Understanding the Association Between Spontaneous Quit Attempts and Improved Smoking Cessation Success Rates: A Population Survey in England With 6-Month Follow-up

National Smoking Cessation Services (NSCS) enrollment and their effect on long-term tobacco cessation in Korea: Results from a 1-year prospective follow-up of NSCS participants

INTRODUCTION

The study aimed to identify predictors associated with long-term tobacco cessation at 12-month follow-up among users of the National Smoking Cessation Services (NSCS) in Korea.

METHODS

To measure the long-term effect of NSCS delivery, the target sample size of 5167 adult smokers registered in the NSCS in 2018 was enrolled with proportional random sampling. A multiple logistic regression analysis (crude, adjusted) was performed to identify the changes in smoking status at the 12-month follow-up after the last NSCS enrollment and the potential factors associated with changes in smoking status.

RESULTS

The response rate to reach the number of subjects targeted was 22.4%. A total of 41.2% of the tobacco users enrolled had successfully quit at baseline, and the 7-day point prevalence of tobacco cessation at the follow-up at 12 months, via a telephone survey, was 34.4%. Factors positively associated with cessation at the 12-month follow-up were longer experience with tobacco abstinence and additional quitting attempts with or without NSCS enrollment, although every additional quit attempt with NSCS use had a better outcome. In addition, having a successful quit outcome with NSCS use at the baseline and having more satisfaction with the service of professional counseling or incentives than others provided by NSCS, increased cessation at follow-up after adjustment of other factors considered.

CONCLUSIONS

In addition to multiple quitting attempts, longer experience with tobacco abstinence, and additional enrollment in NSCS, the service experience, and satisfaction with the content that NSCS offered, might improve the lasting success of abstinence. These results might be considered to improve the contents and protocols of the NSCS for better outcomes.

Effect of age of tobacco initiation and number of failed quit attempts on maintenance of tobacco abstinence

BACKGROUND

The decision to make a quit attempt is the first step toward the tobacco cessation process. It is well established in the literature that if someone does not take tobacco till the age of 21 years then his chances of remaining tobacco-free for life are higher than his counterparts who start tobacco at early developmental ages.

METHODOLOGY AND TOOLS

The present study was conducted among 400 university undergraduate students. A cross-sectional survey design was used, multi-stage sampling was done, and four colleges were selected via random sampling. The motivation to quit tobacco, tobacco craving, and maintenance of tobacco abstinence was assessed via contemplation ladder, tobacco craving questionnaire Short Form, and smoking abstinence questionnaire. To validate subjective data, a urine cotinine test was performed.

RESULTS

The age of tobacco initiation significantly impacts intentions to quit tobacco and tobacco craving levels. The number of unsuccessful quit attempts was also significantly associated with the maintenance of tobacco abstinence. The failed quit attempts play a vital role in altering tobacco cravings and make the withdrawals more complicated to handle for recent tobacco quitters.

Covariates of success in quitting smoking: a systematic review of studies from 2008 to 2021 conducted to inform the statistical analyses of quitting outcomes of a hospital-based tobacco dependence treatment service in the United Kingdom

Background

Smoking cessation interventions are being introduced into routine secondary care in the United Kingdom (UK), but there are person and setting-related factors that could moderate their success in quitting smoking. This review was conducted as part of an evaluation of the QUIT hospital-based tobacco dependence treatment service ( https://sybics-quit.co.uk). The aim of the review was to identify a comprehensive set of variables associated with quitting success among tobacco smokers contacting secondary healthcare services in the UK who are offered support to quit smoking and subsequently set a quit date. The results would then be used to inform the development of a statistical analysis plan to investigate quitting outcomes.

Methods

Systematic literature review of five electronic databases. Studies eligible for inclusion investigated quitting success in one of three contexts: (a) the general population in the UK; (b) people with a mental health condition; (c) quit attempts initiated within a secondary care setting. The outcome measures were parameters from statistical analysis showing the effects of covariates on quitting success with a statistically significant (i.e., p-value <0.05) association.

