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Abstract Background Mobile health (mHealth) is promising in developing personalised smoking cessation interventions. By using an adaptive trial design, we aim to evaluate the effectiveness of personalised mHealth intervention in increasing smoking cessation. Methods This study is a two-arm, parallel, accessor-blinded Sequential Multiple-Assignment Randomised Trial (SMART) that randomises 1200 daily cigarette smokers from 70 community sites at two timepoints. In the first phase, participants receive brief cessation advice plus referral assistance to smoking cessation services and are randomly allocated to receive personalised instant messaging (PIM) or regular instant messaging (RIM). In the second phase, PIM participants who are non-responders (i.e. still smoking at 1 month) are randomised to receive either optional combined interventions (multi-media messages, nicotine replacement therapy sampling, financial incentive for active referral, phone counselling, and family/peer support group chat) or continued-PIM. Non-responders in the RIM group are randomised to receive PIM or continued-RIM. Participants who self-report quitting smoking for 7 days or longer at 1 month (responders) in both groups continue to receive the intervention assigned in phase 1. The primary outcomes are biochemical abstinence validated by exhaled carbon monoxide (< 4 ppm) and salivary cotinine (< 10 ng/ml) at 3 and 6 months from treatment initiation. Intention-to-treat analysis will be adopted. Discussion This is the first study using a SMART design to evaluate the effect of adaptive mHealth intervention on abstinence in community-recruited daily smokers. If found effective, the proposed intervention will inform the development of adaptive smoking cessation treatment and benefits smokers non-responding to low-intensity mHealth support. Trial registration ClinicalTrials.gov NCT03992742 . Registered on 20 June 2019.

Abstract Background Little is known about the risk and addiction perceptions of e-cigarettes among Asian populations. We examined e-cigarette perceptions among young adults in Hong Kong and the association between the perceptions and e-cigarette use patterns. Methods An online survey was administered to a convenience sample of Hong Kong residents aged 18–35 (N = 1186). Measures of e-cigarette perceptions included perceived harm and addictiveness of e-cigarettes, perceived harm of secondhand e-cigarette aerosol, and perceived popularity of e-cigarette use among peers. Separate multinomial logistic regression models were conducted to examine the associations between the four perceptions and former and current use of e-cigarettes relative to never use, controlling for demographics and current cigarette smoking status. Interactions of e-cigarette perceptions and current cigarette smoking were assessed in all models. Among current e-cigarette users, bivariate exact logistic regression models were used to examine the relationships between each of the perceptions and frequent e-cigarette use (≥3 days in past 30-day vs. 1–2 days). Among participants who had never used e-cigarettes, separate multivariable logistic regression models were conducted to examine the associations between e-cigarette perceptions and susceptibility to e-cigarette use. Results Overall, 97.2% of participants were aware of e-cigarettes, and 16.1% had tried e-cigarettes (11.3% former users; 4.8% current users). Young adults perceived e-cigarettes (and aerosol) as less harmful, less addictive, and less popular than cigarettes. Current cigarette smokers reported significantly lower perceived harmfulness and addictiveness of e-cigarettes, lower perceived harmfulness of e-cigarette aerosol, and higher perceived popularity than nonsmokers. The lower degree of harm and addiction perceptions, and higher levels of popularity perceptions were associated with greater odds of e-cigarette use, and these relationships were generally stronger among nonsmokers compared to current cigarette smokers. E-cigarette perceptions were not associated with frequent e-cigarette use. Perceiving e-cigarettes (and aerosol) as less harmful and less addictive were associated with greater susceptibility to e-cigarette use. Compared to nonsmokers, current smokers were more likely to report e-cigarette use and susceptibility. Conclusions Continued monitoring of e-cigarette use and perceptions is needed. Educational programs should emphasize the potential harmful and addictive properties of e-cigarettes and the risks of secondhand exposure to e-cigarette aerosol.

