Cannabis Inhalation Not Associated With Increased Risk for COPD

Findings from a longitudinal study comprised of an older cohort of patients who smoke tobacco cigarettes reveals no association between cannabis use and the development of chronic obstructive pulmonary disease (COPD). Led by a team of researchers from the David Geffen School of Medicine at the University of California, Los Angeles, the authors found that even heavy cannabis smoking did not increase the risk for developing COPD nor did it increase the risk of progression among patients with COPD.

Study participants included a cohort of 1863 older patients with or without COPD from the Subpopulations and Intermediate Outcomes in COPD Study (SPIROMICS), who reported current-, former-, or never-smoking cannabis. The researchers longitudinally followed participants for at least 4 years. The study, published in Chronic Obstructive Pulmonary Disease: Journal of the COPD Foundation, found no connection between cannabis use and COPD onset or progression.

“While a significant association of marijuana smoking with symptoms of chronic bronchitis has been reported, associations with changes in lung function or other aspects of lung health over time, especially in those at risk of or with diagnosed [COPD], has been less studied,” the author wrote. “We evaluated whether self-reported marijuana smoking among SPIROMICS participants without spirometric evidence of COPD at baseline would affect the subsequent development of COPD.”

The researchers also assessed whether SPIROMICS participants with COPD and a history of cannabis smoking would have faster progression of the disease, and they found that was not the case. Health status, respiratory symptoms, extent of emphysema and exacerbations were not different between current, former, or never cannabis smokers.  

The authors caution that their analysis could be underpowered due to the small sample size and limited follow-up, and the fact that the study sample was not random.

However, the study cohort did include a variety of sites around the United States, included women, and multiple ethnicities, suggesting some generalizability of the results. They recommend further studies with a larger sample that are specifically designed to assess the potential long-term effects of cannabis smoking on patients with or at risk for COPD.