Evaluating the Performance of an Institution Using an Intensive Care Unit Benchmark

Abstract

To describe the performances of selected intensive care units (ICUs) in a single institution using the Acute Physiology and Chronic Health Evaluation (APACHE) III benchmark and to propose interventions that may improve performance. In this retrospective study, we analyzed APACHE III data from critically ill patients admitted to ICUs at the Mayo Clinic in Rochester, Minn, between October 1994 and December 2003. We retrieved ICU performance measures based on first ICU day APACHE III values. Standardized ratios were defined as ratios of measured to predicted values. The primary performance measure was the standardized mortality ratio, and secondary performance measures were length of stay (LOS) ratios, low-risk monitor ICU admission rates, and ICU readmission rates. We calculated 95% confidence intervals (CIs) for each performance, graded as good, average, or poor. Among 46,381 patients admitted during the study period, 57.5% were in surgical ICUs, 24.8% in a medical ICU, and 17.7% in a surgical-medical ICU. Low-risk monitoring accounted for 37.2% of admissions. Hospital standardized mortality ratios (95% CI) were 0.95 (0.90-0.99), 0.86 (0.81-0.91), and 0.70 (0.66-0.74) for medical, multispecialty, and surgical ICUs, respectively. Hospital LOS ratios (95% CI) were 0.83 (0.81-0.85), 0.91 (0.88-0.93), and 0.99 (0.97-1.00) for medical, multispecialty, and surgical ICUs, respectively. The ICU readmission rate for each ICU was higher than the 6.7% reported in the medical literature. Performances were good in mortality, average to good in LOS, average in low-risk admission, and poor in ICU readmission. A national benchmarking database can highlight the strengths and weaknesses of ICUs. The performances of ICUs in a single institution may differ; therefore, the performance of each unit should be evaluated individually.