Hospital nurse staffing: choice of measure matters.

BACKGROUND: Researchers frequently use nurse staffing measures to examine hospital quality of care. Measure choices include nurse-reported perception of staffing adequacy, nurse-reported patient workloads, and empirically derived hours per patient day (HPPD).
OBJECTIVE: To examine the correlations across these measures and identify factors associated with these staffing measures. DESIGN, SETTINGS, AND
SUBJECTS: A cross-sectional correlational study of 92 medical-surgical, rehabilitation, and intermediate in 11 acute care hospitals was carried out.
METHODS: We surveyed registered nurses on their perceived staffing adequacy, last shift patient workload, and unit-level structures and processes of care delivery. Individual responses to these measures were aggregated to the nursing unit level, and unit-level HPPD, unit-level case mix index were obtained from each hospital's administrative data. After examining the correlation matrix across variables, those associated with the 3 staffing measures were then examined using linear regression.
RESULTS: HPPD and the nurse-reported patient workload on last shift were correlated (r=-0.276, P=0.008), and perceptions of the adequacy of staffing and nurse-reported patient workload on last shift were correlated (r=-0.384, P=0.000). In multivariable analyses, inadequate numbers of assistive personnel was significantly associated with both perceived staffing adequacy and nurse-reported patient loads. Unit-level case mix index was significantly associated with both HPPD and nurse-reported patient loads. These data suggest that the 3 measures of nurse staffing are not highly correlated, and may capture different elements of the unit context to explain nurse staffing. Researchers should consider the correlates of these measures when selecting nurse staffing measures for future investigations.