Controlled administration of cannabis to mitigate cannabis-attributable harm among recreational users: a quasi-experimental study in Germany

Abstract

Background: New approaches are required to slow down or reverse increasing trends of levels of delta-9-tetrahydrocannabinol (THC) and cannabis-attributable hospitalizations in Germany. Legal access to cannabis may constitute one viable effective policy response; however, available evidence does not suffice to inform a regulation model for Germany. The proposed study aims to reduce harm for cannabis users through legal access to herbal cannabis through pharmacies. Protocol: A quasi-experimental study comparing cannabis users with legal access to herbal cannabis (Berlin, intervention group) to those without legal access (Hamburg, control group) (total N=698). As the primary outcome, we hypothesize that: 1) illegal THC consumption will reduce by at least 50% in the intervention group and 2) total THC exposure in the intervention group will be reduced by at least 10% lower than that of the control group, taking into account baseline values. Secondary outcomes comprise measures of frequency of use, THC-impaired driving, and mode of administration. Paired t-tests and multilevel regression models will be performed for statistical analyses. Discussion: This study proposal is currently being reviewed by the ‘Federal Institute for Drugs and Medical Devices’ – the body responsible for approving research studies on classified substances, including cannabis. Upon approval and prior to the start of the study, a full ethical review will be undertaken. Results may inform a regulation model for Germany and other jurisdictions and are expected to deepen the understanding of the effects of legal access to cannabis. Pre-registration: German Clinical Trials Register (DRKS), DRKS00020829

Cannabis and public health: a global experiment without control

“…Thus, identifying causal agents and processes poses methodological challenges which may not be overcome easily in analyzing natural, large‐scale experiments. To improve understanding of the effects of le­galization, we strongly advocate for small‐scale, controlled experiments, such as those proposed in the city of Berlin, Germany 4 . There, the effects of legal access to cannabis are to be studied in a restricted sample of registered users, while users without legal access serve as controls.…”