Core Outcome Measures in Effectiveness Trials

Establishing a core endpoints set for studies examining treatments for cannabis use disorder and problematic cannabis use

General Information

Cannabis is one of the most frequently used illicit drugs in North America. In 2015, 12% of Canadians aged 15 years and older reported cannabis use within the prior 12 months (3% for medical purposes). Data suggest 1 in 3 individuals who use cannabis will develop problematic use, and 1 in 11 will develop an addiction.

The medicinal cannabis is known to have positive health effects for some conditions, however, this must be balanced with potential negative effects. Potential long-term effects of cannabis are not yet fully understood, but may include greater risk of psychotic disorders, depression, mania, suicidal ideation, cognitive impairment and adverse respiratory effects (e.g. chronic bronchitis). Cannabis use disorder (CUD) involves the problematic use of cannabis leading to clinically significant impairment. Problematic cannabis use (PCU) is less well defined but can significantly impact the quality of life of individuals.

Recommended treatment for CUD/PCU currently consists of psychosocial and self-help/mutual support groups, however, substantial variability in core endpoints is present making evidence synthesis difficult. Outcome assessment (i.e. collection of different patient endpoints between studies; e.g., adherence versus changes in dependence symptoms) and measurement methods (e.g. self-report of drug use versus biologically confirmed measures) have been identified in previous reviews as highly problematic, and are a key obstacle in research for CUD/PCU treatment (and other drug dependence research)

In this work our objectives are to:
(1) conduct a systematic review with planned meta-analyses to assess the relative benefits of different psychosocial therapies in people with CUD or PCU; and
(2) use information gathered from the review along with structured focus groups, interviews and Delphi surveys to establish a core outcomes set of patient oriented outcomes to be used in future studies comparing interventions for treatment of individuals with CUD or PCU.

- Principal Investigators Brian Hutton (Ottawa Hospital Research Institute) and Kim Corace (The Royal Ottawa Mental Health Center and University of Ottawa)

-Co-Investigators Danielle Rice (McGill University and Ottawa Hospital Research Institute), David Moher (Ottawa Hospital Research Institute), Dianna Wolfe (Ottawa Hospital Research Institute), Peter Tugwell (Ottawa Hospital Research Institute), Bev Shea (Ottawa Hospital Research Institute), Kednapa Thavorn (Ottawa Hospital Research Institute)

-Knowledge Users: Canadian Center on Substance Use and Addiction; Public Health Ontario; Melanie Willows (the Royal Ottawa Mental Health Center and president elect of the Canadian Society of Addiction Medicine); Community Addictions Peer Support Association; Moms United and Mandated to Saving the Lives of Drug Users (

Further Study Information

Current Stage:
April 2019 - April 2021
Funding source(s):
A funding application was submitted in Fall 2018 and we are awaiting feedback (estimated date of January 2019)

Health Area

Disease Category
Tobacco, drugs, & alcohol dependence

Disease Name
Cannabis use disorder/problematic cannabis use

Target Population

Age Range
12 - 80


Nature / type of Intervention


Consensus meeting
Delphi process
Focus group(s)
Literature review
Systematic review

Our planned work consists of two objectives: (1) performance of a systematic review to evaluate the benefits of different psychosocial interventions for treatment of individuals with CUD, PCU; and (2) development of a core outcome set for future studies related to interventions for treatment of CUD, PCU.

Details of the systematic review and planned meta-analyses/network meta-analyses will be described in depth in our planned open access protocol. The core outcomes set will be derived by use of well established methods for the development of such information, including a thorough review of the literature to identify candidate clinical and patient related outcome measures as well as use of consensus Delphi methods to determine agreed upon core outcomes for opioid use disorder. To pursue the second objective, we will establish candidate measures reflecting the outcomes, and subsequently we will evaluate their face validity, feasibility and measurement properties. Our planned deliverables from this work include: (a) a published protocol describing methods for our systematic review and approach to core outcome set development; (b) one (and possibly multiple) publications describing findings from our systematic review; and (c) a core outcomes set for CUD/PCU for dissemination to inform the design of future research studies.

Stakeholders Involved

Clinical experts
Consumers (caregivers)
Consumers (patients)
Governmental agencies
Patient/ support group representatives
Policy makers
Service providers

Study Type

COS for clinical trials or clinical research
COS for practice
Recommended outcome measures (measurement)

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