Issues in quality measurement: target population, risk adjustment, and ratings.

This review investigates three fundamental issues in health care performance measurement: selection of a homogeneous target population, risk adjustment, and assignment of quality rating categories. Many but not all organizations involved in quality measurement have adopted similar approaches to these important methodological issues. To illustrate the practical implications of different profiling strategies, we use The Society of Thoracic Surgeons' data to compare profiling results derived using prevailing analytical methodologies with those obtained from alternative approaches, exemplified by those of a well-known health care performance rating organization. We demonstrate the differences in provider classification that may result from these methodologic decisions.