HEALTH SYSTEMS Evaluation of a Patient Care Delivery Model: Patient Outcomes in Acute Cardiac Care Raquel M. Meyer, RN, BScN 1 , Sping Wang, PhD 2 , Xiaoqiang Li, PhD 3 , Donna Thomson, RN, MBA 4 , & Linda O’Brien-Pallas, RN, PhD, FCAHS 5 1 Lambda Pi, Doctoral Fellow & Research Ofﬁcer, Nursing Health Services Research Unit, Lawrence Bloomberg Faculty of Nursing, University of Toronto, Toronto, Ontario, Canada 2 Research Associate, Nursing Health Services Research Unit, Lawrence Bloomberg Faculty of Nursing, University of Toronto, Toronto, Ontario, Canada 3 Research Associate, Nursing Health Services Research Unit, Lawrence Bloomberg Faculty of Nursing, University of Toronto, Toronto, Ontario, Canada 4 Senior VP Clinical Operations & Chief Nursing Executive, St. Peter’s Health System, Hamilton, Ontario, Canada 5 Lambda Pi, Professor & CHSRF/CIHR Chair in Nursing Human Resources, Lawrence Bloomberg Faculty of Nursing, University of Toronto, Nursing Health Services Research Unit, Toronto, Ontario, Canada Key words Nurse stafﬁng, work environments, patient outcomes Correspondence Raquel Meyer, 155 College Street, Room 130, Lawrence Bloomberg Faculty of Nursing, University of Toronto, Toronto, Ontario, Canada M5T 1P8. E-mail: raquel.meyer@utoronto.ca Accepted: June 13, 2009 doi: 10.1111/j.1547-5069.2009.01308.x Abstract Purpose: To evaluate the inﬂuence of nurse stafﬁng and work environment variables on patient outcomes by testing a conceptual model. Design: A prospective, correlational design with cross-sectional and longitu- dinal components was conducted in Canadian cardiac and cardiovascular care inpatient units. Methods: Data were collected from multiple sources. Hierarchical linear mod- eling was used to examine relationships among variables. Conclusions: The ﬁndings indicate that patient outcomes are inﬂuenced not only by patient and nurse characteristics, but also by organizational stafﬁng practices. Organizations that manage the complexity of work conditions and target stafﬁng utilization levels between 80% and 88% at the unit level can optimize patient outcomes. Clinical Relevance: Empirical validation of the model provides evidence to inform management decisions about hospital nurse stafﬁng. As health systems evolve, the need to improve health- care service outcomes through the management of or- ganizational factors that inﬂuence nurses’ working con- ditions and work lives remains salient (Rafferty, Maben, West, & Robinson, 2005). Work environment factors and nurse stafﬁng are closely linked to outcomes for patients, nurses, and organizations (Lankshear, Sheldon, & May- nard, 2005). A greater understanding of the complexity of work conditions and the effects of hospital nurse stafﬁng at the unit level are essential to meet increased demand for cost and quality accountability in health care. Guided by the Patient Care Delivery Model (PCDM), interrelationships between variables theorized to inﬂu- ence patient outcomes were examined. As part of a larger study by O’Brien-Pallas, Thomson, et al. (2004), this pa- per identiﬁes key work factors related to patients, nurses, and units that inﬂuenced patient outcomes and provides evidence-based standards for adjusted ranges of nurse stafﬁng utilization levels for patients receiving cardiac and cardiovascular care in tertiary care hospitals. Patient out- comes included adverse medical consequences (e.g., fall with injury, mortality), physical and mental health, and patients’ knowledge, behavior, and status. The ﬁndings will assist health system and nurse managers in develop- ing stafﬁng and work environment strategies to optimize productivity returns and minimize stafﬁng costs, while ensuring quality outcomes. Conceptual Model The PCDM is based on Open System Theory, and its de- velopment and testing in hospital (O’Brien-Pallas, Irvine, Peereboom, & Murray, 1997) and community (O’Brien- Pallas et al., 2001, 2002) settings has been detailed Journal of Nursing Scholarship, 2009; 41:4, 399–410. 399 c  2009 Sigma Theta Tau International