What does the ecological and epidemiological evidence indicate about the potential for cannabinoids to reduce opioid use and harms ? A comprehensive review Gabrielle Campbell, Wayne Hall and Suzanne Nielsen International Review of Psychiatry, 2018, 1-16. Doi : 10.1080/09540261.2018.1509842   ABSTRACT Pre-clinical research supports that cannabinoids reduce opioid dose requirements, but few studies have tested this in humans. This review evaluates ecological and epidemiological studies that have been cited as evidence that medical cannabis use may reduce opioid use and opioidrelated harms. Medline and Embase were searched for relevant articles. Data were extracted on study setting, analyses approach, covariates, and outcomes. Eleven ecological and 14 epidemiological [...]