Ecological Adverse Selection Theory: A Structural Framework for Understanding Health System Inequity

The inverse care law-the persistent pattern whereby those with greatest health need receive the least care-has remained stubbornly intact for over fifty years. Despite universal health coverage commitments, health systems continue to concentrate disadvantage in hospitals and exclude the most vulnerable from effective care. This paper argues that we lack a mechanism-level explanation for why the inverse care law persists. It introduces Ecological Adverse Selection Theory (EAST) to fill this gap. Drawing on Akerlof's adverse selection framework, EAST argues that health systems are designed around implicit assumptions about patient capacities-stable housing, supportive caregivers, reliable transport-that are not universally held. When systems cannot distinguish patients who possess these capacities from those who do not, they inadvertently select for those who fit and select against those who do not. This process-structural sorting-operates in two dimensions: barriers to access for disadvantaged patients, and accumulation in hospitals when they do access care. EAST introduces three measurable constructs-Predictive Governance Intensity (PGI), Structural Scarcity Index (SSI), and Behavioural Diversity Distribution (BDD)-that enable empirical testing and accountability. Anchored throughout in a case from Manenberg, a Cape Town township where chronic gang violence and structural scarcity make visible the stakes of health system failure, the paper demonstrates how EAST contributes to structural approaches within public health ethics. The paper concludes by identifying the normative implications of EAST, including a capacities-first principle, and by situating EAST within the broader fields of public health ethics and global health ethics.