When information shadows speak: A meta-narrative review of invisible health system actors and decision-making in developing countries

Health systems in low- and middle-income countries are often shaped by information flows that operate outside formal structures. This review explores the nature, functions, and influence of such informal or shadow information practices on health system governance, responsiveness, and equity. A structured search across six databases yielded 6,280 records, of which 33 studies met the inclusion criteria. Using a meta-narrative synthesis approach, the review examined diverse forms of non-codified knowledge, such as tacit experience, verbal exchanges, locally crafted indicators, and workaround systems, and their roles in decision-making and adaptation. Most studies were grounded in qualitative or ethnographic traditions and focused on community health workers, frontline nurses, and local administrators operating in community and primary care settings. Findings show that these informal flows are not merely substitutes for formal systems but serve as vital mechanisms for navigating uncertainty, preserving continuity, and enabling decentralised action. At the same time, they raise concerns about opacity, fragmentation, and uneven accountability. Conceptual frameworks such as governance, learning health systems, and sensemaking theory have been applied, but important gaps remain in addressing ethical, political, and power-related dimensions. The review concludes that recognising and engaging with shadow information practices is essential for understanding how health systems function in practice. Rather than being marginal or anomalous, these flows are integral to everyday system performance and deserve greater attention in both research and policy.