Abstract
Introduction
Dual use of tobacco products has gained increasing attention due to its potential implications for tobacco control efforts. This study utilized data from the 2022-2023 Vietnam Population-based Provincial Global Adult Tobacco Survey (PGATS) to examine the association between dual tobacco use (conventional cigarettes and e-cigarettes) and smoking cessation intention among Vietnamese adults aged 15 years and older.
Methods
This cross-sectional study included 9821 adults who were currently smokers from 30 provinces and cities in Vietnam. Data were collected using a standardized questionnaire adapted from previous rounds of PGATS and administered via the REDCap platform. Univariable and multivariable logistic regression models, including refined models, were employed to examine the association between dual tobacco use and smoking cessation intention.
Results
Among the 9821 smokers, 5.4% reported smoking cessation intention within the next month, 15.1% within the next 12 months, and the remaining participants had no quit plan. Dual users accounted for 1.8% of the sample. After adjusting for potential confounders, dual users were associated with higher odds of smoking cessation intention compared to single conventional cigarette use, with an adjusted odds ratio of 1.53 (95% CI: 1.09-2.16).
Conclusion
Although dual tobacco use was uncommon among Vietnamese adult smokers, it was associated with a higher likelihood of smoking cessation. These findings suggest the need for future research into usage patterns, user motivations, and contextual factors that influence cessation behavior and sustaining this behavior.
Introduction
Tobacco use remains a major global public health concern, as it harms nearly every organ of the human body.1,2 It is associated with higher risks of cancers, cardiovascular disease, chronic obstructive pulmonary disease (COPD), as well as other serious health conditions such as type 2 diabetes and reproductive health problems.3,4 In recent years, the global tobacco market has significantly diversified, largely due to the emergence of new tobacco products (NTPs) such as electronic cigarettes (e-cigarettes) and heated tobacco products (HTPs). 5 These products are frequently marketed as harm-reducing alternatives or cessation aids, especially targeting younger populations through digital media and social networks.6-10
The increasing availability and use of new tobacco products have led to the emergence of dual tobacco use, defined as the simultaneous use of conventional tobacco products and other forms of tobacco products. This pattern has become common as e-cigarette adoption has increased. Dual and multiple tobacco products use are linked with greater nicotine exposure, nicotine dependence, and poorer smoking cessation outcomes, as compared to cigarette-only use. 11 According to a Global systematic review, the current prevalence of dual use of tobacco products ranges from 0.2% (Ukraine, Mexico) to 17.9% (Nepal) and is common in low and middle-income countries, particularly in Southeast Asia. 12 Regional differences in the prevalence of dual tobacco use may be influenced by cultural, social, and economic factors. In the United States, approximately half of the youth who used tobacco products reported using two or more products; among high school students who reported currently using two or more tobacco products, the most common combinations reported were e-cigarettes and cigarettes (14.8%). 13 A study conducted among Chinese university students indicated that 16.3% of males and 2.2% of females were current users of conventional cigarettes, while 6.6% of males and 2.7% of females reported current use of e-cigarettes. The prevalence of dual use was 20.9% among males and 5.3% among females, and over half (51.2%) of dual users had initially been exclusive cigarette smokers. 14 Dual users are often demographically distinct. In Vietnam, for instance, study data showed that current e-cigarette users (the majority of whom are dual users) were overwhelmingly male (∼89%), young (over 80% under age 35), urban, and moderately educated. 15
NTPs are often marketed as reduced-risk or smoking-cessation aids, which has fueled controversy over the public health implications of dual use of tobacco products. Public health authorities note that e-cigarette marketing has aggressively targeted youth and non-smokers, raising concerns that dual use may sustain, rather than eliminate tobacco dependence. A recent meta-analysis reported that dual users of cigarettes and e-cigarettes were 28% less likely to quit smoking cigarettes compared to those who smoked only cigarettes. 16 In contrast, from a harm-reduction perspective, dual use can be viewed as an interim stage on the path to quitting. 17 A comprehensive systematic review independently reached a different conclusion, identifying low-certainty evidence, primarily from controlled trials, that e-cigarettes may help with smoking cessation. 18 However, while some evidence indicates that dual users may have higher quit intentions at baseline, they do not necessarily achieve higher quit success. 19 A study in the United States found that after six months, compared to cigarette smokers, dual users were more likely to report abstinence from cigarettes at six months but not at 12 or 18 months. This suggests that dual use of tobacco products may support short-term reductions in smoking, but complete cessation is rarely sustained over time. 19
In 2020, the prevalence of current tobacco smoking among the population aged 15 and older in Vietnam was 20.8%, with a much higher rate among males compared to females (41.1% and 0.6%). 20 In addition, the use of electronic cigarettes has also emerged among young people, with 2.2% reporting former use and 2.4% reporting current use. As mentioned previously, NTPs are often advertised as less harmful than conventional cigarettes and as an alternative way to reduce or quit combustible cigarettes. 21 This may cause misconceptions among traditionally smoking users, adolescents and youths, particularly as these products have not been comprehensively regulated in Vietnam. As a result, the risk of increasing dual use is considerable.
