The Quebec Cannabis Registry: Investigating the Safety and Effectiveness of Medical Cannabis

Objective: To investigate the safety and effectiveness of medical cannabis (MC) in the real-world clinical practice setting. Design: A 4-year prospective noncomparative registry of adult patients who initiated MC for a variety of indications. This paper reports on patients followed for up to 12 months, with interim visits at 3, 6, and 9 months after enrollment. Setting: Public or private outpatient clinics certified to authorize MC in the province of Quebec, Canada. Participants: Overall, 2991 adult (age ≥18 years) patients (mean age 51 years; 50.2% women) were enrolled between May 2015 and October 2018, with the last follow-up ending in May 2019. Interventions/Exposures: Cannabis products (dried, oil, or other) purchased from a Canadian licensed cannabis producer as authorized by physicians. Main Outcome Measures: The primary outcomes were self-reported pain severity, interference and relief (Brief Pain Inventory [BPI]), symptoms using the Revised Edmonton Symptom Assessment System (ESAS-r) and health-related quality of life dimensions (EQ-5D-5L) at baseline and each follow-up visit. The secondary outcomes were self-reported adverse events (AEs) and characteristics of cannabis treatment. Results: All patient-reported outcomes (BPI, ESAS-r, and EQ-5D-5L) showed a statistically significant improvement at 3 months (all p<0.01), which was maintained or further improved (for pain interference, tiredness, and well-being) over the remainder of the 12-month follow-up. Results also revealed clinically significant improvements in pain interference and tiredness, anxiety, and well-being from baseline. There were 79 AE reports (77 patients), 16 met the regulatory definition of seriousness, in which only 8 AEs were certainly or probably related to MC. Conclusions: MC directed by physicians appears to be safe and effective within 3 months of initiation for a variety of medical indications.