The Impact of Three Alternate Nicotine-Delivery Products on Combusted Cigarette Use: A Randomized Controlled Trial.

INTRODUCTION: Smoking cessation is a critical public health goal. This study examined the ability of e-cigarettes and very low nicotine cigarettes (VLNCs) to serve as cigarette substitutes and whether a substitution was supported by steady-state nicotine from a nicotine patch. AIMS AND METHODS: This mixed design experiment with study product (between-subjects) and patch (within-subjects) factors recruited adults smoking cigarettes daily and not motivated to quit (N = 160). Participants were randomized to 4 weeks of: (1) VLNCs; (2) e-cigarettes; or (3) no product. During two switch weeks, one with an active nicotine patch and one with a placebo patch (in a double-blind and counterbalanced fashion), participants were told to not smoke their usual cigarettes. RESULTS: During the switch weeks, participants in the VLNC (M = 2.88, SD = .65) and e-cigarette (M = 3.20, SD = .63) groups smoked fewer of their own cigarettes per day than did no product group participants who continued to smoke their own cigarettes (M = 5.48, SD = .63); the VLNC and e-cigarette groups did not differ. There was no main effect of patch on mean usual brand cigarettes smoked per day (P = .09), nor was there a product × patch interaction (P = .51). There was a product × age interaction (P = .03); smokers aged 60-74 smoked more of their own cigarettes if they were randomized to no product group. CONCLUSIONS: VLNCs and e-cigarettes appear to reduce usual brand cigarettes smoked per day to a similar degree, regardless of patch condition. Behavioral factors, in addition to nicotine dependence, play an important role in sustaining smoking behavior and need to be addressed in smoking cessation treatment. IMPLICATIONS: This study found that behavioral substitutes for cigarettes, whether or not they delivered nicotine, reduced the number of usual brand cigarettes smoked. Specifically, both e-cigarettes delivering nicotine and VLNCs equally reduce usual brand cigarettes smoked among adults who smoke daily and do not want to quit.

Effects of Very Low Nicotine Content Cigarettes and Nicotine Vaping Device Characteristics on Choices to Smoke, Vape, or Abstain in Early Young Adults.

INTRODUCTION: A national nicotine reduction policy could reduce the public health toll of smoking. However, reducing nicotine in cigarettes may lead to changes in the use of other tobacco products such as nicotine vaping devices, particularly among young people. Product use outcomes may depend on characteristics of available nicotine vaping devices. We aimed to determine the impact of cigarette nicotine content, vaping device nicotine concentration, and vaping device flavors on choices to smoke, vape, or abstain. METHODS: Early young adults (ages 18-20 inclusive, N=80) who reported smoking daily and vaping nicotine at least twice in their lifetime participated in a laboratory study. Participants received either Very Low Nicotine Content (VLNC; 0.4 mg nicotine/g of tobacco) or Normal Nicotine Content (NNC; 15.8 mg/g) cigarettes. First, participants chose between their assigned cigarette or abstaining. Subsequently, participants chose between 2 cigarette puffs, 2 vape puffs, or abstaining. Vaping device nicotine concentration (3mg vs. 18mg/ml) and flavor (tobacco vs. non-tobacco) were manipulated within-subjects. RESULTS: When only cigarettes were available, there were no differences between the VLNC and NNC groups on cigarette choices. When the nicotine vaping device was concurrently available, the VLNC group made fewer choices to smoke than the NNC group. Non-tobacco flavors and lower vaping device nicotine concentration were associated with fewer choices to smoke. CONCLUSIONS: Nicotine vaping device availability reduced choices to smoke VLNC cigarettes, and vaping devices with lower nicotine and non-tobacco flavors led to the fewest choices to smoke. Regulators should consider that the availability and characteristics of alternative tobacco products can moderate the product standard's impact. IMPLICATIONS: The U.S. Food and Drug Administration may enact a reduced nicotine product standard that would affect all commercially-available cigarettes. One important population affected by this policy would be early young adults who smoke. We aimed to determine the impact of cigarette nicotine content, vaping device nicotine concentration, and vaping device flavors on choices to smoke, vape, or abstain. Lower nicotine in cigarettes, along with non-tobacco flavors and lower nicotine concentration in the vaping device, were associated with the fewest choices to smoke. Regulators should consider that the availability and characteristics of alternative tobacco products can moderate the product standard's impact.

Immediate Switching to Reduced Nicotine Cigarettes in a U.S.-Based Sample: The Impact on Cannabis Use and Related Variables at 20 Weeks.