There is a lack of data on smoking cessation behaviors among dual users, particularly in low- and middle-income countries such as Vietnam. We therefore focused on individuals with quit intentions rather than on quit success, as intentions are a measurable predictor of cessation behaviors in cross-sectional studies, especially where long-term follow-up data on quit outcomes are limited. 22 This approach will clarify behavioral factors influencing cessation and provide broader perspectives than studies limited to successful quitters.23,24 Psychosocial and demographic correlates of smoking cessation success among dual users, such as age, gender, motivation, and support systems, are also understudied. In this context, our study aims to examine the associations between dual use of tobacco products and smoking cessation intention among Vietnamese adult smokers aged 15 years and older using data from the PGATS 2022-2023 in Vietnam. Findings from this study are expected to fill the critical gaps in the literature on dual use of tobacco products in a middle-income country setting and inform tobacco control strategies, particularly in the context of emerging tobacco product use in Vietnam.
Methodology
Study Design and Setting
The PGATS 2022-2023 data was used, which was a cross-sectional study with data collected from August 2022 to April 2023 across 30 provinces and centrally controlled municipalities, encompassing urban and rural areas of diverse socioeconomic status. This cross-sectional study was reported in accordance with the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines.
Study Population and Sampling
The target population comprised Vietnamese residents aged 15 years and older. The formula for estimating population proportion with a specified relative precision was applied: ○ n is the minimum sample size ○ p is the prevalence of smoking in adults.
25
○ ○
The estimated sample size was 725 males. Adjusting for an anticipated 10% nonresponse rate and cluster design effect, the necessary sample size was 1196 males, which was rounded up to 1200. Since the survey was also conducted on females, the final sample size for one province/city was 2400 people (with 1200 males and 1200 females). For a total of 30 provinces and cities, the planned sample size was 72 000 individuals (2400 per province/city), yielding 71 981 completed interviews (99.97% response rate).
A multistage, stratified cluster sampling approach was used in each province: one urban area, one district of average economic status, and one district of lower economic status were selected. Within those strata, communes, towns, neighborhoods, and villages were randomly chosen, and households were randomly sampled (600 households per urban commune; 300 per town or commune in districts). One member who was 15-year-old or older in each household was chosen. If the to-be-selected member was male (or female), and the household had only one member who was 15-year-old or older and fited the sex criteria, that member was chosen. If the household had two or more members who were 15-year-old or older, the KISH method was applied to the selection process. If any selected household didn’t have members that met the sex criteria, the nearest household was chosen for replacement. Any participant with mental health issues or other health conditions was excluded from the sample. In this analysis, we selected a subgroup of those who self-reported as current smokers. A total of 9821 current smokers were eligible and included in the final analytical sample.
Data Source
Data were sourced from the PGATS 2022-2023 dataset, which employed a validated questionnaire used from previous national Global Adult Tobacco Survey rounds.4,26-28 The survey instrument covered tobacco use behaviors, cessation intentions, exposure to tobacco control measures, and sociodemographic characteristics. Provincial Centers for Disease Control, Departments of Health, the Vietnam Tobacco Control Fund, and the Hanoi University of Public Health collaboratively oversaw survey implementation, quality control, and real-time data management via the REDCap platform.
