[OR minute myth : Guidelines for calculation of DRG revenues per OR minute]

The economic situation in German Hospitals is tense and needs the implementation of differentiated controlling instruments. Accordingly, parameters of revenue development of different organizational units within a hospital are needed. This is particularly necessary in the revenue and cost-intensive operating theater field. So far there are only barely established productivity data for the control of operating room (OR) revenues during the year available. This article describes a valid method for the calculation of case-related revenues per OR minute conform to the diagnosis-related groups (DRG).For this purpose the relevant datasets from the OR information system and the § 21 productivity report (DRG grouping) of the University Medical Center Göttingen were combined. The revenues defined in the DRG browser of the Institute for Hospital Reimbursement (InEK) were assigned to the corresponding process times--incision-suture time (SNZ), operative preparation time and anesthesiology time--according to the InEK system. All full time stationary DRG cases treated within the OR were included and differentiated according to the surgical department responsible. The cost centers "OR section" and "anesthesia" were isolated to calculate the revenues of the operating theater. SNZ clusters and cost type groups were formed to demonstrate their impact on the revenues per OR minute. A surgical personal simultaneity factor (GZF) was calculated by division of the revenues for surgeons and anesthesiologists. This factor resembles the maximum DRG financed personnel deployment for surgeons in German hospitals.The revenue per OR minute including all cost types and DRG was 16.63 €/min. The revenues ranged from 10.45 to 24.34 €/min depending on the surgical field. The revenues were stable when SNZ clusters were analyzed. The differentiation of cost type groups revealed a revenue reduction especially after exclusion of revenues for implants and infrastructure. The calculated GZF over all surgical departments was 2.2 (range 1.9-3.6). A calculation of this factor at the DRG level can give economically relevant information about the case-related personnel deployment.This analysis shows for the first time the DRG-conform calculation of revenues per OR minute. There is a strong dependency on the considered cost type and the performing surgical field. Repetitive analyses are necessary due to the lack of reference values and are a suitable tool to monitor the revenue development after measures for process optimization. Comparative analyses within different surgical fields on this data base should be avoided. The demonstrated method can be used as a guideline for other hospitals to calculate the DRG revenues within the OR. This enables pursuing cost-effectiveness analysis by comparing these revenues with cost data from the cost unit accounting at a DRG or case level.