Regular cannabis use was significantly associated with higher risk of asthma, COPD, and pneumonia regardless of whether the person also used tobacco, based on electronic health records of nearly 9,000 cannabis users.
Cannabis smokers, pulmonologists, and public health researchers.
COPD risk doubled for cannabis users without tobacco
What the researchers found
Regular cannabis use was associated with increased risk of asthma (OR 1.32-1.50), COPD (OR 1.44-2.17), and pneumonia (OR 1.80-2.13) across all groups. Importantly, cannabis users without tobacco use disorder still showed elevated respiratory disease risk: asthma OR 1.32, COPD OR 2.17, pneumonia OR 2.13. Tobacco users had the highest overall prevalence regardless of cannabis status.
Why it matters
Most studies of cannabis and respiratory disease are confounded by concurrent tobacco use. This study specifically examined cannabis users without tobacco use disorder and still found elevated respiratory risk.
The numbers in context
8,932 cannabis users total. 4,678 with tobacco use disorder. 4,254 without tobacco use disorder. Non-tobacco cannabis users: asthma OR 1.32, COPD OR 2.17, pneumonia OR 2.13.
How the study worked
Retrospective analysis using IBM Watson Health Explorys electronic health records. 8,932 cannabis-using patients matched to controls using propensity score methods, controlling for demographics, zip code income, BMI, and tobacco status.
What this study cannot tell us
Retrospective EHR data. Cannabis use identified by diagnosis codes and urine screens, which may miss occasional users or include former users. Cannot determine method of cannabis consumption. Residual confounding possible.
How to read the evidence
Large matched cohort from electronic health records with propensity score methods, though subject to EHR data limitations.
When this study was published
2019 study.
The bigger picture
The finding that cannabis alone (without tobacco) is associated with respiratory disease challenges the common belief that cannabis smoking is less harmful to the lungs than tobacco.
Questions still open
- Would non-smoked cannabis (edibles, tinctures) show the same respiratory associations? Is there a dose-response relationship?
Common questions
Does cannabis cause lung disease without tobacco?
How does cannabis compare to tobacco for lung risk?
Read the original research
Regular cannabis use, with and without tobacco co-use, is associated with respiratory disease.
Drug and alcohol dependence, 204, 107557
Citation
Winhusen, Theresa; Theobald, Jeff; Kaelber, David C; Lewis, Daniel. (2019). Regular cannabis use, with and without tobacco co-use, is associated with respiratory disease.. Drug and alcohol dependence, 204, 107557. https://doi.org/10.1016/j.drugalcdep.2019.107557
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