"Three studies evaluated cannabis use prevention interventions. Two studies evaluated school-based interventions and the third study evaluated two family-centred interventions and a web-based intervention.

"A school-based educational programme integrated within different curriculums was evaluated by Mitchel et alReference Mitchel, Hu, Donnell and Swisher28 in the USA. The CEA used a pre–post study design with a 10-month time frame. This study resulted in one of three integrated curriculums being effective. The study did not report an ICER, but instead presented an ‘effective cost’ or a cost-effectiveness ratio by dividing the societal cost of an intervention by the number of students with positive intervention effects. The study showed that the ‘effective cost’ for the religion curriculum with prevention education programme was US$181 per case prevented of cannabis and cigarette consumption.Reference Mitchel, Hu, Donnell and Swisher28 The second school-based intervention, Project ALERT (Adolescent, Learning, Experiences, Resistance and Training), was evaluated with an economic model in the Swedish setting by Deogan et al.Reference Deogan, Zarabi, Stenström, Högberg, Skärstrand and Manrique-Garcia22 Project ALERT aimed to prevent cannabis experimentation and continuation of use compared with a ‘do nothing’ scenario under a societal perspective. In their modelling, they included prevention of regular use of cannabis and transitioning to using other illicit drugs. The study found that the intervention was cost-effective at 20 years, with an ICER of US$2845 per QALY gained. When the time horizon was extended to a lifetime time horizon, the ICER reduced to US$1904 per QALY gained.Reference Deogan, Zarabi, Stenström, Högberg, Skärstrand and Manrique-Garcia22

"The third cannabis prevention study by Pennington et alReference Pennington, Collins, Leigh, Martin, Owen and Fischer30 simulated three different targeted behavioural interventions identified from literature review. Two family-based interventions (Focus on Families and Familias Unidas) were evaluated against active comparators with short time horizons of 1 and 2 years, respectively. The cannabis model generated for the evaluation included intervention, crime and treatment of potential psychotic disorder costs that was described as a partial public sector perspective. Considering the reported WTP threshold of US$31 014, none of the interventions were cost-effective. Reported ICERs were US$153 915 305 per QALY gained (Focus on Families) and US$373 711 per QALY gained (Familias Unidas). The third intervention was modelled over 2 years and was a web-based intervention that resulted in an ICER of US$741 697 per QALY gained, which also exceeded the WTP threshold."


Faller J, Le LK-D, Chatterton ML, et al. A systematic review of economic evaluations for opioid misuse, cannabis and illicit drug use prevention. BJPsych Open. 2023;9(5):e149. doi:10.1192/bjo.2023.515