Results

The review identified 29 relevant studies and 14 covariates of quitting success, which we grouped into four categories: demographics (age; sex; ethnicity; socio-economic conditions; relationship status, cohabitation and social network), individual health status and healthcare setting (physical health, mental health), tobacco smoking variables (current tobacco consumption, smoking history, nicotine dependence; motivation to quit; quitting history), and intervention characteristics (reduction in amount smoked prior to quitting, the nature of behavioural support, tobacco dependence treatment duration, pharmacological aids).

Conclusions

In total, 14 data fields were identified that should be considered for inclusion in datasets and statistical analysis plans for evaluating the quitting outcomes of smoking cessation interventions initiated in secondary care contexts in the UK.

PROSPERO registration

CRD42021254551 (13/05/2021).

Vaping among Norwegians who smoke or formerly smoked: reasons, patterns of use, and smoking cessation activity

BACKGROUND

The majority of Norwegians who use e-cigarettes are adults who have smoked. Little is known about vaping reasons and -patterns in this group. The aim of this paper was to study vaping prevalence, patterns, and motivations among adults who smoke. Furthermore, to investigate smoking intensity and smoking cessation behaviour differences between those who vape and those who do not.

METHODS

This study was based on two separate Norwegian samples: People who had ever smoked, from 2017 (N = 2099), and people who currently smoked and recent quitters, from 2018/2019 (N = 1336). Measures of vape frequencies, vape motives, and smoking cessation behaviours were utilised in descriptive analyses of relationships between vaping and smoking behaviour.

RESULTS

Less than 1 in 10 in the ever-smoked group, 1 in 5 of the currently smoked or recently quit group, were currently vaping. Ever trial rates for vaping were much higher at 1 in 3 in the ever-smoked group, and 1 in 2 in the currently smoked or recently quit group. Dual use with combustible cigarettes was common, but people who smoked tended to use e-cigarettes less frequently while those who formerly smoked tended to use them more frequently. Both quitting attempts and smoking intensity reduction were positively associated with vaping, and the most common reasons for e-cigarette use were reported to be desires to reduce harm, to stop smoking, or to reduce smoking intensity.

CONCLUSION

The results indicate that Norwegians who smoke tend to see e-cigarettes as a tool to reduce or completely stop smoking. The predominance of use-motivations related to reducing harm points at the importance of conveying correct information about relative harmfulness of tobacco- and nicotine products.

Indexing Quit-Smoking Interest among Norwegian Smokers 2019-2021

Even if smoking prevalence is declining in several western countries, continued smoking cessation is required to reduce tobacco-related harms and to achieve future goals of smoke-free societies or the tobacco endgame. But how many of the current smokers want to quit? Estimates vary and depend on the type of question asked. We investigate how a pooled sample of Norwegian smokers (N = 1321) is distributed over four indicators of interest in quitting: (i) degree of desire to quit, (ii) prediction of future smoking status, (iii) reported plan for quitting smoking, and (iv) statements on previous attempts to quit. Based on these variables, we constructed an index. One-third of the smokers (32.6%) was categorized as having a high or very high interest in quitting. However, nearly half of the smokers (47.8%) had low or very low interest in quitting. Like several other countries, Norway has legislated a vision of a smoke-free society and, under the government's plans; this goal will be achieved by intensified use of structural measures such as tax hikes, tighter restrictions on outdoor smoking, and reduced availability of cigarettes. For the third who want to quit smoking, such constraints on their behaviour may help them to pursue their desire to quit. However, for the half who want to continue smoking, these measures may not be helpful but instead be experienced as a loss of welfare, less freedom to act, and increased social disqualification.

Smoking cessation aids and strategies: a population-based survey of former and current smokers in Norway

BACKGROUND

In Norway, tobacco consumption is equally divided between combustible (cigarettes) and non-combustible (snus) tobacco. In the process of quitting, people who smoke can choose between several smoking cessation aids and strategies based on what is available on the market or what are recommended as cessation aids. A quit attempt may be planned or unplanned and consist of a gradual decline in consumption or an abrupt quitting. This study explores smoking cessation aids and strategies used at the latest quit attempt among people who have ever smoked. How prevalent is the use of various cessation aids and strategies, and do they correlate with each other? Are there any differences in successful quits depending on the use of a specific cessation aid or strategy?

