This is a pivotal time in the world of cannabis policy and research. Shifting public sentiment, conflicting and impeded scientific research, and legislative battles have fueled the debate about what, if any, harms or benefits can be attributed to the use of cannabis or its derivatives. The committee has put forth a substantial number of research conclusions on the health effects of cannabis or cannabinoids. Based on their research conclusions, the members of the committee formulated four specific recommendations to address research gaps, improve research quality, improve surveillance capacity, and address research barriers. The report’s full recommendations are described below.
To address the research gaps outlined throughout this report, a comprehensive national research agenda will be required. The aspirational goal and organizing principle of this agenda should be to maximize the population-health impact of cannabis research. Achieving this objective will require coordination and collaboration among researchers and research groups; support from stakeholders at the local, state, and national levels; and the concurrent pursuit of several distinct research streams, including clinical and observational research and research in the areas of health policy, health economics, public health, and public safety.
The research agenda should include basic science studies to help inform efforts to minimize harms and maximize benefits associated with
the acute and chronic use of cannabis and cannabinoids, as well as health policy and public health research to examine the health effects of broader social and behavioral changes associated with the legalization of recreational and/or medical cannabis and other changes in cannabis policy. To support the statistical associations identified in epidemiological research, the research agenda should also include basic science research that identifies plausible mechanisms by which cannabis affects specific health endpoints. Furthermore, translational research should be embedded in each of these research streams to ensure that research findings will be of practical use to help inform health care practices, public health priorities, national and state policy, and public safety standards.
Recommendation 1: To develop a comprehensive evidence base on the short- and long-term health effects of cannabis use (both harmful and beneficial effects), public agencies,1 philanthropic and professional organizations, private companies, and clinical and public health research groups should provide funding and support for a national cannabis research agenda that addresses key gaps in the evidence base. Prioritized research streams and objectives should include, but need not be limited to:
Clinical and Observational Research
- Examine the health effects of cannabis use in at-risk or under-researched populations, such as children and youths (often described as less than 18 years of age) and older populations (generally over 50 years of age), pregnant and breastfeeding women, and heavy cannabis users.
- Investigate the pharmacokinetic and pharmacodynamic properties of cannabis, modes of delivery, different concentrations, in various populations, including the dose–response relationships of cannabis and tetrahydrocannabinol (THC) or other cannabinoids.
- Determine the harms and benefits associated with understudied cannabis products, such as edibles, concentrates, and topicals.
- Conduct well-controlled trials on the potential harmful and beneficial health effects of using different forms of cannabis, such as inhaled (smoked or vaporized) whole cannabis plant and oral cannabis.
1 Agencies may include the Centers for Disease Control and Prevention (CDC), relevant agencies of the National Institutes of Health (NIH), and the U.S. Food and Drug Administration (FDA).
- Characterize the health effects of cannabis on unstudied and understudied health endpoints, such as epilepsy in pediatric populations; symptoms of posttraumatic stress disorder; childhood and adult cancers; cannabis-related overdoses and poisonings; and other high-priority health endpoints.
Health Policy and Health Economics Research
- Identify models, including existing state cannabis policy models, for sustainable funding of national, state, and local public health surveillance systems.
- Investigate the economic impact of recreational and medical cannabis use on national and state public health and health care systems, health insurance providers, and patients.
Public Health and Public Safety Research
- Identify gaps in the cannabis-related knowledge and skills of health care and public health professionals, and assess the need for, and performance of, continuing education programs that address these gaps.
- Characterize public safety concerns related to recreational cannabis use and evaluate existing quality assurance, safety, and packaging standards for recreational cannabis products.
In order to effectively guide health care decisions and inform public policy, the proposed cannabis research agenda must produce conclusive, actionable evidence. This will require research studies to be carefully designed and rigorously conducted and to have their data results accurately and comprehensively reported.
Ensuring that cannabis research is of uniformly high quality will require the development of guidelines for data collection, standards for research design and reporting, standardized terminology, and a minimum dataset for clinical and epidemiological studies.
Data collection guidelines could prioritize alternate methods for assessing cannabis use, such as whole blood or urine analysis, over those based on self-report or prescriptions. Standards for research design and methodology could require that researchers attempt to account for the confounding effects of alcohol, tobacco, or other relevant substances of abuse. Standards for research reporting could require that authors of systematic reviews report the key demographic characteristics of the study
population, as well as information related to cannabis dose, frequency of use, and route of administration. A universal, standardized terminology would help to create standard units for describing cannabis use. Because much of the existing epidemiological research on cannabis use fails to distinguish between cannabis that is smoked and cannabis that is administered orally, topically, or via other routes, health effects associated with cannabis use may be conflated with those associated with smoking per se. To correct this, future research will need to employ data collection methods that distinguish between different types of cannabis and different routes of cannabis administration.
Wherever possible, these efforts should adapt existing tools to the particular needs and constraints of cannabis research. For example, workshop participants could build on commonly used guidelines and standards for conducting and reporting research, including Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), Consolidated Standards of Reporting Trials (CONSORT), Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), and Cochrane guidelines for systematic reviews.
Adequately addressing these topics will require input from numerous stakeholders, including clinical and public health cannabis researchers; research methodologists; representatives from working groups that have developed research reporting guidelines; organizations engaged in standards development; representatives from scientific publications; and representatives from government agencies directly or indirectly involved in the research process, including the U.S. Department of Health and Human Services (HHS), including CDC and NIH, and FDA.
