Data source and injury classification methods

The main source of information for this web report is the AIHW’s Disease Expenditure Database. It provides a broad picture of the use of health system resources classified by disease groups and conditions, and is a reference point for planners and researchers interested in costs and use patterns for particular diseases.

Generally, the methods used for estimating disease expenditure is a mixture of ‘top-down’ and ‘bottom-up’ approaches, where total expenditure across the health system is estimated and then allocated to the relevant conditions based on the available service use data. An advantage of this approach is that it yields consistency, good coverage and totals that add up to known expenditure but it is not as comprehensive for any specific disease as a detailed ‘bottom-up’ analysis, which would include the actual costs incurred for that disease. In most cases, however, a lack of amenable data sources means that a more granular ‘bottom-up’ analysis is not possible.

Data were drawn from the following sources:

  • National Hospital Morbidity Database (NHMD),
  • National Public Hospitals Establishments Database (NPHED),
  • National Non-admitted Patient Emergency Department Care Database (NNAPEDC),
  • National Non-admitted Patient Databases (aggregate, NAPAGG, and unit record, NAPUR),
  • National Hospital Costs Data Collection (NHCDC),
  • Private Hospital Data Bureau (PHDB) collection,
  • Bettering the Evaluation and Care of Health (BEACH) survey,
  • Health Expenditure Database.

Injuries are classified by either the cause of injury (such as road traffic accidents), or the nature of injury (such as fractures), consistent with the Australian Burden of Disease Study (ABDS) conditions. The nature of injury classification is intended to identify the type of harm which happened to the patient, whereas the cause of injury best describes the circumstances in which the injury occurred. Both classifications are included in the disease expenditure database, though each episode of care is recorded using only one of the two. The cause of injury is generally only reported in Public Hospital Emergency Departments.

Expenditure is able to be fully reported using both classifications using mapping files. To map between the recorded cause and nature of injury, the injury correspondences used in the ABDS 2015 were applied to the aggregated expenditure data by age and sex. These correspondences are based on epidemiological data, and detail the relationship between each cause of injury and nature of injury allowing for mapping between the two schemas. Total expenditure in this report is consistent across both classifications, whether reported by cause or nature of injury, as data clinically recorded by one has been mapped to the other.

Further information can be found in the Australian Burden of Disease Study: methods and supplementary material 2015 report.