Abstract
Objective:
Substantial segments of the US public are misinformed about the relative risks of nicotine products. There have been recent calls to educate the public about these relative risks. This study analyses correlates of “don’t know” responses on the relative risks of e-cigarettes and combustible cigarettes.
Design and setting:
Self-reported, nationally representative data from the USA’s Health Information National Trends Survey 2022 cycle (HINTS 6) were used (n = 5835).
Methods:
Multivariable logistic regression examined associations between sociodemographic characteristics and “don’t know” responses to a question about the relative risks of e-cigarettes compared to cigarettes. Analyses used jackknife estimation sampling weights to provide population representative estimates.
Results:
Over one-third (38.2%) of adults indicated they “don’t know” the relative harm of e-cigarettes compared to cigarettes, with increasing prevalence with older age. In adjusted models, middle-aged/older adults, race/ethnicities other than White, and adults with lower incomes had higher odds of selecting a “don’t know” response (p < 0.05, compared to respective reference groups). Adults with some college education/college degree, females, current/former users of cigarettes, and current/former users of e-cigarettes had lower odds of selecting “don’t know” (p < 0.05).
Conclusions:
An improved understanding of “don’t know” responses assessing the public’s understanding of the relative risks of nicotine products could serve as a vital tool to identify knowledge gaps among older adults and in other marginalised populations, serving as an indicator for targeted educational programmes and interventions. Data such as this are necessary to inform populations about the risks of smoking and the benefits of cessation and harm-reduction strategies.
Introduction
The prevalence of cigarette smoking in the US population is at an all-time low, declining to 9.1% among US adults (Norris et al., 2026). While quitting smoking is the optimal outcome for reducing smoking-related harms among people who smoke cigarettes, the inconsistent success of cessation strategies for all individuals suggests the need for alternative approaches, such as harm-reduction strategies (Hatsukami and Carroll, 2020). One such tobacco harm-reduction strategy may be completely switching to electronic cigarettes (e-cigarettes). Despite controversies about their use in the general population, e-cigarettes may serve as a harm-reduction strategy for adults who have been unable to or uninterested in quitting smoking (Hatsukami and Carroll, 2020). For instance, completely switching to e-cigarettes can lower the risk for people who smoke cigarettes (Shahab et al., 2017). In addition, e-cigarette use may promote readiness to quit (Kasza et al., 2022) and smoking cessation (Auer et al., 2024; Lindson et al., 2025), even among those who did not plan to quit (Kasza et al., 2021). E-cigarette use among those uninterested in quitting may have a disproportionately greater impact on older adults and other populations who experience smoking-related health disparities (Kasza et al., 2022), especially since e-cigarette uptake is growing among younger adults compared to older adults (Mok et al., 2026).
Unfortunately, large segments of the US population are misinformed about the relative risks of nicotine and tobacco products. Because product risk perceptions predict product use (Elton-Marshall et al., 2020), the US Food and Drug Administration’s Center for Tobacco Products has noted the importance for adults who smoke cigarettes to understand the relative risks of nicotine and tobacco products (U.S. Food and Drug Administration, 2024), and there have been recent calls to educate adults who smoke cigarettes and healthcare providers about the relative risks of nicotine and tobacco products (Toll et al., 2024). Notably, people of ages ⩾65 years are more likely to have misconceptions about e-cigarette harms, such as believing that e-cigarettes are equally as harmful as combustibles (Rubenstein et al., 2023); similar findings have been observed in other populations that experience smoking-related health disparities (Harlow et al., 2023).
Misinformation about the relative risks of e-cigarettes may explain the low levels of e-cigarette interest in older populations, where uptake is 0.9% (Rubenstein et al., 2023). Indeed, limited experience with a product may contribute to misunderstandings or uncertainty about that product, which leads to an unwillingness to try said product (Shiffman et al., 2008; Wackowski et al., 2023). Therefore, individuals who perceive e-cigarettes as equally or more harmful than cigarettes are less likely to transition from smoking to exclusive e-cigarette use (Harlow et al., 2023; Sharma et al., 2024). Characterising which segments of the population understand, misunderstand, or “don’t know” relative risk information can inform targeted interventions to facilitate harm reduction or promote prevention.
Recent studies indicate that trends in consumers’ knowledge about the relative health risks of e-cigarettes and combustible cigarettes are declining. Population Assessment of Tobacco and Health (PATH) study findings indicate that the proportion of people who perceived e-cigarettes to be less harmful than combustible cigarettes has decreased (Bansal-Travers et al., 2025). These findings support earlier findings from studies that used data from the Health Information National Trends Survey (HINTS; Bandi et al., 2022), as well as longitudinal data from England (Jackson et al., 2024). Whereas these data are important indicators of relative risk and harm perceptions, none of these papers made “don’t know” response the focal point of their analyses.
