Abstract
Critically ill patients require huge resources because of dysfunction of several vital organs. The heterogeneity and complexity of the ICU patient have generated interest in systems that would be capable of assessing the severity of illness with the objective of predicting the outcomes, comparing the quality of care, and stratifying patients for clinical trials. Because the ICU mortality rate has been strongly correlated with the number of failing organs and with the degree of organ dysfunction, quantification of organ dysfunction/failure is also important. The advantages of accurate assessment of a patient's risk include the opportunity to give a more accurate prognosis and choose the most appropriate therapy. This review describes three different general severity-of-illness models, including several versions, four single organ failure scoring models, and four multiple organ failure models. As there are several pitfalls related to the interpretation of the numbers supplied by the systems, they should not be used without knowledge of the science of severity scoring. Pertinent use of the tools would make it possible to judge the severity of illness accurately and would be useful for discrimination of critically ill patients, providing optimum therapy, and decreasing the ICU mortality.
