ICU mortality rates biased

Although in-hospital mortality rates measure quality in intensive care units, new research finds that the performance metric may be biased, unfairly penalizing large, academic hospitals due to "discharge bias."

"Hospitals differ in the number of patients they transfer to other hospitals or post-acute care facilities," lead study author Lora Reineck, post-doctoral fellow at the University of Pittsburgh School of Medicine, said in a research announcement. "These differences can affect in-hospital mortality measurement if some hospitals discharge patients more frequently or earlier than others, since in these cases the mortality burden is shifted to other facilities."

Researchers found that smaller hospitals, as well as facilities that serve fewer commercial HMO patients, appeared to perform better and rank higher. Nearly 30 percent of hospitals jumped in rank by at least one quartile, and 27 percent dropped in rank by at least one quartile because of discharge bias.

The research could point to holes in the pay-for-performance system, which rewards hospitals based on quality metrics, including the National Quality Forum-endorsed ICU mortality measure.

"If discharge practices vary between different types of hospitals, use of in-hospital mortality as a performance measure in quality improvement may lead to health disparities," the study states. The researchers further called for state and national programs that can account for discharge bias to fairly assess performance.

Meanwhile, another study from the University of Pittsburgh, published in the New England Journal of Medicine, found that using night-time intensivist physician staffing in ICUs with a low-intensity daytime staffing model reduces mortality. More hospitals are hiring intensivists, doctors that are particularly trained for critically ill patients, to work around the clock. However, researchers found that intensivists improve patient outcomes only in some circumstances.  

"[W]e found that ICUs with high-intensity daytime staffing did not share the same benefit from nighttime intensivists," Jeremy Kahn, associate professor of critical care medicine and health policy and management at the University of Pittsburgh, said in the research announcement.

The 24-hour staffing, however, may be reason enough to adopt the model if that means the small number of very sick patients, such as those in severe shock or cardiac arrest, can avoid death.

For more information:
- see the research announcement and abstract on mortality rates
- here's the research announcement and abstract on intensivists

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