One of the methods developed for taking into account a patient’s severity of illness, in addition to simply the diagnosis and surgical procedures, in predicting and analyzing the length of stay, cost, and outcome. For a number of diagnoses, objective factors have been identified by which the patient’s condition can be classified into several “stages” representing degrees of severity. For example, a diabetic person whose diabetes is under control could be in “Stage 1,” and not require hospitalization, while one in diabetic coma (a life-threatening condition) could be in “Stage 4,” and require intensive care in the hospital. In this system, the severity score is specific to the disease. As currently applied, using discharge abstract (see abstract) data, only the severity on discharge from the hospital can be estimated.