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Studies Show Lower Nurse Staffing Levels Contribute To Poor Patient Outcomes

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Press Release Date: May 3, 2004

The Agency for Healthcare Research and Quality today issued a new synthesis of research studies funded by AHRQ and others that indicates that hospitals with lower nurse staffing levels, nurses who spent less time with patients, or fewer registered nurses compared with licensed practical nurses or nurses' aides tend to have higher rates of poor patient outcomes, including pneumonia, shock, cardiac arrest, and urinary tract infections.

The six studies reviewed for the synthesis found different rates of adverse events, depending on the reason for the hospitalization (medical or surgical), as well as other factors. Three of the studies found that pneumonia rates are particularly sensitive to nurse staffing levels, which were measured as the ratio of nurses to patients or nursing hours per patient per day.

Several studies indicated that nurse staffing levels may also be associated with mortality rates. Two studies showed that the 30-day mortality rate and the likelihood of failure to rescue are higher when nurse staffing levels are lower. Another showed that a higher proportion of more highly educated nurses can reduce the 30-day mortality rate and the odds of failure to rescue. Closely related to the issue of nurse staffing level is patient acuity—the level of care and services needed by the patient. One study adjusted the total number of patient days of in-hospital care by the severity of illnesses, and showed that as patient acuity rose while nurse staffing levels remained the same, the ratio of nurses to patient days therefore declined.

Another important finding was that increasing nurse staffing levels does not significantly decrease a hospital's profits, in contrast to increases in non-nurse staffing. Furthermore, the costs associated with adverse events that might otherwise be avoided are considerable.

The report, the latest in a series of Research in Action syntheses titled "Research in Action: Hospital Nurse Staffing and Quality of Care," is meant to provide decision makers with the information they need to make more informed choices about nurse staffing levels. It is available online at, from the AHRQ Publications Clearinghouse at (800) 358-9295, or by sending an E-mail to

For more information, please contact AHRQ Public Affairs: Karen Migdail, (301) 427-1862 (


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