Recommendation 2: To promote the development of conclusive evidence on the short- and long-term health effects of cannabis use (both harmful and beneficial effects), agencies of the U.S. Department of Health and Human Services, including the National Institutes of Health and the Centers for Disease Control and Prevention, should jointly fund a workshop to develop a set of research standards and benchmarks to guide and ensure the production of high-quality cannabis research. Workshop objectives should include, but need not be limited to:
- The development of a minimum dataset for observational and clinical studies, standards for research methods and design, and guidelines for data collection methods.
- Adaptation of existing research-reporting standards to the needs of cannabis research.
- The development of uniform terminology for clinical and epidemiological cannabis research.
- The development of standardized and evidence-based question banks for clinical research and public health surveillance tools.
The development of a comprehensive and conclusive evidence base on the health effects of cannabis must begin with data collection. In turn, data collection on a scale sufficient to guide state and national policy will require a diverse array of powerful surveillance tools and technologies.
In many cases, existing surveillance tools can be adapted to further the cannabis research agenda. For example, a recurrent and comprehensive set of cannabis-related questions could be added to existing national health surveys. Researchers could use the Behavioral Risk Factor Surveillance System to track changes in the prevalence of medical and recreational cannabis use; the Medical Expenditure Panel Survey to assess the impact of medical cannabis laws on health care treatments and costs; and the National Vital Statistics System to monitor changes in the incidence rate of cannabis-related overdose deaths.
In other cases, novel diagnostic technologies will need to be developed to aid data collection efforts. For example, the growing incidence of cannabis poisonings among children and the demonstrated risks associated with driving under the influence of cannabis underscore the need for rapid and noninvasive methods of assessing for acute cannabis intoxication.
Multiple stakeholders can contribute to these efforts. CDC’s Center for Surveillance, Epidemiology and Laboratory Services, the Questionnaire Design Research Laboratory at the National Center for Health Statistics, and the Center for Behavioral Health Statistics and Quality at the Substance Abuse and Mental Health Services Administration (SAMHSA) can aid in the design and evaluation of survey questions that accurately capture key data points relating to cannabis use. State public health departments can collaborate with Association of Public Health Laboratories to use existing public health laboratories to provide diagnostic tools and other laboratory resources to meet the needs of clinical and public health professionals engaged in cannabis research. Because of differences in cannabis product type, availability, access, and regulation, such surveillance efforts need to be state based, for the time being.
In their potential role as conveners, the National Association of County and City Health Officials (NACCHO) and the Association of State and Territorial Health Officials (ASTHO) can aid federal agencies
and state and local health departments in assessing the capacity to expand the resources of public health surveillance systems, as well as in articulating strategies and prioritizing the actions necessary to meet the needs of a comprehensive cannabis research agenda.
Recommendation 3: To ensure that sufficient data are available to inform research on the short- and long-term health effects of cannabis use (both harmful and beneficial effects), the Centers for Disease Control and Prevention, the Substance Abuse and Mental Health Services Administration, the Association of State and Territorial Health Officials, the National Association of County and City Health Officials, the Association of Public Health Laboratories, and state and local public health departments should fund and support improvements to federal public health surveillance systems and state-based public health surveillance efforts. Potential efforts should include, but need not be limited to:
- The development of question banks on the harmful and beneficial health effects of therapeutic and recreational cannabis use and their incorporation into major public health surveys, including the National Health and Nutrition Examination Survey, National Health Interview Survey, Behavioral Risk Factor Surveillance System, National Survey on Drug Use and Health, Youth Risk Behavior Surveillance System, National Vital Statistics System, Medical Expenditure Panel Survey, and National Survey of Family Growth.
- Determining the capacity to collect and reliably interpret data from diagnostic classification codes in administrative data (e.g., International Classification of Diseases-10).
- The establishment and utilization of state-based testing facilities to analyze the chemical composition of cannabis and products containing cannabis, cannabinoids, or THC.
- The development of novel diagnostic technologies that allow for rapid, accurate, and noninvasive assessment of cannabis exposure and impairment.
- Strategies for surveillance of harmful effects of cannabis for therapeutic use.
The designation of cannabis as a Schedule I substance imposes numerous regulatory barriers that limit access to the funding and material
resources necessary to conduct cannabis research. Unless these barriers are directly addressed, or creative solutions are developed to circumvent the challenges they pose, a comprehensive national cannabis research agenda will remain an elusive goal.
The evidence discussed in this report suggests that cannabis has both therapeutic value and public health risks. The public health case for pursuing cannabis research, which is premised on this potential for both harm and benefit, is sharpened by the increased prevalence of cannabis use in states where medical and recreational cannabis has been legalized.
To ensure that policy makers are better informed to make decisions on cannabis research and policy, and to explore and characterize the full scope of political and nonpolitical strategies for resolving regulatory barriers to cannabis research, an objective and evidence-based analysis of cannabis policy is necessary.
Recommendation 4: The Centers for Disease Control and Prevention, National Institutes of Health, U.S. Food and Drug Administration, industry groups, and nongovernmental organizations should fund the convening of a committee of experts tasked to produce an objective and evidence-based report that fully characterizes the impacts of regulatory barriers to cannabis research and that proposes strategies for supporting development of the resources and infrastructure necessary to conduct a comprehensive cannabis research agenda. Committee objectives should include, but need not be limited to:
- Proposing strategies for expanding access to research-grade marijuana, through the creation and approval of new facilities for growing and storing cannabis.
- Identifying nontraditional funding sources and mechanisms to support a comprehensive national cannabis research agenda.
- Investigating strategies for improving the quality, diversity, and external validity of research-grade cannabis products.
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