INTRODUCTION: The FDA proposed rule-making to reduce nicotine in cigarettes to minimally addictive levels. Research suggests decreasing nicotine levels (i.e. very low nicotine content cigarettes [VLNCs]) produced greater quit attempts, reduced smoking, and reduced exposure to harmful constituents among smokers. The impact of long-term VLNC use among people who co-use cigarettes and cannabis on non-tobacco-specific toxicant and carcinogen exposure has not been investigated. AIMS AND METHODS: This study presents secondary analyses of a controlled clinical trial examining switching to VLNC (versus a normal nicotine cigarettes control group [NNCs]) between people who co-use cigarettes and cannabis (n = 174) versus smoked cigarettes (n = 555). Linear mixed-effects models compared changes in smoking behavior, and tobacco-specific (i.e. total nicotine equivalents [TNE], 4-[methylnitrosamino]-1-[3-pyridyl]-1-butanone [NNK; total NNAL]) and non-tobacco-specific (i.e. carbon monoxide (CO), 2-cyanoethylmercapturic acid [CEMA], phenanthrene tetraol [PheT]) toxicant and carcinogen exposure at week 20 (with random intercept for participants). Cannabis use was measured among co-use groups. RESULTS: CO was significantly lower only among the cigarette-only group assigned VLNCs (interaction: p = .015). Although both VLNC groups demonstrated decreased CEMA, greater decreases emerged among the cigarette-only group (interaction: p = .016). No significant interactions emerged for TNE, cigarettes per day (CPD), NNAL, and PheT (ps > .05); both VLNC groups decreased in TNE, CPD, and NNAL. Only the cigarette-only group assigned VLNCs demonstrated decreased PheT (p < .001). The VLNC co-use group showed increased cannabis use over time (p = .012; 0.5 more days per week by week 20). CONCLUSIONS: Those who co-use cannabis and cigarettes may still be at risk for greater exposure to non-tobacco-specific toxicants and carcinogens compared to those who only smoke cigarettes. IMPLICATIONS: The present study is the longest longitudinal, prospective comparison study of smoking behavior and exposure to harmful constituents among those who co-use cigarettes and cannabis versus cigarette-only after immediately switching to very low nicotine content cigarettes (VLNC). Those who co-use experienced similar reductions in CPD and tobacco-specific exposure, compared to those who only use cigarettes. However, co-use groups experienced smaller reductions in non-tobacco-specific toxicants and carcinogens compared to the cigarette-only group, potentially because of combustible cannabis use. Additionally, those who co-use and switched to VLNC may be susceptible to slight increases in cannabis use (approximately two more days per year).

Effect of nicotine corrective messaging on nicotine-related beliefs in US adults: a randomised controlled trial.

INTRODUCTION: Widespread misperceptions of the health risks of nicotine could undermine the public health benefits of the Food and Drug Administration's actions, including modified risk tobacco product authorisations and a reduced nicotine product standard for cigarettes. METHODS: 794 US adults (aged 18+) in NORC's AmeriSpeak panel participated in a randomised controlled trial in Spring 2021 to test the effect of three exposures to eight nicotine corrective messages (NCM) on beliefs about nicotine, nicotine replacement therapy (NRT), e-cigarettes and reduced nicotine content (RNC) cigarettes at 3-month follow-up. Analyses conducted in 2022 examined the effect of study condition (NCM (n=393) vs no message control (n=401)) on nicotine beliefs, use intentions and use of nicotine and tobacco products. RESULTS: Exposure to three NCM doses reduced nicotine (b=-0.33; 95% CI -0.60, -0.07), NRT (b=-0.49; 95% CI -0.85, -0.14), e-cigarette (b=-0.32; 95% CI -0.59, -0.05) and RNC cigarette false beliefs (b=-0.64; 95% CI -1.26, -0.02) compared with the control, controlling for baseline beliefs. Baseline tobacco use and concern about nicotine addiction attenuated intervention effects on false beliefs about RNC cigarettes. There were few intervention effects on intention or use of nicotine and tobacco products. CONCLUSIONS: Repeated exposure to NCM was necessary to reduce false beliefs about nicotine and tobacco products. Future studies will improve understanding of the dose and duration of nicotine education needed to shift intentions and behaviour, as well as tailored content for tobacco product users to achieve similar reductions in false beliefs as non-users. TRIAL REGISTRATION NUMBER: NCT04805515.

