Is more better?: the relationship between nurse staffing and the quality of nursing care in hospitals.

OBJECTIVE The objective of this study was to examine the effects of nurse staffing and process of nursing care indicators on assessments of the quality of nursing care. RESEARCH DESIGN This study examined the variation in inpatient hospital staff nurses' assessments of the quality of nursing care and the effects of nurse staffing (patient workload), patient safety problems (medication errors and patient falls with injuries), and unfinished care (number of nursing tasks left undone) on the variation in those assessments. Secondary analysis of a survey of nurses using multivariate regression models was undertaken. SUBJECTS Data were derived from a 1999 statewide survey of 8670 inpatient staff nurses working in acute care hospitals in Pennsylvania. RESULTS Quality of nursing care ratings were significantly associated with the number of patients who nurses care for, rates of unfinished care for those patients, and the frequency of patient safety problems. The effect of patient workload on quality ratings was attenuated substantially by the effects of unfinished care and patient safety problems. Unfinished care had the strongest relationship of all, with over 40% of the variation in quality ratings associated with the number of tasks left undone. CONCLUSIONS Assessments of the quality of nursing are associated with both structural (workload) and process of care indicators (unfinished clinical care and patient safety problems), with the relationship strongest between process of care and quality. Explicating the interrelationship between structure and process of care is key to understanding the influence of both on quality. Studies that assess the causal influence of these features on quality of care and patient outcomes are warranted.