Technical notes
Definitions
Potentially preventable hospitalisations (PPH) are hospital admissions for specific conditions that could potentially be prevented through timely and effective primary care, early disease management, or public health interventions. PPH are grouped into three main categories, each encompassing specific conditions identified by the National Health Agreement.
For this report PPH are defined in accordance with the National Healthcare Agreement: PI 18-Selected potentially preventable hospitalisations, 2024.
Amendments to the defining statements of PPH can have a large effect on what is measured. Significant definition changes have occurred in 2013, 2014, 2015 (most notably), and in 2021.
- In 2013 there were changes to procedure codes for congestive cardiac failure, hypertension, and cellulitis.
- In 2014 there was a change to diabetes complications to remove the option of additional diagnoses, and the removal of dehydration and gastroenteritis as a valid condition.
- In 2015, definitions were amended for 18 out of 21 PPH conditions, and Eclampsia was added as a valid condition.
- In 2021 there were changes to procedure codes for congestive cardiac failure, angina, hypertension, and cellulitis.
Rationale for applying 2024 PPH definitions
To ensure consistency and comparability in the time series analysis of potentially preventable hospitalisations (PPH), this report applies the 2024 PPH definitions to data from 2024 and prior years. When year-specific PPH definitions are applied to their respective annual data, certain PPH conditions exhibit series discontinuities that are not easily explainable, likely due to changes in clinical diagnostic criteria, evolving coding practices, and updates to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM). Classification changes complicate the time-series and obfuscate trends in PPH counts, rates, costs, length of stay, and same-day hospitalisations. By consistently applying the 2024 PPH definitions across all years and using concordances for diagnosis and procedure codes (for example, mapping earlier ICD-10-AM codes to 2024 equivalents), we achieve clearer and more comparable results. This approach enhances the reliability of the analysis and provides more robust insights for health-care policy and planning.
Cost Data
Potentially preventable hospitalisations (PPH) costs are sourced from the AIHW’s Health system spending on disease and injury in Australia 2023–24 database. In this database, costs for public hospital separations are estimated using the Independent Health and Aged Care Pricing Authority’s National Weighted Activity Unit (NWAU) calculators and the National Efficient Price (NEP), for each financial year. The NWAU calculators assign a weight to each hospital separation based on service-level information, including diagnoses (principal and secondary diagnoses), clinical complexity, length of stay, and procedures undertaken, and some patient demographic information (such as age and remoteness). The number of NWAU’s reflect the relative resource intensity of each service, which is then multiplied by the NEP to estimate the cost per separation.
Costs for private hospitals are estimated based on data reported in the Private Hospital Data Bureau database, and MBS in-hospital services.
Costs for First Nations PPH are adjusted for under-identification.
Total cost estimates for both public and private hospital separations are scaled to the relevant total hospital spending estimate from the Health Expenditure Australia database.
All costs in this report are expressed in constant prices (adjusted for inflation), enabling comparison across different time periods by removing the effect of price changes. In this report, constant prices are calculated by adjusting nominal costs using the Consumer Price Index (CPI) for health services, as published by the ABS (ABS Consumer Price Index). Costs are in 2023–2024 dollars.