Summary: Background: Many smokers do not use existing free or low-cost smoking cessation services, cost-effective interventions to increase use are needed. Methods: We did a 2-armed cluster randomised controlled trial (cRCT) in Hong Kong, China, to evaluate the effectiveness of active referral plus a small financial incentive on abstinence. Chinese adult smokers who smoked at least 1 cigarette per day were proactively recruited from 70 community sites (clusters). Random allocation was concealed until the recruitment started. The intervention group received an offer of active referral to cessation services at baseline plus an incentive (HK$300/US$38) after using any cessation services within 3 months. The control group received general brief cessation advice. The primary outcomes were biochemically validated abstinence at 3 and 6 months. Operating costs in real-world implementation was calculated. Trial Registry: ClinicalTrials.gov NCT03565796. Findings: Between June and September 2018, 1093 participants were randomly assigned to the intervention (n=563) and control (n=530) groups. By intention-to-treat, the intervention group showed higher validated abstinence than the control group at 3 months (8.4% vs. 4.5%, risk ratio [RR] 1.88, 95% CI 1.01-3.51, P=0.046) and 6 months (7.5% vs. 4.5%, RR 1.72, 95% CI 1.01-2.93, P=0.046). Average cost per validated abstinence was lower in the intervention (US$ 421) than control (US$ 548) group. Interpretation: This cRCT has first shown that a simple, brief, and low-cost intervention with active referral plus a small monetary incentive was effective in increasing smoking abstinence and smoking cessation service use in community smokers. Funding: Hong Kong Council on Smoking and Health.

Summary: Background: Mobile instant messaging apps offer a modern way to deliver personalised smoking cessation support through real-time, interactive messaging (chat). In this trial, we aimed to assess the effect of chat-based instant messaging support integrated with brief interventions on smoking cessation in a cohort of smokers proactively recruited from the community. Methods: In this two-arm, pragmatic, cluster-randomised controlled trial, we recruited participants aged 18 years or older who smoked at least one cigarette per day from 68 community sites in Hong Kong, China. Community sites were computer randomised (1:1) to the intervention group, in which participants received chat-based instant messaging support for 3 months, offers of referral to external smoking cessation services, and brief advice, or to the control group, in which participants received brief advice alone. The chat-based intervention included personalised behavioural support and promoted use of smoking cessation services. Masking of participants and the research team was not possible, but outcome assessors were masked to group assignment. The primary outcome was smoking abstinence validated by exhaled carbon monoxide concentrations lower than 4 parts per million and salivary cotinine concentrations lower than 10 ng/mL at 6 months after treatment initiation (3 months after the end of treatment). The primary analysis was by intention to treat and accounted for potential clustering effect by use of generalised estimating equation models. This trial is registered with ClinicalTrials.gov, number NCT03182790. Findings: Between June 18 and Sept 30, 2017, 1185 participants were randomly assigned to either the intervention (n=591) or control (n=594) groups. At the 6-month follow-up (77% of participants retained), the proportion of validated abstinence was significantly higher in the intervention group than in the control group (48 [8%] of 591 in intervention vs 30 [5%] of 594 in control group, unadjusted odds ratio 1·68, 95% CI 1·03–2·74; p=0·040). Engagement in the chat-based support in the intervention group was low (17%), but strongly predicted abstinence with or without use of external smoking cessation services. Interpretation: Chat-based instant messaging support integrated with brief cessation interventions increased smoking abstinence and could complement existing smoking cessation services. Funding: Hong Kong Council on Smoking and Health.

Introduction Positive perceptions of electronic cigarettes (e-cigarettes) relative to combustible cigarettes (CCs) may erode support for endgame policies on CCs through smoking renormalization (increasing public acceptance of smoking). We investigated the associations between perceptions of e-cigarettes relative to CCs and support for endgame policies on CCs in Hong Kong. Methods Adult respondents (N=2004) were surveyed using landline random digit dialing in 2015. Perceived relative harm and relative addictiveness of e-cigarettes were combined as an overall perception of e-cigarettes relative to CCs with 5 levels and we analyzed individually ‘neutral/positive/mixed/unknown’ perceptions against the ‘negative’ perception. Five individual items with dichotomous responses assessed the support for endgame policies on CCs. Support for banning the sale/use of CCs (yes/no) was also assessed. Multivariable regressions yielded adjusted odds ratios (AORs) of supporting endgame policies (individual policy items, all 5 policy items, at least 1 policy item, banning the sale/use of CCs) in relation to perceptions of e-cigarettes relative to CCs, adjusting for age, education attainment, marital status, CC smoking status and ever e-cigarette use. Results Support for individual endgame policy items (from 51.8% to 80.0%), banning the sale (63.8%) and use (67.5%) of CCs were generally high. Few respondents perceived e-cigarettes as more harmful (16.6%) or more addictive (9.3%) than CCs. Positive perceptions of e-cigarettes (24.0%) were associated with less support for ‘ban CC sales in 10 years if there is a product providing nicotine not made from tobacco’ (AOR=0.62, 95% CI: 0.40–0.97), ‘ban CC use when it’s prevalence falls below 5%’ (AOR=0.66, 95% CI: 0.44–0.98) and ‘banning the sale of CCs’ (AOR=0.63, 95% CI: 0.42–0.94). Conclusions Positive perceptions of e-cigarettes relative to CCs were associated with less support for endgame policies on CCs in Hong Kong. Public health actions are needed to disseminate evidence-based knowledge of e-cigarettes.