METHOD

We used repeated cross-sectional representative surveys in Norway for 2017, 2018, 2019 and 2020. The analytic sample consists of people aged 20 years or older who have ever smoked daily, more precisely current daily smokers with at least one quit attempt (n = 476), and former daily smokers who quit in 2012 or later (n = 397). Participants answered questions on cessation aids and strategies used at their last quit attempt. Logistic regression analysis was used to estimate the associations between cessation aids and strategies and sociodemographic and smoking-related variables and successful quit attempts.

RESULTS

Fifty-six percent of people who ever smoked daily reported any use of cessation aids, and nicotine replacement therapy (NRT), snus and e-cigarettes were the most commonly used cessation aids. Snus and web/mobile use was associated with successful quits, while NRT was associated with unsuccessful quit attempts. When exclusive use was separated from the combined use of several aids, only snus was associated with successful quits.

CONCLUSION

Snus use was found to be a "stand-alone" cessation aid, and only weakly associated with the use of other cessation aids. Further investigation of cessation aid preferences is needed, especially among smokers with little or no contact with health services and/or for whom traditional cessation aids have no appeal.

Abrupt versus gradual smoking cessation with pre-cessation varenicline therapy for Chinese treatment-seeking smokers: A retrospective, observational, cohort study

INTRODUCTION

This study aimed to explore the efficacy of abrupt and gradual smoking cessation with pre-cessation varenicline therapy.

METHODS

A total of 278 smokers who experienced moderate-to-severe nicotine dependence and visited a Chinese smoking cessation outpatient clinic from March 2017 to February 2021 were enrolled. This was a retrospective, observational, cohort study. Participants were divided into two groups by the cessation strategy they received: the abrupt cessation group (n=139, tobacco was not controlled during the first 3 weeks before the target cessation date and smoking was entirely discontinued on the 22nd day) and the gradual cessation group (n=139, tobacco was gradually reduced in the first 3 weeks before the target cessation date and smoking was discontinued on the 22nd day). The abstinence rates were compared between groups (7-day point prevalence abstinence rates at 1, 3 and 6 months post-treatment; and 1-month and 3-month continuous abstinence rates of 6-month follow-up). Possible factors that influence efficacy, reasons for smoking cessation failure, and associated adverse events were also analyzed.

RESULTS

No significant difference in the 7-day point prevalence abstinence rates at 1, 3 and 6 months post-treatment was observed between the groups (p>0.05). The 1-month continuous abstinence rate of the gradual cessation group was higher than that of the abrupt cessation group (51.1% vs 31.7%; χ²=10.812, p=0.001). The 3-month continuous abstinence rate of the gradual cessation group was also higher than that of the abrupt cessation group (42.4% vs 27.3%; χ²=6.983, p=0.008). Abrupt cessation was a risk factor for successful smoking cessation than gradual cessation (AOR=2.39; 95% CI: 1.15–3.85, p=0.013),the motivation of ‘prevention and treatment of own diseases’ reduced the risk of incomplete abstinence (AOR=0.87; 95% CI: 0.38–0.99, p=0.049). The incidence of adverse events was higher in the abrupt cessation group than in the gradual cessation group. The incidence rates of nausea and insomnia were statistically significant differences.

CONCLUSIONS

Compared with abrupt cessation, gradual smoking cessation with pre-cessation varenicline therapy produced higher abstinence rates and relatively milder withdrawal symptoms.

Potential Explanations for Conflicting Findings on Abrupt Versus Gradual Smoking Cessation: A Population Study in England

INTRODUCTION

Observational and trial evidence conflict on the efficacy of two contrasting behavioral approaches to quitting smoking-gradual and abrupt. Observational data suggest an abrupt approach to quitting is superior to a gradual approach, whilst trials show no difference. One potential explanation is self-selection in observational data, whereby people can choose their quit approach, and those who find it harder to quit may be more likely to choose a gradual quit approach. This study aims to investigate potential explanations for these conflicting findings.

