Multiple Organ Dysfunction Score

Abstract

To develop an objective scale to measure the severity of the multiple organ dysfunction syndrome as an outcome in critical illness. Systematic literature review; prospective cohort study. Surgical intensive care unit (ICU) of a tertiary-level teaching hospital. All patients (n equals 692) admitted for more than 24 hrs between May 1988 and March 1990. None. Computerized database review of MEDLINE identified clinical studies of multiple organ failure that were published between 1969 and 1993. Variables from these studies were evaluated for construct and content validity to identify optimal descriptors of organ dysfunction. Clinical and laboratory data were collected daily to evaluate the performance of these variables individually and in aggregate as an organ dysfunction score. Seven systems defined the multiple organ dysfunction syndrome in more than half of the 30 published reports reviewed. Descriptors meeting criteria for construct and content validity could be identified for five of these seven systems: a) the respiratory system (PO2 /FIO2 ratio); b) the renal system (serum creatinine concentration); c) the hepatic system (serum bilirubin concentration); d) the hematologic system (platelet count); and e) the central nervous system (Glasgow Coma Scale). In the absence of an adequate descriptor of cardiovascular dysfunction, we developed a new variable, the pressure-adjusted heart rate, which is calculated as the product of the heart rate and the ratio of central venous pressure to mean arterial pressure. This multiple organ dysfunction score, constructed using simple physiologic measures of dysfunction in six organ systems, mirrors organ dysfunction as the intensivist sees it and correlates strongly with the ultimate risk of ICU mortality and hospital mortality. The variable, Delta Multiple Organ Dysfunction Score, reflects organ dysfunction developing during the ICU stay, which therefore is potentially amenable to therapeutic manipulation. As an outcome measure complementary to predictive scores now widely available, such a score may find use in epidemiologic studies of the multiple organ dysfunction syndrome. Moreover, an instrument that can provide an objective measure of the severity of organ dysfunction at the time of ICU admission and that can quantify subsequent deterioration over the course of the ICU stay may prove useful as an alternative end point for clinical trials involving critically ill patients.