Health impact bonds as an innovative payment model for health prevention programs: A scoping review.

Health impact bonds (HIBs) are an innovative outcome-based financing model increasingly applied in public health programs. This study aimed to comprehensively summarize their applications, benefits, and challenges in health prevention programs. In this scoping, 31 peer-reviewed papers and 19 websites were eligible for inclusion. Key characteristics of the programs were extracted, including details of the interventions, health and financial outcomes, and stakeholders' involvement. We identified 23 HIB programs across 13 countries, with durations ranging from 2 to 7.5 years. These programs targeted various health issues, including non-communicable diseases, cancer screening, maternal and child health, infectious diseases, mental health, and assistance for older people. Of completed programs with disclosed financial outcomes, 11 programs fully met their targets. Initial investments ranged from under US$100,000 to over US$29 million, with investor returns varying from 5% to 27.4%. Benefits included risk transfer, innovation, cross-sector collaboration, and improved accountability. Key challenges were investor risk, high transaction costs, outcome attribution complexity, limited evidence, and stakeholder coordination issues. HIBs may be a promising complementary model for financing health prevention initiatives to alleviate burdens for healthcare systems. However, some major challenges, including modest return relative to risk, limited investor participation, and stakeholder misalignment, need to be addressed to enable a broader adoption across diverse health issues and healthcare contexts.