AIMS AND METHODS

This study aims to investigate potential explanations for these conflicting findings. We used observational data from a nationally representative sample of adults in England from November 2006 to February 2020 who reported smoking and had made at least one quit attempt in the past year (n = 21 542). We used logistic regression models to assess the association between abrupt versus gradual quit attempts and quit success, adjusting for sociodemographic, smoking, and quit attempt characteristics.

FINDINGS

Abrupt, versus gradual, attempts were associated with improved quit success in an unadjusted model (odds ratio = 2.02, 95% CI = 1.86 to 2.19). This association remained after adjusting for a broad range of relevant confounders (odds ratio = 1.75, 95% CI = 1.59 to 1.93).

CONCLUSIONS

Among a representative sample of adults who had smoked and made a quit attempt in the past year, there was evidence of an association between abrupt attempts and quit success before and after adjusting for relevant confounders. This suggests that the differences in quit success seen between abrupt and gradual quit attempt types are not completely driven by self-selection in observational data.

IMPLICATIONS

We investigated explanations for conflicting findings on the efficacy of gradual versus abrupt approaches to quitting smoking between trial and observational data. Despite adjusting observational data for sociodemographic, smoking, and quit attempt characteristics, an association between abrupt quitting and quit success remained. Therefore, differences in quit success were not completely driven by the self-selection of a gradual approach by people who found it especially difficult to quit or differences in the use of quitting aids. However, characteristics adjusted for were limited by the data available, and future research should continue to investigate the difference in findings across study types to inform cessation support.

Self-Reported Smoking Status 10-Months After a Single Session Intervention Including an Education Conference About Smoking Harms and Announcement of Spirometric Lung-Age

Background

Studies investigating the effects of announcing spirometric lung-age (SLA) on the smokers' self-reported smoking status reported conflicting results.

Main objective

To evaluate the effects of a single session intervention including an education conference about smoking harms and announcement of SLA on the participants' self-reported smoking status.

Methodology

An interventional study was conducted in a cable factory. The intervention included four steps: PowerPoint presentation about raising smoking hazards awareness; general questionnaire; measurement of the anthropometric and spirometric data, and announcement of SLA; and evaluation of the smokers' self-reported smoking status 10 months later (quitted smoking, decreased consumption; stable consumption, increased consumption).

Results

Thirty-six smokers completed the four steps. Ten months after the intervention, 11.1% of smokers quitted smoking, 52.7% decreased their consumption by 7  ±  4 cigarettes/day, 30.5% kept a stable consumption, and 5.5% increased their consumption by 9  ±  6 cigarettes/day.

Conclusion

Providing an education conference combined with announcing SLA motivated 64% of smokers to quit smoking or to reduce their cigarette consumption.

Prevalence and Correlates of Successful Smoking Cessation in Bladder Cancer Survivors

OBJECTIVE

To assess the prevalence and correlates of successful smoking cessation in bladder cancer survivors.

MATERIALS AND METHODS

A population-based sample of bladder cancer survivors diagnosed over a 3 year period was obtained from the California Cancer Registry. Respondents completed a survey about their tobacco use and attempts at smoking cessation. Contingency tables and logistic regression analyses were used to evaluate for correlates of successful smoking cessation.

RESULTS

Of total survey respondents, 19% (151 of 790) were active smokers at bladder cancer diagnosis and made up our analytic cohort. The majority of included respondents were male, older than 60, and had smoked for >40 years prior to diagnosis. After diagnosis, 76% (115 of 151) of active smokers made a quit attempt and 56% (65 of 115) were successful. Success with smoking cessation was more frequent among those who attempted to quit around the time of initial bladder cancer diagnosis. The majority (66%) of successful quitters did so "cold turkey" without pharmacotherapy or behavioral therapy. After adjustment for demographic and tobacco-related factors, quit attempts specifically motivated by the bladder cancer diagnosis were highly associated with smoking cessation success (OR 11.6; 95% CI 3.73-35.8). Use of pharmacologic or behavioral therapies in the quit attempt were not significantly associated with successful smoking cessation.

