Article Text

other Versions

Download PDFPDF
Cohort study of medical cannabis authorisation and healthcare utilisation in 2014–2017 in Ontario, Canada
  1. Dean Eurich1,
  2. Cerina Lee1,
  3. Arsene Zongo1,2,
  4. Jasjett K Minhas-Sandhu1,
  5. John G Hanlon3,
  6. Elaine Hyshka1,4,
  7. Jason Dyck5
  1. 1School of Public Health, University of Alberta, Edmonton, Alberta, Canada
  2. 2Faculty of Pharmacy, Universite Laval, Quebec City, Quebec, Canada
  3. 3Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada
  4. 4Inner City Health and Wellness Program, Royal Alexandra Hospital, Edmonton, Alberta, Canada
  5. 5Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
  1. Correspondence to Professor Dean Eurich, School of Public Health, University of Alberta, Edmonton, AB T6G 2E1, Canada; deurich{at}


Background The impact of medical cannabis on healthcare utilisation between 2014 and 2017 in Ontario, Canada. With cannabis legalisation in Canada and some states in the USA, high-quality longitudinal cohort research studies are of urgent need to assess the impact of cannabis use on healthcare utilisation.

Methods A matched cohort study of 9925 medical cannabis authorised adult patients (inhaled (smoked or vaporised) or orally consumed (oils)) at specialised cannabis clinics, and inclusion of 17 732 controls (not authorised) between 24 April 2014 and 31 March 2017 from Ontario, Canada. Interrupted time series and multivariate Poisson regression analyses were conducted. Medical cannabis impact on healthcare utilisation was measured over 6 months: all-cause physician visits, all-cause hospitalisation, ambulatory care sensitive conditions (ACSC)-related hospitalisations, all-cause emergency department (ED) visits and ACSC-related ED visits.

Results For medical cannabis patients compared with controls, there was an initial (within the first month) increase in physician visits (additional 4330 visits per 10 000 patients). However, a numerical reduction was noted over the 6-month follow-up, and no statistical difference was observed (p=0.126). Likewise, in hospitalisations and ACSC ED visits, there was an initial increase (44 per 10 000 people, p<0.05) but no statistical difference after follow-up (p=0.34). Conversely, no initial increase in all-cause ED visits was observed with a slight decrease (19 visits per 10 000 patients, p=0.014) in follow-up.

Conclusions An initial increase (within first month) in healthcare utilisation may be expected among medical cannabis users that appears to wane over time. Proactive follow-up of patients using medical cannabis is warranted to minimise initial risks to patients and actively assess potential benefits/harms of ongoing use.

  • health services
  • public health
  • epidemiology
  • cohort studies

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Contributors DE, AZ, JD, JGH and EH designed the study and DE and JD acquired the data. DE, AZ, JKM-S analysed the data. CL, DE and JKM-S drafted the manuscript. All authors revised it critically for important intellectual content and approved the final version to be published. All authors are accountable for the work and integrity of the work. The corresponding author and guarantor accepts full responsibility of the work and/or conduct of the study, had access to the data and controlled the decision to publish. DE attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding This study was funded by a Canadian Institutes of Health research Project grant (CIHR PS 159668) to DE, JGH, EH and JD.

  • Competing interests JD is on the board of directors of Aurora Cannabis, which is a for-profit, company licensed for the cultivation and sale of medical cannabis. JGH has worked as a paid advisor and speaker for Canadian Cannabis Clinics. JD and JGH have a financial interest in Aurora Cannabis. DE holds a Mitacs Grant with Aurora as a partner. Mitacs is a national, not-for-profit organisation that works with universities, private companies, and both federal and provincial governments, to build partnerships and administer research funding that supports industrial and social innovation in Canada. This study made use of deidentified data from the ICES Data Repository, which is managed by the Institute for Clinical Evaluative Sciences with support from its funders and partners: Canada’s Strategy for Patient-Oriented Research (SPOR), the Ontario SPOR Support Unit, the Canadian Institutes of Health Research and the Government of Ontario. The opinions, results and conclusions reported are those of the authors. No endorsement by ICES or any of its funders or partners is intended or should be inferred. Parts of this material are based on data and information compiled and provided by CIHI. However, the analyses, conclusions, opinions and statements expressed herein are those of the author, and not necessarily those of CIHI.

  • Patient consent for publication Not required.

  • Ethics approval Ethics approval was obtained for the study by the University of Alberta Health Research Ethics board (PRO 00083651) and Veritas Research Ethics Board in Ontario (16111-13:21:103-01-2017).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement No data are available.

Linked Articles