Cystic fibrosis is a chronic lung disease that can commonly cause pain, anxiety, depression and insomnia as well as chronic dyspnoea. One study demonstrated that 32.6% of CF patients regularly experience intense to severe pain, while the average rates in adults with CF of anxiety and depression are 21.8 and 27.2% respectively [3, 8]. Medical marijuana has been proposed as a possible treatment for these conditions.

No study has ever documented the usage rates of marijuana specifically for medical use in the CF population. Two prior studies did evaluate the use of recreational marijuana, with a rate of 20% in the study by Stern et al. in 1987, while in 1998 Britto found a rate of 9.7% [6, 7]. In this study, we found a rate of medical marijuana use of 15.4% in the year prior. The reasons for usage in this CF population were varied, with anxiety, musculoskeletal pain and appetite stimulation the most common. Those who used it overwhelmingly found it to be very effective, and adverse events were rare although controlled studies are lacking.

The incidence of medical marijuana use in CF has the potential to increase as this survey was done prior to a legal indication for CF in the states of residence of those surveyed. As reported in this study, 46% of subjects indicated they would be interested in trying marijuana if it were legally available. This would be a substantial rise from the current 15.4% who have used it in the past year.

Use of marijuana has been overall increasing in the U.S. recently, and current rates in the general population mirror usage in this CF population. In a poll conducted in 2018, 14.6% of adults in the U.S. had used marijuana in the past year [9]. In a 2012—2013 poll, the rate of adults in the U.S. who had used marijuana in the past year was 9.5%, while in 2001–2002 the rate was 4.1% [10].

In comparison to CF and the general usage frequency in the U.S. of about 15%, other disease-specific studies have shown variable, but generally higher, rates. One study in the U.S. analysed utilisation in orthopaedic surgery patients, with 34% of patients using marijuana out of a total of 275 completed surveys [11]. Another study in the U.S., analysing a population with gynaecological cancer, showed a rate of 26.7% of 225 surveys analzyed [12]. A 2004 Canadian study found that 28.8% of 104 patients with HIV reported use [13]. In multiple sclerosis, a Spanish study of 175 patients showed a rate of 17.1%, while in the U.K. in 254 surveys the rate was 30% [14, 15]. A large 2019 study demonstrated a higher usage rate of medical marijuana in younger patients, a trend that was also seen in this study [16].

It is possible that the somewhat lower rates seen in our survey compared to other chronic diseases is related to the presence of lung disease, which creates a perceived barrier to either smoking or vaporisation. The cigarette smoking rate in the CF population is 2.1%, much lower than 16.9% in 2017 in the general population [3]. This perceived barrier would potentially disappear with legalized medical marijuana as alternative regulated forms like tinctures and creams would be available.

The use of marijuana does not come without potential for side effects, both short and long term. In a 2015 meta-analysis of 79 medical marijuana studies, overall as well as serious adverse events were greater in the marijuana group [2]. Common short-term adverse events were dizziness, dry mouth, nausea, fatigue, loss of balance and hallucination. A 2010 meta-analysis noted a consistent association between marijuana use and psychotic episodes [17]. Neurocognitive issues, motor vehicle accidents and emergency department visits may also be increased with marijuana use [9]. Deleterious lung effects documented include an increased prevalence of chronic cough, sputum production, wheezing, shortness of breath as well as episodes of acute bronchitis [18]. This lung morbidity could be more deleterious in the CF population which already has underlying pulmonary disease.

Given this, physicians will need to discuss marijuana use with their CF patients and counsel them on the potential for side effects. As importantly, the route of use should be discussed. In this study, vaporisation or smoking marijuana was the preferred delivery for 45% of subjects. In light of their pre-existing lung disease as well as the recent crisis of severe disease with vaporisation, inhalation of marijuana from any delivery system should be discouraged [19].

A limitation of the study was a somewhat low survey return rate, which could imply bias, but overall the cohort was broad based, with 79% reporting pancreatic insufficiency and 74% perceiving either fair or good lung function, both of which are typical of an adult CF population. The data do capture what a substantial segment of CF patients think about medical marijuana. Questions on medical marijuana use were also part of a larger questionnaire on alternative medicine use, so the results would not have been biased by those specifically interested in the subject.