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Journal Article


Hospital Workload and Adverse Events

The Issue

Peter Sprivulis, a 2004–05 Harkness Fellow in Health Care Policy and Practice, and his coauthors sought to determine the relationship between peak hospital workload and the rate of adverse events. Using administrative data from four U.S. hospitals, the researchers reviewed 6,841 cases for patients treated from October 2000 to September 2001. They determined workload by examining volume, throughput (the number of admissions and discharges), intensity (the diagnosis-related groups of the patient census), and staffing (patient-to-nurse ratios). 

What the Study Found

One of the four hospitals was found to have over 100 percent occupancy—or more than one person occupying the same bed in a given day—for most of the year. At that hospital, the number of admissions and patients was significantly related to the likelihood of adverse events. The occupancy rate, number of discharges, and diagnosis-related group census were also significantly related to the number of such events. For example, a 0.1 percent increase in the patient-to-nurse ratio led to a 28 percent increase in the rate of adverse events. Results at the other three hospitals were varied and for the most part uncovered no significant relationships between workload and adverse events.


The authors conclude that "hospitals that operate at or over capacity may experience heightened rates of patient safety events and might consider re-engineering the structures of care to respond better during periods of high stress." For example, they suggest that administrators might give nursing supervisors leeway to set staffing levels or institute policies to create a pool of on-call nurses.

Publication Details



J. S. Weissman, J. M. Rothschild, E. Bendavid et al., "Hospital Workload and Adverse Events," Medical Care, May 2007 45(5):448–55.