Glossary

additional diagnosis: The diagnosis of a condition or recording of a complaint—either coexisting with the principal diagnosis or arising during the episode of admitted patient care (hospitalisation), episode of residential care or attendance at a health care establishment—that requires the provision of care. Multiple diagnoses may be recorded.

admission: An admission to hospital. The term hospitalisation is used to describe an episode of hospital care that starts with the formal admission process and ends with the formal separation process.

Age-specific rate: A rate for a specific age group. The numerator and denominator relate to the same age group.

Age-standardisation: A way to remove the influence of age when comparing populations with different age structures. This is usually necessary because the rates of many diseases vary strongly (usually increasing) with age. The age structures of the different populations are converted to the same 'standard' structure, and then the disease rates that would have occurred with that structure are calculated and compared.

Alzheimer’s disease: A degenerative brain disease caused by nerve cell death resulting in shrinkage of the brain.

Anatomical Therapeutic Chemical (ATC) classification: Anatomical Therapeutic Chemical (ATC) codes are used to classify medicines. The ATC classification of medicines is recommended by the World Health Organization, and is the Australian standard for presenting and comparing drug usage data. The ATC classification groups medicines according to the body organ or system on which they act, and their therapeutic and chemical characteristics. More information on the ATC classification system can be found at structure and principles.

Associated cause(s) of death: Any condition(s), diseases and injuries—other than the underlying cause of death—considered to contribute to a death.

Australian Refined Diagnosis Related Groups (AR-DRGs): An Australian system of diagnosis related groups (DRGs). DRGs provide a clinically meaningful way of relating the number and type of patients treated in a hospital (that is, its casemix) to the resources required by the hospital. Each AR-DRG represents a class of patients with similar clinical conditions requiring similar hospital services.

average length of stay: The average number of patient days for admitted patient episodes. Patients who have an admission and a separation on the same date are allocated a length of stay of 1 day.

care type: The care type defines the overall nature of a clinical service provided to an admitted patient during an episode of care (admitted care), or the type of service provided by the hospital for boarders or posthumous organ procurement (care other than admitted care).

Admitted patient care consists of the following categories: acute care, rehabilitation care, palliative care, geriatric evaluation and management, psychogeriatric care, maintenance care, newborn care, mental health care and other admitted patient care—where the principal clinical intent does not meet the criteria for any of the other care types.

Care other than admitted care includes: posthumous organ procurement and hospital boarder.

casemix: The range and types of patients (the mix of cases) treated by a hospital or other health service. Casemix classifications (such as AR-DRGs) provide a way of describing and comparing hospitals and other services for management purposes.

cholinesterase inhibitor: A class of anti-dementia medication that prevents the breakdown of acetylcholine, an important component in cognitive pathways in the brain. Levels of acetylcholine decrease in people with Alzheimer disease and some other dementias. By increasing the availability of acetylcholine in the brain these medications are thought to improve or stabilise cognitive function in people with dementia. Examples of these medications include Donepezil, Galantamine and Rivastigamine.

COVID-19: A disease of the respiratory system, particularly in the early stages of the illness, caused by the coronavirus SARS-CoV-2. Common early symptoms are similar to other respiratory illnesses, but the infection can have a wide variety of manifestations. In some people the infection can progress to become a more severe disease, with the immune system overreacting, resulting in inflammation and lack of oxygen to many parts of the body. This can lead to multiple organ failure and death. Severe symptoms tend to develop in the second week of the disease.

disability-adjusted life years (DALY): A year (1 year) of healthy life lost, either through premature death or equivalently through living with disability due to illness or injury. It is the basic unit used in burden of disease and injury estimates.

dementia: A general term used to describe a group of similar conditions (such as Alzheimer’s disease or vascular dementia) characterised by the gradual impairment of brain function. It is commonly associated with memory loss, but can affect speech, cognition (thought), behaviour and mobility.

dementia with Lewy bodies: Caused by the degeneration and death of nerve cells in the brain due to the presence of abnormal spherical structures, called Lewy bodies, which develop inside nerve cells.

episode of care: The period of admitted patient care between a formal or statistical admission and a formal or statistical separation, characterised by only one care type (see care type and separation).

Excess mortality: A term used to describe additional mortality during a given period of time, relative to what would have been expected based on modelling historical deaths data. Further information on excess mortality during the COVID-19 pandemic can be found in the Australian Bureau of Statistics report: Measuring excess mortality in Australia during the COVID-19 pandemic.

fronto-temporal dementia: Caused by progressive damage to the frontal and/or temporal lobes of the brain.

hospitalisation: Synonymous with separation; that is, an episode of hospital care that starts with the formal admission process and ends with the formal separation process. An episode of care can be completed by the patient’s being discharged, being transferred to another hospital or care facility, or dying, or by a portion of a hospital stay starting or ending in a change of type of care (for example, from acute to rehabilitation).