Introduction Never smokers’ responses to tobacco control policy are often overshadowed by the opposition from smokers and tobacco industry during policy advocacy and legislation. Very few studies have examined never smokers’ exposure to point-of-sale (POS) tobacco displays and their effects. Therefore, we investigated the exposure, pro-smoking responses due to and attitudes towards such displays in never smokers in Hong Kong. Methods We conducted two-stage, randomized cross-sectional telephone-based surveys in 2015 and 2016 of 1833 never-smoking adults. They were asked how often they noticed POS displays in the past 30 days (often, sometimes, never), whether they found POS displays attractive, felt encouraged to smoke, perceived POS displays as advertisements, and if they supported banning them. The distributions of the outcomes were analyzed by descriptive statistics with weighting to the general population. Risk ratios (RR) from Poisson regression models adjusted for sociodemographic characteristics were used to analyze the associations. Results Our results showed that, in never smokers, the younger were more likely to often notice POS displays (RR=0.80, 95% CI: 0.72–0.89, p

Background E-cigarettes have become increasingly popular. We examined perceptions of e-cigarettes, and their associations with e-cigarette use, frequency of use, and use susceptibility among young adults in Hong Kong. Methods An online survey was administered to 1,186 Hong Kong residents aged 18-35 in 2016-17. On a 0-10 visual scale, participants rated the perceived harm of e-cigarettes, perceived harm of secondhand exposure to e-cigarette aerosols, and perceived addictiveness. An overall perception score was calculated by averaging the values of non-missing perception items. Multinomial logistic regression examined the relationship of the overall perception score with former and current e-cigarette use relative to never use, controlling for age, gender, education, place of birth, current cigarette smoking, and perceived popularity of e-cigarettes among peers. Bivariate exact logistic regression assessed the association between perceptions and frequency of e-cigarette use (“≥3 days” vs. “1-2 days” in past 30-day) among current users. Multivariate logistic regression assessed the relationship between perceptions and e-cigarette susceptibility among never users. Results 97.2% of participants were aware of e-cigarettes, and 16.1% had ever used e-cigarettes (11.3% former users; 4.8% current users). Of current e-cigarette users, 63.2% reported infrequent use. Among never users, 34.0% were susceptible to e-cigarette use. E-cigarettes were perceived as less harmful and less addictive than cigarettes, particularly among current cigarette smokers. Low overall perception score was associated with former and current e-cigarette use, frequent use, and use susceptibility. Current cigarette smoking and perceived higher popularity of e-cigarettes were also related to e-cigarette use. Current cigarette smoking was associated with e-cigarette susceptibility. Conclusions Continued surveillance on e-cigarette use is needed. Interventions must address the conceptions about e-cigarettes. Health communication messages emphasizing the harmful and addictive nature of e-cigarette use and secondhand exposure to e-cigarette aerosols, and health warning labels on e-cigarette packages may help reduce e-cigarette use in young people.

