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Studies examine the impact of nurse staffing on complications, mortality, and length of hospital stay

Two new studies supported by the Agency for Healthcare Research and Quality (HS10153) add to the growing body of research linking nurse staffing to quality of care. The first study found that more hours of care provided by registered nurses (RNs) were related to fewer postoperative problems among hospitalized children. The second study revealed that, despite lower RN staffing in for-profit than not-for-profit hospitals, the mortality rates and length of stay were similar after controlling for population and market characteristics.

The impact of managed care on both types of hospitals may have played a role. Both studies, led by Barbara A. Mark, Ph.D., R.N., F.A.A.N., of the University of North Carolina at Chapel Hill, are discussed here.

Mark, B.A., Harless, D.W., and Berman, W.F. (2007, May). "Nurse staffing and adverse events in hospitalized children." Policy, Politics, & Nursing Practice 8(2), pp. 83-92.

More hours of care provided by RNs are related to significantly fewer postoperative pulmonary complications, pneumonia, and septicemia among hospitalized children, according to this study. The researchers used administrative data from 1996-2001 to examine discharges of 3.65 million children in 286 general and children's hospitals in California. In this group of children, septicemia occurred most often, followed by postoperative cardiopulmonary complications, deaths, postoperative pneumonia, and postoperative urinary tract infections.

Increasing hours of RN staffing had no effect on mortality rates. However, for three of the four complications (cardiopulmonary complications, postoperative pneumonia, and postoperative septicemia/other infections), there were significant staffing effects at the 25th, 50th, and 75th percentiles of nurse staffing. The increase in RN hours had the largest impact at the lowest level of RN staffing. For example, the researchers estimated that from 425 to 596 fewer post-operative cardio-pulmonary complications (75th vs. 25th percentile) would have occurred during the 6-year study period with a 1-hour increase in RN hours per patient day. Similarly, from 95 to 124 postoperative pneumonia complications and from 719 to 787 postoperative septicemia and other infections might have been averted. These results are consistent with studies on the impact of nurse staffing on adverse outcomes for hospitalized adults.

Mark, B.A. and Harless, D.W. "Nurse staffing, mortality, and length of stay in for-profit and not-for-profit hospitals." (2007, Summer). Inquiry 44, pp. 167-186.

This study found that RN staffing (adjusted for case mix) was significantly lower in for-profit than not-for-profit hospitals. Yet, mortality rates and length of hospital stay were similar between the two types of hospitals, after controlling for population and market characteristics. Both types of hospitals also became more similar over time in terms of distribution of RN staffing and length of stay ratio.

The lack of differences in patient outcomes among the two types of hospitals found during the study period, despite RN staffing differences, may reflect the dramatic changes in the operating environment for both types of hospitals due to the growing dominance of managed care in the early to mid-1990s.

Not-for-profit hospitals may have responded to increased competitive pressures by behaving more like their for-profit counterparts. For example, they may have implemented initiatives to improve the efficiency of their internal operations, such as changing the volume and mix of services, explain the researchers. They suggest that future research examine the impact of RN staffing on other outcomes such as in-hospital complications and occurrence of certain adverse events. Their findings were based on analysis of the Healthcare Cost and Utilization Project (HCUP) National Inpatient Sample of U.S. community hospitals. A total of 422 hospitals were included in each of the study years 1990 through 1995.

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