CONCLUSION

Our data underscore the importance of motivation, timing, and the role of the urologist in the quit attempts of bladder cancer survivors. Emphasis should be placed on ensuring the newly diagnosed make a timely quit attempt informed by the causal role of smoking in their malignancy.

Exploratory Analyses of the Popularity and Efficacy of Four Behavioral Methods of Gradual Smoking Cessation

INTRODUCTION

Around half of smokers attempt to stop by cutting-down first. Evidence suggests that this results in similar quit rates to abrupt quitting. Evidence for the effectiveness and popularity of different gradual cessation methods is sparse.

METHODS

Secondary, exploratory, analyses of a randomized trial of gradual versus abrupt smoking cessation. Gradual participants (N = 342) chose between four methods of cutting-down over 2 weeks: cutting-out the easiest cigarettes first (HR-E); cutting-out the most difficult cigarettes first (HR-D); smoking on an increasing time schedule (SR); and not smoking during particular periods (SFP). Nicotine replacement therapy and behavioral support were provided before and after quit day. We used logistic and linear regression modeling to test whether the method chosen was associated with smoking reduction, quit attempts, and abstinence, while adjusting for potential confounders.

RESULTS

Participants were on average 49 years old, smoked 20 cigarettes per day, and had a Fagerstrom Test for Cigarette Dependence score of 6. 14.9% (51/342) chose HR-E, 2.1% (7/342) HR-D, 46.2% (158/342) SFP, and 36.8% (126/342) SR. We found no evidence of adjusted or unadjusted associations between method and successful 75% reduction in cigarette consumption, reduction in percentage cigarettes per day or exhaled carbon monoxide, quit attempts, or abstinence at 4-week or 6-month follow-up.

CONCLUSIONS

Future research and practice could focus more heavily on the SR and SFP methods as these appeared notably more popular than HR. There was substantial imprecision in the efficacy data, which should be treated with caution; however, none of the gradual cessation methods showed clear evidence of being more efficacious than others.

IMPLICATIONS

There is evidence that people who would like to quit smoking gradually should be supported to do so. However, as this is relatively new thinking and there is large potential for variation in methods, guidance on the best way to offer support is sparse. This article is an exploratory analysis of the popularity and efficacy of various methods in an attempt to move the topic forward and inform the implementation of gradual smoking cessation methods in practice. The identified popularity of some methods over others signposts directions for future research.

If at first you don't succeed, when should you try again? A prospective study of failed quit attempts and subsequent smoking cessation

OBJECTIVE

To assess the association between likelihood of success of smoking cessation attempts and time since most recent attempt.

METHODS

Prospective study of 823 smokers who reported a failed quit attempt in the last 12 months at baseline and ≥1 quit attempt over 6-month follow-up. The input variable was time in months between the end (and in an exploratory analysis, the start) of the most recent failed quit attempt reported retrospectively at baseline and start of the first attempt made during the 6-month follow-up period. The outcome variable was success in the latter quit attempt.

RESULTS

Success rates for failed quitters who waited <3, 3-6, and 6-12 months between their failed quit attempt ending and making a subsequent quit attempt were 13.8%, 17.5%, and 19.0% respectively. After adjustment for covariates, the odds of cessation relative to those who made a subsequent quit attempt within 3 months were 1.42 (95%CI 0.79-2.55) and 1.52 (95%CI 0.81-2.86) for those who waited 3-6 and 6-12 months respectively before trying again. Bayes factors indicated the data were insensitive. The exploratory analysis showed the odds of cessation were 1.55 (95%CI 0.78-3.08), 1.92 (95%CI 0.94-3.92), and 2.47 (95%CI 1.04-5.83) greater for those with an interval of 3-6, 6-12, and 12-18 months respectively than those who tried again within 3 months.

