In recent years, the Australian Institute of Health and Welfare (AIHW) has worked towards developing a reliable, valid and meaningful method to measure access to services relative to need as it relates to primary health care for Aboriginal and Torres Strait Islander people.

While the aim was clear, finding a way to develop such a measure proved difficult because there was no agreed methodology.

Following a literature review, the AIHW determined that measures of service availability, access and predicted need for primary health care could be incorporated into one reportable indicator by creating a geospatial index of access to health services relative to need for health care. This index could be constructed so it allowed for comparison among and between Indigenous and non-Indigenous communities.

Developing and validating the index

In order to determine the suitability of using a geospatial index to measure access relative to need for the Indigenous population, a pilot study was undertaken using Western Australian data. The pilot study used a similar methodology to that developed by McGrail and Humphreys (2009) for their index of access to primary health care in rural Victoria.

Substantial refinements to the methodology were made before expanding the analysis nationally.

The index (Access Relative to Need index, or ARN index) was developed to identify variation in access at the smallest geographical level with available data-Statistical Area Level 1 (SA1). In both the pilot and national studies, access to primary health-care services was estimated based on travel time by road to general practitioners (GPs) and total demand on these GPs from all the populations they serve.

Predicted need for primary health care was calculated using demographic and socioeconomic variables known to be correlated with health outcomes. The index was validated by confirming the association between index scores and health outcomes that reflect unmet health need.


The results of the national study show that health outcomes improve more dramatically with improved access to GPs in areas with relatively high predicted need for primary health care than in areas with low predicted need. This suggests that access to primary care relative to need is an important factor underlying geographic variation in health outcomes in Australia.

The index suggests that Indigenous people experience a general pattern of worsening access to GPs relative to need with increasing remoteness. This pattern was attributed to relatively poor access to GPs and relatively high predicted need for primary health care in more remote areas.

The index suggests that the non-Indigenous population experiences a less dramatic decrease in access to GPs relative to need with increasing remoteness. Average access to GPs does worsen with increasing remoteness, but non-Indigenous people in Very remote areas tend to live in SA1s with higher access to GPs than Indigenous people.