The inclusion of “don’t know” responses on surveys could serve as a tool to identify knowledge gaps in older adults, individuals of lower socioeconomic status (SES), and other sub-populations regarding the risks of smoking and the benefits of cessation and harm-reduction strategies. Health decisions are often based on evaluating risks to benefits, and emerging evidence suggests that negative health outcomes can impact risk-reducing decisions (Waters et al., 2022). “Don’t know” responses can indicate limited knowledge of the subject area or health information avoidance and are often associated with marginalised socioeconomic groups (Waters et al., 2022). In cancer research, “don’t know” responses are associated with populations affected by health disparities, making them vulnerable to poor health outcomes (Waters et al., 2013). The analysis of “don’t know” responses on the relative risks of e-cigarettes and combustible cigarettes could serve as a critical indicator for targeted educational interventions. Given that understanding consumer risk perceptions is important, the goal of this paper was to explore sociodemographic differences in “don’t know” responses to a question about the relative risks of e-cigarettes compared to smoking using a population survey. These data are necessary to inform the regulation of nicotine products and begin the development of targeted educational programmes and interventions about the relative risks of nicotine and tobacco products with the goal of benefitting population health.
Methods
Participants and data source
The HINTS is a cross-sectional, nationally representative survey of adults aged 18 years or older administered by the US National Cancer Institute. HINTS 6 was conducted from March 2022 to November 2022 via US mail and used a sampling strategy to provide data for selected minority populations in both rural and urban geographic areas (National Cancer Institute, 2023). The use of weights and sampling strategy provides valid estimates of the target population and corrects for nonresponse and noncoverage bias (National Cancer Institute, 2023); details of this methodology have been previously described (National Cancer Institute, 2023). The HINTS 6 survey administration had an overall response rate for this administration of 28%, resulting in 6252 completed surveys. There were differences in response rate when stratified by minority status, but rural and urban geographic areas did not differ in this (National Cancer Institute, 2023).
Measures
Primary outcome variables
Perceived relative harms
Perceived harms of e-cigarettes relative to combustible cigarettes were assessed with one question, “Compared to smoking cigarettes, would you say that using e-cigarettes that contain nicotine is . . .?” Response options included much less harmful, less harmful, just as harmful, more harmful, much more harmful, but also the option to select “I don’t know.” Two variables were created; one to compare “don’t know” responses (coded as 1) with any other response (coded as 0). The other variable was coded such that “correct” responses (much less harmful, less harmful; coded as 1) and “incorrect” responses (just as harmful, more harmful, much more harmful; coded as 2) could be compared to “don’t know” responses (coded as 0; Yayan et al., 2024).
Covariates
Age
Age was a categorical variable, coded into four categories: 18–29 years, 30–49 years, 50–64 years, and 65 years and older.
Sex
Sex at birth was a binary variable with response options of male or female.
Race/ethnicity
Race was a categorical variable, coded into four categories: non-Hispanic White, non-Hispanic Black, Hispanic, and other.
Education
Education was a categorical variable, coded as less than a high school education, completed high school, completed some college education, or holds a college degree.
Perceived income
Perceptions about one’s income was assessed with the question, “Which one of these comes closest to your own feelings about your household’s income?” Response options included living comfortably on present income, getting by on present income, finding it difficult on present income, and finding it very difficult on present income. Perceived income was used as subjective social status may capture unique dimensions of resource security that are not fully captured in objective income measures alone (Cundiff, 2017; Singh-Manoux, 2003).
Combustible cigarette use
Smoking status was assessed with two questions, (1) “Have you smoked at least 100 cigarettes in your entire life?” and (2) “Do you now smoke cigarettes every day, some days, or not at all?” Participants were categorised as adults who had never smoked combustible cigarettes if they had never smoked at least 100 lifetime cigarettes; former adults who smoke combustible cigarettes if they had smoked 100 lifetime cigarettes but currently did not smoke; and current adults who smoke combustible cigarettes if they had smoked 100 lifetime cigarettes and currently smoked every day or some days.
E-cigarette use
E-cigarette use was assessed with two questions, (1) “Have you ever used an e-cigarette, even one or two times?” and (2) “Do you now use an e-cigarette every day, some days, or not at all?” Participants were categorised as an adult who never used an e-cigarette if they had never used an e-cigarette at least once; as an adult who formerly used an e-cigarette if they had ever used an e-cigarette, but not currently; and as an adult who currently used an e-cigarette if they had ever used an e-cigarette and currently used every day or some days.
