Investing in Prevention Before Treatment: A Systematic Literature Review of Determinants of Public Expenditure on Health Promotion and Disease Prevention, with Implications for Thailand

Abstract

Despite compelling evidence that prevention is more cost-effective than treatment, most countries systematically underinvest in health promotion and disease prevention relative to curative care—a pattern commonly termed the “prevention paradox.” This systematic literature review synthesizes international evidence on the determinants of public expenditure for health promotion and disease prevention. Following PRISMA 2020 guidance, structured searches of five databases (2002–2023) yielded 23 eligible studies, which were appraised against transparent, design-sensitive quality criteria and integrated through narrative synthesis across five determinant categories: socioeconomic and demographic; political–institutional; organizational decision-making; health-system resources; and decentralization. Gross domestic product per capita emerged as the strongest single determinant, consistent with Wagner’s Law, yet political factors—particularly democratic institutions and governance quality—proved comparably important for allocative efficiency, while path dependency and incremental budgeting substantially constrained reallocation toward prevention. The evidence further indicates that economic capacity translates into preventive investment chiefly when mediated by governance quality, and that decentralization’s effects are conditional on institutional capacity. Synthesizing these patterns, we advance a simplified multi-level framework linking macro-, meso-, and micro-level determinants. For Thailand—a middle-income country transitioning to a super-aged society while non-communicable diseases consume a growing share of its health budget—raising preventive investment will require coordinated action: macro-level fiscal alignment, meso-level governance strengthening, and micro-level budget-process reform, including carefully phased zero-based budgeting that accounts for entrenched incremental practices. Future research should employ longitudinal, context-sensitive designs within developing economies.