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New Analysis Confirms Direct Link Between Nurse Staffing and Patient Complications and Deaths in Hospitals

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Press Release Date: May 29, 2002

Analysis of data on nurse staffing levels confirms that there is a direct link between the number of registered nurses and the hours they spend with patients and whether patients develop a number of serious complications or die while in the hospital.

Funded by the Agency for Healthcare Research and Quality (AHRQ), investigators reexamined and refined their previous analysis released by the Health Resources and Services Administration (HRSA) in April 2001 as part of an ongoing collaboration within the Department of Health and Human Services to improve nursing care in American hospitals. The partnership also included AHRQ, the Centers for Medicare and Medicaid Services, and the National Institute for Nursing Research.

The original HRSA report and the new analysis, which is being published in the May 30, 2002, issue of the New England Journal of Medicine, were conducted by Jack Needleman, Ph.D., of the Harvard School of Public Health, and Peter Buerhaus, Ph.D., R.N., F.A.A.N., of the Vanderbilt University School of Nursing.

"AHRQ was very pleased to be a partner in this important project to ensure that we fully understand the significant role that nurses play in ensuring that patients have safe hospital stays and are discharged in better health than when they were admitted," said Carolyn Clancy, M.D., AHRQ's acting director. "We now must use this information to work together to resolve the nursing shortage in American health care and to make sure that nurses have adequate education and improved working conditions."

Needleman, Buerhaus, and their colleagues, reviewed their original discharge and staffing data from 799 hospitals in eleven states—California, New York, Maryland, Virginia, West Virginia, Arizona, Massachusetts, Missouri, Nevada, South Carolina, and Wisconsin—to estimate nurse staffing levels for RNs, LPN/LVNs, and aides, as well as the frequency of a wide range of complications that patients developed during their hospital stay. These data cover 6 million patients discharged from hospitals in 1997.

Specifically, they confirmed their initial findings that low levels of RNs among a hospital's nurses were associated with rates of serious complications such as pneumonia, upper gastrointestinal bleeding, shock, and cardiac arrest, including deaths among patients with these three complications, as well as sepsis or deep vein thrombosis. These complications occurred 3 to 9 percent more often than in hospitals with higher RN staffing.

Both studies also found that rates for urinary tract infections, a less serious but common infection among hospital patients, and length of time spent in the hospital were also higher in hospitals with lower RN staffing. When comparing hospitals, the study controlled for how ill patients were in different hospitals and differences across hospitals in how likely patients were to suffer these complications.

Researchers again found an association between nurse staffing and deaths from more serious complications, but they found no evidence of an association between nurse staffing and overall deaths among medical or surgical patients.

"Low RN staffing at hospitals makes it more likely that some patients will suffer pneumonia, shock and cardiac arrest, and gastrointestinal bleeding, and that some patient may die as a result," said Dr. Needleman. "We will need to address nurse staffing in hospitals if we are going to prevent these complications."

"This research clearly shows that we need more and better-educated nurses to ensure that hospitals patients don't suffer needlessly from complications," said Dr. Buerhaus. "However, we need more research to understand the factors influencing nurse staffing levels and the mix of different types of nurses working in a particular hospital."

For more information, please contact AHRQ Public Affairs, (301) 427-1364: Karen J. Migdail, (301) 427-1855 (


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