CONCLUSIONS

While pre-planned analyses were inconclusive, exploratory analysis of retrospective reports of quit attempts and success suggested the likelihood of success of quit attempts may be positively associated with number of months since beginning a prior quit attempt. However, only the longest inter-quit interval examined (12-18 months) was associated with significantly greater odds of quit success relative to a <3 month interval in fully adjusted models; all other comparisons were inconclusive.

Changes in smoker characteristics in England between 2008 and 2017

AIMS

At a time of declining smoking prevalence in England, it is useful to document any changes in the characteristics of smokers. This has implications for targeting tobacco control policies and interventions. This study compared the characteristics of smokers from 2008 to 2017 to assess changes in smoking and quitting patterns and socio-demographic profile.

DESIGN AND SETTING

Analysis of annual trends in results from repeated cross-sectional surveys of representative samples of the population in England from 2008 to 2017.

PARTICIPANTS

The study included 208 813 adults aged 16+.

MEASUREMENTS

Information was gathered on age, sex, social grade and region, cigarette consumption, cigarette dependence as measured by time to first cigarette of the day, daily smoking, smoking roll-your-own cigarettes, attempts to cut down, use of an e-cigarette or nicotine replacement therapy, attempts to cut down or quit, use of support in quit attempts and whether the quit attempt was abrupt.

FINDINGS

During the period, mean daily cigarette consumption [B = -0.30, 95% confidence interval (CI) = -0.33 to -0.27] and the time to first cigarette score decreased (B = -0.03, 95% CI = -0.03 to -0.02). The proportion of smokers attempting to cut down or quit decreased (odds ratio (OR) range = 0.96-0.97, 95% CI range = 0.95-0.97). Use of behavioural support [odds ratio (OR) = 0.89, 95% CI = 0.86-0.92] or no support decreased (OR = 0.98, 95% CI = 0.96-0.99), while use of pharmacological support, including e-cigarettes, increased (OR = 1.04, 95% CI = 1.02-1.05). There was no significant change in the difference in social grade between smokers and non-smokers comparing 2008 with 2017. Changes in smoking and quitting behaviour were independent of changes in socio-demographic characteristics.

CONCLUSIONS

Between 2008 and 2017 in England, smokers appear to have become less dependent on cigarettes but less likely to try to quit or cut down. Of those who tried to quit, fewer used behavioural support and more used pharmacological support. The proportion from more disadvantaged backgrounds did not change significantly.

Smoking reduction interventions for smoking cessation

BACKGROUND

The standard way most people are advised to stop smoking is by quitting abruptly on a designated quit day. However, many people who smoke have tried to quit many times and may like to try an alternative method. Reducing smoking behaviour before quitting could be an alternative approach to cessation. However, before this method can be recommended it is important to ensure that abrupt quitting is not more effective than reducing to quit, and to determine whether there are ways to optimise reduction methods to increase the chances of cessation.

OBJECTIVES

To assess the effect of reduction-to-quit interventions on long-term smoking cessation.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group Specialised Register, MEDLINE, Embase and PsycINFO for studies, using the terms: cold turkey, schedul*, cut* down, cut-down, gradual*, abrupt*, fading, reduc*, taper*, controlled smoking and smoking reduction. We also searched trial registries to identify unpublished studies. Date of the most recent search: 29 October 2018.

SELECTION CRITERIA

Randomised controlled trials in which people who smoked were advised to reduce their smoking consumption before quitting smoking altogether in at least one trial arm. This advice could be delivered using self-help materials or behavioural support, and provided alongside smoking cessation pharmacotherapies or not. We excluded trials that did not assess cessation as an outcome, with follow-up of less than six months, where participants spontaneously reduced without being advised to do so, where the goal of reduction was not to quit altogether, or where participants were advised to switch to cigarettes with lower nicotine levels without reducing the amount of cigarettes smoked or the length of time spent smoking. We also excluded trials carried out in pregnant women.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods. Smoking cessation was measured after at least six months, using the most rigorous definition available, on an intention-to-treat basis. We calculated risk ratios (RRs) and 95% confidence intervals (CIs) for smoking cessation for each study, where possible. We grouped eligible studies according to the type of comparison (no smoking cessation treatment, abrupt quitting interventions, and other reduction-to-quit interventions) and carried out meta-analyses where appropriate, using a Mantel-Haenszel random-effects model. We also extracted data on quit attempts, pre-quit smoking reduction, adverse events (AEs), serious adverse events (SAEs) and nicotine withdrawal symptoms, and meta-analysed these where sufficient data were available.