Variables and Covariates
The main outcome in this analysis, “Smoking cessation intention”, was assessed with the survey question “Which of the following best describes your thinking about quitting smoking?” Response options were planning to quit within one month; planning to quit within the next 12 months; thinking about quitting someday but not within the next 12 months; and no intention to quit. For this analysis, participants who indicated plans to quit within one month or within 12 months were coded as “have smoking cessation intention,” and all other responses were coded as “have no plans to quit”.
Independent variables in this analysis consist of: Sociodemographic factors included gender (male, female), age group (15-24, 25-44, 45-64, 65+ years), place of residence (urban, rural), educational level (elementary, secondary, high school, tertiary), current employment status (formal sector, self-employment, housewife/student/retirement, unemployed), and marital status (single, married, separated/widowed). Tobacco use-related variables comprised user type: single user (conventional cigarette only) vs dual user (conventional cigarettes AND other new tobacco products, i.e. e-cigarettes, HTPs, smokeless cigarettes), knowledge of the smoke-free law (yes/no), noticing health warnings on tobacco products (yes/no), exposure to any tobacco advertisements or events (yes/no), and exposure to any tobacco promotion (yes/no).
Data Management and Statistical Analysis
All analyses were conducted on a complete-case dataset of 9821 observations for both univariable and multivariable analyses. Descriptive statistics summarized sample characteristics, reporting frequencies and percentages for categorical variables. Univariable and multivariable logistic regression models estimated associations between each independent variable and smoking cessation intentions, with adjusted odds ratios (ORs), 95% confidence intervals (CIs), and P-values presented. Variables demonstrating statistical significance at a significance level of α = 0.05 in univariable analyses were entered into a multivariable logistic regression. If variables did not reach statistical significance in univariable analysis but have priori evidence26,29,30 (e.g. gender, place of residence…) and consistent adjustment for these factors in prior smoking cessation research, they were still kept in our base model. The refined model was created by retaining only those predictors with P < .05, yielding adjusted ORs and 95% CIs. Model fit was compared using Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), and Pseudo R2. All statistical tests were two-sided, and analyses were performed using Stata version 19.5 (StataCorp, College Station, TX).
Ethical Consideration
The Vietnam PGATS 2022-2023 protocol and data collection procedures adhered to international ethical standards and local regulations. Ethics approval was obtained from the Ethical Committee of Hanoi University of Public Health (Decision No. 242/2022/YTCC-HD3, dated June 15, 2022). Written informed consent was obtained from all adult participants prior to interview administration. For participants aged less than 18 years, written informed consent was obtained from their parents or legally authorized representatives/guardians, in accordance with ethical requirements. In all cases, interviewers explained the study objectives, voluntary nature of participation, and the right to withdraw at any time without penalty, prior to obtaining consent. Participant confidentiality was strictly maintained: no personally identifying information was recorded, and all data were anonymized before analysis. Survey procedures complied with the World Health Organization’s Global Tobacco Surveillance System ethical guidelines and the principles of the Declaration of Helsinki, ensuring respect for persons, beneficence, and justice throughout the study.
Results
Characteristics of Study Participants
The study enrolled 9821 current smokers, with the vast majority being conventional cigarette (CC) users only (n = 9,640, 98.2%), and the rest were dual users (n = 181, 1.8%).
Characteristics of Study Participants
Participants were geographically distributed between urban (46.5%) and rural (53.5%) areas with no significant differences between user groups (P > .05). Educational attainment varied considerably, with elementary school completion being most common (35.5%), followed by secondary school (33.1%), high school (22%), and tertiary education (9.4%), showing significant differences between groups (P < .05). Employment patterns revealed that three-quarters of participants were self-employed (75.4%), while 10% worked in the formal sector, 7.8% were housewives/students/retirees, and 6.8% were unemployed, with significant employment status differences between user groups (P < .01). Most participants were married (almost 89%), with singles comprising 8.5% and separated/widowed individuals representing 2.6%, demonstrating highly significant marital status differences between groups (P < .001).
