ED Visits, Hospitalizations 22% Higher Among Cannabis Users

There is an association between cannabis use and the risk of all-cause emergency department (ED) visits or hospitalization, indicating a greater risk of serious adverse health events, according to a study published to BMJ Open Respiratory Research.

Researchers at Health Toronto and ICES found that ED visits and hospitalizations are 22% higher among cannabis users compared to those who do not use cannabis. Respiratory-related reasons were the second most common cause for ED visits and hospitalizations among cannabis users.

"Unlike tobacco, there is some uncertainty or controversy regarding the adverse health impacts of cannabis. Some individuals may perceive that cannabis has some health benefits and is otherwise benign,” lead author Nicholas Vozoris, MD, FRCPC, MHSc, said in a statement.

To evaluate the association between cannabis use and serious, acute, adverse respiratory events, Vozoris and his colleagues conducted a retrospective, population-based, cohort study, linking health survey and health administrative data for residents of Ontario, Canada.

Data was collected on participants aged 12 to 65 years between January 2009 and December 2015.

Individuals self-reporting cannabis use within the past year were matched to controlled individuals who reported never using cannabis or only using cannabis once, over 12 months ago. Using propensity-score matching methods, 4807 cannabis users were matched to 10,395 control individuals.

The researchers included 31 different variables in the matching process, including demographics, physical and mental health diseases, tobacco, alcohol, and drug use.

Odds of respiratory-related ED visits or hospitalizations in the propensity score matched cohort were not found to be significantly greater among cannabis users than the control group (odds ratio [OR] 0.91, 95% CI 0.77 to 1.09).

The authors noted that the observation of no significant association between cannabis use and respiratory-related ED visits or hospitalizations somewhat challenges previous research.

However, the study demonstrated that cannabis use was associated with significantly increased all-cause ED visits or hospitalizations (OR 1.22, 95% CI 1.13 to 1.31). Respiratory-related reasons were the second most common etiology for all-cause ED visits and hospitalizations among cannabis users.

Among cannabis users, there was no significant difference with respect to all-cause mortality, compared with the control group (OR 0.99, 95% CI 0.49 to 2.02).

A surprising finding, according to the authors, was that cannabis use was associated with significantly decreased odds of respiratory-related ED visits/hospitalizations in the group of current/former tobacco smokers. However, in the same subgroup of current/former tobacco smokers, odds of all-cause ED visits or hospitalizations were significantly elevated among cannabis users.

Both sexes were at similar heightened odds for all-cause ED visits/hospitalizations in association with cannabis use. This finding contrasts previous research demonstrating that male, but not female, cannabis smokers were more susceptible to worse health.

The authors believed it was noteworthy that the leading etiology of the increased all-cause ED visit/hospitalization outcome among cannabis users was acute trauma (~18%), as it aligns with a growing body of literature linking cannabis to increased risks of generalized body injury, motor vehicle accidents, falls, and skeletal fractures.

However, the authors noted that it was beyond the scope of this study to further describe possible associations between cannabis use and physical trauma.

Overall, these findings indicate that recreational consumption of cannabis is not benign.

“Our results suggest that cannabis use is associated with increased risk for serious adverse health events, and therefore, its recreational consumption in the general population should be discouraged,” wrote the researchers from Health Toronto and ICES, though they encouraged further research.

Reference

Vosoris NT, Zhu J, Ryan CM, Chow CW, To T. Cannabis use and risks of respiratory and all-cause morbidity and mortality: a population-based, data-linkage, cohort study. BMJ Open Respiratory Research. 2022;9(1): e001216. doi:10.1136/bmjresp-2022-001216