Background Gambling is a highly profitable commercial activity with providers that include international corporations and governments. However, growing international recognition that gambling is a source of serious harm, and of inequity in the distribution of this harm, has led to demands for action and the production of policy documents proposing public health strategies to reduce harms at international, national and local levels. We aimed to identify review level evidence on interventions to address or prevent gambling related harm, to document the scope and nature of the evidence base, any gaps in the evidence, and identify policy implications, including where further development and evaluation of interventions was most urgently needed to support the development of evidence-informed policy.

Methods Systematic mapping review and narrative synthesis of review level evidence for any intervention that aimed to address or prevent gambling related harm. Inclusion criteria included all forms of gambling; all populations (whole population; identified/self-defined gamblers and specific populations at risk (e.g. children and young people); all reported outcome measures.

Results After duplication, the searches generated 1080 records. Of 43 potential papers, 13 were excluded at the full paper stage and 30 papers were included in the review. We identified seven studies relating to whole population preventative interventions (demand reduction interventions to reduce the demand for gambling (n=3), and supply reduction interventions to limit opportunities to gamble (n=4)). Twenty three studies provided evidence relating to targeted treatment interventions for individuals with an identified gambling addiction (therapeutic interventions (n=12), pharmacological interventions (n=4), self-help/mutual support interventions (n=5), and studies comparing two or more of these approaches (n=2)). Two further types of intervention we had expected to find were not represented in the systematic review level evidence. These were interventions to screen, identify and support individuals at risk of gambling related harm (whole population) and interventions to support ongoing recovery and prevent relapse into gambling related harm for individuals with an identified gambling addiction.

Conclusion A public health approach suggests that to reduce gambling related harm, there is potential to deliver interventions across the whole pathway - from population-level regulation of provision of opportunity to gamble to screening to identify those at risk, to targeted services for populations with an identified problem already causing harms. Whilst there is some evidence for downstream interventions, there is a dearth of evidence for wider public policy interventions suggesting that implementation of these must be accompanied by robust evaluation of effectiveness.