In order to provide a strong empirical framework for assessing the health effects of changes in cannabis policy in Europe, rigorous public health monitoring of cannabis in Europe is crucial [33]. Currently, public health monitoring of adult cannabis use is carried out by two international bodies that routinely collect and publish data on several cannabis indicators, including prevalence of use, treatment rates, and potency levels. First, the United Nation Office on Drugs and Crime (UNODC) collects annual data on prevalence of illegal drug use as well as further drug-related indicators (cultivation, trafficking) from all UN member states [34]. In their annual “World Drug Reports”, these data are summarized at the regional as well as global level [1]. Second, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) – the responsible body for monitoring illegal drug use and drug addiction in Europe – compiles a number of cannabis-related indicators, which also serve as base for the annual European Drug Reports [2]. In addition to these two agencies collecting empirical data on cannabis, the GBD study routinely estimates the prevalence of CUD for all countries [16].
