ICU Quality Measure Easily Biased

New research suggests that the standardized mortality ratio (SMR), the outcome-based measure of intensive care unit (ICU) performance, may be easily biased. Overall, an SMR greater than one indicates a higher than expected mortality and less than one indicates a lower than expected mortality. However, researchers from the University of Washington in Seattle speculated how hospital transfers might affect the SMR. A baseline SMR of 1.06 В± 0.19 was calculated for 85 ICUs and compared with an adjusted SMR that was based on a simulation of a set number of patients being transferred out of the ICU alive. In the simulation, increasing the number of transfers by 2 percent and 6 percent over baseline decreased the SMR by 0.10 В± 0.03 and 0.14 В± 0.03, respectively. In addition, results showed that transferring as few as one patient out of the ICU per month can create a bias greater than 0.1 in 27 ICUs. Researchers conclude that a greater understanding of the factors affecting the SMR is needed before it should be widely used to benchmark ICU outcomes.

This study appears in the January issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians.

Contact: Jennifer Stawarz
American College of Chest Physicians