Effects of advertising features on smokers' and non-smokers' perceptions of a reduced nicotine cigarette modified risk tobacco product.

INTRODUCTION: Research is needed to determine the impact of marketing on perceptions and use of reduced nicotine content (RNC) cigarettes, particularly as US regulators have permitted the sale of an RNC cigarette modified risk tobacco product (MRTP) that seeks further authorisation to advertise using modified risk claims. This study examined the effects of two advertising elements (product name and disclaimer content) on perceptions of an RNC cigarette MRTP. METHODS: Adult participants (n=807, 28.7% smokers, 58.2% male, 74.2% non-Latinx white) completed an online MTurk survey. Participants were randomised to view one of six RNC cigarette advertisements, using a 2×3 between-subject factorial design to manipulate product name ('Moonlight' vs 'Moonrise') and disclaimer content (industry-proposed: 'Nicotine is addictive. Less nicotine does NOT mean a safer cigarette' vs focused: 'Less nicotine does NOT mean a safer cigarette' vs no content), then completed recall and product perception questionnaires. RESULTS: All participants who viewed the industry-proposed disclaimer (vs no content) perceived greater addiction risk (p's<0.05). Non-smokers who viewed this disclaimer also perceived greater health risks and held fewer false beliefs (p's<0.05). Smokers who viewed Moonlight (vs Moonrise) ads perceived lower health risks (p<0.05). CONCLUSIONS: Disclaimer content may effectively inform consumers about addiction risk of a new RNC cigarette MRTP, and further inform non-smokers about health risks. This element, however, had little effect on perceived health risks among smokers, among whom the Moonlight product name was associated with health risk misperceptions similar to the banned 'light' descriptor.

Dynamic borrowing in the presence of treatment effect heterogeneity.

A number of statistical approaches have been proposed for incorporating supplemental information in randomized clinical trials. Existing methods often compare the marginal treatment effects to evaluate the degree of consistency between sources. Dissimilar marginal treatment effects would either lead to increased bias or down-weighting of the supplemental data. This represents a limitation in the presence of treatment effect heterogeneity, in which case the marginal treatment effect may differ between the sources solely due to differences between the study populations. We introduce the concept of covariate-adjusted exchangeability, in which differences in the marginal treatment effect can be explained by differences in the distributions of the effect modifiers. The potential outcomes framework is used to conceptualize covariate-adjusted and marginal exchangeability. We utilize a linear model and the existing multisource exchangeability models framework to facilitate borrowing when marginal treatment effects are dissimilar but covariate-adjusted exchangeability holds. We investigate the operating characteristics of our method using simulations. We also illustrate our method using data from two clinical trials of very low nicotine content cigarettes. Our method has the ability to incorporate supplemental information in a wider variety of situations than when only marginal exchangeability is considered.

A Bayesian hierarchical model for individual participant data meta-analysis of demand curves.

Individual participant data meta-analysis is a frequently used method to combine and contrast data from multiple independent studies. Bayesian hierarchical models are increasingly used to appropriately take into account potential heterogeneity between studies. In this paper, we propose a Bayesian hierarchical model for individual participant data generated from the Cigarette Purchase Task (CPT). Data from the CPT details how demand for cigarettes varies as a function of price, which is usually described as an exponential demand curve. As opposed to the conventional random-effects meta-analysis methods, Bayesian hierarchical models are able to estimate both the study-specific and population-level parameters simultaneously without relying on the normality assumptions. We applied the proposed model to a meta-analysis with baseline CPT data from six studies and compared the results from the proposed model and a two-step conventional random-effects meta-analysis approach. We conducted extensive simulation studies to investigate the performance of the proposed approach and discussed the benefits of using the Bayesian hierarchical model for individual participant data meta-analysis of demand curves.

Preliminary evidence on cigarette nicotine reduction with concurrent access to an e-cigarette: Manipulating cigarette nicotine content, e-liquid nicotine content, and e-liquid flavor availability.

