Measuring the affordability of medicines: importance and challenges.

The issue of affordability of health care services remains high on the (health) policy agenda. Determining whether health care services are affordable is complex, however, as the concept 'affordability' is inherently normative. With a focus on measuring affordability in low- and middle-income countries, we discuss different methods used to operationalize this concept. Using the example of medicine purchases in Indonesia, we show the choice of method and threshold to have a significant impact on outcomes. We argue it is important to further standardize methods and appropriate threshold use in applied research to increase comparability of results and to facilitate sound assessments of affordability.