Statistical analysis
P.
A power analysis conducted for the primary outcome of the main trial (time by group interaction on reduction in cannabis use) indicated that 12 participants per group would provide 80% power to detect an effect of CBD on cannabis use, based on a previous study of CBD on cigarette use in tobacco smokers (T. P. Freeman et al. The effect of CBD treatment compared to placebo on each cognitive outcome was analysed using linear mixed-effects models, using the “lme4” package in R. Data from all patients randomly assigned to placebo, 400 mg CBD and 800 mg CBD groups were analysed on an intention-to-treat basis. Models included data from baseline and end of treatment only (week 4) in order to focus on the effect of the treatment period, consistent with the primary endpoint analysis of the main trial (T. P. Freeman et al. 