ObjectiveTo review and summarise the current evidence on the uptake of combustible cigarette smoking following e-cigarette use in non-smokers—including never-smokers, people not currently smoking and past smokers—through an umbrella review, systematic review and meta-analysis.DesignUmbrella review, systematic review and meta-analysis.Data sourcesPubMed, Scopus, Web of Science, PsychINFO (Ovid), Medline (Ovid) and Wiley Cochrane Library up to April 2020.ResultsOf 6225 results, 25 studies of non-smokers—never, not current and former smokers—with a baseline measure of e-cigarette use and an outcome measure of combustible smoking uptake were included. All 25 studies found increased risk of smoking uptake with e-cigarette exposure, although magnitude varied substantially. Using a random-effects model, comparing e-cigarette users versus non-e-cigarette users, among never-smokers at baseline the OR for smoking initiation was 3.25 (95% CI 2.61 to 4.05, I2 85.7%) and among non-smokers at baseline the OR for current smoking was 2.87 (95% CI 1.97 to 4.19, I2 90.1%). Among former smokers, smoking relapse was higher in e-cigarette users versus non-users (OR=2.40, 95% CI 1.50 to 3.83, I2 12.3%).ConclusionsAcross multiple settings, non-smokers who use e-cigarettes are consistently more likely than those avoiding e-cigarettes to initiate combustible cigarette smoking and become current smokers. The magnitude of this risk varied, with an average of around three times the odds. Former smokers using e-cigarettes have over twice the odds of relapse as non-e-cigarettes users. This study is the first to our knowledge to review and pool data on the latter topic.PROSPERO registration numberCRD42020168596.
Background Improved survival means that cancer is increasingly becoming a chronic disease. Understanding and improving functional outcomes are critical to optimising survivorship. We quantified physical and mental health-related outcomes in people with versus without cancer, according to cancer type. Methods Questionnaire data from an Australian population-based cohort study (45 and Up Study (n = 267,153)) were linked to cancer registration data to ascertain cancer diagnoses up to enrolment. Modified Poisson regression estimated age- and sex-adjusted prevalence ratios (PRs) for adverse person-centred outcomes—severe physical functional limitations (disability), moderate/high psychological distress and fair/poor quality of life (QoL)—in participants with versus without cancer, for 13 cancer types. Results Compared to participants without cancer (n = 244,000), cancer survivors (n = 22,505) had greater disability (20.6% versus 12.6%, respectively, PR = 1.28, 95%CI = (1.25–1.32)), psychological (22.2% versus 23.5%, 1.05 (1.02–1.08)) and poor/fair QoL (15.2% versus 10.2%; 1.28 (1.24–1.32)). The outcomes varied by cancer type, being worse for multiple myeloma (PRs versus participants without cancer for disability 3.10, 2.56–3.77; distress 1.53, 1.20–1.96; poor/fair QoL 2.40, 1.87–3.07), lung cancer (disability 2.81, 2.50–3.15; distress 1.67, 1.46–1.92; poor/fair QoL 2.53, 2.21–2.91) and non-Hodgkin’s lymphoma (disability 1.56, 1.37–1.78; distress 1.20, 1.05–1.36; poor/fair QoL 1.66, 1.44–1.92) and closer to those in people without cancer for breast cancer (disability 1.23, 1.16–1.32; distress 0.95, 0.90–1.01; poor/fair QoL 1.15, 1.05–1.25), prostate cancer (disability 1.11, 1.04–1.19; distress 1.09, 1.02–1.15; poor/fair QoL 1.15, 1.08–1.23) and melanoma (disability 1.02, 0.94–1.10; distress 0.96, 0.89–1.03; poor/fair QoL 0.92, 0.83–1.01). Outcomes were worse with recent diagnosis and treatment and advanced stage. Physical disability in cancer survivors was greater in all population subgroups examined and was a major contributor to adverse distress and QoL outcomes. Conclusions Physical disability, distress and reduced QoL are common after cancer and vary according to cancer type suggesting priority areas for research, and care and support.
