An exploration of flavours in studies of e-cigarettes for smoking cessation: secondary analyses of a systematic review with meta-analyses

Effects of interventions to combat tobacco addiction: Cochrane update of 2021 to 2023 reviews

AIMS

To summarise systematic reviews on tobacco addiction published by the Cochrane Tobacco Addiction Group (CTAG) from 2021 to 2023.

METHODS

We identified all new and updated Cochrane Reviews published by CTAG between 2021 and 2023. We present key results from these reviews and discuss promising avenues for future research.

RESULTS

CTAG published five new reviews and one overview of reviews, and updated eight reviews. Review evidence showed that all main pharmacotherapies (varenicline, cytisine, bupropion and nicotine replacement therapy [NRT], especially when patches are combined with fast acting forms like gum) are effective for smoking cessation, as are nicotine e-cigarettes. Evidence suggested similar magnitude of effects of varenicline, cytisine, and nicotine e-cigarettes; these emerged as the most effective treatments. Evidence also supported behavioural counselling and financial incentives for smoking cessation. Secondary analyses of the Cochrane review of e-cigarettes for smoking cessation showed over half of participants assigned to e-cigarette conditions were still using them at six months or longer, that biomarkers of potential harm significantly reduced in people switching from smoking to vaping or to dual use, and that there was insufficient evidence to draw associations between e-liquid flavours and smoking cessation. Findings on mindfulness-based interventions, interventions delivered by dental and primary care professionals, interventions to prevent weight gain after smoking cessation, and interventions for waterpipe cessation were less certain. Reviews of observational evidence showed that smoking cessation reduced cardiovascular events and mortality in people living with cardiovascular disease, and improved mental health.

CONCLUSIONS

Nicotine replacement therapy (especially patches combined with fast acting forms), varenicline, cytisine, bupropion, nicotine e-cigarettes, behavioural counselling, and financial incentives are all effective ways to help people quit smoking. Quitting smoking improves mental health and reduces cardiovascular events and mortality in people living with cardiovascular disease.

Acute analgesic effect of nicotine vaping using three experimental pain induction tasks: a randomized, placebo-controlled laboratory study

RATIONALE

Pain and nicotine use are co-occurring conditions with a significant impact on health. Experimental evidence supports an acute analgesic effect of nicotine which may reinforce nicotine use among those with chronic pain. Evidence for nicotine analgesia have primarily been gathered in combustible cigarette users and have not been extended to electronic nicotine delivery systems (ENDS or vaping). Furthermore, the mechanisms of nicotine analgesia in humans are not well understood.

OBJECTIVES

Assess the effect of acute vaped nicotine on subjective and behavioral indices of pain sensitivity using three tasks designed to probe distinct mechanisms of analgesia.

METHODS

This study recruited ENDS users (N = 86) to undergo a paced vaping protocol followed by pain tasks in counterbalanced order. Across four sessions, participants vaped e-liquid containing nicotine or placebo, and flavor or no-flavor in a 2 × 2 within-subject design. Assessments included cold pressor, submaximal effort tourniquet to induce ischemic pain, and temporal summation of heat pain, an index of central sensitization.

RESULTS

Compared to placebo, nicotine increased cold pressor pain tolerance (ηp2 = 0.031), ischemic pain threshold (ηp2 = 0.073) and tolerance (ηp2 = 0.056) but had no effect on temporal summation of pain. Flavor did not affect pain sensitivity. Females reported greater ischemic pain sensitivity (ηp2 = 0.027) and greater reductions in craving (ηp2 = 0.086).

CONCLUSIONS

Consistent with research from tobacco smoking, analgesia may be reinforcing and contribute to nicotine dependence among ENDS users. More research on sex differences is warranted.

Psychometric properties of measures for electronic cigarette dependence among former-smoking electronic cigarette users

BACKGROUND

Measures designed to assess electronic cigarette (ECIG) dependence are largely adapted from those developed for cigarette smoking, and have been evaluated mainly among dual ECIG-cigarette users. The present study evaluated the psychometric properties of four dependence measures among former-smoking ECIG users.

METHODS

Respondents (N = 187) were daily ECIG users who had formerly smoked cigarettes regularly. As part of an online survey, they completed four dependence measures: Penn State Electronic Cigarette Dependence Index (PSECDI); E-Cigarette Dependence Scale (EDS-4); Glover Nilsson Behavioral Questionnaire (GNBQ); and Diagnostic and Statistical Manual 5th Edition (DSM-5).

RESULTS

Confirmatory factor analysis revealed a single factor structure for all four measures, and fit indices were adequate for all models. Most inter-item correlations (mean r's = 0.21 to 0.45) and all item-total correlations (mean r's = 0.53 to 0.80) were significant for all four measures. Internal consistency was highest for the GNBQ (α = 0.86) followed by the EDS-4 (α = 0.81), PSECDI (α = 0.76), and DSM-5 (α = 0.75). Age of ECIG initiation was correlated negatively with scores on the EDS-4 and DSM-5, while number of ECIG quit attempts was correlated positively with scores on all measures except the GNBQ. Convergent validity was highest for comparisons between the EDS-4 and PSECDI (r = 0.75) though all comparisons were significant (p's < 0.001).

CONCLUSIONS

All four measures demonstrated acceptable reliability and validity in this sample of former-smoking ECIG users.

Effects of Nicotine Content and Preferred Flavor on Subjective Responses to E-cigarettes: A Randomized, Placebo-controlled Laboratory Study

INTRODUCTION

Evidence suggests that e-liquid flavor and nicotine concentration are important factors in the initiation and maintenance of e-cigarette use (vaping). Flavors may increase the initiation and maintenance of vaping, and nicotine content is a factor in e-cigarette dependence and the efficacy of e-cigarettes for cigarette smoking cessation. Few human laboratory studies have assessed the joint and interactive effects of flavor and nicotine on subjective responses to e-cigarettes.

METHODS

Regular e-cigarette users (N = 89) completed a multi-session study involving a paced vaping procedure with e-liquid cartridges containing their preferred flavor (berry, menthol, or tobacco) or no flavor, with or without nicotine (18 mg). Subjective effects of vaping (satisfaction, reward, aversion, airway sensations, and craving relief) were assessed.

RESULTS

Nicotine significantly increased psychological reward and craving relief, whereas flavor significantly increased vaping satisfaction and taste. Nicotine dependence severity moderated the effect of nicotine on reward, such that those with the greatest dependence severity reported the greatest reward.

CONCLUSIONS

These findings support differential and noninteractive effects of e-liquid nicotine content and flavor on reinforcing effects of e-cigarettes.

IMPLICATIONS

E-liquid flavor and nicotine content have independent, non-interactive effects on subjective responses to vaping under controlled laboratory conditions. Among regular e-cigarette users, vaping a preferred flavor increased taste and satisfaction, but did not interact with nicotine to alter reward or craving. Further research on the ways in which these subjective effects may motivate vaping behavior among different populations of e-cigarette users would be useful to inform regulatory policy of ENDS products.