Naval Submarine Medical Research Laboratory Submarine Base, Groton, Conn. Report Number 1119 a Severity of Illness Index for Evaluation Pre-hospital Care of Submariners with Abdominal Pain

It is difficult to compare the severity of different illnesses. Medical outcome measurements — morbidity and mortality ■— are not useful indicators. Another indicator is needed. A Severity of Illness Scale has been developed and validated on patients hospitalized with abdominal pain. A maximum likelihood factor analysis was carried out on the following variables: the number of bed days occupied by the patient, the number of diagnoses, procedures, preoperative, postoperative, and convalescent days, and the hospital admissions. This produced a two factor solution which reflected (i) the intensity of the treatment and (ii) the severity of the illness. There was a significant effect of the specific diagnosis on the treatment instituted, which demonstrated the validity of the Severity of Illness Scale. Other uses of the scale are discussed.