Analysis
All analyses used Stata’s version 18 (College Station, TX) (StataCorp LP, 2023) survey analysis package with jackknife estimation weights provided with the HINTS dataset (National Cancer Institute, 2023). A multivariable logistic regression model was used to assess associations between “don’t know” responses (versus any other valid response) and sociodemographic characteristics. Odds ratios greater than 1.0 indicate an increased likelihood of reporting a “don’t know” response. Next, a multinomial regression model was used to assess factors associated with providing correct or incorrect harm perceptions relative to “don’t know” responses, with analyses segmented by cigarette smoking status (currently smoking, never smoked). Model 1 examined sociodemographic predictors, and models 2 and 3 additionally controlled for cigarette smoking and e-cigarette use, respectively. Significance for all models was determined by p-values < 0.05.
Ethical considerations
The HINTS 6 general population survey was designated “exempt research” under 45 CFR 46.104 and approved by the Westat Institutional Review Board on 10 May 2021 (Project # 6632.03.51), with a subsequent amendment approved on 24 November 2021 (Amendment ID #3597). HINTS 6 also received a “Not Human Subjects Research” determination from the US NIH Office of IRB Operations on 16 August 2021 (iRIS reference number: 562715).
Results
Descriptive analyses
Just over 20% of the analytic sample were adults aged 65 years or older. There was equal representation of males and females. More than half (62%) of participants were non-Hispanic White, one-third had a college degree, and just under 20% (18.4%) were finding it difficult or very difficult to get by financially. Characteristics of the sample can be found in Table 1.
Sample characteristics and “don’t know” responses by selected sociodemographic characteristics and cigarette and e-cigarette use status.
Each value is the percent within that category who responded “don’t know.”
Figure 1 shows responses to the relative risk question among the full sample of respondents. Overall, 38% (95% confidence interval [CI] = 35%, 40%) of all adults selected they “don’t know” the relative harms of cigarettes and e-cigarettes (see Figure 1). “Don’t know” prevalence increased with increasing age. Approximately 47% (95% CI = 44%, 50%) of older adults (aged 65 years or older) indicated they “don’t know” how the harm of e-cigarettes compares to the harm of cigarettes. In comparison, 25% (95% CI = 21%, 31%) of younger adults (18–34) indicated “don’t know.”
Responses to the survey question, “compared to smoking cigarettes, would you say that using e-cigarettes that contain nicotine is . . .?”
Focal analyses
Model 1 of the multivariable logistic regression examined sociodemographic predictors for responding “don’t know” to the relative harms of e-cigarettes compared to cigarette use. Participants aged 35–49 (adjusted odds ratio [AOR] = 2.16), 50–64 (AOR = 2.64), and 65 and older (AOR = 3.58), compared to 18- to 34-year-olds, had higher odds of selecting they “don’t know” how using e-cigarettes compares to smoking cigarettes (see Table 2, model 1). In addition, individuals identifying as non-Hispanic Black (AOR = 3.17), Hispanic (AOR = 1.87), and non-Hispanic another race (AOR = 1.82), compared to non-Hispanic White individuals, had higher odds of indicating “don’t know” responses. By contrast, participants with some college experience (AOR = 0.49) or a college education (AOR = 0.30) had lower odds of selecting “don’t know” responses than those with less than a high school degree, as did females (AOR = 0.81) compared to males. This pattern of findings held in adjusted models 2 and 3.
Adjusted odds ratios (AOR) of associations between “don’t know” responses and sociodemographic characteristics, combustible smoking, and e-cigarette use.
Note: AOR = adjusted odds ratio; CI = confidence interval; ref = referent group. Bold values indicate p < 0.05.
Model 2 adds combustible cigarette smoking to the demographics model. In model 2, former (AOR = 0.69) and current (AOR = 0.62) adults who smoke combustible cigarettes had lower odds of selecting a “don’t know” response than adults who never smoked combustible cigarettes (see Table 2, model 2). In addition, those finding it very difficult to get by financially had higher odds of selecting “don’t know” responses (AOR = 1.55; see Table 2, model 2).
Finally, model 3 added e-cigarette use to the previous model. In model 3, former (AOR = 0.38) and current (AOR = 0.18) adults who used an e-cigarette had lower odds of selecting a “don’t know” response than adults who never used an e-cigarette. Combustible cigarette smoking was no longer significant (p > 0.05) in model 3 when e-cigarette use was added to the model (see Table 2). The pattern of findings by sociodemographics, including age, race/ethnicity, college education, and perceived income, held in model 3.
