High-quality health care is an important goal for all societies. Most people would agree that societies should reward health care providers or organizations providing high-quality care while those whose care can improve should be actively encouraged to get better. Rewarding excellence and encouraging improvement requires the ability to measure health care quality.

Two important attributes of a quality indicator are its ability to be measured accurately (reliability) and its ability to actually measure health care quality (validity). At first glance, early unplanned hospital readmissions would seem to meet both of these criteria. Early unplanned hospital readmissions can be definitively measured accurately using routinely collected health administrative data. Most people would think that early unplanned readmissions must reflect, in some way, a deficit of care during the index hospitalization. Therefore, it is not unexpected that unplanned early hospital readmission is a commonly used health quality indicators.