Background and challenges to implementation Studies found that actively referring smokers to smoking cessation (SC) services increased quitting. We compared 2 different intensities of SC active referral for community smokers in Hong Kong. Intervention or response A single-blinded, parallel three-armed cluster randomized controlled trial was conducted among smokers who joined 2016 “Quit-to-Win” Contest organized by the Hong Kong Council on Smoking and Health. Biochemically validated (CO >4ppm) daily smokers were proactively recruited and randomly assigned to onsite SC active referral (Group A) (n= 395), text messaging on promoting and encouraging smokers to attend SC services (Group B) (n=385) and control group on general brief SC advice (Group C) (n=383). Group A and B also received model guided (AWARD) brief SC advice with a warning leaflet and a referral card at baseline and telephone brief advice at 1-month and 2-month. Telephone survey at 3-month (retention rate 63.4%) to assess primary outcome: self-reported 7-day point prevalence abstinence (PPA) and secondary outcomes: smoking reduction rate (SRR, daily cigarette consumption reduced by ≥50%; excluding quitters) and biochemically validated quit rate (CO < 4ppm). Analyses were done by intention to treat. Results and lessons learnt Group A, B and C had self-reported PPA: 14.4%, 13.0% and 8.6% (A vs. C; B vs. C, p 0.05), respectively. Corresponding SRRs were 18.7%, 16.9% and 16.2% (all p>0.05). Compared with Group C, Group A had a higher odds ratio (OR) of 1.65 (95% CI 1.08-2.52) and Group B smokers had a higher OR of 1.56 (95% CI 1.02 - 2.04) for self-reported PPA, adjusting for baseline intention to quit and clustering effect. Conclusions and key recommendations Proactive intervention with AWARD guided brief SC advice and onsite active referral or text messaging may be effective in increasing quitting at 3-month compared with general brief SC advice in community smokers.

Background Secondhand smoke (SHS) contributes to significant morbidity and mortality worldwide including Hong Kong, a densely-populated city with the lowest daily smoking prevalence (10.5%) in the developed world. Most Hong Kong citizens reside in multiunit housing where SHS can transmit from one unit to another because of the shared ventilation system and crowded living environment. We explored the prevalence of SHS infiltration and its sociodemographic correlates in the Hong Kong general population. Methods A cross-sectional sample of 5151 randomly selected Hong Kong residents aged 15+ were interviewed by telephone (response rate = 85.8%) for the Hong Kong Tobacco Control Policy-related Survey in 2016. Participants reported the number of days experiencing SHS infiltration from neighbour at home in the past 7 days, and their sociodemographic characteristics and smoking status. Data were weighted by the Hong Kong official data on age, gender and smoking status distributions. Chi-square tests and multivariable logistic regression examined the associations of home SHS infiltration with sociodemographic and smoking status. Results Overall, the prevalence (95% CI) of ever and daily SHS infiltration at home in the past 7 days were 22.2% (20.3 to 24.2%) and 5.8% (4.8 to 7.1%) respectively. SHS infiltration was individually associated with female (P = 0.002), younger age (P < 0.001) and never smoking status (P < 0.001) but not with indices of socioeconomic status including highest education level (P = 0.07), family income (P = 0.43), employment (0.89) or immigrant (P = 0.09) statuses. Multivariable regression analyses showed that current smokers were less likely to report home SHS infiltration (OR = 0.43, 95% CI 0.32-0.58). Conclusions In Hong Kong, the prevalence of home SHS infiltration was very high given the low prevalence of smoking and did not vary with socioeconomic status. Implementation of smoke-free policy in multiunit housing is imperative to safeguard its residents from passive smoking.

Background Point-of-sale (POS) tobacco displays can promote smoking and purchase of tobacco in current and former smokers, but no studies have examined such effect in never smoking adults. We investigated the correlates of frequent exposure to, and responses and attitudes towards POS tobacco displays in never smokers in Hong Kong, China. Methods We included 1,833 never smokers aged 15+ years from two random telephone surveys in 2015 (n=932) and 2016 (n=901). All respondents reported how often they noticed POS tobacco displays in the past 30 days (often, sometimes, not noticing), whether they perceived displays as attractive, felt encouraged to smoke by them, perceived them as advertisements, and supported the banning displays. Risk ratio (RR) adjusting for socio-demographic characteristics was used to examine factors associated with often noticing the display and other responses. Results Young adults aged 15-29 years (vs 60+) were more likely to report often noticing POS displays (RR = 2.39, 95% CI 1.47-3.91). Those with primary education or below (vs tertiary) reported less often noticing (RR = 0.41, 95% CI 0.23-0.73), but more perceiving displays as attractive (RR = 2.52, 95% CI 1.51-4.22). Often noticing displays (vs not noticing) was associated with perceiving them as attractive (RR = 1.90, 95% CI 1.32-2.75), and being encouraged to smoke (RR = 4.05, 95% CI 0.98-16.85). Sometimes (RR = 0.89, 95% CI 0.80-0.997) or often noticing (RR=0.86, 95% CI 0.77-0.97) displays were associated with lower support for banning displays. Conclusions In never smokers, younger adults were more exposed to POS tobacco displays and those with low education level were more attracted by them. Frequent exposure could induce never smokers to smoke, and reduce their support for banning displays. To eliminate the advertising and normalization of POS tobacco displays in the retail environment, the ban on tobacco advertisements should include those displays simultaneously.