The multinomial regression model, stratified by smoking status, examined factors associated with providing correct or incorrect harm perceptions relative to “don’t know” responses. Among people who currently smoked cigarettes, participants aged 35–49 (relative risk ratio [RRR] = 0.13) and 65+ (RRR = 0.16), compared to 18- to 34-year-olds, were less likely to provide an incorrect response rather than report a “don’t know” response (see Table 3). Participants who smoked cigarettes and had a high school education were also less likely to provide an incorrect response versus to report “don’t know” (RRR = 0.37), compared to those with less than a high school degree. In contrast, people who smoked but had never used e-cigarettes were less likely to provide a correct response rather than report a “don’t know” response than current e-cigarette users (RRR = 0.05; Table 3).
Relative risk ratios (RRR) of associations between correct and incorrect responses relative to “don’t know” responses, among people who currently smoke cigarettes.
Bold values indicate p < 0.05.
p < 0.05. **p < 0.01.
In multinomial regression models among people who never smoked cigarettes (Table 4), several demographic characteristics were associated with both correct and incorrect responses relative to “don’t know” responses. Compared with participants aged 18–34, all older age groups (35–49, 50–64, 65+) were less likely to provide either correct or incorrect responses versus reporting a “don’t know” response. Females who never smoked were less likely than males who never smoked to provide correct responses rather than provide a “don’t know” response (RRR = 0.52). Non-Hispanic Black (RRR = 0.096) and Hispanic (RRR = 0.23) participants were less likely to provide either correct or incorrect responses relative to “don’t know” responses, compared to non-Hispanic White participants. Higher educational attainment was associated with greater likelihood of providing incorrect responses versus reporting a “don’t know” response among those with some college education (RRR = 3.36) and a college degree (RRR = 5.25), compared to those with less than high school education. Finally, among people who never smoked cigarettes, people who never or formerly used e-cigarette were less likely than people who currently used e-cigarettes to provide either correct or incorrect responses rather than report a “don’t know” response (see Table 4).
Relative risk ratios (RRR) of associations between correct and incorrect responses relative to “don’t know” responses, among people who never smoked cigarettes.
Bold values indicate p < 0.05.
p < 0.05. **p < 0.01.
Discussion
This study examined the selection of “don’t know” responses among US adults when questioned about the relative harms of e-cigarettes compared to cigarettes. Previous work has highlighted that many US adults hold misperceptions about the relative risks of nicotine and tobacco products, holding misinformed beliefs that e-cigarettes are as harmful, or more harmful, as cigarettes (Bandi et al., 2022; Toll et al., 2024). Understanding “don’t know” responses can also be a vital means to identify knowledge gaps surrounding the risks of smoking and the benefits of cessation and alternate harm-reduction strategies. Whereas the current study aimed to understand “don’t know” responses among different age cohorts, there were other important demographic (i.e. race/ethnicity) and socioeconomic (i.e. perceived income) differences in adults who indicated that they “don’t know” the differences in harms related to combustible and electronic cigarettes. Results indicate that the prevalence of “don’t know” responses was greater in populations commonly affected by health disparities.
Results indicated that 38% of all US adults provided a response of “don’t know”; these “don’t know” responses increased with age. This is a substantial portion of US residents who do not understand the relative risks of nicotine products. Of course, a proportion of these individuals are never product users who would not have a reason to know about relative harms. This is consistent with the pattern that current users of both products are less likely to report “don’t know” responses, which may mean that relative risk messages are getting out to current product users. Interestingly, analyses limited to adults who smoke cigarettes revealed few reliable differences between those who reported “don’t know” compared to correct or incorrect responses. However, results suggest that messaging is failing to reach certain demographics facing nicotine and tobacco-related disparities. Specifically, individuals of older age, Hispanic and non-White racial backgrounds, and those experiencing significant financial hardship were more likely to respond with “don’t know.” This is notable given that these sociodemographic predictors stayed consistent even when controlling for current cigarette smoking and e-cigarette use in the fully adjusted models (i.e. models 2 and 3). These findings dovetail with those of Snell et al. (2025), who found that lower SES individuals, and those identifying as Black or African American, were more likely to perceive e-cigarettes as equally or more harmful than cigarettes (Harlow et al., 2023; Snell et al., 2025). Importantly, those who perceive products as less harmful are more likely to switch to them (Harlow et al., 2023; Sharma et al., 2024); together, these findings emphasise the importance of communicating reduced-risk messages to adults who smoke combustible cigarettes, especially those within the Black, Hispanic, and lower SES communities.
