Objective. To evaluate previous research findings of the relationship between nurse staffing and quality of care by examining the effects of change in registered nurse staffing on change in quality of care.
Data Sources/Study Setting. Secondary data from the American Hospital Association (AHA)(nurse staffing, hospital characteristics), InterStudy and Area Resource Files (ARF) (market characteristics), Centers for Medicare and Medicaid Services (CMS) (financial performance), and Healthcare Cost and Utilization Project (HCUP) (quality measures—in-hospital mortality ratio and the complication ratios for decubitus ulcers, pneumonia, and urinary tract infection, which were risk-adjusted using the Medstat® disease staging algorithm).
Study Design. Data from a longitudinal cohort of 422 hospitals were analyzed from 1990–1995 to examine the relationships between nurse staffing and quality of care.
Data Collection/Extraction Methods. A generalized method of moments estimator for dynamic panel data was used to analyze the data.
Principal Findings. Increasing registered nurse staffing had a diminishing marginal effect on reducing mortality ratio, but had no consistent effect on any of the complications. Selected hospital characteristics, market characteristics, and financial performance had other independent effects on quality measures.
Conclusions. The findings provide limited support for the prevailing notion that improving registered nurse (RN) staffing unconditionally improves quality of care.