Leveraging the cigarette purchase task to understand relationships between cumulative vulnerabilities, the relative reinforcing effects of smoking, and response to reduced nicotine content cigarettes.

We examined if the relative-reinforcing effects of smoking increase with greater cumulative vulnerability and whether cumulative vulnerability moderates response to reduced nicotine content cigarettes. Participants were 775 adults from randomized clinical trials evaluating research cigarettes differing in nicotine content (0.4, 2.4, 15.8 mg/g). Participants were categorized as having low (0-1), moderate (2-3), or high (≥4) cumulative vulnerability. Vulnerabilities included rural residence, opioid use disorder, affective disorder, low educational attainment, poverty, unemployment, and physical disability. We used the cigarette purchase task (CPT) to assess the relative-reinforcing effects of participants' usual-brand cigarettes at baseline and study cigarettes during the 12-week trial. The CPT is a behavioral-economic task wherein participants estimate likely smoking (demand) over 24 h under escalating cigarette price. Demand is characterized by two factors: Amplitude (demand volume at zero/minimal price) and Persistence (demand sensitivity to price). Greater cumulative vulnerability was associated with greater demand Amplitude (F[2709] = 16.04,p < .0001) and Persistence (F[2709] = 8.35,p = .0003) for usual-brand cigarettes. Demand Amplitude for study cigarettes increased with increasing cumulative vulnerability (F[2619] = 19.59, p < .001) and decreased with decreasing nicotine content ([4879] = 5.45, p < .001). The only evidence of moderation was on demand Persistence (F[8867] = 2.00,p = .04), with larger reductions at the 0.4 mg/g compared to 15.8 mg/g doses among participants with low compared to moderate or high cumulative vulnerability. The relative-reinforcing effects of smoking clearly increase with greater cumulative vulnerability. Reducing nicotine content would likely reduce demand Amplitude across cumulative-vulnerability levels but reductions in demand Persistence may be more limited among those with greater cumulative vulnerability.

Cumulative vulnerabilities as a potential moderator of response to reduced nicotine content cigarettes.

Risk for smoking increases in a summative manner corresponding to the number of co-occurring vulnerabilities present (cumulative vulnerability). We examined whether cumulative vulnerabilities moderate response to reduced nicotine content cigarettes in a secondary analysis of results from 775 participants in three 12-week randomized clinical trials examining research cigarettes varying in nicotine content (0.4, 2.4, 15.8 mg nicotine/g tobacco). Participants were categorized as having 0-1, 2-3, or ≥ 4 cumulative vulnerabilities. Vulnerabilities included: rural residence, current substance use disorder, current affective disorder, low educational attainment, poverty, unemployment, physical disability. The primary outcome was total cigarettes per day (CPD) during Week 12; secondary outcomes included CPD across weeks, toxin exposure, dependence severity, craving/withdrawal (17 dependent measures). Results were analyzed using repeated measures analysis of covariance and growth-curve modeling. Total CPD during Week 12 increased as cumulative-vulnerability increased (P = 0.004), and decreased as nicotine content decreased (P < 0.001), with no significant interaction of cumulative vulnerability and dose (P = 0.67). Effects on other outcomes generally followed that same pattern. The only exception across the other outcomes was on Questionnaire-on-Smoking-Urges Factor-2 ratings for usual-brand cigarettes where cumulative vulnerability, dose, and time interacted (P = 0.007), with craving at the 0.4 and 2.4 mg/g doses decreasing over time, but inconsistently across vulnerability categories. Overall, we saw little evidence that cumulative vulnerabilities moderate response to reduced nicotine content cigarettes suggesting that a policy reducing nicotine content in cigarettes to minimally addictive levels could benefit even highly vulnerable smokers including those residing in rural or other regions with overrepresentation of co-occurring vulnerabilities. Clinicaltrials.gov identifiers: NCT02232737, NCT02250664, NCT02250534.

Calibrated dynamic borrowing using capping priors.

Multisource exchangeability models (MEMs), a BayeTsian approach for dynamically integrating information from multiple clinical trials, are a promising approach for gaining efficiency in randomized controlled trials. When the supplementary trials are considerably larger than the primary trial, care must be taken when integrating supplementary data to avoid overwhelming the primary trial. In this paper, we propose "capping priors," which controls the extent of dynamic borrowing by placing an a priori cap on the effective supplemental sample size. We demonstrate the behavior of this technique via simulation, and apply our method to four randomized trials of very low nicotine content cigarettes.

