National Healthcare Agreement: PI 43-Unplanned/unexpected readmissions within 28 days of selected surgical admissions, 2012 QS

Identifying and definitional attributes

Metadata item type:Quality Statement
METeOR identifier:500176
Registration status:Health, Superseded 14/01/2015

Relational attributes

Indicators linked to this Quality statement:

National Healthcare Agreement: PI 43-Unplanned/unexpected readmissions within 28 days of selected surgical episodes of care, 2012 Health, Superseded 25/06/2013

Data quality

Quality statement summary:
  • The National Hospital Morbidity Database (NHMD) is a comprehensive data set that has records for all separations of admitted patients from essentially all public and private hospitals in Australia.
  • The indicator is an underestimate of all possible unplanned/unexpected readmissions because:
    • it could only be calculated for public hospitals and for readmissions to the same hospital.
    • episodes of non-admitted patient care provided in outpatient clinics or emergency departments which may have been related to a previous admission are not included.
    • the unplanned and/or unexpected readmissions are limited to those having a principal diagnosis of a post-operative adverse event for which a specified International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM) diagnosis code has been assigned. This does not include all possible unplanned/unexpected readmissions.
  • Calculation of the indicator for Western Australia was not possible using data from the NHMD. Data for Western Australia were supplied by WA Health and Australian rates and numbers do not include Western Australia.
  • Variations in admission practices and policies lead to variation among providers in the number of admissions for some conditions.
Institutional environment:

The Australian Institute of Health and Welfare (AIHW) has calculated this indicator.

The AIHW is an independent statutory authority within the Health and Ageing portfolio, which is accountable to the Parliament of Australia through the Minister for Health and Ageing. For further information see the AIHW website.

The data were supplied to the AIHW by state and territory health authorities. The state and territory health authorities received these data from public and private hospitals. States and territories use these data for service planning, monitoring and internal and public reporting. Hospitals may be required to provide data to states and territories through a variety of administrative arrangements, contractual requirements or legislation.

States and territories supplied these data under the terms of the National Health Information Agreement (see link below).


The reference period for this data set is 2009–10.


The AIHW provides a variety of products that draw upon the NHMD. Published products available on the AIHW website are:

  • Australian hospital statistics with associated Excel tables.
  • interactive data cubes for Admitted patient care (for Principal diagnoses, Procedures and Diagnosis Related Groups).

Some data are also included on the MyHospitals website.

Interpretability:Supporting information on the quality and use of the NHMD are published annually in Australian hospital statistics (technical appendixes), available in hard copy or on the AIHW website. Readers are advised to note caveat information to ensure appropriate interpretation of the performance indicator. Supporting information includes discussion of coverage, completeness of coding, the quality of Indigenous data, and changes in service delivery that might affect interpretation of the published data. Metadata information for the NMDS for Admitted patient care is published in the AIHW’s online metadata repository (METeOR) and the National health data dictionary.

The purpose of the NMDS for Admitted patient care is to collect information about care provided to admitted patients in Australian hospitals. The scope of the NMDS is episodes of care for admitted patients in essentially all hospitals in Australia, including public and private acute and psychiatric hospitals, free-standing day hospital facilities, alcohol and drug treatment hospitals and dental hospitals. Hospitals operated by the Australian Defence Force, corrections authorities and in Australia's off-shore territories are not included. Hospitals specialising in ophthalmic aids and other specialised acute medical or surgical care are included.

The hospital separations data do not include episodes of non-admitted patient care provided in outpatient clinics or emergency departments.

The analyses by remoteness and socioeconomic status are based on the Statistical Local Area (SLA) of usual residence of the patient. The Socio-Economic Indexes for Areas (SEIFA) categories for socioeconomic status represent approximately the same proportion of the national population, but do not necessarily represent that proportion of the population in each state or territory (each SEIFA decile or quintile represents 10 per cent and 20 per cent respectively of the national population). The SEIFA scores for each SLA are derived from 2006 Census data and represent the attributes of the population in that SLA in 2006. To allocate a 2006 SEIFA score to 2009 SLAs (used for 2009–10 data), 2009 SLA boundaries are mapped backed to 2006 SLA boundaries. It is possible that the demographic profile of some areas may have changed between 2006 and 2009 due to changes in the socioeconomic status of the existing population, or changes to population size, thus potentially diminishing the accuracy of that area’s SEIFA score over time. This is likely to impact most those quintiles in jurisdictions with a greater number of areas experiencing substantial population movement or renewal.

