Objectives: To compare the outcomes for patients with one or more organ system failures treated in 1988 to 1990 with those outcomes from 1979 to 1982; to document risk factors for developing organ system failure; and investigate the relationship of these factors to hospital survival.
Design: Prospective, multicenter, inception cohort analysis.
Setting: Sixty intensive care units (ICUs) at 53 U.S. hospitals.
Patients: A total of 17,440 ICU admissions treated in 1988 to 1990 and 5,677 ICU admissions treated in 1979 to 1982.
Interventions: None.
Measurements and main results: At the time of organ system failure, patients were classified by demographic, physiologic, and diagnostic information. The type and number of organ system failures and physiologic responses were recorded for < or = 7 days of ICU treatment, and all patients were followed for status at hospital discharge. Hospital survival and the prognostic value of assessing the number of organ system failures were compared with risk assessment, based on use of a prognostic scoring system that estimated the patient's probability of hospital mortality. The incidence of organ system failure (48%) among patients treated in 1988 to 1990 was similar (44%) to the occurrence rate in patients in 1979 to 1982; and an identical proportion (14%) developed multiple organ system failure. There was a significant (p < .0003) improvement in hospital mortality for patients with three or more organ system failures on day 4 or later of organ system failure. However, overall hospital mortality rates from multiple organ system failure were not different over this 8-yr period. The most important predictor of hospital mortality was the severity of physiologic disturbance on the initial day of failure. Discrimination of patients by risk of hospital mortality was better using the prognostic scoring system on day 1 of organ system failure (receiver operating characteristic curve = 0.88) than using a model based on the number of organ system failures (receiver operating characteristic curve = 0.68).
Conclusions: Organ system failure remains a major contributor to death in patients in ICUs. The incidence and overall outcome have not significantly changed over the past 8 yrs, but there has been significant improvement in survival for patients with persistent severe organ system failure. A continuous measure of individual patient severity of illness is a more sensitive and accurate method for describing patients and estimating outcome than counting the number of organ system failures.