The amount that each country spends on health, for both individual and collective services, and how this changes over time can be the result of a wide array of social and economic factors, as well as the financing and organisational structures of a country's health system.

The change in how much a country spends on healthcare in relation to spending on all the other goods and services in the economy can depend on both fluctuations in the rate of health spending itself as well as growth in the economy as a whole. The 2000s were characterised by a period of health spending growth above that of the overall economy so that health expenditure as a share of GDP rose sharply in many OECD countries. However, the economic crisis that took hold in 2008 resulted in an initial rise followed by a reduction in the health spending to GDP ratio across many OECD countries.

Spending on inpatient care and outpatient care combined covers the major part of health expenditure across OECD countries – almost two-thirds of current health expenditure on average in 2013 (). A further 20% of health spending was allocated to medical goods (mainly pharmaceuticals), while 12% went towards long-term care and the remaining 6% on collective services, such as public health and prevention services as well as administration.

Across all OECD countries, health care is financed by a mix of public and private spending. In some countries, public health spending is mostly confined to spending by the government using general revenues. In others, social insurance funds finance the bulk of health expenditure. Private financing of health care consists mainly of payments by households (either as standalone payments or as part of co-payment arrangements) as well as various forms of private health insurance.

Attributing health care expenditure by disease and age is important for health policy makers in order to analyse resource allocations in the health care system. This information can also play a role in assessing the impact of population ageing and changing disease patterns on spending. Furthermore, the linking of health expenditures by disease to appropriate measures of outputs (e.g. hospital discharges by disease) and outcomes (e.g. survival rates after heart attack or cancer) helps in monitoring the performance of health care systems at a disease-based level (Heijink et al., 2006).

Knowing how much a health system is investing in hospitals, medical technology and other equipment is very relevant for policy making and analysis. Although health systems remain a highly labour-intensive sector, capital has been increasingly important as a factor of production of health services over recent decades. This is illustrated, for example, by the growing importance of diagnostic and therapeutic equipment or the expansion of information, computer and telecommunications technology in health care over the last few years. The availability of statistics on capital expenditure is essential to the analysis of the health system’s production capacity (that is, whether capacity is appropriate, deficient or excessive), which is needed in turn to inform policy implementation (for example, if excess capacity exists, the marginal cost of expanding coverage will be lower than if the health care system is already straining to fill current demand).