Objective To review and synthesise the global evidence regarding the health effects of electronic cigarettes (e‐cigarettes, vapes). Study design Umbrella review (based on major independent reviews, including the 2018 United States National Academies of Sciences, Engineering, and Medicine [NASEM] report) and top‐up systematic review of published, peer‐reviewed studies in humans examining the relationship of e‐cigarette use to health outcomes published since the NASEM report. Data sources Umbrella review: eight major independent reviews published 2017–2021. Systematic review: PubMed, MEDLINE, Scopus, Web of Science, the Cochrane Library, and PsycINFO (articles published July 2017 – July 2020 and not included in NASEM review). Data synthesis Four hundred eligible publications were included in our synthesis: 112 from the NASEM review, 189 from our top‐up review search, and 99 further publications cited by other reviews. There is conclusive evidence linking e‐cigarette use with poisoning, immediate inhalation toxicity (including seizures), and e‐cigarette or vaping product use‐associated lung injury (EVALI; largely but not exclusively for e‐liquids containing tetrahydrocannabinol and vitamin E acetate), as well as for malfunctioning devices causing injuries and burns. Environmental effects include waste, fires, and generation of indoor airborne particulate matter (substantial to conclusive evidence). There is substantial evidence that nicotine e‐cigarettes can cause dependence or addiction in non‐smokers, and strong evidence that young non‐smokers who use e‐cigarettes are more likely than non‐users to initiate smoking and to become regular smokers. There is limited evidence that freebase nicotine e‐cigarettes used with clinical support are efficacious aids for smoking cessation. Evidence regarding effects on other clinical outcomes, including cardiovascular disease, cancer, development, and mental and reproductive health, is insufficient or unavailable. Conclusion E‐cigarettes can be harmful to health, particularly for non‐smokers and children, adolescents, and young adults. Their effects on many important health outcomes are uncertain. E‐cigarettes may be beneficial for smokers who use them to completely and promptly quit smoking, but they are not currently approved smoking cessation aids. Better quality evidence is needed regarding the health impact of e‐cigarette use, their safety and efficacy for smoking cessation, and effective regulation. Registration Systematic review: PROSPERO, CRD42020200673 (prospective).
Objective: To systematically review and meta-analyse evidence regarding the efficacy of electronic nicotine delivery systems (ENDS) as smoking cessation aids. Data Sources: PubMed, Scopus, Web of Science, PsycINFO, MEDLINE and Cochrane Library were searched up to February-March 2020 (PROSPERO registration CRD42020170692). Study selection: Published peer-reviewed randomised controlled trials (RCTs) of the efficacy of ENDS for sustained cessation of combustible tobacco smoking and/or nicotine use, compared with no intervention, placebo or nicotine replacement therapy (NRT) by intention-to-treat, with a minimum of four months follow-up. Data Extraction: Data were extracted independently into a pre-specified template. Risk of bias was assessed with the Cochrane Collaboration′s tool and evidence quality rated using GRADE. Data Synthesis: From 3,973 titles identified, nine RCTs were identified; 330 of 5,445 smokers randomised quit. Smoking cessation did not differ significantly for randomisation to ENDS versus: no intervention (three studies, random-effects meta-analysis RR 1.95; 95%CI 0.90-4.22); placebo (three studies, 1.61; 0.93-2.78) or NRT (three studies; 1.25; 0.74-2.11). Fixed-effects sensitivity analyses showed significant results for ENDS vs NRT (1.43; 1.10-1.86). Smokers randomised to ENDS were substantially more likely than control to use nicotine at follow-up. Overall evidence quality was low. Considering only studies without potential competing interests further limited evidence but did not materially change conclusions. Conclusions: There is insufficient evidence that ENDS are efficacious for smoking cessation compared to no intervention, placebo or NRT. Results are promising, particularly for therapeutic use, but vary according to analytic method. ENDS may lead to greater ongoing nicotine exposure than other smoking cessation methods.
Introduction The “hardening hypothesis” proposes that as the prevalence of smoking in a population declines, there will be a “hardening” of the remaining smoker population. This review examines the evidence regarding smokers’ motivation, dependence and quitting behaviour as smoking prevalence declines, to assess whether population “hardening” (decreasing propensity to quit) or “softening” (the converse) is occurring. Methods MEDLINE, PsychINFO, Scopus, Web of Science and Cochrane Library were searched to July 2019, using terms related to smoking and hardening, for reviews and large, population-based repeat cross-sectional studies. There were additional searches of reference lists and citations of key research articles. Two reviewers screened half the titles and abstracts each, and two reviewers screened full texts independently using tested criteria. Four reviewers independently and systematically extracted data from eligible publications, with one reviewer per study, checked by another reviewer. Results Of 265 titles identified, three reviews and ten repeat cross-sectional studies were included. Reviews concluded that hardening has not occurred among the general smoking population over time. Among repeated cross-sectional studies, five examined motivation, nine examined dependence, five examined hardcore smoking, and two examined quit outcomes. All but one study found a lack of hardening. Most found softening within the smoking population, consistent across hardening indicators, definitions, countries (and tobacco control environments) and time periods examined. Conclusions Tobacco control reduces smoking prevalence and fosters a smoking population more amenable to evidence-based interventions. Based on the weight of the available evidence, the “hardening hypothesis” should be rejected and the reality of softening accepted. Implications This umbrella review and systematic review provides a critical consideration of evidence from psychology and other fields regarding the “hardening hypothesis” – a persistent myth undermining tobacco control. It reaches the conclusion that the sum-total of the world-wide evidence indicates either “softening” of the smoking population, or a lack of hardening. Hence, tobacco control reduces smoking prevalence and fosters a smoking population more amenable to evidence-based interventions. The review indicates that the time has come to take active steps to combat the myth of hardening and to replace it with the reality of “softening”.
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