Knowledge of smoke-free laws was reported by 58.9% of participants, with no significant difference between user groups (P > .05), while 75.9% had noticed health warnings on tobacco products, again showing no significant group differences (P > .05). Regarding smoking cessation intentions, the majority (79.4%) had no plans to quit, 15.1% planned to quit within 12 months, and only 5.4% intended to quit within one month, with significant differences between user groups (P < .01). Exposure to tobacco marketing was minimal, with 89.8% reporting no exposure to any advertisements or events and 97.8% reporting no exposure to promotions, both showing highly significant differences between CC-only users and dual users (P < .001 for both measures).
Smoking Cessation Intentions Among Study Participants
Univariable Association Between Smoking Cessation Intentions and Study Participants’ Characteristics
Among the 9821 study participants, 7801 individuals (79.4%) reported no intention to quit smoking, while 2020 (20.6%) expressed an intention to quit. Gender showed no significant association with cessation intentions (P > .05), with similar proportions of males and females across both groups. Age demonstrated a significant association with quit intention (P < .05), with younger participants, particularly those aged 15-24 years, showing a higher proportion of quit intention (4.2%) compared to those without intention to quit in the same age group (3.9%). Educational attainment revealed a highly significant inverse relationship with cessation intentions (P < .001), where individuals with elementary education comprised 37.4% of non-quitters but only 28.4% of those planning to quit, while tertiary education graduates represented 8.6% of non-quitters and 12.5% of potential quitters. Employment status also showed highly significant associations (P < .001), with self-employed individuals more prevalent among non-quitters (76.8%) compared to those with quit intentions (70.2%), while formal sector employees showed the opposite pattern (9.2% vs 13.1%).
Several health-related factors were significantly associated with smoking cessation intentions. Dual tobacco use patterns were notably associated with quit intentions (P < .01), with dual users representing 2.7% of individuals intending to quit, compared to 1.6% among those without quit intention. Awareness of smoke-free laws was significantly associated with cessation intentions (P < .001), as was noticing health warnings on tobacco packages (P < .05), 77.6% of respondents intending to quit had noticed warnings, compared to 75.5% of those not intending to quit. Exposure to tobacco marketing showed significant associations with cessation intentions in different ways. Specifically, while exposure to promotion (P < .001) were more common among individuals not intending to quit, exposure to any type of advertisements/events (P > .05) were similar between two individual groups. Although noticing health warnings on tobacco packaging was associated with higher odds of quit intention (aOR = 1.12, 95% CI: 1.01-1.25), the absolute difference in proportions was small (77.6% vs 75.5%, Δ = 2.1%). Besides, place of residence and marital status showed no significant or only marginally significant associations with cessation intentions, with P-values of 0.789 and 0.044, respectively.
Association Between Dual Use of Tobacco Products and Smoking Cessation Intentions
Association Between Smoking Cessation Intentions and Other Participants’ Characteristics
***P < .001, **P < .01, *P < .05.
Model 1: Base model with all variables.
Model 2: Model with all variables with statistical significance from Model 1.
Dual users of conventional cigarettes and other new tobacco products were more likely to express intention to quit compared to conventional-cigarette-only users, with an adjusted OR of 1.53 (95%CI: 1.09-2.16). Awareness of smoke-free laws significantly increased the likelihood of intending to quit by 35% (adjusted OR = 1.35, 95%CI: 1.21-1.51, P < .001). In contrast, noticing health warnings on tobacco product packages and exposure to any tobacco advertisements or events were not significantly associated with quit intentions in Model 2. However, exposure to promotions was positively associated with quit intentions (adjusted OR = 1.52, 95%CI: 1.11-2.07, P < .01). The model intercept indicated a baseline odds of intending to quit smoking of 0.17 (95%CI: 0.12-0.24), reflecting low overall intention to quit in the absence of the predictors included in the model.
Model 2 demonstrates a modest improvement in overall model fit compared to Model 1. Specifically, Model 2’s AIC is 9238.79 vs 9243.87 for Model 1, indicating a slightly better model fit. Similarly, the BIC decreases from 9379.32 in Model 1 to 9352.85 in Model 2, suggesting improved model performance when accounting for model complexity. Despite these differences in model fit indices, both models explain a similarly small proportion of the variance in smoking cessation intentions, as indicated by Pseudo R2 values of 0.0170 for Model 1 and 0.0169 for Model 2. Thus, while Model 2 demonstrates marginally better information criteria, the two models exhibit essentially equivalent explanatory power. Both Model 1 and Model 2 yielded low pseudo R2 values (0.0170 and 0.0169, respectively), indicating that our set of predictors explains less than 2% of the variance in smoking cessation intentions.