Abuse liability of cigarettes with very low nicotine content in pregnant cigarette smokers.

The U.S. Food and Drug Administration has proposed reducing the nicotine content of cigarettes to a minimally-addictive level. To our knowledge, this study is the first to examine how pregnant smokers respond to very low nicotine content (VLNC) cigarettes. In Phase 1, participants blindly sampled two VLNC cigarettes (0.4 and 2.4 mg/g of tobacco) and their usual brand (UB) cigarette in separate sessions, then completed a behavioral economic simulation task and measures of subjective effects, craving/withdrawal, and smoking topography. Phase 2 directly compared the relative reinforcing effects of the cigarettes using concurrent choice testing. All possible dose-pair combinations were tested in separate sessions where puffs were earned ad libitum by clicking the code associated with their preferred cigarette 10 times. Phase 3 tested the 0.4 mg/g-UB dose-pair where UB puffs could be earned with a progressively incremented number of clicks (maximum 8400). Ten pregnant smokers in Burlington, VT and Baltimore, MD participated in 2017-2018. Regarding abuse liability, participants chose the 0.4-mg/g dose less than UB (22% vs. 78%) during concurrent choice testing and the 0.4-mg/g dose sustained less demand than the 2.4-mg/g and UB doses on the simulation task. Positive subjective effects were also lower for both VLNC cigarettes vs. UB. Each cigarette reduced nicotine craving/withdrawal and no significant changes indicative of compensatory smoking were noted. Reducing the nicotine content of cigarettes may decrease their abuse liability in pregnant smokers without causing untoward craving/withdrawal or compensatory smoking. Studies of extended exposure to VLNCs in pregnant women are warranted.

Editorial: 5th Special Issue on behavior change, health, and health disparities.

This Special Issue of Preventive Medicine (PM) is the 5th in a series on behavior change, health, and health disparities. Unhealthy behavior patterns (i.e., lifestyle choices) including cigarette smoking and other substance abuse, physical inactivity, unhealthy food choices, and non-adherence with recommended medical regimens, undermine U.S. population health by increasing risk for chronic disease and premature death. This Special Issue brings together scholarly contributions from the emerging area of tobacco regulatory science to examine current topics of critical importance to reducing the burden of cigarette smoking on U.S. population health. More specifically, three related topics are examined including (a) the potential for reducing smoking by adopting a national policy that would cap the nicotine content of cigarettes at minimally-addictive levels; (b) increasing scientific understanding of cigarette smoking and other tobacco use among populations that are especially vulnerable to initiating smoking, tobacco addiction, and its adverse health consequences; and (c) the potential of a harm-reduction strategy for reducing the burden of smoking by advocating that those who are unwilling or unable to quit nicotine use substitute electronic cigarettes or other non-combusted sources of nicotine for cigarettes in order to avoid exposure to the other toxins in tobacco smoke that are most responsible for smoking morbidity and mortality. While tremendous progress has been made in reducing overall U.S. smoking prevalence and its adverse health impacts, more needs to be done. This Special Issue offers some ideas that have the potential to make a substantive contribution towards that goal.

Response to reduced nicotine content cigarettes among smokers differing in tobacco dependence severity.

This study examines whether tobacco dependence severity moderates the acute effects of reducing nicotine content in cigarettes on the addiction potential of smoking, craving/withdrawal, or smoking topography. Participants (N = 169) were daily smokers with mild, moderate, or high tobacco-dependence severity using the Heaviness of Smoking Index. Following brief abstinence, participants smoked research cigarettes varying in nicotine content (0.4, 2.4, 5.2, 15.8 mg nicotine/g tobacco) in a within-subject design. Results were analyzed using repeated measures analysis of co-variance. No main effects of dependence severity or interactions with nicotine dose were noted in relative reinforcing effects in concurrent choice testing or subjective effects on the modified Cigarette Evaluation Questionnaire. Demand for smoking in the Cigarette Purchase Task was greater among more dependent smokers, but reducing nicotine content decreased demand independent of dependence severity. Dependence severity did not significantly alter response to reduced nicotine content cigarettes on the Minnesota Tobacco Withdrawal Scale nor Questionnaire of Smoking Urges-brief (QSU) Factor-2 scale; dependence severity and dose interacted significantly on the QSU-brief Factor-1 scale, with reductions dependent on dose among highly but not mildly or moderately dependent smokers. Dependence severity and dose interacted significantly on only one of six measures of smoking topography (i.e., maximum flow rate), which increased as dose increased among mildly and moderately but not highly dependent smokers. These results suggest that dependence severity has no moderating influence on the ability of reduced nicotine content cigarettes to lower the addiction potential of smoking, and minimal effects on relief from craving/withdrawal or smoking topography.

