National Hospital Morbidity Database
Data are sourced from the National Hospital Morbidity Database (NHMD); a collation of data on admitted patient care in Australian hospitals defined by the Admitted Patient Care National Minimum Data Set (APC NMDS). It is possible for patients to have multiple hospitalisations in any given reference period. The statistical measures presented are derived based on episodes of care that ended within a collection period. The NHMD is a compilation of episode-level records from admitted patient morbidity data collections in Australian hospitals. It includes demographic, administrative and length of stay data for each hospitalisation. Clinical information such as diagnoses, procedures undergone and external causes of injury and poisoning are also recorded. For further details on the scope and quality of data in the NHMD, refer to Admitted patient care: Australian Hospital Statistics 2019–20.
The 2019–20 collection contains data for separations (referred to as hospitalisations in this report) that occurred between 1 July 2019 and 30 June 2020. Admitted patient episodes of care/hospitalisations that began before 1 July 2019 are included if the hospitalisation date fell within the collection period (2019–20). A record is generated for each hospitalisation rather than each patient. Therefore, those patients who separated from hospital more than once in the reference year have more than one record in the database.
Specialised mental health care is identified by the patient having 1 or more psychiatric care days recorded—that is, care was received in a specialised psychiatric unit or ward during that hospitalisation. In public acute hospitals, a ‘specialised’ episode of care or hospitalisation may comprise some psychiatric care days and some days in general care. An episode of care from a public psychiatric hospital is deemed to comprise psychiatric care days only and to be ‘specialised’, unless some care was given in a unit other than a psychiatric unit, such as a drug and alcohol unit.
Although there are national standards for data on admitted patient care, the results presented here may be affected by variations in admission and reporting practices between states and territories. Interpretation of the differences between states and territories therefore needs to be made with care. The principal diagnosis refers to the diagnosis established after observation by medical staff to be chiefly responsible for the patient’s episode of admitted patient care. For 2019–20, diagnoses are classified according to the International Statistical Classification of Diseases and Related Health Problems, 11th revision, Australian Modification (ICD‑10‑AM 11th edition) (ACCD 2016). Further information on this is included in the technical information section.
For 2019–20, procedures are classified according to the Australian Classification of Health Interventions, 10th edition. Further information on this classification is included in the technical information section. More than 1 procedure can be reported for a hospitalisation and not all hospitalisations have a procedure reported.
The large decline in patient days associated with public hospital mental health-related hospitalisations from 2016–17 to 2017–18 followed large increases from 2014–15 to 2016–17. These fluctuations are likely to be related to the introduction of the Mental health care type from 1 July 2015. For example, to change the care type of patients receiving mental health care, Queensland (in 2015–16) and New South Wales (in 2016–17) discharged and readmitted patients, causing the rise in hospitalisations and patient days counted in those years. The rise in patient days is substantially impacted by long stay mental health patients, who can individually account for hundreds, or in some cases thousands, of days. The subsequent decline in patient days seen in 2017–18 is impacted by days accrued before the change in care type being counted in an earlier year.