Nurse staffing and quality: the unanswered question.

Researchers have spent decades trying to answer the question: Does more nurse staff lead to better quality of nursing home care? Many nurses, consumers, nursing home providers, and other stakeholders believe intuitively that the answer is “yes.” Yet, the research literature fails to give us a clear answer. Bostick and colleagues1 reached a relatively positive conclusion about the nurse staffing and quality relationship from their review of 87 articles and reports published from 1975 to 2003. Spilsbury and colleagues,2 in their systematic review of 50 carefully screened studies from 1987 to 2008, were much more critical of methods and findings from these studies. In this issue of the Journal, Backhaus and colleagues3 offer a systematic review of more recent research, with most of the reviewed studies conducted between 2000 and 2012. They limited their review to studies using a longitudinal design, which is better able to detect causal effects and less susceptible to spurious interpretation than a cross-sectional design. Backhaus and colleagues3 assessed the strength of the study design, generalizability, control variables, and other issues, and they examined studies from different angles: staffing level and skill mix; different care processes and outcomes; and resident, facility, and multiple levels of measurement and analysis. Echoing the conclusions reached by Spilsbury and colleagues,2 they found “no consistent evidence for a positive relationship between staffing and quality,” and “major methodological and theoretical weaknesses limit the interpretation of findings” from these studies. Our purpose in this editorial was to expand on the conceptual and methodological issues raised by Backhaus and colleagues3 and to suggest research directions that can help better understand the relationships between staffing and nursing home quality.