Abstract: There is an increase in the medical use of cannabis. However, the safety of medical cannabis, particularly for mental health conditions, has not yet been clearly established. Thus, this study assessed the risk of emergency department (ED) visits and hospitalization for depressive disorders among medical cannabis users. We conducted a retrospective longitudinal cohort study of patients who received medical authorization to use cannabis from 2014 to 2019 in Ontario, matched (1:3 ratio) to population-based controls using propensity scores. Conditional Cox regressions were used to assess the association between cannabis authorization and the outcome. A total of 54,006 cannabis-authorized patients and 161,265 controls were analyzed. Approximately 39% were aged under 50 years, 54% were female, and 16% had a history of anxiety or mood disorders. The adjusted hazard ratio (aHR) for depressive disorders was 2.02 (95%CI: 1.83–2.22). The aHR was 2.23 (1.95–2.55) among subjects without prior mental health disorders. The interaction between sex (or age) and exposure was not significant. In conclusion, medical cannabis authorization was associated with an increased risk of depressive disorders. This finding highlights the need for a careful risk-benefit assessment when authorizing cannabis, particularly for patients who seek cannabis to treat a depressive condition.
Study design: We performed a retrospective longitudinal cohort study of patients who received an authorization from a healthcare provider to use medical cannabis to treat a health condition from June 19, 2014 to January 28, 2019 (i.e., accrual start and end dates) in a group of Ontario’ cannabis clinics. These patients, identified as the exposed patients, were matched to controls without medical cannabis authorization, selected from the general population of Ontario. Matching was done using propensity
Results: From 60,414 cannabis-authorized patients initially matched by ICES to 182,240 controls (Supplemental file 1), 54,006 cannabis-authorized patients and 161,265 matched controls were included for the present analysis (Fig. 1). The majority of patients were female (54.46%), were aged 31–60 years (53.09%), and lived in an urban area (88.76%) (Table 1). The most prevalent morbidities for the matched cohorts were musculoskeletal disorders (49.43%), metabolic disorders (23.02%), asthma (22.69%),
Discussion: This retrospective longitudinal cohort study, that assessed the risk of ED visits and/or hospitalization for depressive disorders among medical cannabis users, found that patients with medical cannabis authorization had a significant increased risk of ED visits and/or hospitalizations for depressive disorders compared with matched controls. The same trend was observed when the analyses were performed among subjects without prior healthcare utilization for any mental health disorders.
Conclusion: Our study showed that patients with medical cannabis authorization have a higher risk of emergency department visits or hospitalizations for depression compared to patients with no authorization. Our results also suggest that this risk is increased among patients without prior mental health disorders at cannabis authorization. The findings emphasize the need for a careful risk-benefit assessment that takes into account this observation prior to cannabis authorization. Further longitudinal