Chemical, physical, and in vitro characterization of research cigarettes containing denicotinized tobacco.

The use of very low nicotine tobacco cigarettes is currently being investigated as a possible harm reduction strategy. Here, we report the smoke chemistry, toxicity, and physical characteristics of very low nicotine cigarettes that were made using blended tobacco processed through a supercritical CO2 fluid extraction, which resulted in elimination of 96% of nicotine content (denicotinized (denic) tobacco). Three types of test cigarettes (TCs) were manufactured with tobacco filler containing 100% denic tobacco (TC100), 50% denic tobacco and 50% unextracted tobacco (TC50/50), and 100% unextracted tobacco (TC0). Mainstream smoke (MS) was generated for measurement of 46 analytes and cytotoxicity and mutagenicity determination. Analysis of physical characteristics of TCs demonstrated they were well made with <5% variability among cigarettes for most parameters measured. We observed significant changes in the levels of smoke constituents, including decreases in formaldehyde, nitrosamines, and phenol, and increases in aliphatic hydrocarbons, aliphatic nitrogen compounds, aromatic amines, halogen compounds, and metals. Use of denic tobacco resulted in changes in the chemical composition of MS, but these changes did not modify biological activity as measured in the mutagenicity and cytotoxicity assays.

Effects of immediate versus gradual nicotine reduction in cigarettes on biomarkers of biological effects.

AIM: A previous study showed significantly greater reductions in number of cigarettes smoked and biomarkers of toxicant and carcinogen exposure in smokers assigned to immediate reduction of nicotine in cigarettes to very low levels versus gradually over time or continued smoking of normal nicotine content cigarettes. This study examines the effects of these approaches on selected biomarkers associated with harmful biological effects. DESIGN: Three-arm, randomized controlled trial. SETTING: Ten United States academic institutional sites. PARTICIPANTS: Daily smokers uninterested in quitting smoking with a mean age of 45.1 [standard deviation (SD) = 13.4)] years and smoking 17.1 (SD = 8.5) cigarettes/day; 43.9% (549 of 1250) female; 60.6% (758 of 1250) white ethnicity. INTERVENTIONS: (1) Smoking cigarettes where nicotine content was immediately reduced to very low levels (n = 503); (2) smoking cigarettes where nicotine content was gradually reduced, with dose changes occurring monthly (n = 498); and (3) continued smoking with normal nicotine content cigarettes (n = 249). MEASUREMENTS: Smokers were assessed at baseline while smoking their usual brand cigarettes, and again at 4, 8, 12, 16 and 20 weeks. Outcomes were areas under the concentration time curve (AUC) for the period of study of biomarkers of inflammation, oxidative stress and hematological parameters. FINDINGS: No consistent significant differences were observed across groups (Bayes factors showing data to be insensitive), with the only exception being red blood cell size variability, which was observed to be lower in the immediate versus gradual nicotine reduction [mean difference =  -0.11; 95% confidence interval (CI) = -0.18, -0.04, P = 0.004] and normal nicotine control groups (mean difference = - 0.15, 95% CI = -0.23, -0.06, P = 0.001). CONCLUSION: It remains unclear whether switching to very low nicotine cigarettes leads to a short-term reduction in biomarkers of tobacco-related harm.

Acceptability of SPECTRUM Research Cigarettes among Participants in Trials of Reduced Nicotine Content Cigarettes.