Discussion
Main Findings of This Study
In this provincial cross-sectional study of 9821 Vietnamese adults who were current smokers, 1.8% reported dual use of conventional cigarettes and e-cigarettes. Overall, 20.6% of participants expressed an intention to quit smoking (5.4% within one month; 15.1% within 12 months), while 79.4% had no quit plan. Univariable analyses identified age, education, employment, marital status, dual use, smoke-free law awareness, health warning notice, and tobacco promotion exposure as correlates of quit intention. In multivariable logistic regression adjusted for these factors, dual users had 1.53 (95% CI: 1.09-2.16) times the odds of intending to quit compared to cigarette-only smokers. Higher education (secondary: OR = 1.37, 95% CI: 1.20-1.56; high school: OR = 1.45, 95% CI: 1.25-1.69; tertiary: OR = 1.62, 95% CI: 1.31-2.00), rural residence (OR = 1.13, 95% CI: 1.02-1.26), marriage (OR = 1.46, 95% CI: 1.16-1.84), and exposure to tobacco promotions (OR = 1.52, 95% CI: 1.11-2.07) were also independently associated with quit intention. Both models exhibited low explanatory power (Pseudo R2 < 0.02), indicating that additional factors beyond those assessed are likely important determinants of cessation motivation.
Prevalence of Dual Users
In the present study, the prevalence of dual users of conventional cigarettes and e-cigarettes was 1.8% among smokers and 0.3% in the overall adult population, showing lower rates than those reported in other countries. For example, among smokers, the prevalence of dual use was 13% in Canada, 12.4% in England, 10.2% in the USA, and 2.6% Australia based on data from the ITC Four Country Smoking and Vaping Survey. 31 Among the general adult population, our findings are also considerably lower than those reported in Scotland (3.6%) 32 and England, where recent estimates ranged from 3.5% to 5.3% from 2016 to 2024. 33 These comparisons suggest that dual use remained relatively uncommon in Vietnam at the time of data collection. One possible explanation for the lower prevalence of dual use in Vietnam is the relatively low prevalence of e-cigarette use among the adult population. According to national data, only 3.6% of Vietnamese adults reported using e-cigarettes in 2020, compared to 5.8% in Scotland in 2021, 32 10.9% in England in 2022, 33 and 5.8% in Malaysia in 2023. 34 Since dual use necessarily involves the use of both cigarettes and e-cigarettes, the limited uptake of e-cigarettes in Vietnam might contribute to the lower rate of dual users observed in this study. This pattern reflects the current tobacco landscape in Vietnam, where conventional cigarette smoking remains dominant, particularly among older men, while the use of new tobacco products is still emerging. However, the growing popularity of e-cigarettes among youth and urban populations in the region suggests that the prevalence of dual use may increase over time. Studies reveal a growing trend of e-cigarette use among adolescents and young adults in Vietnam, increasing from 0.2% in 2015 35 to approximately 2.4% by 2020. 36 Localized findings from 2020 in Hanoi and Ho Chi Minh City further indicate higher rates among youth aged 15-24, with 7.4% reporting ever use and 4.8% expressing an intention to use e-cigarettes in the future. 37
Prevalence of Quit Attempt Among Dual Users (Traditional Smoking/e-Cigarette Users) and Associations Between Dual Users and Quit Attempts
Our study also investigated differences in smoking cessation intentions between dual users and exclusive conventional cigarette users. Notably, dual users were more likely to report an intention to quit smoking than single cigarette users, with 29.8% of dual users expressing cessation intentions compared to 20.4% of exclusive smokers. This association was statistically significant, with 2.7% of dual users indicating an intention to quit, compared to only 1.6% among those without such intention (P < .05). The strength of this association was consistently observed across both multivariable models. These findings suggest that dual users may be more inclined toward considering smoking cessation than exclusive cigarette smokers. This aligns with evidence from high-income countries, where dual users are often more likely to report quit attempts or intention to quit within the next 6 months than exclusive cigarette smokers. 31 Similarly, Jackson et al. (2020) found higher rates of smoking cessation intention among dual users in England, although the success rates of these attempts were comparable to those of exclusive smokers. 17 In some cases, dual users may turn to e-cigarettes with the hope of reducing harm or as a gradual step toward cessation, however, without adequate cessation support, they may remain dependent on nicotine. 17
Our findings differ from those of a prior Vietnam 2020 PGATS study, which reported that dual users were less likely to attempt quitting e-cigarettes compared to exclusive e-cigarette users (41.8% vs 50.0%). 15 Several key differences in study design and measured outcomes may account for this discrepancy. First, the earlier study examined quit attempts to stop using e-cigarettes among a subgroup of current e-cigarette users (557 participants), whereas our study focused on intentions to quit cigarette smoking among a nationally representative sample of smokers (9821 participants). Second, differences in the study populations (exclusive e-cigarette users vs all smokers) and measures of cessation behavior (quit attempt vs quit intention) are likely to contribute to the variation in findings.
