Consistent assignment of nursing staff to residents in nursing homes: a critical review of conceptual and methodological issues.

PURPOSE OF STUDY Consistent assignment of nursing staff to residents is promoted by a number of national organizations as a strategy for improving nursing home quality and is included in pay for performance schedules in several states. However, research has shown inconsistent effects of consistent assignment on quality outcomes. In order to advance the state of the science of research on consistent assignment and inform current practice and policy, a literature review was conducted to critique conceptual and methodological understandings of consistent assignment. DESIGN AND METHODS Twenty original research reports of consistent assignment in nursing homes were found through a variety of search strategies. RESULTS Consistent assignment was conceptualized and operationalized in multiple ways with little overlap from study to study. There was a lack of established methods to measure consistent assignment. Methodological limitations included a lack of control and statistical analyses of group differences in experimental-level studies, small sample sizes, lack of attention to confounds in multicomponent interventions, and outcomes that were not theoretically linked. IMPLICATIONS Future research should focus on developing a conceptual understanding of consistent assignment focused on definition, measurement, and links to outcomes. To inform current policies, testing consistent assignment should include attention to contexts within and levels at which it is most effective.