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> Marijuana smokers.—Cases were identified by searching for the terms marijuana and cannabis in The Ottawa Hospital picture archiving and communications system, and results were filtered to include only those in which chest CT was performed. Charts were reviewed to assess the frequency and duration of marijuana use, as well as for concomitant tobacco use. A total of 56 marijuana smokers were identified with chest CT performed between October 2005 and July 2020. Patient ages were sorted into 5-year age blocks (15–19 years, 20–24 years, 25–30 years, etc), and the number of men and women in each age category was determined. Marijuana consumption was quantified using the conversion of 0.32 g of marijuana per joint, as described by Ridgeway et al (14). > Our study had limitations. First, the small sample size precluded us from drawing strong conclusions. Second, the retrospective nature of the study had its own inherent limitations. Third, there was inconsistent quantification of patient marijuana use, due in part to the previous illegal nature of marijuana possession, which led to a lack of patient reporting. Accurate quantification is further complicated by the fact that users often share joints, use different inhalation techniques, and use marijuana of varying potency. Fourth, given that most marijuana smokers also smoke tobacco, the synergistic effects of these two substances cannot be effectively evaluated. Fifth, only a portion of patients could be age matched, since the tobacco-only cohort was taken from the lung cancer screening study and the patients were aged at least 50 years. Due to the age mismatch in the larger cohort, there are differences in the duration of smoking. Lastly, variable interobserver agreement limits our ability to draw strong conclusions about bronchial wall thickening and bronchiectasis. So it reads like marijuana only smokers were not distinguished from marijuana + tobacco smokers. Aka the comparison was really between a) non-smokers b) tobacco only smokers c) marijuana only smokers d) marijuana and tobacco smokers. With c) and d) combined into the same group. Meaning there could be many interpretations like: 1) “People that smoke more have more adverse effects” - since it’s possible that some people in “marijuana smokers” group consumed the same amount of tobacco as did people in “tobacco-only” group in addition to also smoking marijuana 2) Marijuana when combined with tobacco results in a synergetic effect that causes more morbidity Smaller sample size + not having a “marijuana only” group makes it difficult to attribute specific effects to marijuana, to tobacco or to combination thereof. The only “definitive” conclusion is that not smoking at all is certainly better than being a smoker of any kind - which is not very surprising. |