An automatic calculation algorithm that can calculate the contribution margin (gross margin) for each case and each procedure (surgery/anesthesia) using data from the supply, processing and distribution (SPD), and anesthesia information systems was developed and introduced in 2010. Costs of materials not considered as consumables for individual patients were divided into 3 categories in the material master and allocated to each case in a manner proportional to the surgical and anesthesia fees. As a result of using the algorithm for 8 years, the contribution margin could be calculated for all 41,067 cases, and annual changes in the contribution margin in each surgical department and in the Department of Anesthesiology indicated the potential for long-term use of the algorithm. In addition, it was shown that not only medical, but also economic aspects can be included in case statistics. Furthermore, the contribution margin of surgery for each department, contribution margin of anesthesia, the material consumption costs, contribution margin ratio, and other items were also shown to be useful for cost management.
As a result of the aggregation of consumable material costs, costs specific to each patient accounted for 86% and costs not specific to each patient, but were allocated to each case and accounted for the remaining 14%, consisted of the surgery costs (61%), anesthesia costs (15%) and those common to surgical departments (24%). On the whole, the algorithm allowed clearer visualization of the medical and economic aspects of surgical departments.
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