Separations are reported by jurisdiction of hospitalisation, regardless of the jurisdiction of usual residence. Hence, rates represent the number of separations for patients living in each remoteness area or SEIFA population group (regardless of their jurisdiction of residence) divided by the total number of separations for people living in that remoteness area  or SEIFA population group and hospitalised in the reporting jurisdiction. This is relevant if significant numbers of one jurisdiction’s residents are treated in another jurisdiction.

The unplanned and/or unexpected readmissions counted in the computation for this indicator have been limited to those having a principal diagnosis of a post-operative adverse event for which a specified ICD‑10‑AM diagnosis code has been assigned. Unplanned and/or unexpected readmissions attributable to other causes have not been included.

In regards to hysterectomy, there are three procedures that are in scope of the indicator, but currently not included in any NHA reporting (all years). These are (in ICD-10 6th edition), 35750-00—Laparoscopically assisted vaginal hysterectomy; 35753-02—Laparascopically assisted vaginal hysterectomy with removal of adnexa; 35653-00—Subtotal abdominal hysterectomy. In 2009–10, 4,460 separations involved one of these procedures, representing approximately 40 per cent of all separations involving hysterectomy and in scope for this indicator.

The calculation of the indicator is limited to public hospitals and to readmissions to the same hospital.

Other Australians includes separations for non‑Indigenous people and those for whom Indigenous status was not stated.


For 2009–10, almost all public hospitals provided data for the NHMD. The exception was a mothercraft hospital in the Australian Capital Territory and about 2400 separations for one public hospital in Western Australia.

The majority of private hospitals provided data, with the exception of the private day hospital facilities in the Australian Capital Territory and the Northern Territory. Western Australia was not able to provide about 10 600 separations for one private hospital.

States and territories are primarily responsible for the quality of the data they provide. However, the AIHW undertakes extensive validations on receipt of data. Data are checked for valid values, logical consistency and historical consistency. Where possible, data in individual data sets are checked against data from other data sets. Potential errors are queried with jurisdictions, and corrections and resubmissions may be made in response to these edit queries. The AIHW does not adjust data to account for possible data errors or missing or incorrect values.

The Indigenous status data are of sufficient quality for statistical reporting for the following jurisdictions: New South Wales, Victoria, Queensland, South Australia and Western Australia (public and private hospitals) and Northern Territory (public hospitals only). National totals include these six jurisdictions only. Indigenous status data reported for Tasmania and Australian Capital Territory (public and private hospitals) should be interpreted with caution until further assessment of Indigenous identification is completed.

For this indicator, the linkage of separations records is based on the patient identifiers which are reported for public hospitals. As a consequence, only readmissions to the same public hospital are in scope; and readmissions to different public hospitals and readmissions involving private hospitals are not included.

For Western Australia the indicator was calculated and supplied by WA Health.

To calculate this indicator, the readmissions needed to be reported in the 2009–10 financial year. This led to the specification of 19 May as the cut‑off date for the initial separations. This cut-off date ensures that about 98 per cent of all eligible readmissions will be reported in 2009–10.

Data on procedures are recorded uniformly using the Australian Classification of Health Interventions. Data on diagnoses are recorded uniformly using the ICD‑10‑AM.

Cells have been suppressed to protect confidentiality where the presentation could identify a patient or a service provider or where rates are likely to be highly volatile, for example where the denominator is very small. The following rules were applied:

  • Rates were suppressed where the numerator was less than 5 and/or the denominator was less than 200.
  • Rates were suppressed where the numerator was zero and the denominator was less than 200.
  • Counts were suppressed when the number was less than 3.
  • Data for private hospitals in Tasmania, Australian Capital Territory and the Northern Territory were suppressed.

The information presented for this indicator is calculated using the same methodology as data published in Australian hospital statistics 2009–10 and the National healthcare agreement: performance report 2009–10.

The data can be meaningfully compared across reference periods for all jurisdictions.

However, caution is required when analysing SEIFA over time for the reasons outlined above (see Relevance section). Methodological variations also exist in the application of SEIFA to various data sets and performance indicators. Any comparisons of the SEIFA analysis for this indicator with other related SEIFA analysis should be undertaken with careful consideration of the methods used, in particular the SEIFA index used and the approach taken to derive quintiles and deciles.

Relational attributes

Related metadata references:

Has been superseded by National Healthcare Agreement: PI 23-Unplanned hospital readmission rates, 2013 QS Health, Superseded 14/01/2015

Supersedes National Healthcare Agreement: PI 43: Unplanned/unexpected readmissions within 28 days of selected surgical admissions, 2011 QS Health, Superseded 04/12/2012