Additive effects also were observed among e-cigarette only tobacco users. In addition, dual users of cigarettes and ecigarettes had notably elevated probability of reporting respiratory conditions relative to other tobacco user groups. The increased respiratory symptoms among e-cigarette and cigarette users in particular may reflect the potential motivating influence of respiratory conditions on encouraging cigarette smokers to use e-cigarettes for cessation or to cut down on cigarettes.One limitation of this study is that users of traditional cigars, cigarillos, and filtered cigars were grouped together into cigar users rather than explored as separate product user groups. As cigar products are tied to use of blunts, this is an important group to explore in discrete sub-groups in future research. In addition, neither the frequency nor quantity of use of marijuana were available in Wave 1 of the PATH Study. Further, wave 1 participants were not asked about the specific marijuana product used limiting our ability to establish the specific contribution of inhaled marijuana to respiratory problems. Available data suggest that combusted marijuana is preferred by a large majority of users , but further study of the relative contribution of inhaled tobacco and inhaled marijuana to lung health is needed . Lastly, this study used cross-sectional data, thus precluding our understanding of temporal interactions of product use. Longitudinal examination of the role of efforts to quit tobacco use are needed among concurrent tobacco and marijuana users to understand whether continued use of marijuana decreases the likelihood of tobacco quit attempts or impacts the likelihood of success in quitting.
Electronic cigarettes are an emerging harm reduction strategy,4×8 grow table with wheels replacing smoking tobacco and the associated deleterious health effects with the less harmful effects of “vaping.”Cigarette smoking delivers nicotine through inhaling the smoke from combusted tobacco, whereas vaping delivers nicotine through inhaling an aerosol produced from heating e-liquid. Given the lack of combustion, e-cigarette use is associated with reduced carbon monoxide ,a marker for gas-phase exposure to combustibles, and fewer self-reported respiratory symptoms for exclusive users compared with dual users.For current smokers, use of e-cigarettes satisfies urges to smoke and withdrawal symptoms while reducing harms associated with combustion. However, some smokers engage in additional behaviors involving combustion that may diminish the harm reduction potential of switching to e-cigarettes. Marijuana may be used through multiple routes including ingestion or vaporization, but is typically smoked, and is marked by the psychoactive properties of tetrahydrocannabinol.Couse of combusted marijuana is frequent among cigarette smokers and shares similar health concerns from combustion such as exposure to CO, tar, and many harmful compounds also found in tobacco smoke.Marijuana use among smokers ranges from 18% to 40% varying by study, population, and survey questions used. Combustion of plant-based material exposes marijuana and tobacco users alike to CO, which impedes oxygen delivery in the body by competing with oxygen for binding to hemoglobin.Smoking blunts, containing both marijuana and tobacco, results in higher CO than smoking marijuana in the form of joints,while non-combustibles do not increase CO.Smoking a joint increases blood carboxyhemoglobin saturation four times that of a single filtered tobacco cigarette, indicative of greater CO exposure.
Furthermore, marijuana use is associated with morning cough, sputum production, and wheeze among cigarette smokers, even after adjusting for current and cumulative tobacco smoking.Given the effects of smoking marijuana, it is plausible that marijuana use will diminish the expected reduction in CO and improvement of respiratory symptoms that would occur when switching from cigarettes to e-cigarettes. Shared sensory and behavioral associations between marijuana and cigarette smoking raise the concern that marijuana co-use may impede switching from combustible cigarettes to e-cigarettes. Observational studies show marijuana use is associated with continued tobacco use,and marijuana use has been a barrier to cigarette reduction in previous intervention studies.Marijuana use was associated with reduced likelihood of smoking abstinence in a 12-week study administering varenicline,in a 12-month study using online support groups and counseling,and a 26-week study using nicotine replacement therapy.In an intervention using nicotine replacement therapy plus behavioral support for 8 weeks, smoking abstinence rates did not vary between marijuana and non-marijuana users.To date, no study has investigated how marijuana use affects smokers switching to e-cigarettes and related health effects in a clinical trial. This study tests the contribution of marijuana use on cigarettes smoked per week at week 6, the primary outcome point of a harm reduction trial, hypothesizing more cigarettes smoked for marijuana users. Secondary aims test the contribution of marijuana use on e-cigarette substitution, CO levels, and respiratory symptoms at week 6. It was hypothesized that marijuana use would contribute to lower e-cigarette substitution, higher CO levels, and increased respiratory symptoms.
