Beyond the price tag: a scoping review of the determinants of informal payments in health systems and strategies for curbing them

BACKGROUND: Informal payments (IPs) remain a persistent challenge across health systems worldwide and may undermine equity, transparency, and public trust in healthcare delivery. Despite a growing body of research, evidence regarding the determinants of IPs and the strategies proposed to address them remains fragmented and lacks a comprehensive synthesis. This scoping review aimed to: (1) map and synthesize existing evidence on the key determinants of IPs in health systems globally; and (2) identify, categorize, and summarize the range of strategies proposed to curb them. METHODS: Following the Joanna Briggs Institute (JBI) methodology, we conducted a systematic search across five databases-PubMed, Web of Science, Scopus, ProQuest, and ScienceDirect-from database inception through January 2025. Two reviewers independently screened all records against predefined eligibility criteria. Data from the included studies were extracted using a standardized form and thematically analyzed. RESULTS: This review synthesized evidence from 68 studies. Determinants of IPs were categorized into five interconnected levels: (1) patient-level factors (e.g., fear of poor-quality care, desire for faster services, and limited knowledge); (2) structural/contextual factors (e.g., underfunding, weak regulation, and type of service); (3) provider-level factors (e.g., low salaries and shortages of supplies); (4) cultural/ethical factors (e.g., norms of gratitude and social acceptance of informal payments); and (5) organizational-level factors (e.g., corruption and lack of accountability). Proposed interventions were grouped into five strategic categories: patient empowerment (education and patient-rights mechanisms); cultural-normative strategies (shifting social norms and fostering trust); financial strategies (improving provider remuneration, formalizing payments, and expanding insurance coverage); structural strategies (strengthening health systems and improving service accessibility); and governance and regulatory strategies (legal frameworks, oversight mechanisms, and sanctions). An analytical framework was developed to illustrate the mechanisms of action and key contextual considerations associated with each strategy, highlighting that implementation processes and outcomes are highly context dependent. CONCLUSIONS: IPs are a multifactorial phenomenon rooted in systemic weaknesses, economic incentives, and sociocultural norms. Isolated interventions are unlikely to be effective. Addressing IPs requires integrated, multi-pronged strategies that reduce financial pressures on providers, strengthen governance and transparency, improve service quality and accessibility, empower patients, and reshape cultural norms. This review provides a foundational evidence map to support the design of context-sensitive, system-level policies aimed at reducing and ultimately eliminating informal payments. Future research should evaluate the effectiveness and sustainability of interventions across diverse health system contexts, particularly in underrepresented settings, and further examine the institutional and contextual factors that perpetuate informal payment practices. CLINICAL TRIAL NUMBER: Not applicable.