Estimating costs

All costs were based on 2020 averages and fees (2020 EUR 1.00 = NOK 10.73). According to Norwegian guidelines, prices and health estimates during future years were discounted at a 4% discount rate [30].

At the OAEOC, average personnel costs (per hour) were delivered by the finance consultant at the City of Oslo Health Agency. Chest x-ray and venous blood samples were calculated as outpatient radiological and laboratory services. According to The Norwegian Medicines Agency’s Guidelines for the submission of documentation for single technology assessment of pharmaceuticals, [30] the costs of the personnel used were based on average pay multiplied by 1.3 to include payroll taxes and other social charges. Hospital services were estimated as if financed by full reimbursements from The Norwegian Health Economics Administration (HELFO). Services provided by GPs and primary care emergency clinics were calculated by multiplying the HELFO reimbursements by two to cover other financing sources. Outpatient radiological and laboratory services were estimated as the reimbursed sum from HELFO plus the fee paid by the patient, multiplied by two, to include personnel costs at the radiology and lab units [30]. The estimated reduction in low-risk ED admissions with the 0/1-h algorithm at the primary care emergency clinic is visualised by the missing yellow square at hospital level in Fig. 1B.

At Drammen Hospital, the overall costs were based on the reported DRG codes for the low-risk cohort. In addition, the total number of diagnostic tests, procedures, and length of stay were reported separately. Estimated mean costs related to the use of ambulances, including personnel and equipment, were reported by the Prehospital Division at Oslo University Hospital, Ullevaal.