MAIN RESULTS

We identified 51 trials with 22,509 participants. Most recruited adults from the community using media or local advertising. People enrolled in the studies typically smoked an average of 23 cigarettes a day. We judged 18 of the studies to be at high risk of bias, but restricting the analysis only to the five studies at low or to the 28 studies at unclear risk of bias did not significantly alter results.We identified very low-certainty evidence, limited by risk of bias, inconsistency and imprecision, comparing the effect of reduction-to-quit interventions with no treatment on cessation rates (RR 1.74, 95% CI 0.90 to 3.38; I2 = 45%; 6 studies, 1599 participants). However, when comparing reduction-to-quit interventions with abrupt quitting (standard care) we found evidence that neither approach resulted in superior quit rates (RR 1. 01, 95% CI 0.87 to 1.17; I2 = 29%; 22 studies, 9219 participants). We judged this estimate to be of moderate certainty, due to imprecision. Subgroup analysis provided some evidence (P = 0.01, I2 = 77%) that reduction-to-quit interventions may result in more favourable quit rates than abrupt quitting if varenicline is used as a reduction aid. Our analysis comparing reduction using pharmacotherapy with reduction alone found low-certainty evidence, limited by inconsistency and imprecision, that reduction aided by pharmacotherapy resulted in higher quit rates (RR 1. 68, 95% CI 1.09 to 2.58; I2 = 78%; 11 studies, 8636 participants). However, a significant subgroup analysis (P < 0.001, I2 = 80% for subgroup differences) suggests that this may only be true when fast-acting NRT or varenicline are used (both moderate-certainty evidence) and not when nicotine patch, combination NRT or bupropion are used as an aid (all low- or very low-quality evidence). More evidence is likely to change the interpretation of the latter effects.Although there was some evidence from within-study comparisons that behavioural support for reduction to quit resulted in higher quit rates than self-help resources alone, the relative efficacy of various other characteristics of reduction-to-quit interventions investigated through within- and between-study comparisons did not provide any evidence that they enhanced the success of reduction-to-quit interventions. Pre-quit AEs, SAEs and nicotine withdrawal symptoms were measured variably and infrequently across studies. There was some evidence that AEs occurred more frequently in studies that compared reduction using pharmacotherapy versus no pharmacotherapy; however, the AEs reported were mild and usual symptoms associated with NRT use. There was no clear evidence that the number of people reporting SAEs, or changes in withdrawal symptoms, differed between trial arms.

AUTHORS' CONCLUSIONS

There is moderate-certainty evidence that neither reduction-to-quit nor abrupt quitting interventions result in superior long-term quit rates when compared with one another. Evidence comparing the efficacy of reduction-to-quit interventions with no treatment was inconclusive and of low certainty. There is also low-certainty evidence to suggest that reduction-to-quit interventions may be more effective when pharmacotherapy is used as an aid, particularly fast-acting NRT or varenicline (moderate-certainty evidence). Evidence for any adverse effects of reduction-to-quit interventions was sparse, but available data suggested no excess of pre-quit SAEs or withdrawal symptoms. We downgraded the evidence across comparisons due to risk of bias, inconsistency and imprecision. Future research should aim to match any additional components of multicomponent reduction-to-quit interventions across study arms, so that the effect of reduction can be isolated. In particular, well-conducted, adequately-powered studies should focus on investigating the most effective features of reduction-to-quit interventions to maximise cessation rates.