Objectives: To assess how nurse to patient ratios and nurse work hours were associated with patient outcomes in acute care hospitals, factors that influence nurse staffing policies, and nurse staffing strategies that improved patient outcomes.
Data sources: MEDLINE (PubMed), CINAHL, Cochrane Databases, EBSCO research database, BioMed Central, Federal reports, National Database of Nursing Quality Indicators, National Center for Workforce Analysis, American Nurses Association, American Academy of Nurse Practitioners, and Digital Dissertations.
Review methods: In the absence of randomized controlled trials, observational studies were reviewed to examine the relationship between nurse staffing and outcomes. Meta-analysis tested the consistency of the association between nurse staffing and patient outcomes; classes of patient and hospital characteristics were analyzed separately.
Results: Higher registered nurse staffing was associated with less hospital-related mortality, failure to rescue, cardiac arrest, hospital acquired pneumonia, and other adverse events. The effect of increased registered nurse staffing on patients safety was strong and consistent in intensive care units and in surgical patients. Greater registered nurse hours spent on direct patient care were associated with decreased risk of hospital-related death and shorter lengths of stay. Limited evidence suggests that the higher proportion of registered nurses with BSN degrees was associated with lower mortality and failure to rescue. More overtime hours were associated with an increase in hospital related mortality, nosocomial infections, shock, and bloodstream infections. No studies directly examined the factors that influence nurse staffing policy. Few studies addressed the role of agency staff. No studies evaluated the role of internationally educated nurse staffing policies.
Conclusions: Increased nursing staffing in hospitals was associated with lower hospital-related mortality, failure to rescue, and other patient outcomes, but the association is not necessarily causal. The effect size varied with the nurse staffing measure, the reduction in relative risk was greater and more consistent across the studies, corresponding to an increased registered nurse to patient ratio but not hours and skill mix. Estimates of the size of the nursing effect must be tempered by provider characteristics including hospital commitment to high quality care not considered in most of the studies. Greater nurse staffing was associated with better outcomes in intensive care units and in surgical patients.