Data source

National Hospital Morbidity Database

The National Hospital Morbidity Database (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 hospital separation. 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 the data quality statement from Admitted patient care: Australian Hospital Statistics 2017–18.

Further information on admitted patient care for the 2017–18 reporting period can be found in the report Admitted patient care 2017–18: Australian hospital statistics  (AIHW 2019). The 2017–18 collection contains data for hospital separations that occurred between 1 July 2017 and 30 June 2018. Admitted patient episodes of care/separations that began before 1 July 2017 are included if the separation date fell within the collection period (2017–18). A record is generated for each separation 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 separation. In public acute hospitals, a ‘specialised’ episode of care or separation 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 2017–18 diagnoses are classified according to the International Statistical Classification of Diseases and Related Health Problems, 10th revision, Australian Modification (ICD‑10‑AM 10th edition) ( ACCD 2016). Further information on this is included in the technical information section.

For 2017–18,  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 separation and not all separations have a procedure reported.


AIHW (Australian Institute of Health and Welfare) 2019. Admitted patient care 2017–18: Australian hospital statistics. Health services series no. 90. Cat. no. HSE 225. Canberra: AIHW.

ACCD (Australian Consortium for Classification Development) 2016. The international statistical classification of diseases and related health problems, 10th revision, Australian modification (ICD‑10‑AM), Australian Classification of Health Interventions (ACHI) and Australian Coding Standards (ACS), 10th edn. Sydney: University of Sydney.