OBJECTIVES: SPECTRUM research cigarettes (SPECTRUMs) are being used in trials evaluating the effects of switching to reduced nicotine content (RNC) cigarettes. Because smokers have a high brand affinity, we evaluated if they were willing to switch and continue smoking normal nicotine content (NNC) SPECTRUMs. METHODS: We asked smokers (N = 341) to rate their own brand of cigarettes and NNC SPECTRUMs (after 2 weeks of use) using subjective measures including satisfaction, reward, taste, and craving reduction. We measured plasma cotinine, exhaled carbon monoxide (CO), and cigarettes per day (CPD), and recorded reasons for dropping out. RESULTS: After 2 weeks, 95% of participants chose to continue using SPECTRUMs for an additional 18 weeks. Moreover, 67% said SPECTRUMs were as good as or better than their own brand, and 65% said they would consider purchasing them. Ratings of satisfaction, reward, and craving reduction were 10%-15% lower on SPECTRUMs than on their own brand (p < .01). There were no differences in these ratings between menthol and non-menthol smokers. CONCLUSIONS: Menthol and non-menthol SPECTRUMs are acceptable to smokers. Lower SPECTRUM ratings were likely due to brand switching and did not hinder study retention.

Response to reduced nicotine content cigarettes among smokers with chronic health conditions.

Individuals with chronic health conditions persist in smoking despite the presence of smoking-related illness. The aim of this study was to examine whether chronic health conditions moderate response to reduced nicotine content cigarettes (0.4, 2.4, 5.2, 15.8 mg/g of tobacco). This is a secondary analysis of a controlled clinical laboratory study that examined the acute effects of cigarettes varying in nicotine content among individuals especially vulnerable to smoking and tobacco dependence. Participants in the present study were categorized as having 0, 1-2, or ≥3 smoking-related chronic health conditions (i.e., chronic condition severity, CCS). Repeated-measures analysis of variance was used to examine whether CCS moderated response to cigarettes across measures of addiction potential (i.e., concurrent choice testing between nicotine dose pairs, Cigarette Purchase Task (CPT) performance, positive subjective effects), tobacco withdrawal, cigarette craving, and smoking topography. No main effects of CCS or interactions of CCS and nicotine dose were observed for concurrent choice testing, positive subjective effects, tobacco withdrawal, or smoking topography. Main effects of CCS were noted on the CPT with greater CCS being associated with less persistent demand. There was an interaction of CCS and nicotine dose on Factor 1 of the Questionnaire on Smoking Urges with the effects of dose significant only among those with 1-2 chronic conditions. Overall, we see minimal evidence that chronic condition severity affects response to reduced nicotine content cigarettes. A policy that reduces the nicotine content of cigarettes to minimally addictive levels may benefit smokers already experiencing smoking-related chronic conditions.

Reduced nicotine content cigarettes in smokers of low socioeconomic status: study protocol for a randomized control trial.

BACKGROUND: The Family Smoking Prevention and Tobacco Control Act gave the Food and Drug Administration jurisdiction over the regulation of all tobacco products, including their nicotine content. Under this act, a major strategy to reduce harm from cigarette tobacco is lowering the nicotine content without causing unintended adverse consequences. Initial research on reduced nicotine content (RNC) cigarettes has shown that smokers of these cigarettes gradually decrease their smoking frequency and biomarkers of exposure. The effectiveness of this strategy needs to be demonstrated in different populations whose response to RNC cigarettes might be substantially mediated by personal or environmental factors, such as low socioeconomic status (SES) populations. This study aims to evaluate the response to a reduced nicotine intervention in low SES smokers, as defined here as those with less than 16 years of education, by switching smokers from high nicotine commercial cigarettes to RNC cigarettes. METHODS/DESIGN: Adults (N = 280) who have smoked five cigarettes or more per day for the past year, have not made a quit attempt in the prior month, are not planning to quit, and have less than 16 years of education are recruited into a two-arm, double-blinded randomized controlled trial. First, participants smoke their usual brand of cigarettes for 1 week and SPECTRUM research cigarettes containing a usual amount of nicotine for 2 weeks. During the experimental phase, participants are randomized to continue smoking SPECTRUM research cigarettes that contain either (1) usual nicotine content (UNC) (11.6 mg/cigarette) or (2) RNC (11.6 to 0.2 mg/cigarette) over 18 weeks. During the final phase of the study, all participants are offered the choice to quit smoking with nicotine replacement therapy, continue smoking the research cigarettes, or return to their usual brand of cigarettes. The primary outcomes of the study include retention rates and compliance with using only research cigarettes and no use of other nicotine-containing products. Secondary outcomes are tobacco smoke biomarkers, nicotine dependence measures, smoking topography, stress levels, and adverse health consequences. DISCUSSION: Results from this study will provide information on whether low SES smokers can maintain a course of progressive nicotine reduction without increases in incidence of adverse effects. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01928719 . Registered on 21 August 2013.

Reduced nicotine content cigarettes and use of alternative nicotine products: exploratory trial.

