Emergency Department Presentations: identifying hotspots of inequality

A Geographic and Temporal Analysis

Published: July 2023

Purpose of the project

Public hospital emergency departments (ED) are a key element of the health system providing an essential gateway to health care for patients with acute or chronic conditions of differing severities for all ages of the Australian public. Mapping the geographic variation in the rates of ED presentations provides an area-based indicator that reflects the interaction between the demand for, and, supply of, health care services. Weber, 2017 suggests that ED visits can be used to detect and describe the health of our communities, their access to care and the resources they need. Extending the mapping this variation over time can highlight areas of concern, such as areas that are over- or under- serviced, prompting the need for further exploration to understand why some areas have high presentation rates or to investigate why in other instances rates are low. Given that the range in geographic variation in ED presentations can be large, a ‘one-size fits all’ approach by health policy to reducing this variation may not be the appropriate solution (Weber, 2017).

The presentations that make up the ED dataset comprises of a wide range of patient care pathways determined by clinical and non-clinical factors which vary across different geographic location across Australia. Because of these differences, we selected a range of indicators to represent this variation of ED utilisation that are commonly investigated in the policy and research realms in Australia.

Reporting on the rates of ED presentations over time are often calculated through direct age-standardisation when presentations are at the population level. If the variable is age-specific, presentation rates are calculated as crude presentation rates (i.e. age-specific presentations/age-specific population). When calculating age-standardised rates the occurrence of small numbers in terms of both the number of presentations and populations within each age group living in a small area means that the rates can be erroneously inflated. This approach becomes problematic when we want to identify areas that consistently have high presentation rates as areas that warrant intervention. To overcome this issue, we implemented the Empirical Bayes estimation method, within the direct age-standardisation process, to estimate presentation rates at the small area level for three years, 2017 to 2020, across Australia. This approach minimises the effects of statistical issues in the calculation of the ED presentation rates by weighing the presentation rate of an area together with the presentation rates from all areas under investigation.

Hotspot analysis was then undertaken on this dataset highlighting the heat of each area, from "Cold" to "Hot", in relation to the area’s annual presentation rate compared to the annual Australian average for the selected types of ED presentation. We provide a range of thresholds above and below the Australian average to investigate the sensitivity and persistence of these classifications over time.

It is important to note that the state of New South Wales and in particular their rural areas have a high rate of ED presentations. These high rates will bias the analysis towards these areas. This issue highlights the benefit of using the multiple heat threshold approach. Users whose regions are outside rural NSW may need to select lower heat thresholds to highlight the geographic and temporal persistence of ED presentations that are more appropriate for their regions of analysis.

The increasing trend in ED presentations over time (AIHW, 2023a) signifies that the ED is a focal point of care for many patients and a continuing pathway to hospital admission. The significant geographic inequalities of utilisation across Australia found by past research and the persistent call for locally tailored interventions warrant a more in-depth investigation into, not only the geographic variation but the temporal persistence of its utilisation across Australia. Identifying these distributions can help prioritise where alternative models of care or additional resources could be allocated to reduce this dependence on this form of health care.

We hope that this new analysis, and its presentation in geographical maps, heat map graphs and data sheet, will provide information that is useful to the various levels of the health system, from state and territory health agencies, local and regional health networks and boards, Primary Health Network (PHN) and primary care practitioners, with an aim to work together to gain a better understanding of the underlying issues that drive ED presentations. The interpretation of the data and its presentation is complex, and we encourage users to read the detailed notes below, and, to take note of the document on Using the Atlas.

Further information can be obtained by contacting the Public Health Information Development Unit.

Authored by PHIDU