Improved estimates of Belgian private health expenditure can give important lessons to other OECD countries.

OECD Health Data are a well-known source for detailed information about health expenditure. These data enable us to analyze health policy issues over time and in comparison with other countries. However, current official Belgian estimates of private expenditure (as published in the OECD Health Data) have proven not to be reliable. We distinguish four potential major sources of problems with estimating private health spending: interpretation of definitions, formulation of assumptions, missing or incomplete data and incorrect data. Using alternative sources of billing information, we have reached more accurate estimates of private and out-of-pocket expenditure. For Belgium we found differences of more than 100% between our estimates and the official Belgian estimates of private health expenditure (as published in the OECD Health Data). For instance, according to OECD Health Data private expenditure on hospitals in Belgium amounts to €3.1 billion, while according to our alternative calculations these expenses represent only €1.1 billion. Total private expenditure differs only 1%, but this is a mere coincidence. This exercise may be of interest to other OECD countries looking to improve their estimates of private expenditure on health.