Synthesising the available evidence to identify the health impact of gambling harm and gambling problems

Gambling-related harm (GRH) significantly impacts health-related quality of life (HRQoL), though its measurement remains challenging due to varied methodologies. This study synthesises existing research on HRQoL effects of gambling, highlighting the complementary strengths of direct and indirect elicitation methods. We reviewed studies measuring GRH's impact on HRQoL, focusing on the maximum effect of severe problems and the shape of the impact curve across the harm spectrum. Results revealed consistent maximum HRQoL disutility of approximately 0.45 for severe gambling problems in direct elicitation studies, while indirect methods showed scaling that implies an arguably implausible maximum. We propose a novel hybrid approach that leverages the strengths of both methods: using direct elicitation to establish the maximum impact and indirect methods to determine the relative impacts across the harm spectrum. This approach mitigates attribution biases in direct measures for lower levels of harm while still benefiting from their ability to accurately capture the impact of gambling at severe levels. To assess lower levels of impact, it uses relative scaling from indirect methods that better reflect how quality of life changes as harms accumulate. Our final best-of-both-worlds estimate synthesises available evidence of GRH's impact on HRQoL, grounded in recognised public health metrics.