VARIATIONS IN MORTALITY AND LENGTH OF STAY IN INTENSIVE-CARE UNITS

Objective: To evaluate the amount of variation in in-hospital mortalit y and length of intensive care unit (ICU) stay that can be accounted f or by clinical data available at ICU admission. Design: Inception coho rt study. Setting: Forty-two ICUs in 40 hospitals, including 26 hospit als that were randomly selected and 14 large tertiary care hospitals t hat volunteered for the study. Participants: A consecutive sample of 1 6 622 patients and 17 440 ICU admissions. Measurements and Main Outcom es: Data on selected demographic characteristics, comorbidity, and spe cific physiologic variables were recorded during the first ICU day for an average of 415 admissions at each ICU; hospital discharge status ( dead or alive) and length of ICU stay were recorded for individual pat ients; and the ratio of actual to predicted in-hospital mortality, sta ndardized mortality ratios, and the ratio of actual to predicted lengt h of ICU stay were recorded for individual ICUs. Results: Unadjusted i n-hospital mortality rates for the 42 units varied from 6.4% to 40%, a nd 90% (R2 = 0.90) of this variation was attributable to patient chara cteristics at admission. The standard mortality ratio varied from 0.67 to 1.25. The mean unadjusted length of ICU stay varied from 3.3 to 7. 3 days, and 78% of the variation (R2 = 0.78) was attributed to patient and selected institutional characteristics. The best performing unit had a length of stay ratio of 0.88, whereas the poorest performing uni t had a ratio of 1.21. Conclusions: Clinicians can use readily availab le admission data to adjust for considerable variations in patient sev erity and type in different ICUs. Such data should permit precise eval uation and comparison of ICU effectiveness and efficiency, which varie d substantially in this study, and result in improved methods of risk prediction and evaluation of new medical practices.