Evidence in Context: High Risk of Bias in Medical Cannabis and Cannabinoid Clinical Trials Dictates the Need for Cautious Interpretation.

• Studies designed as randomized controlled trials (RCTs) are intended to produce high-quality evidence and are crucial tools in the assessment of medical cannabis and cannabinoid efficacy and safety. However, high risk of bias was demonstrated by the majority of medical cannabis and cannabinoid RCTs in a comprehensive meta-analysis. Risk of bias makes it difficult to interpret and apply findings from these studies. • Risk of bias introduced into and observed in cannabis RCTs warrants scrutiny, and standardized tools are recommended when reviewing RCT reports of findings. Clinical practice should ideally be altered only when sufficient evidence is available and an understanding of the “levels of scientific evidence” and common limitations to RCTs should be communicated to clinicians. • Patients should be informed that no RCT should influence their behaviors. Open lines of communication with their physicians and other healthcare providers can help facilitate more informed consumption of media coverage and other dissemination of research findings.