratio (OR) used for the Manzoli study2 compared smokers with dual users and disregarded the exclusive e-cigarette group, which reportedly had a much higher cessation rate. The OR used for the ASCEND trial 3 compared exclusive users of e-cigarettes with nicotine patch users. Unfortunately, the proportion of exsmokers in the so-called exclusive e-cigarette group is not reported in the Manzoli study, and therefore we cannot determine the number of exclusive e-cigarette users in this group who remained abstinent from regular cigarette smoking. Different group comparisons will lead to different ORs included in the model and ultimately affect the final result. Using the Manzoli study as an example, the combination of all e-cigarette users (197 regularly abstinent from tobacco use, out of 662) compared with the tobacco-only group (101 abstinent of 693) results in an OR of 3·57 (95% CI 2·69–4·74); Kalkhoran and Glantz’s model used 0·83 (95% CI 0·53–1·29). We are also concerned with the quality of unverified self-reported cessation data derived from telephone or online surveys. Surprisingly,
the study by Shi and colleagues 4 reported that both medications and e-cigarettes were negatively associated with abstinence. Clinical trial data on pharmaceutical cessation drugs5 contradict this notion, which raises doubts about the results regarding e-cigarettes. Any positive or negative effects of e-cigarettes on smoking cessation are probably diluted in the metaanalysis because the proportion of individuals actually using e-cigarettes is extremely variable in the studies included (ranging from 1·5% current e-cigarette use reported by Sutfin and colleagues,6 up to 69% in the trial by Hajek and colleagues7). The type of e-cigarette and pattern of use are also an important aspect that many of the surveys do not provide. We should not group individuals who have only experimented with e-cigarettes with those who may use them to substitute for regular tobacco cigarettes (partly or completely), as demonstrated in the Biener study.8 These comments merit attention, because a substantial amount of the data included in the meta-analysis is derived from studies “not aimed at determining whether e-cigarettes can be used as cessation aids”.9 As clinicians, we are invested in keeping patients away from cigarettes, and those who have never smoked should be advised to never use e-cigarettes given their reported short-term deleterious cardiac and pulmonary effects. 10 However, their role as smoking cessation aids is yet unclear, and making assertions on the basis of confusing data may cloud, rather than
clarify, our vision of a potential role for harm reduction. We declare no competing interests.
Lancet Respir Med 2016
*Menfil Andres Orellana-Barrios, Drew Payne, Kenneth Nugent
Published Online April 25, 2016 http://dx.doi.org/10.1016/ S2213-2600(16)30023-6
menfi[email protected] Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA 1
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Kalkhoran S, Glantz SA. E-cigarettes and smoking cessation in real-world and clinical settings: a systematic review and meta-analysis. Lancet Respir Med 2016; 4: 116–28. Manzoli L, Flacco ME, Fiore M, et al. Electronic cigarettes efficacy and safety at 12 months: cohort study. PLoS One 2015; 10: e0129443. Bullen C, Howe C, Laugesen M, et al. Electronic cigarettes for smoking cessation: a randomised controlled trial. Lancet 2013; 382: 1629–37. Shi Y, Pierce J, White M, et al. E-cigarette use, smoking cessation and change in smoking intensity in the 2010/2011 TUS-CPS Longitudinal Cohort. Society for Nicotine and Tobacco Research Annual Meeting; Feb 25–28, 2015; Philadelphia, PA, USA: POS5-52. Cahill K, Stevens S, Perera R, Lancaster T. Pharmacological interventions for smoking cessation: an overview and network metaanalysis. Cochrane Database Syst Rev 2013; 5: CD009329. Sutfin EL, McCoy TP, Morrell HE, Hoeppner BB, Wolfson M. Electronic cigarette use by college students. Drug Alcohol Depend 2013; 131: 214–21. Hajek P CLLDaSE. Adding e-cigarettes to specialist stop-smoking treatment: city of london pilot project. J Addict Rese Ther 2015; 6: 1–4. Biener L, Hargraves JL. A longitudinal study of electronic cigarette use in a population-based sample of adult smokers: association with smoking cessation and motivation to quit. Nicotine Tob Res 2014; published online Oct 9. DOI:10.1093/ntr/ntu200. Al-Delaimy WK, Myers MG, Leas EC, Strong DR, Hofstetter CR. E-cigarette use in the past and quitting behavior in the future: a populationbased study. Am J Public Health 2015; 105: 1213–19. Orellana-Barrios MA, Payne D, Mulkey Z, Nugent K. Electronic cigarettes—a narrative review for clinicians. Am J Med 2015; 128: 674–81.
