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Commonly used definitions and abbreviations


Acute myocardial infarction

Commonly known as heart attack, occurs when a blockage of a blood vessel in the heart causes death or injury of the heart muscle. AMI is categorised based on the pattern that appears on the electrocardiogram (ECG). ST segment elevation myocardial infarct (STEMI) is when the ST segment on the ECG appears elevated. Non-ST segment elevation myocardial infarct (non-STEMI) does not have elevation of the ST segment, however there is clinical evidence that injury to the heart muscle has occurred. STEMI heart attacks are more serious and treated with greater urgency as they represent a more severe blockage of the coronary (heart) arteries and therefore greater risk of death.


The formal process, using registration procedures, under which a person is accepted by a hospital or district health service facility as an inpatient.

Aetiologic fraction

A measure of the amount of disease associated with an exposure within a population. In a situation in which exposure to a given factor is believed to be a cause of a given disease, the population attributable fraction (or population aetiologic fraction) is the proportion of the disease in the total population that can be attributed to exposure to the factor.

Age-adjusted rate

Rate adjusted to account for differences in age composition when rates for different populations are compared.

Age-specific fertility rate

Rate calculated by dividing the number of live births in each age group by the total female population (in thousands) in each age group.

Age-specific rate

Rate for a specified age group. Both numerator and denominator refer to the same age group.


Percutaneous angioplasty with and without stenting. This is the surgical repair of a blocked coronary (heart) blood vessel, usually by inflating a small balloon at the end of a catheter through a small incision in the skin under the guidance of an X-ray. A small metal scaffold, called a stent, may be inserted to keep the blood vessel open.

APGAR score

A numerical scoring system routinely administered 1 and 5 minutes after birth to evaluate the condition of the baby. It takes account of 5 physical signs, each of which is assigned a component score of 0, 1 or 2: heart rate, respiration, muscle tone, reflexes and colour.The score ranges from 0-10, 10 being perfect. Scores 7 and above are regarded as normal, 4 to 6 as fairly low, and 3 and below are critically low.


A condition in which the airways of the lungs narrow and swell and may produce extra mucus. Symptoms include difficulty breathing, coughing, a whistling sound (wheezing) when breathing out and shortness of breath.


Birth weight

The newborn infant's first bare weight in grams.

Body mass index (BMI)

BMI = weight(kg)/height(m)2

Categories for this indicator in adults include: underweight (BMI less than 18.5), healthy weight (BMI from 18.5 to 24.9), overweight (BMI from 25.0 to 29.9) and obese (BMI of 30.0 and over).

Obesity was further classified into: Obesity Class I (BMI between 30.0 and 34.9), Obesity Class II (BMI between 35.0 and 39.9) and Obesity Class III (BMI of 40.0 or over).

For children and adolescents, the same categories are used but are linked to international cut off points defined by sex to pass through a BMI of 16, 17, and 18.5 for underweight, 25 for overweight, and 30 for obesity at age 18 years (Cole et al. 2000; Cole et al. 2007).


Caesarean section

Birth of the fetus through an abdominal incision. Elective caesarean section: a caesarean section (planned or unplanned) performed before the onset of labour. Emergency caesarean section: a caesarean section performed after the onset of labour, whether or not the onset of labour was spontaneous.

Carotid endarterectomy

A surgical procedure used to reduce the risk of stroke, by correcting a blockage or narrowing in the carotid artery in the neck. Endarterectomy is the removal of material on the inside of an artery.


Also known as Varicella. It is a highly contagious infection caused by the varicella-zoster virus. It is usually a mild disease of short duration in healthy children with symptoms such as slight fever, runny nose, feeling generally unwell and a skin rash that turns to blisters. However, it is more severe in adults and can cause serious and even fatal illness in individuals who are immunosuppressed.

Childbearing age

In Australia childbearing age is defined as 15-49 years. However, the definition varies between jurisdictions.


A sexually transmissible infection caused by the bacterium Chlamydia trachomatis. Many people who are infected do not have symptoms of infection but can still transmit the bacterium.

Chronic kidney disease (CKD)

All conditions of the kidney, lasting at least 3 months, where a person has had evidence of kidney damage and/or reduced kidney function, regardless of the specific diagnosis of disease or condition causing the disease.

Chronic obstructive pulmonary disease (COPD)

A chronic inflammatory lung disease that causes obstructed airflow from the lungs. Symptoms include breathing difficulty, cough, mucus production and wheezing. It includes progressive lung conditions such as emphysema, chronic bronchitis and chronic asthma.

