title: The association of registered nurse staffing levels and patient outcomes: systematic review and meta-analysis.
abstract: OBJECTIVE
  To examine the association between registered nurse (RN) staffing and patient outcomes in acute care hospitals.
  
  
  METHODS
  Twenty-eight studies reported adjusted odds ratios of patient outcomes in categories of RN-to-patient ratio, and met inclusion criteria. Information was abstracted using a standardized protocol.
  
  
  RESULTS
  Random effects models assessed heterogeneity and pooled data from individual studies. Increased RN staffing was associated with lower hospital related mortality in intensive care units (ICUs) [odds ratios (OR), 0.91; 95% confidence interval (CI), 0.86-0.96], in surgical (OR, 0.84; 95% CI, 0.80-0.89), and in medical patients (OR, 0.94; 95% CI, 0.94-0.95) per additional full time equivalent per patient day. An increase by 1 RN per patient day was associated with a decreased odds ratio of hospital acquired pneumonia (OR, 0.70; 95% CI, 0.56-0.88), unplanned extubation (OR, 0.49; 95% CI, 0.36-0.67), respiratory failure (OR, 0.40; 95% CI, 0.27-0.59), and cardiac arrest (OR, 0.72; 95% CI, 0.62-0.84) in ICUs, with a lower risk of failure to rescue (OR, 0.84; 95% CI, 0.79-0.90) in surgical patients. Length of stay was shorter by 24% in ICUs (OR, 0.76; 95% CI, 0.62-0.94) and by 31% in surgical patients (OR, 0.69; 95% CI, 0.55-0.86).
  
  
  CONCLUSIONS
  Studies with different design show associations between increased RN staffing and lower odds of hospital related mortality and adverse patient events. Patient and hospital characteristics, including hospitals' commitment to quality of medical care, likely contribute to the actual causal pathway.
authors.affiliation: University of Minnesota School of Public Health, Minneapolis, Minnesota 55455, USA. kanex001@umn.edu
authors.forename: Robert L
authors.initials: RL
authors.lastname: Kane
authors.forename: Tatyana A
authors.initials: TA
authors.lastname: Shamliyan
authors.forename: Christine
authors.initials: C
authors.lastname: Mueller
authors.forename: Sue
authors.initials: S
authors.lastname: Duval
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Wilt
mesh_terms: D000208:Acute Disease / Q000451:nursing*; D017052:Hospital Mortality; D006801:Humans; D015999:Multivariate Analysis; D015401:Nursing Administration Research; D009741:Nursing Staff, Hospital / Q000458:organization & administration* / Q000592:standards; D010561:Personnel Staffing and Scheduling / Q000458:organization & administration* / Q000592:standards; D011787:Quality of Health Care / Q000458:organization & administration* / Q000706:statistics & numerical data; D016896:Treatment Outcome; D016526:Workload