The association between nursing factors and patient mortality in the Veterans Health Administration: the view from the nursing unit level

Med Care. 2008 Sep;46(9):938-45. doi: 10.1097/MLR.0b013e3181791a0a.


Context: Nurse staffing is not the same across an entire hospital. Nursing care is delivered in geographically-based units, with wide variation in staffing levels. In particular, staffing in intensive care is much richer than in nonintensive care acute units.

Objective: To evaluate the association of in-hospital patient mortality with registered nurse staffing and skill mix comparing hospital and unit level analysis using data from the Veterans Health Administration (VHA).

Design, settings, and patients: A retrospective observational study using administrative data from 129,579 patients from 453 nursing units (171 ICU and 282 non-ICU) in 123 VHA hospitals.

Methods: We used hierarchical multilevel regression models to adjust for patient, unit, and hospital characteristics, stratifying by whether or not patients had an ICU stay during admission.

Main outcome measure: In-hospital mortality.

Results: : Of the 129,579 patients, mortality was 2.9% overall: 6.7% for patients with an ICU stay compared with 1.6% for those without. Whether the analysis was done at the hospital or unit level affected findings. RN staffing was not significantly associated with in-hospital mortality for patients with an ICU stay (OR, 1.02; 95% CI, 0.99-1.03). For non-ICU patients, increased RN staffing was significantly associated with decreased mortality risk (OR, 0.91; 95% CI, 0.86-0.96). RN education was not significantly associated with mortality.

Conclusions: Our findings suggest that the association between RN staffing and skill mix and in-hospital patient mortality depends on whether the analysis is conducted at the hospital or unit level. Variable staffing on non-ICU units may significantly contribute to in-hospital mortality risk.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Clinical Competence / statistics & numerical data
  • Diagnosis-Related Groups / statistics & numerical data
  • Education, Nursing, Baccalaureate / statistics & numerical data
  • Female
  • Gastrointestinal Hemorrhage / mortality
  • Hospital Mortality*
  • Hospitals, Veterans / statistics & numerical data*
  • Humans
  • Intensive Care Units
  • Male
  • Multivariate Analysis
  • Nursing Staff, Hospital / education
  • Nursing Staff, Hospital / supply & distribution*
  • Odds Ratio
  • Outcome Assessment, Health Care / statistics & numerical data
  • Pneumonia / mortality
  • Probability
  • Retrospective Studies
  • Risk
  • Sepsis / mortality
  • Shock / mortality
  • Survival Analysis
  • United States
  • Venous Thrombosis / mortality
  • Workforce