A revised method to assess intensive care unit clinical performance and resource utilization

Crit Care Med. 2007 Aug;35(8):1853-62. doi: 10.1097/01.CCM.0000275272.57237.53.


Objective: In 1994, Rapoport et al. published a two-dimensional graphical tool for benchmarking intensive care units (ICUs) using a Mortality Probability Model (MPM0-II) to assess clinical performance and a Weighted Hospital Days scale (WHD-94) to assess resource utilization. MPM0-II and WHD-94 do not calibrate on contemporary data, giving users of the graph an inflated assessment of their ICU's performance. MPM0-II was recently updated (MPM0-III) but not the model for predicting resource utilization. The objective was to develop a new WHD model and revised Rapoport-Teres graph.

Design: Multicenter cohort study.

Setting: One hundred thirty-five ICUs in 98 hospitals participating in Project IMPACT.

Patients: Patients were 124,855 MPM0-II eligible Project IMPACT patients treated between March 2001 and June 2004.

Interventions: None.

Measurements and main results: WHD was redefined as 4 units for the first day of each ICU stay, 2.5 units for each additional ICU day, and 1 unit for each non-ICU day after the first ICU discharge. Stepwise linear regression was used to construct a model to predict ICU-specific log average WHD from 39 candidate variables available in Project IMPACT. The updated WHD model has four independent variables: percent of patients dying in the hospital, percent of unscheduled surgical patients, percent of patients on mechanical ventilation within 1 hr of ICU admission, and percent discharged from the ICU to an external post-acute care facility. The first three variables increase average WHD and the last decreases it. The new model has good performance (R = 0.47) and, when combined with MPM0-II, provides a well-calibrated Rapoport-Teres graph.

Conclusions: A new WHD model has been derived from a large, contemporary critical care database and, when used with MPM0-III, updates a popular method for benchmarking ICUs. Project IMPACT participants will likely perceive a decline in their ICU performance coordinates due to the recalibrated graph and should instead focus on their unit's performance relative to their peers.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benchmarking / methods*
  • Benchmarking / statistics & numerical data
  • Cohort Studies
  • Health Resources / statistics & numerical data*
  • Hospital Mortality*
  • Humans
  • Intensive Care Units / economics
  • Intensive Care Units / standards*
  • Length of Stay
  • Linear Models
  • Middle Aged
  • Models, Statistical*
  • Probability
  • Reproducibility of Results
  • Risk Assessment / methods
  • Survival Rate
  • United States