The reinforcing characteristics of e-cigarettes could moderate the impact of reducing cigarette nicotine content. In this study, people who smoke daily were recruited from North Carolina and Pennsylvania (US) in 2018 and 2019. Within a randomized 2 × 2 × 2 factorial design, participants received investigational cigarettes and an e-cigarette for 12 weeks. Cigarette nicotine content was very low (0.4 mg/g of tobacco; VLNC) or normal (15.8 mg/g; NNC). E-liquids were 0.3% ("low") or 1.8% ("moderate") freebase nicotine, and available in tobacco flavors or tobacco, fruit, dessert and mint flavors. Study recruitment concluded before reaching the planned sample size (N = 480). Fifty participants were randomized and 32 completed the study. We found that randomization to VLNC, relative to NNC cigarettes, reduced self-reported cigarettes per day (CPD; mean difference: -12.96; 95% CI: -21.51, -4.41; p = 0.005); whereas e-liquid nicotine content and flavor availability did not have significant effects. The effect of cigarette nicotine content was larger in the moderate vs. low nicotine e-liquid groups and in the all flavors versus tobacco flavors e-liquid groups; tests of the interaction between e-liquid characteristics and cigarette nicotine content were not significant. Biomarkers of smoke exposure at Week 12 did not differ across conditions, which may reflect variability in adherence to only using VLNC cigarettes. In conclusion this study offers preliminary evidence that the extent to which cigarette nicotine reduction decreases smoking may depend on the reinforcing characteristics of alternative products, including the available nicotine contents and flavors of e-cigarettes.

Centering racial justice for Black/African American and Indigenous American people in commercial tobacco product regulation.

Although overall health in the United States (US) has improved dramatically during the past century, long-standing health inequities, particularly the unequal and unjust burden of tobacco-related disease and death among racialized populations, persist. A considerable gap exists in our understanding of how commercial tobacco product regulations and policies cause and/or exacerbate race-based health inequities among Black/African American (B/AA) and Indigenous American people. The purpose of this paper is to 1) describe how existing US commercial tobacco regulatory policies may contribute to structural racism and undermine the full benefits of tobacco prevention and control efforts among B/AA and Indigenous American groups; and 2) initiate a call to action for researchers and regulators of tobacco products to examine policies using an equity lens. These actions are imperative if empirically-informed regulation of commercial tobacco products is to address health equity.

Smoking abstinence and cessation-related outcomes one month after an immediate versus gradual reduction in nicotine content of cigarettes.

The United States Food and Drug Administration has the authority to reduce the nicotine content in cigarettes to minimal or non-addictive levels and could do so immediately or gradually over time. A large clinical trial compared the two approaches. This secondary analysis assesses abstinence and cessation-related outcomes one month after the trial concluded, when participants no longer had access to very low nicotine content (VLNC) research cigarettes. Smokers not interested in quitting (N = 1250) were recruited for the parent trial from 2014 to 2016 across 10 sites throughout the US and randomized to a 20-week study period during which they immediately switched to VLNC cigarettes, gradually transitioned to VLNC cigarettes with five monthly dose reductions, or smoked normal nicotine research cigarettes (control). At the one-month follow-up, both immediate and gradual reduction resulted in greater mean cigarette-free days (4.7 and 4.6 respectively) than the control group (3.2, both p < .05). Immediate reduction resulted in fewer mean cigarettes per day (CPD = 10.3) and lower Fagerström Test for Cigarette Dependence (FTCD = 3.7) than the gradual (CPD = 11.7, p = .001; FTCD = 3.8, p = .039) and control (CPD = 13.5, p < .001; FTCD = 4.0, p < .001) groups. Compared to controls, gradual reduction resulted in reduced CPD (p = .012) but not FTCD (p = .13). Differences in CO-verified 7-day point-prevalence abstinence were not significant. Findings demonstrate that switching to VLNC cigarettes resulted in reduced smoking and nicotine dependence severity that was sustained for at least a month after the VLNC trial period in smokers who were not interested in cessation. The greatest harm reduction endpoints were observed in those who immediately transitioned to VLNC cigarettes.

Educating the Public on the Health Risks of Very Low Nicotine Content Cigarettes: Results From a US-Based Convenience Sample.