Our findings contrast with results from a previous meta-analysis reported that e-cigarettes users overall had 28% lower odds of successfully quitting smoking compared to e-cigarette non-users. 16 Importantly, this meta-analysis did not specifically analyze dual users, but rather examined e-cigarette use more broadly. The difference between our results and those of the meta-analysis emphasizes the complexity of the relationship between e-cigarette use, dual use, and cessation outcomes, which may vary across contexts and populations. Our results support the hypothesis that, for some smokers, dual use may reflect a transitional phase toward cessation, as e-cigarettes are adopted with the intention of reducing or quitting conventional cigarette.38,39 For example, a study reported that more than two-thirds of smokers intended to use e-cigarettes as a complete replacement for conventional cigarettes. 39 In the US, a nationally representative study found that smokers who used e-cigarettes were more likely to make quit attempts, and frequent e-cigarette use was strongly associated with a higher likelihood of cessation. 38 However, evidence from longitudinal study indicated that higher quit intentions in short term among dual users do not necessarily translate into successful long-term smoking cessation. 19 In addition, a recent systematic review provided a more cautious view, concluding that while fewer dual users transitioned to nicotine abstinence, the majority either remained dual users or reverted to exclusive cigarette smoking. 40 These conflicting findings emphasize the complexity of dual use behavior, and the need for more future research into user patterns, user motivations and contextual factors influencing e-cigarette access. While dual use remains rare in Vietnam, targeted cessation support is essential to convert these intentions into successful and sustained quitting. Another aspect should be considered is that, acknowledging the widespread use of health warnings as a tobacco control strategy, it is important to consider their actual impact on smokers’ intentions. However, the minimal absolute increase in quit intention (2.1%) suggests that, while health warnings may raise awareness, they may need to be supplemented by more intensive cessation support or larger graphic warnings to achieve meaningful behavioral change.
Finally, our multivariable results indicate that being aware of the smoke-free law is associated with stronger intentions to quit – this finding is consistent with policy models (e.g., the ITC framework) in which awareness shifts norms and efficacy and, in turn, strengthens quit intentions. 41 Prior evidence also shows that engagement with smoke-free policies predicts cessation behaviors: smokers who support smoke-free laws are more likely to attempt quitting and to be abstinent at follow-up, and smoke-free air laws can bolster intentions to quit and subsequent quit attempts.42,43 Our findings align with this literature but extend it by highlighting knowledge of the law (not just policy support or exposure) as a correlate of quit intention in our setting.42,43
Public Health and Policy Implications
Our findings have important implications for tobacco control policy in Vietnam. Although dual users were more likely to express quit intentions than exclusive smokers, international evidence on the effectiveness of alternative tobacco products for cessation remains inconsistent, and dual users have a prolonged exposure to toxicants from both products, including nicotine. It is important to note that our data were collected in 2022, prior to the National Assembly’s resolution prohibiting e-cigarettes and heated tobacco products, which was enacted on January 1, 2025. 44 Accordingly, our findings should be interpreted within this policy context, highlighting the importance of developing a comprehensive regulatory framework through revisions to the Law on Prevention and Control of Tobacco Harms and related legal documents to ensure effective implementation of the ban and to prevent uptake among the Vietnamese population.
