Why measure severity and risk of adverse outcomes?
There are many ways to evaluate the quality of health care services. One increasingly popular way is to examine the rate of adverse health outcomes. Mortality is frequently used to categorize outcomes for patients who have acute, life threatening illness. Within both the group of patients who live and the group that dies, some patient might receive good care while others receive poor care. Some patients may be so ill that they cannot be saved by the best of care. Other patients may get well despite poor care. One way to measure quality of health care is to examine across a group of patients the rates of mortality and decide that these rates are lower or higher than what would be expected given the patients’ severity of illness. When we want to do so, it is important to be able to separate the influence of the patients’ severity of illness from the quality of care. There are at least two ways for doing so. One is to randomly assign patients to different providers, making sure that provi