INTRODUCTION: US FDA issued an advance notice of proposed rulemaking to reduce nicotine in cigarettes. To maximize the benefits of this potential standard, very low nicotine content (VLNC) cigarettes must be communicated in a way that does not result in misperceptions. AIMS AND METHODS: Adults (n = 567 who smoke; n = 610 non-smokers) from an online platform were randomized to a control message previously associated with accurate addictiveness perceptions of VLNC cigarettes but health misperceptions or to one of five messages that also included messaging on nicotine morbidity effects or VLNC cigarettes morbidity or mortality effects. p value <.01 was significant. RESULTS: In participants who smoke, perceived lung cancer risk (responses: 1, very little risk to 10, very high risk) if smoked VLNC cigarettes regularly was higher in conditions that communicated mortality effects of VLNC cigarettes compared to the control (7.12-7.18 vs. 5.97, p values < .01). In non-smokers, perceived lung cancer risk was higher in all five message conditions when compared with the control (7.58-8.22 vs. 6.35, p values < .01). Proportion who responded accurately (ie, False) to the statement Cigarettes with 95% less nicotine are safer than cigarettes with normal nicotine levels was higher in conditions describing VLNC morbidity or mortality effects when compared with the control in both participants who smoke (52.04-67.37% vs. 30.85%, p values < .01) and do not smoke (62.50-72.38% vs. 32.00%, p values < .01). CONCLUSIONS: Messaging on mortality effects of VLNC cigarettes (ie, cigarettes with 95% less nicotine are as deadly as current cigarettes) was associated with more accurate perceptions of the health risks of VLNC cigarettes than the control; however, misperceptions remained in one-third of participants. IMPLICATIONS: One approach to communicating a VLNC cigarette standard to the public is to include messaging on the mortality effects of VLNC cigarettes. However, further study and possible refinement of this message condition are recommended since approximately one-third of participants exposed to this message still perceived VLNC cigarettes to be safer than normal nicotine content cigarettes.

Reappraising Choice in Addiction: Novel Conceptualizations and Treatments for Tobacco Use Disorder.

The introduction of alternative nicotine and tobacco products (such as e-cigarettes, heat-not-burn devices, nicotine pouches) warrants an updated framework from which to conceptualize tobacco use disorder (TUD). The following review provides considerations for TUD within the context of novel products. Historically, the tobacco industry falsely claimed that cigarettes were not addictive or harmful and that those who smoked simply chose to do so. This generated an inaccurate lay perception that smoking is a free or informed choice. Research on nicotine pharmacology demonstrates the powerful addictive potential of nicotine, which is shaped by dose, speed of delivery, and other constituents generated. In addition, non-pharmacologic reinforcers motivate and maintain tobacco use behaviors for both traditional cigarettes and novel products. The negative consequences of combustible tobacco use are well known; however, these outcomes may differ for alternative products. Strategies used for combustible product cessation may be adapted for novel products, and treatment recommendations for TUD should be made within the context of a harm reduction framework wherein alternative product use may be the desired outcome. Providers must therefore be willing to modify their perceptions of products and treatment recommendations accordingly. Better public health outcomes are accomplished through promotion of abstinence from combustible smoking. For those who cannot wean from nicotine entirely, switching to less risky modes of delivery might be a secondary goal, with an eventual aim of stopping use of the alternative product. Implications: Given the advent of novel, alternative tobacco products, tobacco use disorder (TUD) must be conceptualized within a contemporary framework that includes harm reduction and alternative outcomes. The unique contributions of nicotine pharmacology, non-pharmacologic reinforcers, and consequences of use can be used to inform treatments for TUD with the ultimate goal of improving the health of individuals who use tobacco.

Early Changes in Puffing Intensity When Exclusively Using Open-Label Very Low Nicotine Content Cigarettes.

INTRODUCTION: In response to reducing cigarette nicotine content, people who smoke could attempt to compensate by using more cigarettes or by puffing on individual cigarettes with greater intensity. Such behaviors may be especially likely under conditions where normal nicotine content (NNC) cigarettes are not readily accessible. The current within-subject, residential study investigated whether puffing intensity increased with very low nicotine content (VLNC) cigarette use, relative to NNC cigarette use, when no other nicotine products were available. AIMS AND METHODS: Sixteen adults who smoke daily completed two four-night hotel stays in Charleston, South Carolina (United States) in 2018 during which only NNC or only VLNC cigarettes were accessible. We collected the filters from all smoked cigarettes and measured the deposited solanesol to estimate mouth-level nicotine delivery per cigarette. These estimates were averaged within and across participants, per each 24-h period. We then compared the ratio of participant-smoked VLNC and NNC cigarette mouth-level nicotine with the ratio yielded by cigarette smoking machines (when puffing intensity is constant). RESULTS: Average mouth-level nicotine estimates from cigarettes smoked during the hotel stays indicate participants puffed VLNC cigarettes with greater intensity than NNC cigarettes in each respective 24-h period. However, this effect diminished over time (p < .001). Specifically, VLNC puffing intensity was 40.0% (95% CI: 29.9, 53.0) greater than NNC puffing intensity in the first period, and 16.1% (95% CI: 6.9, 26.0) greater in the fourth period. CONCLUSION: Average puffing intensity per cigarette was elevated with exclusive VLNC cigarette use, but the extent of this effect declined across four days. IMPLICATIONS: In an environment where no other sources of nicotine are available, people who smoke daily may initially attempt to compensate for cigarette nicotine reduction by puffing on individual cigarettes with greater intensity. Ultimately, the compensatory behavior changes required to achieve usual nicotine intake from VLNC cigarettes are drastic and unrealistic. Accordingly, people are unlikely to sustain attempts to compensate for very low cigarette nicotine content.

