Comparing healthcare outcomes.

Governments are increasingly concerned to compare the quality and effectiveness of healthcare interventions but find this a complex matter. Crude hospital statistics can be dangerously misleading and need adjusting for case mix, but identifying and weighting the patient characteristics which affect prognosis are problematical for conceptual, methodological, and practical reasons. These include the inherently uncertain nature of prognosis itself and the practical difficulties of collecting and quantifying data on the outcomes of interest for specific healthcare interventions and known risk factors such as severity.