Marijuana Does Not Increase Pneumonia Risk, Finds Study

According to a new study that will be of little surprise to cannabis advocates, marijuana consumption is not associated with an increased risk of pneumonia among non-heterosexual men either with or without HIV. This is according to a study published in the journal Annals of Epidemiology and titled Marijuana use and pneumonia risk in a cohort of HIV-infected and HIV-uninfected men.

For the study researchers with the University of California, Los Angeles examined the relationship between cannabis use and the risk of pneumonia among a cohort of men who have sex with men (the Multicenter AIDS Cohort Study) over a period of nearly three decades (1984-2013). Nearly 2,800 HIV-positive men and approximately 2,700 HIV-negative men were included in the study, reports NORML. Authors reported that neither weekly nor daily marijuana use was significantly associated with elevated incidences of pneumonia.

The study concluded by stating that that data “does not provide evidence of a significant association between marijuana use and pneumonia incidence”, and “By relying on a population of men who have sex with men, the results may not generalize to other populations such as men who do not have sex with men or to women. Nonetheless, the results and conclusions for the HIV-uninfected group are potentially informative and relevant to the general population.”

This study’s full abstract can be found, in full, below:

Background: The prevalence of marijuana use is increasing in the United States. Marijuana smoking has been shown to impair the microbicidal activity of alveolar macrophages and decrease the number of ciliated epithelial cells in the bronchi with a parallel increase in the number of mucus-secreting surface epithelial cells, which may increase the risk of pneumonia. However, it remains unclear whether there is an association between smoking marijuana and pneumonia.

Methods: Using data from the Multicenter AIDS Cohort Study (MACS), a long-term observational cohort study of men who have sex with men in the United States, we used cox-proportional hazards models to estimate the risk of pneumonia among HIV-infected (n=2,784) and HIV-uninfected (n=2,665) men from 1984-2013, adjusted for time-varying and fixed baseline covariates.

Results: Weekly or daily marijuana use was not significantly associated with increased risk of pneumonia among HIV-uninfected men [adjusted hazard ratio; 95% confidence limits: 0.83, 0.56-1.23]. In the disaggregated dose response analysis , daily use [0.68, 0.34-1.35] was associated with a lower point estimate than weekly use. [0.99, 0.79-1.25].

Conclusion: Marijuana smoking was not associated with a significant increase in risk of pneumonia among HIV-infected or -uninfected men.

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