Estimation of the general practice workload of a metropolitan teaching hospital emergency department

BACKGROUND: A transparent and easily replicated method of estimating the number of, and costs associated with, low acuity presentations to an emergency department is required to assist evaluation of the utilization of emergency department services. This study presents two independent estimates of the number of, and costs associated with, low acuity presentations to an emergency department. METHODS: A retrospective analysis was conducted using emergency department information system data from a metropolitan mixed paediatric/adult teaching hospital emergency department/trauma centre. Low acuity patient presentation estimates were calculated by: Method one: The product of (A) total self-referred presentations for triage categories three, four and five and (B) the difference between the self-referred and general practitioner-referred discharge rates from the emergency department. Total low acuity patient presentations = (A x B). Method two: Summing the number of self-referrals with presenting problems never referred by general practitioners. Costs were calculated using Commonwealth cost weights. RESULTS: Method one gave a low acuity patient estimate of 12.5% (95% CI 12.0-13.0%) and method two 10.6% (95% CI 10.2-11.0%) of total presentations. Costs were 10.5% (method one) and 8.5% (method two) of total costs. Adjusted for assessment time, costs were 6.8% (method one) and 5.5% (method two) of total costs. Low acuity patients were more common outside of normal working hours, method one: 14.4% (95% CI 13.5-15.2%) versus 10.0% (95% CI 9.4-10.6%), P < 0.001; method two: 11.4% (95% CI 10.9-12.0%) versus 8.5% (95% CI 7.8-9.2%), P < 0.001. Provision of alternative daily 0900-2400 general practice services would change low acuity patients by no more than 2-3% of total presentations and change low acuity patient costs by no more than 2% of total costs. CONCLUSIONS: Low acuity patients form a small, relatively constant part of the emergency department workload. The provision of alternative after-hours services for low acuity patients would be unlikely to significantly reduce the overall work load of this metropolitan emergency department.