Responses to Gradual and Immediate Reduction of Nicotine in Cigarettes in Young Versus Older Adult Smokers.

INTRODUCTION: As the FDA works to determine whether a nicotine reduction policy would benefit public health, one key question is whether to mandate an immediate or gradual reduction in nicotine levels in cigarettes. The aim of this study was to determine whether the effects of gradual versus immediate nicotine reduction on cigarettes per day (CPD), total nicotine equivalents, and subjective responses differed in younger adults versus older adults. METHODS: Using data from a recent randomized trial conducted in the United States (N = 1250) that switched smokers over a 20-week period to very low nicotine content (VLNC) cigarettes either immediately, gradually (via monthly reductions in nicotine content), or not at all (control condition, normal nicotine content research cigarette), we analyzed the moderating effect of age (age 18-24 or 25+). RESULTS: For both age groups, CPD in the immediate condition was significantly lower relative to gradual condition (estimated mean difference of 6.3 CPD in young adults, 5.2 CPD in older adults; p's < .05). Younger and older adults in the immediate and gradual reduction conditions had lower total nicotine equivalents at Week 20 (all p's < .05) than those in the control condition; age group did not moderate this effect. Positive subjective responses to cigarettes were lower among young adults relative to older adults in the immediate condition. CONCLUSIONS: These results indicate that an immediate reduction in nicotine would result in beneficial effects in both young and older adults. Young adults show less positive subjective effects of smoking following switching to VLNC cigarettes relative to older adults. IMPLICATIONS: As researchers work to understand how a potential reduced-nicotine product standard for cigarettes may affect public health, one question is whether nicotine should be reduced immediately or gradually. This study demonstrates that both young and older adults who were switched immediately to the lowest content of nicotine smoked fewer CPD and had lower nicotine intake than those in the gradual condition. Furthermore, young adults appear to show lower positive subjective effects following switching to VLNC cigarettes relative to older adults. This is consistent with previous work demonstrating that young people appear to show lower abuse liability for VLNC cigarettes.

An Evaluation of Potential Unintended Consequences of a Nicotine Product Standard: A Focus on Drinking History and Outcomes.

INTRODUCTION: A nicotine product standard reducing the nicotine content in cigarettes could improve public health by reducing smoking. This study evaluated the potential unintended consequences of a reduced nicotine product standard by examining its effects on (1) smoking behaviors based on drinking history; (2) drinking behavior; and (3) daily associations between smoking and drinking. METHODS: Adults who smoke daily (n = 752) in the United States were randomly assigned to smoke very low nicotine content (VLNC) cigarettes versus normal nicotine content (NNC; control) cigarettes for 20 weeks. Linear mixed models determined if baseline drinking moderated the effects of VLNC versus NNC cigarettes on Week 20 smoking outcomes. Time-varying effect models estimated the daily association between smoking VLNC cigarettes and drinking outcomes. RESULTS: Higher baseline alcohol use (vs no use or lower use) was associated with a smaller effect of VLNC on Week 20 urinary total nicotine equivalents (ps < .05). No additional moderation was supported (ps > .05). In the subsample who drank (n = 415), in the VLNC versus NNC condition, daily alcohol use was significantly reduced from Weeks 17 to 20 and odds of binge drinking were significantly reduced from Weeks 9 to 17. By Week 7, in the VLNC cigarette condition (n = 272), smoking no longer predicted alcohol use but remained associated with binge drinking. CONCLUSIONS: We did not support negative unintended consequences of a nicotine product standard. Nicotine reduction in cigarettes generally affected smoking behavior for individuals who do not drink or drink light-to-moderate amounts in similar ways. Extended VLNC cigarette use may improve public health by reducing drinking behavior. IMPLICATIONS: There was no evidence that a VLNC product standard would result in unintended consequences based on drinking history or when considering alcohol outcomes. Specifically, we found that a very low nicotine standard in cigarettes generally reduces smoking outcomes for those who do not drink and those who drink light-to-moderate amounts. Furthermore, an added public health benefit of a very low nicotine standard for cigarettes could be a reduction in alcohol use and binge drinking over time. Finally, smoking VLNC cigarettes may result in a decoupling of the daily associations between smoking and drinking.