AIMS: To compare the use of alternative nicotine products, smoking behavior and tobacco biomarker exposure in smokers unwilling to quit who were assigned randomly to normal nicotine content (NNC) cigarettes or very low nicotine content (VLNC) cigarettes. DESIGN: Randomized, parallel-arm 8-week study with assignment to VLNC (VLNC 1, n = 53) or NNC (NNC, n = 27) with access to non-cigarette combusted and non-combusted tobacco/nicotine products or to VLNC with access to only non-combusted products (VLNC2, n = 56). SETTING: Clinics in Minnesota, USA. PARTICIPANTS: Smokers uninterested in quitting smoking with a mean [± standard deviation (SD)] age of 44 (± 14) years and smoking 16 (± seven) cigarettes/day; 51% female, 72% white. MEASUREMENTS: During the experimental period, the measures taken included: rate of alternative products used, amount of and abstinence from combusted tobacco used and tobacco exposure biomarkers. FINDINGS: There were higher rates of non-combusted alternative tobacco/nicotine product use in both VLNC conditions versus the NNC condition [rate ratio (RR) = 2.18, 95% confidence interval (CI) = 1.94, 2.46 and RR = 1.64, 95% CI = 1.46, 1.85, respectively] and in VLNC1 versus VLNC2 condition (RR = 1.33, 95% CI = 1.23, 1.44), accompanied by reduced biomarkers of exposure primarily in VLNC2 condition compared to NNC condition (Ps < 0.05). Fewer combusted products were smoked at almost all visits (Ps ≤ 0.02) and there were higher rates of abstinence for both VLNC conditions compared with the NNC condition (VLNC1 versus NNC: RR = 9.96, 95% CI = 5.01, 19.81; VLNC2 versus NNC: RR = 11.23, 95% CI = 5.74, 21.97). CONCLUSION: The offer of, and instructions to use, reduced nicotine content cigarettes during an 8-week period led to greater use of alternative tobacco/nicotine products compared with continued use of normal nicotine cigarettes and also reductions in smoking rates.

Estimations and predictors of non-compliance in switchers to reduced nicotine content cigarettes.

BACKGROUND AND AIMS: Clinical trials on the impact and safety of reduced nicotine content cigarettes (RNCs) are ongoing, and an important methodological concern is participant compliance with smoking only RNCs. Our aims were to measure non-compliance biochemically with urine cotinine (COT) and total nicotine equivalents (TNEs), compare with self-reported non-compliance and identify associated covariates. DESIGN: Secondary analysis of a double-blind, parallel, randomized clinical trial. SETTING: Research centers from the United States, enrolling participants from June 2013 to July 2014. PARTICIPANTS: Volunteer sample of 242 participants (55% Caucasian), average age of 41.2 years, smoking at least five cigarettes per day (CPD). INTERVENTION: Smoking very low nicotine cigarettes (VLNCs; 0.4 mg nicotine/g tobacco) for 6 weeks. MEASUREMENTS: The primary outcome was biochemically verified non-compliance, measured as thresholds of COT/CPD and TNE/CPD ratios, considering changes in nicotine content from conventional levels to VLNCs, and as an absolute threshold of week 6 TNEs. Self-reported non-compliance was measured via daily phone calls. Key predictors included age, sex, race, menthol preference, nicotine metabolite ratio, time to first cigarette, dependence, CPD, TNEs, tar level and cigarette evaluation. FINDINGS: Estimates of non-compliance with smoking the VLNCs exclusively include: the biochemical ratios (both 78%), the week 6 TNE threshold (76%) and self-report (39%). Of the key covariates, age, dependence and cigarette evaluations of satisfaction were significant; for age, younger participants more likely to be non-compliant [P = 0.01; odds ratio (OR) = 0.98, 95% confidence interval (CI) = 0.96-0.99]. Dependence was associated significantly with self-reported non-compliance (P = 0.01; OR = 1.28, 95% CI = 1.06-1.55). Cigarette evaluations of satisfaction were associated significantly with non-compliance (P = 0.001; OR = 0.71, 95% CI = 0.61-0.82). CONCLUSIONS: Among smokers volunteering to smoke only very low nicotine cigarettes for 6 weeks, non-compliance was common and biochemical assessments detected more cases of non-compliance than self-report. Despite high levels of non-compliance, smokers reduced their intake of nicotine by an average of 60%.