International experts' perspectives on the state of the nurse staffing and patient outcomes literature.

PURPOSE: To assess the key variables used in research on nurse staffing and patient outcomes from the perspective of an international panel.
DESIGN: A Delphi survey (November 2005-February 2006) of a purposively-selected expert panel from 10 countries consisting of 24 researchers specializing in nurse staffing and quality of health care and 8 nurse administrators.
METHODS: Each participant was sent by e-mail an up-to-date review of all evidence related to 39 patient-outcome, 14 nurse-staffing and 31 background variables and asked to rate the importance/usefulness of each variable for research on nurse staffing and patient outcomes. In two subsequent rounds the group median, mode, frequencies, and earlier responses were sent to each respondent.
FINDINGS: Twenty-nine participants responded to the first round (90.6%), of whom 28 (87.5%) responded to the second round. The Delphi panel generated 7 patient-outcome, 2 nurse-staffing and 12 background variables in the first round, not well-investigated in previous research, to be added to the list. At the end of the second round the predefined level of consensus (85%) was reached for 32 patient outcomes, 10 nurse staffing measures and 29 background variables. The highest consensus levels regarding measure sensitivity to nurse staffing were found for nurse perceived quality of care, patient satisfaction and pain, and the lowest for renal failure, cardiac failure, and central nervous system complications. Nursing Hours per Patient Day received the highest consensus score as a valid measure of the number of nursing staff. As a skill mix variable the proportion of RNs to total nursing staff achieved the highest consensus level. Both age and comorbidities were rated as important background variables by all the respondents.
CONCLUSIONS: These results provide a snapshot of the state of the science on nurse-staffing and patient-outcomes research as of 2005. The results portray an area of nursing science in evolution and an understanding of the connections between human resource issues and healthcare quality based on both empirical findings and opinion.