In the last decade, the landscape of risk behaviors in the adolescent and young adult (AYA) population has changed drastically. Electronic cigarettes (e-cigarettes) have emerged as a popular modality for nicotine delivery, surpassing traditional cigarette use among middle and high school students in 2014, with past 30-day use nearly doubling from 11%-21% among high school students from 2017 to 2018, and increasing to 27.5% among high school students by 2020. (Johnston et al., 2018, Cullen, 2018, Cullen et al., 2019) Compared to combustible tobacco, adolescents tend to have more favorable attitudes toward e-cigarette and smoked marijuana, and e-cigarette use has been associated with future initiation of cigarette smoking in adolescents who have never used combustible tobacco. (Wills et al., 2016, Wills et al., 2017, Miech et al., 2017, Spindle et al., 2017, Gorukanti et al., 2017) Concurrently, lifetime use of smoked marijuana has risen since 2008 as a growing number of US states have legalized the possession, cultivation, and recreational use of marijuana. (Johnston et al., 2018) Healthy adolescents perceive marijuana as less risky than combustible tobacco, similar to e-cigarettes. As more states move toward cannabis legalization, these social influences are likely to become more pervasive. Despite the specific harms these products pose to lung health, adolescents and young adults with chronic diseases are faced with the same exposures to these products as healthier peers. (Lanzkron et al., 2018) One study in 1998 described lower ever- and recent-use, and greater age of initiation of cigarette smoking, as well as lower ever-use of smoked marijuana among adolescents with cystic fibrosis, a disease that causes a lifelong progressive decline in lung function. (Britto et al., 1998) However, by adulthood, ever-use of traditional cigarettes or smoked marijuana in this population has been estimated to be as high as 47% and 31%, respectively. (Mc Ewan et al., 2012)

Cystic Fibrosis (CF) is a progressive disease caused by an impairment in the cystic fibrosis transmembrane conductance regulator (CFTR), a channel that regulates chloride ion transport across the cell membrane in humans. Although CF can affect multiple organ systems, patients most often produce thick mucus in their airways as a result of dysregulated ion transport. This buildup of thick mucus results in trapping of pathogenic organisms resulting in recurrent respiratory tract infections and chronic inflammation of the lungs. Exogenous irritants such as tobacco smoke can cause additional airway inflammation and hasten lung damage in these patients. It is well understood that combustible cigarettes are associated with a decline in pulmonary function and can even result in decreased expression of CFTR. (Cantin et al., 2006) Patient exposed to cigarette smoke, both direct and secondhand, can suffer accelerated impairment of lung function in a dose-dependent manner as well as frequent disease exacerbations. (Gold et al., 1996, Smyth et al., 1994) Similarly, smoked marijuana in this population can result in increased frequency of respiratory exacerbations, hospitalizations, an accelerated decline in lung function. (Stern et al., 1987, Tetrault et al., 2007, Tashkin, 2005) These patterns are not limited to combustibles. Electronic cigarettes (e-cigarettes) have been shown to affect lung function and cellular architecture in human and mouse models. (Garcia-Arcos et al., 2016) E-cigarette use has also been associated with altered expression of numerous immune-regulatory genes similar to changes seen in cigarette smokers, overall reduced antimicrobial activity against bacterial infections common in patients with CF. (Martin et al., 2016, Hwang et al., 2016, Gallagher et al., 2017) Early longitudinal evidence suggests an association between e-cigarette use and higher incidence of chronic respiratory disease. (Bhatta and Glantz, 2019) If left unchecked, patients risk accelerated decline in pulmonary function, after which lung transplantation is not a viable option, as active tobacco or illicit substance use make them ineligible. (Weill et al., 2015)

We hypothesized that patients with CF perceive lower risk of both marijuana and e-cigarettes when compared to traditional cigarettes, and that misperceptions in this population are associated with increased use of these products. There are limited data identifying the degree of tobacco and marijuana use in the CF population, and it is unclear whether CF patients harbor misperceptions of risk, whether they recognize the particular hazard these substances pose in to those with CF, and to what extent patients use these substances given the rising availability of marijuana and e-cigarettes. Addressing these knowledge gaps will not only inform prevention education for patients with CF, but may help guide education concerning organ-specific risky behaviors in other patients with chronic disease.