Background The tobacco industry consistently and persistently exaggerates that tobacco tax increase leads to increased illicit cigarette consumption (ICC). Using a top-down approach, we found that the proportion of ICC was about 11.9% in 2012 in Hong Kong (published in Tobacco Control), versus 35.9% reported in “Asia Illicit Tobacco Indicator 2012” (funded by tobacco industry). Their updated report in 2015 showed that ICC decreased to 29.1% in Hong Kong. We re-assessed the ICC in Hong Kong, where the tobacco tax increased by 41.5% in 2011 and 11.8% in 2014. Methods The top-down approach was done by first estimating the total CC of local residents and visitors (top), which was based on the official data of smoking prevalence and daily CC. Then, ICC was calculated by subtracting the total CC by the legal domestic sales and the duty-free cigarettes imported personally (down). The legal domestic sales were estimated using official revenue data due to the excise duty. The legal import was estimated with three alternative scenarios of cigarettes brought in by local residents and visitors. The estimates in 2015 were validated by a population-based survey that estimated the proportion of local smokers who purchased illicit cigarettes or the cigarettes brought in from overseas personally. Results The mid-point estimate of absolute ICC declined from about 412 million sticks in 2012 to 139 million sticks in 2015. The mid-point proportion of ICC in 2012, 13, 14 and 15 was 11.9% (8.2%-15.4%), 6.5% (2.7%-10.1%), 7.0% (3.2%-10.7%) and 3.9% (0.1%-7.7%), respectively. The estimates of 3.7%-6.3% obtained from the 2015 population-based survey were consistent with those from our top-down approach. Conclusions The industry-funded study has largely inflated ICC in Hong Kong. ICC declined over the 4 years, supporting that increase in tobacco tax does not lead to increase in ICC.

Background and challenges to implementation The labour force participation rate is over 60 percent in Hong Kong and most of the employees spend 8 to 10 hours daily in their workplaces. “Most friends/ colleagues were smokers” was one of the most commonly cited reasons for failing to give up smoking. Smoking causes HK$5.3 billion economic loss per year in Hong Kong, including loss of productivity due to premature death, costs of sick leaves, health care costs and nursing costs. However, corporates seldom put tobacco control or smoke-free promotion at the top of their agenda. Intervention or response Hong Kong Council on Smoking and Health urged the business sector to help promote smoke-free corporate culture through the Hong Kong Smoke-free Leading Company Awards and industry-oriented programmes which assisted corporates in setting up smoke-free policies and measures to promote smoking cessation among their stakeholders to foster an all-win situation for employees, employers and the society. Results and lessons learnt The Awards in 2011, 2013 and 2016 solicited support from over 80 commerce chambers and industry associations and mobilized around 1,000 corporates from a variety of industries to join, including large companies, small and medium enterprises, government departments and non-governmental organizations, benefiting over 175,000 employees and other stakeholders, including the public. Four major construction industry associations supported and referred around 40 companies to join the industry-oriented smoke-free programme launched in 2016, reaching over 16,000 industry workers whose smoking prevalence was over 40 percent. Outstanding companies were commemorated for their effective smoke-free measures and set as industry role models. Conclusions and key recommendations It is important to engage and empower different sectors of the community to maximize the impact and effectiveness of smoke-free promotion and tobacco control. Support from industry associations was crucial to raise awareness and boost participation of the business sector. Guidelines and industry-specific promotion collaterals shall be provided to facilitate companies in planning and implementing smoke-free policies.