International Classification of Diseases (ICD) and Related Health Problems: The World Health Organization’s internationally accepted classification of death and disease. The Tenth Revision (ICD-10) is currently in use. The ICD-10-AM is the Australian Modification of the ICD-10; it is used for diagnoses and procedures recorded for patients admitted to hospitals. 

Mortality: Number or rate of deaths in a population during given time period

N-methyl-D-aspartate (NMDA) receptor antagonist: A type of anti-dementia medication that blocks the functioning of NMDA receptors and reduces the levels of glutamate in the brain, thereby preventing the movement of excess calcium in the brain. Increased levels of glutamate in the brain may contribute to the symptoms and progression of Alzheimer disease and other dementias. NMDA receptor antagonists are thought to improve or stabilise cognitive function in people with Alzheimer disease, with improvements seen in the function of daily activities, thinking and behaviour. Memantine is an example of an NMDA receptor antagonist.

National Hospital Morbidity Database (NHMD): A compilation of episode-level records from admitted patient morbidity data collection systems in Australian hospitals. The data supplied are based on the National minimum data set (NMDS) for Admitted patient care and include demographic, administrative and length of stay data, as well as data on the diagnoses of the patients, the procedures they underwent in hospital and external causes of injury and poisoning.

Pandemic: A new infectious disease that is rapidly spreading across a large region, or worldwide, and affecting large number of people. 

patient days: The total number of days for all patients who were admitted for an episode of care and who separated during a specified reference period. A patient who is admitted and separated on the same day is allocated 1 patient day.

Pharmaceutical Benefits Scheme (PBS): A scheme through which the Australian Government subsidises the cost of a wide range of prescription medicines. Most prescriptions for General Schedule medicines (Section 85) are dispensed through community pharmacies, but the PBS is also available through eligible public hospitals to patients on discharge, and day patients. Several drugs are also distributed under alternative arrangements where these are considered more appropriate (Section 100).

principal diagnosis: The diagnosis established after study to be chiefly responsible for occasioning an episode of patient care (hospitalisation), an episode of residential care or an attendance at the health are establishment.

procedure: A clinical intervention that is surgical in nature, carries a procedural risk, carries an anaesthetic risk, and requires specialist training and/or special facilities or equipment available only in the acute-care setting.

Remoteness classification: Each state and territory is divided into several regions based on their relative accessibility to goods and services (such as to general practitioners, hospitals and specialist care) as measured by road distance. These regions are based on the Accessibility/Remoteness Index of Australia and defined as Remoteness Areas by either the Australian Standard Geographical Classification (ASGC) (before 2011) or the Australian Statistical Geographical Standard (ASGS) (from 2011 onwards) in each Census year. The five Remoteness Areas are Major cities, Inner regional, Outer regional, Remote and Very remote.

Respiratory condition: A condition affecting the airways and characterised by symptoms such as wheezing, shortness of breath, chest tightness and cough. Conditions include asthma and chronic obstructive pulmonary disease (COPD)—which includes emphysema and chronic bronchitis.

Repatriation Pharmaceutical Benefits Scheme (RPBS): A scheme through which the Australian Government subsidises the cost of a wide range of prescription medicines, like the Pharmaceutical Benefits Scheme (PBS) most prescriptions for General Schedule medicines (Section 85) are dispensed through community pharmacies, but the PBS is also available through eligible public hospitals to patients on discharge, and day patients. Several drugs are also distributed under alternative arrangements where these are considered more appropriate (Section 100).

separation (from hospital): The formal process where a hospital records the completion of an episode of treatment and/or care for an admitted patient—in this report, described by the term hospitalisation.

socioeconomic area: Socio-Economic Indexes for Areas (SEIFA) are a set of indexes, created from Census data that aim to represent the socioeconomic position of Australian communities and identify areas of advantage and disadvantage. The index value reflects the overall or average level of disadvantage of the population of an area; it does not show how individuals living in the same area differ from each other in their socioeconomic group. This report uses the Index of Relative Socio-Economic Disadvantage.

Underlying cause of death: The primary or main cause of death: the condition, disease or injury that initiated the sequence of events leading directly to death, or the circumstances of the accident or violence that produced the fatal injury.

vascular dementia: Mainly caused by haemodynamic (blood flow to the brain) disorders (for example, strokes), thromboembolism (small blood clots that block small blood vessels in the brain), small blood vessel disease in the brain, and bleeding into or around the brain.

Virus: An infective agent that typically consists of nucliec acid molecule in a protein coat, is too small to be seen by light microscopy, and isable to multiply only within the living cells of a host.

younger onset dementia: Dementia that affects people under the age of 65.