This is a secondary analysis from the first reported randomized clinical trial of nicotine salt pod system e-cigarettes testing effects on toxicant exposure among members of the two largest racial/ethnic groups in the United States, African American and Latinx smokers.The trial was registered with ClinicalTrials.gov and specific inclusion/exclusion criteria are found in the main outcomes paper.In brief, participants were 21 years or older, smoked 5 cigarettes per day for at least 6 months, had expired CO greater than 5 parts per million at baseline, and were willing to switch from smoking cigarettes to e-cigarettes for 6 weeks. This is a secondary analysis and was not preregistered and the results should be considered exploratory. This multisite study was conducted from July 2018 to May 2019 and consisted of a baseline, week 2, and week 6 visit. Participants were randomly assigned in a 2:1 ratio, stratified by study site to the “e-cigarette group” or “smoking as usual” control group. Legality of marijuana use also differed by site, with medicinal-only use in Missouri and recreational use in California. Those randomized to e-cigarettes received a JUUL e-cigarette and pods in a choice of Virginia tobacco, classic menthol, cool mint, or mango flavor pods for 6 weeks. Participants were given brief education, training, and action planning for making a complete switch to e-cigarettes. At week 6, those in the e-cigarette group demonstrated significant reductions in cigarettes smoked, CO, and respiratory symptoms compared with the “smoking as usual” control group. The study was approved by the Institutional Review Board at California State University San Marcos and the University of Kansas School of Medicine and written consent obtained for each participant.Tobacco and marijuana product use were measured by a 7-day Timeline Follow back method at baseline, week 2, and week 6. TLFB is a reliable and valid source of measuring cigarettes, e-cigarettes, and marijuana use.TLFB has been verified with objective tobacco measures such as interactive voice response, cigarette butt counts,grow tray stand and biological markers of cigarette use .Researchers used a paper calendar to first write down participants’ schedules and memorable events for the past 7 days. Using the calendar to assist with recall, participants were asked about tobacco and marijuana use on each day and quantities recorded. Quantities for the following marijuana products were recorded: blunt , joint , spliff , bowl , mole , hookah with marijuana and tobacco, dabs or vaporized marijuana, edible marijuana, other form of marijuana only, and other form of tobacco with marijuana. Marijuana use was dichotomized into any marijuana use or no marijuana use at baseline, week 2, or week 6, in addition to any or no marijuana use during the 6-week study. Combustible marijuana use was classified for use of blunt, joint, spliff, bowl, pipe/bong with marijuana and tobacco, or hookah with tobacco and marijuana. Tobacco products were also measured by TLFB including cigarettes, little cigars, cigarillos, hand-rolled cigarettes, full-sized cigars, pipes, bidis, hookah/water pipes, and spit/ snuff/smokeless tobacco. An objective measure of e-cigarette use was obtained by counting and weighing participants’ used pods at week 6.
Combustible tobacco product use was classified for use of little cigars, cigarillos, hand-rolled cigarettes, full-sized cigars, pipes, bidis, or hookah/water pipes.E-cigarette substitution was calculated using cigarettes smoked and the number of pods returned at week 6. Cigarettes smoked at week 6 were recorded as the number of cigarettes smoked in the past 7 days using TLFB. As described elsewhere, e-cigarette pods were counted and weighed at week 6 and converted into cigarette equivalents .E-cigarette substitution was calculated as a percent by dividing the total amount of e-cigarettes consumed per week by the sum of total cigarette and e-cigarette consumption.Independent samples t tests and chi-square tests were used to compare baseline characteristics of those who reported marijuana use during the study period with those that did not report marijuana use. Four separate multiple linear regressions tested the effect of marijuana use on the following measures at week 6: cigarettes smoked, e-cigarette substitution, CO, and respiratory symptoms. Any marijuana use during the 6 weeks was used for analyses predicting cigarettes smoked and e-cigarette substitution, whereas combustible marijuana use was used for analyses predicting CO and respiratory symptoms. Due to the time sensitivity of CO, this analysis used combustible marijuana at the week 6 timepoint. Multiple linear regressions were conducted controlling for gender, race/ethnicity or site, age, number of cigarettes smoked at baseline, and use of other combustible tobacco products. Baseline respiratory symptoms were added as a control for the model predicting week 6 respiratory symptoms. Winsorization was applied to outlying continuous variables in which z-scores were less than −3.29 or greater than 3.29.This procedure was applied to three TLFB cigarette values and four CO values . Missing data were excluded using list wise deletion and all analyses were conducted using SPSS v24.0.In the first study to our knowledge examining the impact of marijuana use on smokers switching to e-cigarettes, marijuana use was not a barrier to cigarette reduction in a 6-week trial. Furthermore, there was no evidence that marijuana use inhibited switching to e-cigarettes. The lack of association between marijuana use and switching to e-cigarettes is encouraging, but longer term follow-up may elucidate a different pattern of results over a greater time period. Studies linking marijuana co-use to worse cigarette cessation outcomes infer that marijuana use may need to be a concurrent target of cigarette smoking cessation interventions, and results from the present e-cigarette switching study reveal marijuana users display differential health outcomes for some markers . Past 7-day marijuana use data reveal two distinct patterns of users, those who use marijuana once or twice a week and those who use daily . A survey sample of lifetime marijuana users recruited from Twitter also found approximately half were daily/near daily users of flower/herbal cannabis.Data on marijuana product types reported are similar to a 2016–2017 survey sample reporting most common modes of cannabis consumption being bowl , vaporizer, blunts, and joints.Additionally, proportions of combustible marijuana use are comparable to an online sample finding the majority of past-year marijuana users reported marijuana smoking.Combustible marijuana was not associated with respiratory symptoms at week 6 once cigarette smoking and other risk factors were accounted for. Marijuana use did not compound respiratory symptoms beyond the effect of cigarette smoking and other risk factors over 6 weeks. However, it is possible that an additive effect of respiratory symptoms would emerge over a longer time or with more frequent users, as cannabis dependency has been associated with some respiratory symptoms even after controlling for tobacco use.Combustible marijuana use was uniquely associated with elevated CO at week 6, beyond that explained by cigarette smoking. Marijuana use was associated with approximately four ppm more CO exposure than non-marijuana users, after controlling for cigarette use. This was expected given that combusted marijuana is associated with increased CO exposure.CO is a marker of exposure to combustion toxicants, which have been associated with many diseases. CO reduces oxygen delivery from blood and can be harmful to people with preexisting cardiovascular disease or pulmonary disease.Higher CO levels reflect greater smoke exposure and suggest that smokers who use marijuana may be at increased risk for adverse health effects.Some e-cigarette switching studies include education about the benefit of reduced CO by switching from combustible to electronic cigarettes.Our study suggests that the magnitude of this benefit will not be equal for those who smoke marijuana compared with those who do not. Almost half of our study sample reported at least one incident of marijuana use, corresponding with rates of marijuana use among cigarette smokers ranging from 27% to 46% in previous studies.