www.thelancet.com/respiratory Published online April 25, 2016 http://dx.doi.org/10.1016/S2213-2600(16)30023-6
1
E-cigarettes and smoking cessation We congratulate Sara Kalkhoran and Stanton Glantz on their extensive review and meta-analysis on e-cigarettes and smoking cessation.1 However, we are concerned about the variable and heterogeneous group comparisons made in the metaanalysis model. For instance, the odds ratio (OR) used for the Manzoli study2 compared smokers with dual users and disregarded the exclusive e-cigarette group, which reportedly had a much higher cessation rate. The OR used for the ASCEND trial 3 compared exclusive users of e-cigarettes with nicotine patch users. Unfortunately, the proportion of exsmokers in the so-called exclusive e-cigarette group is not reported in the Manzoli study, and therefore we cannot determine the number of exclusive e-cigarette users in this group who remained abstinent from regular cigarette smoking. Different group comparisons will lead to different ORs included in the model and ultimately affect the final result. Using the Manzoli study as an example, the combination of all e-cigarette users (197 regularly abstinent from tobacco use, out of 662) compared with the tobacco-only group (101 abstinent of 693) results in an OR of 3·57 (95% CI 2·69–4·74); Kalkhoran and Glantz’s model used 0·83 (95% CI 0·53–1·29). We are also concerned with the quality of unverified self-reported cessation data derived from telephone or online surveys. Surprisingly,
the study by Shi and colleagues 4 reported that both medications and e-cigarettes were negatively associated with abstinence. Clinical trial data on pharmaceutical cessation drugs5 contradict this notion, which raises doubts about the results regarding e-cigarettes. Any positive or negative effects of e-cigarettes on smoking cessation are probably diluted in the metaanalysis because the proportion of individuals actually using e-cigarettes is extremely variable in the studies included (ranging from 1·5% current e-cigarette use reported by Sutfin and colleagues,6 up to 69% in the trial by Hajek and colleagues7). The type of e-cigarette and pattern of use are also an important aspect that many of the surveys do not provide. We should not group individuals who have only experimented with e-cigarettes with those who may use them to substitute for regular tobacco cigarettes (partly or completely), as demonstrated in the Biener study.8 These comments merit attention, because a substantial amount of the data included in the meta-analysis is derived from studies “not aimed at determining whether e-cigarettes can be used as cessation aids”.9 As clinicians, we are invested in keeping patients away from cigarettes, and those who have never smoked should be advised to never use e-cigarettes given their reported short-term deleterious cardiac and pulmonary effects. 10 However, their role as smoking cessation aids is yet unclear, and making assertions on the basis of confusing data may cloud, rather than
clarify, our vision of a potential role for harm reduction. We declare no competing interests.
Lancet Respir Med 2016
*Menfil Andres Orellana-Barrios, Drew Payne, Kenneth Nugent
Published Online April 25, 2016 http://dx.doi.org/10.1016/ S2213-2600(16)30023-6
menfi[email protected] Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA 1
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3
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5
6
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Kalkhoran S, Glantz SA. E-cigarettes and smoking cessation in real-world and clinical settings: a systematic review and meta-analysis. Lancet Respir Med 2016; 4: 116–28. Manzoli L, Flacco ME, Fiore M, et al. Electronic cigarettes efficacy and safety at 12 months: cohort study. PLoS One 2015; 10: e0129443. Bullen C, Howe C, Laugesen M, et al. Electronic cigarettes for smoking cessation: a randomised controlled trial. Lancet 2013; 382: 1629–37. Shi Y, Pierce J, White M, et al. E-cigarette use, smoking cessation and change in smoking intensity in the 2010/2011 TUS-CPS Longitudinal Cohort. Society for Nicotine and Tobacco Research Annual Meeting; Feb 25–28, 2015; Philadelphia, PA, USA: POS5-52. Cahill K, Stevens S, Perera R, Lancaster T. Pharmacological interventions for smoking cessation: an overview and network metaanalysis. Cochrane Database Syst Rev 2013; 5: CD009329. Sutfin EL, McCoy TP, Morrell HE, Hoeppner BB, Wolfson M. Electronic cigarette use by college students. Drug Alcohol Depend 2013; 131: 214–21. Hajek P CLLDaSE. Adding e-cigarettes to specialist stop-smoking treatment: city of london pilot project. J Addict Rese Ther 2015; 6: 1–4. Biener L, Hargraves JL. A longitudinal study of electronic cigarette use in a population-based sample of adult smokers: association with smoking cessation and motivation to quit. Nicotine Tob Res 2014; published online Oct 9. DOI:10.1093/ntr/ntu200. Al-Delaimy WK, Myers MG, Leas EC, Strong DR, Hofstetter CR. E-cigarette use in the past and quitting behavior in the future: a populationbased study. Am J Public Health 2015; 105: 1213–19. Orellana-Barrios MA, Payne D, Mulkey Z, Nugent K. Electronic cigarettes—a narrative review for clinicians. Am J Med 2015; 128: 674–81.
www.thelancet.com/respiratory Published online April 25, 2016 http://dx.doi.org/10.1016/S2213-2600(16)30023-6
1