Cost-Effectiveness of School-Based Prevention of Cannabis Use

Cannabis is the most frequently used illicit drug globally. Despite increasing evidence that cannabis use is associated with adverse health effects, the knowledge on preventative strategies is still limited. This study stemmed from a systematic review of effective prevention in which school-based programmes were identified as promising. The primary objective was to evaluate the cost effectiveness of Project ALERT (Adolescent, Learning, Experiences, Resistance, and Training), compared with ordinary ATOD (Alcohol, Tobacco, and Other Drug) education, among Swedish students in the eighth grade of compulsory school.

The cost-effectiveness analysis was performed from the societal perspective with quality-adjusted life-years (QALYs) as an outcome (willingness-to-pay threshold €50,000) and follow-up periods from 1 year to a lifetime, considering a discounting rate of 3%, and with costs inflated to 2013 levels. A Markov model was constructed on the basis of the 'states' of single use, regular use, daily use and use of other illicit drugs, which were associated with 'complications' of psychosis, schizophrenia, traffic accidents, depression and amotivational syndrome. Health and cost consequences were linked to both states and complications.

The programme was cost saving on the basis of evidence from the USA (ratio 1:1.1), and was cost effective (incremental cost-effectiveness ratio €22,384 per QALY) after reasonable adjustment for the Swedish context and with 20 years of follow-up. When the target group was restricted to boys who were neither studying nor working/doing work experience, the programme was cost effective after 9 years and cost saving (ratio 1:3.2) after 20 years.

School-based prevention such as Project ALERT has the potential to be cost effective and to be cost saving if implemented in deprived areas. In the light of the shifting landscape regarding legalization of cannabis, it seems rational to continue the health economic analysis of prevention initiated here.