In conducting a scoping review on the health effects of high-concentration cannabis products, we have uncovered pervasive methodological shortcomings within the cannabis literature. This review begins by defining the “causal effect” of interest for public health and delineating the desirable features of study design that can address crucial questions pertaining to public health and policy. We further delve into the methodological complexities inherent in studying the health effects of high-concentration cannabis products, describing challenges associated with the measurement of exposures and outcomes, confounding, selection bias, and the generalizability of findings. We introduce causal inference methods to mitigate potential biases in observational cannabis use studies. We identify specific areas that necessitate further development and investigation to deepen our understanding of this topic. Finally, this review extends actionable recommendations, serving as a roadmap for upcoming research initiatives in this domain.
In this essay, we address the current state of research in humans and the evidential base concerning high-concentration delta-9-tetrahydrocannabinol (delta-9-THC) products, which are readily available in the United States. Furthermore, we explore the intricate challenges faced in carrying out research on these products, which reflect the full range of study design issues: measurement of exposure and outcomes, confounding, selection bias, and the generalizability of findings. We offer recommendations to guide future research toward providing more informative evidence. By following these recommendations, researchers and funders on this emerging topic could move toward generating the valid and comprehensive evidence needed to effectively inform public health initiatives and guide policy decisions regarding high-concentration delta-9-THC products and their use. The urgency of generating such evidence cannot be overstated, given the widespread legalization and increasing availability and use of these products.
We describe the scoping review on high-concentration cannabis with the dual goals of documenting the utility of this approach to evidence identification and introducing the evidence map to the public health community. The objectives of the scoping review were to (1) identify and describe human studies that explore the relationship of high-concentration cannabis products with any health outcomes and (2) create an interactive evidence map of included studies to facilitate further analysis.