Our findings are also consistent with those of a recent International Tobacco Control (ITC) Four Country Smoking and Vaping Survey study examining whether knowledge of one’s vaping device predicted their knowledge of the relative risks of e-cigarettes compared to combustible cigarettes. Findings showed that those who were better informed about their vape device, such as those aged 18–39 years compared to 55+ years, were also better at discriminating against the relative risks of e-cigarettes and cigarettes (Felicione et al., 2021). Clearer and more complete product labelling may help product users understand both the device they are using and the harms relative to other products on the market (Felicione et al., 2021). Similar parallels about the need for clearer and complete communication about product relative risks were observed in the current study, particularly for populations that experience nicotine and tobacco-related health disparities.
Older adults and other minoritised populations were significantly less likely to respond that e-cigarettes are much less harmful or less harmful than cigarettes; however, they are not more likely to endorse inaccurate (i.e. same/more harmful) comparative harm perceptions. Instead, these groups were more likely to select “don’t know” responses. This suggests that this difference is driven by greater uncertainty rather than product misinformation. These findings have important implications for shaping the regulation of marketing and communication materials of nicotine and tobacco products to more effectively communicate risk and are consistent with recent efforts by the US Food and Drug Administration for adults who smoke cigarettes to understand the relative risks of nicotine and tobacco products (U.S. Food and Drug Administration, 2024). As health decisions are often based on evaluating risks to benefits (Waters et al., 2022), uncertainty around relative risks could negatively influence the adoption of lower-risk nicotine products (e.g. e-cigarettes instead of combustible cigarettes), further exacerbating health disparities among these populations (Harlow et al., 2023; Sharma et al., 2024). Indeed, we observed that among people who currently smoke cigarettes, those who never used e-cigarettes were less likely to select correct harm perceptions than “don’t know,” which reinforces evidence of the association between relative risk knowledge and product uptake.
It is possible the findings presented here are subject to measurement problems. Previous research by Churchill et al. (2020) has demonstrated that wording of questions can have an influential effect on responses and suggests that assessing comparative harms is best done through direct and indirect questioning; the results presented here use only a single direct question. In addition, future qualitative work should be undertaken to better understand what is meant when respondents provide a “don’t know” response or give a response of same or greater risk versus lower risk. One qualitative study of European Union residents indicates people who use e-cigarettes desire reassurance about the safety of the product (Ward et al., 2020). Healthcare providers should educate patients about the relative health risks of smoked versus nonsmoked nicotine/tobacco products, including the importance of an accurate understanding of the nicotine/tobacco harm continuum. Public health messages can support nicotine and tobacco cessation while also addressing uncertainty and misconceptions about the relative risks of different nicotine products, particularly among individuals with limited familiarity or firsthand product experience (Kulak et al., 2023). Public health messaging and e-cigarette marketing that focus on adult smokers using e-cigarettes as a tool to switch away from cigarettes, as opposed to materials depicting young adult use, may help influence risk perceptions and e-cigarette uptake among older adults.
Given that the prevalence of “don’t know” responses were greater in populations commonly affected by health disparities, including age, race, and perceived income, these findings highlight the need to recommit to eliminating health disparities in nicotine and tobacco research, policy, and practice. “Don’t know” responses can serve as an indicator of the need for targeted educational programmes and interventions. In fact, Meza et al. (2023) conclude that the greatest gains in reducing smoking-attributable morbidity and mortality would be made by focusing on lower SES adults. Current research and nicotine-cessation campaigns are predominately focused on younger populations (Meza et al., 2023); therefore, tailored educational actions and interventions specifically designed for older adults, individuals living at lower SES, or other marginalised communities would be highly beneficial and address a significant gap in current efforts.
Limitations
There are several limitations to this study that should be considered. First, we are unable to comment on temporality. For instance, current adults who used an e-cigarette were much less likely to provide “don’t know” responses; however, it is not known whether they use e-cigarettes because they first knew about relative harms, or if they learned about relative harms after they started using e-cigarettes. In addition, while we evaluated knowledge of relative product risks, we did not assess behavioural or health outcomes to evaluate how “don’t know” response may affect the likelihood of transitioning to reduced-risk products and subsequent changes in health.
Conclusion
This study is among the first to examine the selection of “don’t know” responses among US adults when questioned on the differences in harms related to combustible and electronic cigarettes. The prevalence of “don’t know” responses was greater in populations commonly affected by health disparities, including disparities by age, race, and perceived income. Health education interventions targeting understanding of the relative risks of e-cigarettes, compared to cigarettes, could serve as a vital tool to close the knowledge gaps that currently exist among older adults and other marginalised populations.
Footnotes
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
AI declaration
AI was not used in any way as part of the analyses reported here or in the preparation of this paper.