Detecting participant noncompliance across multiple time points by modeling a longitudinal biomarker.

INTRODUCTION: Participant noncompliance, in which participants do not follow their assigned treatment protocol, has long complicated the interpretation of randomized clinical trials. No gold standard has been identified for detecting noncompliance, but in some trials participants' biomarkers can provide objective information that suggests exposure to non-study treatments. However, existing methods are limited to retrospectively detecting noncompliance at a single time point based on a single biomarker measurement. We propose a novel method that can leverage participants' full biomarker history to detect noncompliance across multiple time points. Conditional on longitudinal biomarker data, our method can estimate the probability of compliance at (1) a single time point of the trial, (2) all time points, and (3) a future time point. METHODS: Across time points, we model the biomarker as a mixture density with (latent) components corresponding to longitudinal patterns of compliance. To estimate the mixture density, we fit mixed effects models for both compliance and the biomarker. We use the mixture density to derive compliance probabilities that condition on the longitudinal biomarker data. We evaluate our compliance probabilities by simulation and apply them to a trial in which current smokers were asked to only smoke low nicotine study cigarettes (Center for the Evaluation of Nicotine in Cigarettes Project 1 Study 2). In the simulation, we investigated three different effects of compliance on the biomarker, as well as the effect of misspecification of the covariance structures. We compared probability estimators (1) and (2) to those that ignore the longitudinal correlation in the data according to area under the receiver operating characteristic curve. We evaluated estimator (3) by plotting its calibration lines. For Center for the Evaluation of Nicotine in Cigarettes Project 1 Study 2, we compared estimators (1) and (3) to a probability estimator of compliance at the last time point that ignores the longitudinal correlation. RESULTS: In the simulation, for both compliance at the last time point and at all time points, conditioning on the longitudinal biomarker data uniformly raised area under the receiver operating characteristic curve across all three compliance effect scenarios. The gains in area under the receiver operating characteristic curve were smaller under misspecification. The calibration lines for the prediction of compliance closely followed 45°, though with additional variability under misspecification. For compliance at the last time point of Center for the Evaluation of Nicotine in Cigarettes Project 1 Study 2, conditioning on participants' full biomarker history boosted area under the receiver operating characteristic curve by three percentage points. The prediction probabilities somewhat accurately approximated the non-longitudinal compliance probabilities. DISCUSSION: Compared to existing methods that only use a single biomarker measurement, our method can account for the longitudinal correlation in the biomarker and compliance to more accurately identify noncompliant participants. Our method can also use participants' biomarker history to predict compliance at a future time point.

A mixed effects model for analyzing area under the curve of longitudinally measured biomarkers with missing data.

A simple approach for analyzing longitudinally measured biomarkers is to calculate summary measures such as the area under the curve (AUC) for each individual and then compare the mean AUC between treatment groups using methods such as t test. This two-step approach is difficult to implement when there are missing data since the AUC cannot be directly calculated for individuals with missing measurements. Simple methods for dealing with missing data include the complete case analysis and imputation. A recent study showed that the estimated mean AUC difference between treatment groups based on the linear mixed model (LMM), rather than on individually calculated AUCs by simple imputation, has negligible bias under random missing assumptions and only small bias when missing is not at random. However, this model assumes the outcome to be normally distributed, which is often violated in biomarker data. In this paper, we propose to use a LMM on log-transformed biomarkers, based on which statistical inference for the ratio, rather than difference, of AUC between treatment groups is provided. The proposed method can not only handle the potential baseline imbalance in a randomized trail but also circumvent the estimation of the nuisance variance parameters in the log-normal model. The proposed model is applied to a recently completed large randomized trial studying the effect of nicotine reduction on biomarker exposure of smokers.

Biopsychosocial mechanisms associated with tobacco use in smokers with and without serious mental illness.

