Results
A total of 17 articles met the inclusion and exclusion criteria. Characteristics of included studies are summarized in Table 2.
Characteristics of Included Studies
Thirteen studies were conducted in the United States. Remaining studies were conducted in Australia, Austria, Canada, and Taiwan. Retrospective research designs were used most frequently. Some studies combined retrospective and prospective designs, and few studies used prospective designs which would offer more detailed cost measurement and more flexibility than retrospective designs.
All reviewed studies reported effects of nurse staffing on hospital costs and/or LOS measures. Twelve studies examined the effect of nurse staffing on hospital costs. Of these, three studies used total hospital expenditures obtained from financial reports. Two studies used a cost-to-charge index (expressed as the ratio between total hospital operating cost and hospital revenue) to adjust hospital charges. Two studies estimated costs from LOS, and another two studies used a micro-costing method (measuring most of resources used at the patient level and assigning monetary value to resource utilization).Remaining studies estimated costs from changes in nursing personnel budget and hospital expenditures per patient day. Length of stay referred to the total days of hospitalization per patient from admission to discharge. Various measures of hospital LOS were used including number of calendar days, days at midnight census, total hours, or the relative LOS (expressed as ratios of actual and expected LOS).