Outcome data and scoring systems

Why are scoring systems needed?

Although rigorous experiments or large randomised controlled trials are the gold standard for evaluating existing or new interventions, these are not always possible in intensive care. For example, it is unethical to randomly allocate severely ill patients to receive intensive care or general ward care. The alternative is to use observational methods that study the outcome of care patients receive as part of their natural treatment. However, before inferences can be drawn about outcomes of treatment in such studies the characteristics of the patients admitted to intensive care have to be taken into account This process is known as adjusting for case mix.

The death rate of patients admitted to intensive care units is much higher than that of other hospital patients. Data for 1995-8 on 22 057 patients admitted to 62 units in the case mix programme, the national comparative audit of patient outcome, showed an intensive care mortality of 20.6% and total hospital mortality of 30.9%. However, mortality across units varied more than threefold. Clearly, it is important to account for this variation.

Given the relatively high mortality among intensive care patients, death is a sensitive, appropriate, and meaningful measure of outcome. However, death can result from many factors other than ineffective care Outcome depends not only on the input (equipment, staff) and the processes of care (type, skill, and …