Health system performance assessment (HSPA) is a promising tool to evaluate health system capacity in achieving health systems goals and informed policy for health systems strengthening. Despite its importance, no universal definition is available at global level to support HSPA implementation. This chapter highlights the evolution of HSPA frameworks, which mostly follow the scope and boundaries of health systems. Key characteristics of successful HSPA include regularity, transparency, comprehensiveness, being analytical and systematic, which result in valid assessment and inform policy. HSPA requires selection of indicators suitable to the country context; the criteria for selecting indicators include importance, relevance, feasibility, reliability and validity. Hospital performance assessment, a subset of the HSPA, is necessary as it consumes signification portion of health resources. HPSA also contributes to monitoring achievement of SDG targets 3.8.1 and 3.8.2 on Universal Health Coverage as committed by countries. The chapter concludes by providing evidence how Thailand's health system performed in response to COVID-19 pandemic.

Well-performing health systems are critical for pursuing universal health coverage and for achieving health-related SDGs. It is important to grasp key concepts such as systems approach, analysis, and thinking before taking a deeper dive into health systems. Health systems can be described in broad or restricted terms. The most widely accepted definition includes all the institutions, actors, and activities whose primary purpose is to promote, restore or maintain health. There are many health system frameworks and models of which four have been reviewed - WHO’s Health System Conceptual Framework, Control Knobs Framework, Kielmann’s and Roemer’s Health System Models. No single framework addresses all aspects of a health system. It is more useful to know the strengths and limitations, and usefulness of each in achieving a specific objective such as for description and analysis, designing system reform, or evaluation. Interventions whether system-led, programmatic or those addressing health determinants are part of the wider health system and offer the best opportunity for improving health outcomes when addressed together.

Health systems are made up of multiple interacting components including organisations, people and actions. They perform several functions: delivering healthcare services; maintaining and improving health; protecting households from the costs of illness; enabling economic functioning; and shaping societal norms and values. They are also sites of competition and contestation between actors with different interests and visions.

This chapter outlines the complexity of health systems and explains how they can only be studied and fully understood through a multi-disciplinary lens. It unpacks the different dimensions of health systems complexity, the societal functions performed by health systems, and the contestation between different ideas, values and interest groups. It examines various health systems frameworks and typologies and how they can be used to describe and understand the performance of health systems. It discusses the open and contextual nature of health systems and their relationship with external factors, including shifts in international health policy-making. Finally, the chapter ends with a brief introduction of systems thinking which is discussed further in Chapter 2.