Nurse staffing and patient safety: current knowledge and implications for action

Over the past year, published research has drawn increased attention to issues of hospital nurse staffing and adverse patient outcomes. Among the published articles that have appeared are those by Aiken et al . 1, Kovner et al . 2, and Needleman et al . 3. The article by Aiken et al . focused on post-surgical mortality, and received substantial attention because of its conclusion that, controlling for patient and hospital characteristics, the addition of one patient to a registered nurse's workload was associated with a 7% increase in mortality. Research examining the association between nurse staffing and mortality has reached mixed conclusions. Needleman et al . found an association between nurse staffing levels and ‘failure to rescue’, defined in that study as death among patients who had one of five complications (pneumonia, sepsis, shock or cardiac arrest, upper gastrointestinal bleeding, and deep vein thrombosis), in surgical patients and to a lesser extent in medical patients. While Needleman et al . measured nurse staffing in a different way to Aiken et al ., reanalysis of the study generates an estimate of the magnitude of the impact of nurse staffing on failure to rescue similar to that reported by Aiken and colleagues. Needleman et al . did not, however, find an association with overall in-hospital mortality and nurse staffing. At least four other studies have found an association between nurse staffing and hospital mortality 4–7, while others have not 8–10. How should these conflicting findings be viewed? Firstly, it must be recognized that because many factors influence hospital mortality, it can be difficult to tease out the effect of an individual factor. Many of these studies have used administrative data, including the three studies cited that were …