Background and challenges to implementation The Hong Kong Government proposed to enhance pictorial health warnings (PHW), prominently increasing the size to 85%, since May 2015. Opposition and interference of tobacco industry (TI) was fierce. They formed a strong opposition force by mobilizing front groups and stakeholders to lobby legislators and delayed the legislation for 2 years. TI' intimidations on policy change were resolved with concerted community effort. Intervention or response Tailor-made smoke-free promotion programmes were introduced by Hong Kong Council on Smoking and Health (COSH), targeting at all perspectives of society. Every year, education and community involvement programmes for specific target group, e.g. students, elderly, middle aged, women, medical and health, and business sector, etc were organized to build up smoke-free concept in the community and engage them as persistent working partners in tobacco control. Results and lessons learnt Since July 2015 to May 2017, over 220 organizations' representatives/individuals took part to support the 85% PHW. Apart from health advocates, medical professionals and scholars, participants also included ex-smokers, students, teachers, social workers, community leaders, businessman, etc. It demonstrated to legislators that tobacco control is the whole community's concern and should be superior to TI's commercial interests. The 85% PHW was finally passed in June 2017. Lobbying of TI is ferocious and always with pseudo-science. It should note that TI also mobilized over 110 representatives, including smokers, marketing experts, lawyers, politicians, social activists and scholars. Challenges for advancing smoke-free legislation could be huger as we expected. Wider support and collaborations with the community should be solicited. Conclusions and key recommendations Nearly 90% of Hong Kong population are non-smokers and public support to tobacco control measures is generally high. It is critical to identify and engage these supportive but silent forces in the legislative process. Smoke-free seeds should be sowed broadly, deeply and sustainably in all sectors of community for the policy change.

Background and challenges to implementation In Hong Kong, over 20% of the 641,300 daily smokers aged 60 years or above. Public's awareness on smoking hazards has increased in recent years. But elder people are misled by the misconceptions on smoking and underestimate the health risks. Elder smokers have lower intention and knowledge on the smoking cessation. Intervention or response In order to inform the tobacco hazards, clarify misconceptions and encourage elder smokers to quit, Hong Kong Council on Smoking and Health (COSH) launched the “Elderly Smoking Cessation Promotion Project” in 2012. Health talks and community smoke-free activities are organized. Non-smoking elderly are also engaged as smoke-free agents. Results and lessons learnt Since 2012, COSH has delivered over 140 sessions of health talk and reached over 10,000 elderly. To spread out the smoke-free messages, radio promotions were produced and broadcasted in the channels targeted at elderly. Various smoke-free promotion activities were organized, including centre visits, pledge ceremony, street promotions, photo exhibition and workshops, to increase elder smokers' motivation to quit and arouse public's awareness and support to smoking cessation. The Project has successfully trained about 60 elder volunteers as ambassadors, encouraged over 200 smokers to pledge to quit smoking and engaged 900 elderly to promote smoke-free lifestyle. Mass public education and promotion may not able to reach the elder population. They hold stronger misconceptions on smoking cessation and are more reluctant to quit. Tailor-made and reach-out intervention programmes should be developed to build up smoke-free concepts among elderly. Collaborations with elderly service organizations could add benefit to the interventions. Conclusions and key recommendations Elder smokers have comparatively low awareness on harms of smoking and intention to quit. To address the specific need of elder population, COSH's tailor-made Elderly Smoking Cessation Promotion Project strengthened their knowledge on smoking hazards, cleared their myths of quitting and mobilized elder smokers to quit, through an interactive approach and community engagement.

Electronic cigarettes (e-cigarettes) are being increasingly used. We examined the correlates associated with e-cigarette awareness, use and perceived effectiveness in smoking cessation among Chinese daily smokers in Hong Kong.Daily smokers (N = 1,307) were recruited to a community-based randomised controlled trial ('Quit to Win') in 2014. Socio-demographic characteristics, conventional cigarette smoking status, nicotine addiction level, quit attempts, quit intention, e-cigarette awareness, use and perceived effectiveness on quitting were reported at baseline and 1-week follow-up. Multivariate logistic regression was used to identify factors associated with e-cigarette awareness, use and perceived effectiveness in quitting.Most smokers (82.6%, 95% CI 80.2%-84.9%) had heard about e-cigarettes, and 13.3% (11.3%-15.5%) ever used e-cigarettes. Most users (74.1%) and non-users (91.2%) did not perceive e-cigarettes as effective in quitting. Being younger and having a larger family income were associated with e-cigarette awareness. Being younger, a tertiary education and a stronger addiction to nicotine were associated with e-cigarette use, which was itself associated with lower levels of intention to quit and had no association with attempts to quit (P for trend 0.45). E-cigarette use, the last quit attempt being a month earlier, having made a quit attempt lasting 24 hours or longer and perceiving quitting as important were all associated with the perceived effectiveness of e-cigarettes in quitting (all P