Theory of Change Framework for Economic Evaluation Using Health System Models

All-disease health systems models (HSMs) represent the new frontier of economic evaluation to help guide sector-wide resource allocation, allowing for decision analysis in the context of interacting health system capacity constraints. Although there are frameworks for how health systems and their relationship with health outcomes may be characterised, there is a gap in the literature in providing a comprehensive list of health system components and a template for impact pathways from health system components to health outcomes to consider when designing, using and communicating HSMs for economic evaluation. This paper provides a conceptual framework to serve as a theoretical underpinning for the design and use of HSMs developed for economic evaluation. The framework builds upon previous literature as well as our experience developing the Thanzi La Onse (TLO) Model for Malawi.