Strengths and Limitations of the Study
This study has several notable strengths. We utilized data from the 2022-2023 Vietnam PGATS, a large, population-representative dataset with standardized methodology, thus enhancing the generability of our findings. Additionally, by employing two logistic regression models to examine associations between tobacco use patterns and smoking cessation intentions, we were able to assess the consistency and robustness of our findings.
Nonetheless, several limitations should be acknowledged. Firstly, the cross-sectional design limits causal inference, making it unclear whether smokers who were already intending to quit used e-cigarettes as a support tool, or whether the use of e-cigarettes itself increased their intention to quit smoking. Secondly, both cigarette and e-cigarette use were self-reported and may be subject to recall or social desirability bias, besides, our analysis did not include measures of smoking intensity (e.g., cigarettes per day or heaviness of smoking index), which may influence quit intentions. Thirdly, the analysis also lacked detailed information on the frequency, intensity, or duration of e-cigarette and cigarette use within the past 30 days, limiting our ability to differentiate between daily and occasional users or to classify dual users according to established behavioral typologies. Despite statistically significant associations, the models’ minimal explanatory power (pseudo R2 < 0.02) limits their utility for individual-level prediction or clinical decision-making. These findings underscore the complex, multifactorial nature of quit intentions and the need for richer psychosocial, behavioral, and contextual data in future predictive models. Interpretation of our findings should be cautious, as the models explain only a small fraction of variance in quit intentions and are not intended for clinical application. Finally, the relatively low prevalence of dual users in the sample constrained the statistical power for subgroup analysis. Future longitudinal studies incorporating more detailed behavioral data are needed to explore the quitting trend and better understand the impact of dual use over time.
Conclusion and Recommendations
Although dual tobacco users accounted for a relatively small proportion of adult smokers in Vietnam, they demonstrated a higher intention to quit smoking compared to exclusive cigarette smokers. While this finding is consistent with certain previous studies conducted in high-income countries, it contrasts with some other studies, highlighting the complexity of dual use and its relationship with cessation behavior. To better understand this association, further nationally representative studies are needed. Such studies should aim to characterize dual users, explore their motivations and barriers related to smoking cessation, and examine how different forms of tobacco use influence cessation intention. Furthermore, tobacco control efforts in Vietnam should consider targeted interventions to support smokers willing to quit, ensuring that cessation support services are both accessible and sustainable. Strengthening and integrating these cessation services into broader tobacco control policies could enhance quit success rates and contribute to reducing the national burden of tobacco use.
Footnotes
Acknowledgement
The successful implementation of the 2022-2023 PGATS across 30 provinces and cities in Vietnam was made possible through the contributions of multiple partners. All the authors sincerely acknowledge the support and collaboration of the World Health Organization (WHO) Office in Vietnam, the Vietnam Tobacco Control Fund, and Hanoi University of Public Health, along with the active participation of provincial Centers for Disease Control (CDCs). We also appreciate the valuable involvement and support from governmental and non-governmental organizations, as well as experts working in the field of tobacco harm reduction and control in Vietnam.
Author Contribution
HVM, TTTH, PVC, LTH, LNK, PTH, NTL, and DTA conceived and designed the study, agreed with the results, conclusions and came up with arguments for the manuscript. TTTH, PVC, LTH, LNK, PTH, NTL, DTA, NDT, and HVM coordinated data collection. LTTH, LTH, PVC, NQA, PTTT, NTBT and DLHM analyzed the data. LTTH, LTH, NTBT, TTTH, NQA, PTTT, DLHM and HVM wrote the first draft of the manuscript. All the authors made critical revisions and agreed on the final versions of the manuscript, which was submitted by LTH.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The PGATS 2022-2023 were supported and funded by the Vietnam Tobacco Control Fund under Grant number 29/2022/HĐ-QPCTHTL-ĐHYTCC dated 28/4/2022.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data Availability Statement
Raw data were generated at Hanoi University of Public Health, Vietnam. Derived data supporting the findings of this study are available from the corresponding author on request.