Smokers with serious mental illness (SMI) are less responsive to cessation treatments than those without SMI. In this study, we compared smokers with and without SMI on validated measures of biological and psychosocial factors associated with tobacco use. Smokers with (n = 58) and without SMI (n = 83) who were enrolled in parallel clinical trials were compared on measures of carbon monoxide (CO) exposure, nicotine exposure, tobacco-specific nitrosamine exposure, craving, smoking motives, affect, perceived stress, environmental exposure to smoke/smokers, respiratory symptoms, tobacco-related health risk perceptions, and whether they had received recent advice to quit smoking from a health care provider. Data were collected between 2013 and 2017 in Providence, Rhode Island, USA. Samples were compared using independent-sample t-tests and chi-squared tests. Smokers with SMI had higher CO, nicotine, and tobacco-specific nitrosamine exposure levels, greater cigarette dependence, higher craving, and higher scores on eight out of eleven smoking motives (p's < 0.05). Smokers with SMI reported more severe respiratory symptoms but lower perceived health risks of tobacco (p's < 0.05). These smokers were more likely to report having received advice to quit from a medical provider in the past 6 weeks (p < 0.05). Affect, stress, and exposure to smoke/smokers did not differ across samples. Our findings advance the understanding of the elevated smoking rates of people with SMI by comparing smokers with and without SMI on validated biopsychosocial measures. There is a need for interventions that reduce craving, reduce smoking motives, and increase risk awareness among smokers with SMI.

Nicotine Self-administration Is Not Increased in the Methylazoxymethanol Acetate Rodent Model of Schizophrenia.

INTRODUCTION: Patients with schizophrenia (SCZ) smoke at a rate of 4-5 times higher than the general population, contributing to negative health consequences in this group. One possible explanation for this increased smoking is that individuals with SCZ find nicotine (NIC) more reinforcing. However, data supporting this possibility are limited. METHODS: The present experiments examined self-administration of NIC, alone or in combination with other reinforcers, across a range of doses in the methylazoxymethanol acetate (MAM) rodent model of SCZ. RESULTS: MAM and control animals did not differ in NIC self-administration across a range of doses and schedules of reinforcement, in both standard 1-hour self-administration sessions and 23-hour extended access sessions. However, MAM animals responded less for sucrose or reinforcing visual stimuli alone or when paired with NIC. CONCLUSIONS: To the extent that MAM-treated rats are a valid model of SCZ, these results suggest that increased NIC reinforcement does not account for increased smoking in SCZ patients. IMPLICATIONS: This study is the first to utilize nicotine self-administration, the gold standard for studying nicotine reinforcement, in the methylazoxymethanol acetate model of schizophrenia, which is arguably the most comprehensive animal model of the disease currently available. Our assessment found no evidence of increased nicotine reinforcement in methylazoxymethanol acetate animals, suggesting that increased reinforcement may not perpetuate increased smoking in schizophrenia patients.

Smoking Topography Characteristics During a 6-Week Trial of Very Low Nicotine Content Cigarettes in Smokers With Serious Mental Illness.

INTRODUCTION: A nicotine-reduction policy could have major benefits for smokers with serious mental illness (SMI). However, potential unintended consequences, such as compensatory smoking, should be considered to ensure that such a policy does not negatively affect this population. The purpose of this secondary analysis was to examine the impact of smoking very low nicotine content (VLNC) cigarettes for 6 weeks on smoking topography characteristics, indicators of compensatory smoking, among smokers with SMI. AIMS AND METHODS: After a baseline usual brand smoking phase, smokers with SMI (N = 58) were randomly assigned under double-blind conditions to receive either VLNC (0.4 mg nicotine per g tobacco) or normal nicotine content (NNC; 15.8 mg nicotine per g tobacco) research cigarettes for 6 weeks. During two study visits scheduled 6 weeks apart, participants smoked either their usual brand (baseline) or assigned study cigarettes (postrandomization) through a handheld smoking topography device. Univariate analysis of variance compared smoking topography indices with cigarette condition (VLNC vs. NNC) as the between-subjects factor with corresponding baseline topography results included as covariates. RESULTS: At week 6, participants in the VLNC condition smoked fewer puffs per cigarette and had shorter interpuff intervals compared to participants in the NNC condition (ps < .05). There were no differences between research cigarette conditions at week 6 for cigarette volume, puff volume, puff duration, peak flow rate, or carbon monoxide boost. CONCLUSIONS: Findings are consistent with acute VLNC cigarette topography studies and indicate that a nicotine-reduction policy is unlikely to lead to compensation among smokers with SMI. IMPLICATIONS: Given the high smoking rates among people with SMI, understanding how a nicotine-reduction policy may affect this population is critically important. When considering the smoking topography results as a whole, smokers with SMI did not engage in compensatory smoking behavior when using VLNC cigarettes during a 6-week trial. Study findings suggest that compensatory smoking is not likely to occur among smokers with SMI if nicotine content is lowered to minimally addictive levels.