PURPOSE: Most ICU patients have a stay of 2-4 days, after which they are able to leave the ICU. Although less prevalent, patients with long stays account for a disproportionate number of ICU days and costs. While there is wide recognition of the large impact of outliers, little is known about the makeup of this important sub-group of ICU patients.
METHODS: APACHE® III mortality and LOS data were collected from 20 health systems in the eICU Program Network (154 ICUs) throughout 2006. LOS outliers were patients with ICU stay > 6 days. Patients were grouped based on predicted ICU mortality: < 10% (low risk), 10-50% (medium) and > 50% (high). Outlier data in the three risk groups were examined in aggregate and at the ICU level: ICUs with < 200 patients were excluded from the ICU level analysis. ICU outlier incidence data were compared to mortality performance using least squares regression analysis.
RESULTS: 63,865 ICU admissions were included in the analysis. 8149 patients had an ICU LOS > 6 days (12.7%) and accounted for 50% of all ICU days. The incidence of outliers in low, medium and high risk patients was 8.6, 28.1 and 33.1%, respectively. 54% of all outliers were low risk patients. There was considerable inter-ICU variability in the incidence of low risk outliers (sd = 5.4%). Deaths in low risk outliers exceeded predicted mortality by 400%. There was a positive correlation between ICU standardized mortality ratio and the incidence of low risk outliers (R = 0.63).
CONCLUSION: More than half of all outliers had predicted mortality < 10%. These low risk outliers accounted for ∼ 25% of all ICU days. They also had a significantly higher mortality rate than expected. The incidence of low risk outliers varied considerably among ICUs, and was associated with worse ICU mortality performance.
CLINICAL IMPLICATIONS: These data suggest that high quality ICU care can reduce the incidence of low risk outliers, and thus have a beneficial effect on ICU resource utilization.
DISCLOSURE: Michael Breslow, No Product/Research Disclosure Information; Shareholder I am a shareholder in VISICU, Inc., a company that sells ICU software and services to hospitals; Employee I am an employee of VISICU, Inc., a company that sells ICU software and services to hospitals; Fiduciary position (of any organization, association, society, etc, other than ACCP I am a member of the Board of Directors of VISICU, Inc., a company that sells ICU software and services to hospitals.