Confidence interval

An error margin illustrating the variability in statistics sampled from a population. A 95% confidence interval can be interpreted as a 95% probability that the true value of a variable (such as a rate, mean or proportion) is contained within the interval.


A woman having given birth. Data are based on mothers giving birth (that is, multiple births are counted once).


A person who has been in association with an infected person or a contaminated environment that may provide an opportunity to acquire the infection.

Continuous positive airway pressure (CPAP)

A positive airway pressure, that introduces airflow into the airways to maintain a continuous pressure to constantly stent the airways open, in people who are breathing for themselves.

Coronary artery bypass graft (CABG)

A procedure to improve blood supply to the heart when the coronary arteries are narrowed or blocked. CABG uses blood vessels from another part of the body and connects them to blood vessels above and below the narrowed artery, bypassing the narrowed or blocked coronary arteries.

Coronary heart disease (CHD)

The coronary arteries become too narrow resulting in reduced supply of oxygen and blood to the heart.

There are 2 major clinical formsheart attack (also known as acute myocardial infarction) and angina. A heart attack is a life-threatening event that occurs when a blood vessel supplying the heart is suddenly blocked completely. Angina is a chronic condition in which short episodes of chest pain can occur periodically when the heart has a temporary deficiency in its blood supply.

Coronary revascularisation procedures

Procedures used to restore adequate blood flow to blocked coronary arteries such as coronary artery bypass graft and coronary angioplasty with and without stenting.

Crude birth rate

An estimate of the proportion of a population born in a specified period. It is calculated as the number of live births in a year per 1,000 population.

Crude death rate

An estimate of the proportion of a population that dies in a specified period. It is calculated by dividing the number of deaths in a specified period by the number at risk during that period (typically per year).


Day-only admission

A person who is admitted to hospital and leaves on the same calendar day.


Disease causing the loss of cognitive functioning-thinking, remembering, and reasoning-and behavioural abilities to such an extent that it interferes with daily life and activities. Alzheimer's disease is the most common cause of dementia in older adults. Other dementias include Lewy body dementia, frontotemporal disorders, and vascular dementia.


A chronic, metabolic disease characterized by elevated levels of blood glucose (or blood sugar), which leads over time to serious damage to the heart, blood vessels, eyes, kidneys and nerves. There are three main forms of diabetes mellitus: Type 1 diabetes, Type 2 diabetes and gestational diabetes.


A medical procedure for the filtering and removal of waste products from the bloodstream. It can be conducted at home, in the hospital or in a satellite clinic. A person on dialysis may receive several treatments per week.

There are 2 main types of dialysis:

  • haemodialysis blood flows out of the body into a machine that filters out the waste products and returns the cleansed blood back into the body.
  • peritoneal dialysis fluid is introduced into the peritoneal cavity via a permanent tube in the abdominal wall. Waste products are filtered through the peritoneum, the thin membrane that surrounds the abdominal organs, from the blood vessels into the fluid, which is drained out periodically.


A contagious and potentially life-threatening bacterial infection that causes severe breathing difficulties, heart failure and nerve damage.

Disability-adjusted life years (DALY)

Measure of years healthy life lost, either through premature death (YLL) or living with ill health due to illness or injury (YLD). One DALY represents one lost year of healthy life.

Discharge against medical advice

Patients who have been admitted to hospital who leave against the expressed advice of their treating physician. Patients who discharge against medical advice have higher readmission rates, higher levels of multiple admissions, and a higher rate of in-hospital mortality. This measure provides indirect evidence of the cultural competence of hospital services, and the extent of patient satisfaction with the quality of care provided.


The process of experiencing respiratory impairment from submersion/immersion in liquid.


Electronic cigarettes

Battery powered devices that heat a liquid to a vapour so it can be inhaled. Some of the liquids used in these devices may contain nicotine. They may also be known as e-cigarettes, e-cigs, vapes, vape pans and e-hookahs.

Emergency department presentation

Occurs following the arrival of the patient at the emergency department and is the earliest occasion of the patient being registered clerically or triaged. The patient may be subsequently provided with a service by a treating medical officer or nurse, and a provisional diagnosis is recorded. A 'presentation' is equal to a 'visit' or an 'attendance' at the emergency department.


Injection of analgesic agent outside the dura mater which covers the spinal canal; includes lumbar, spinal, and epidural anaesthetics.


A surgical incision of the perineum and vagina to enlarge the vulvar orifice before or during birth. It is undertaken in cases of instrumental vaginal birth or when there is suspected fetal compromise. Episiotomy is not performed routinely in spontaneous vaginal birth.

Exclusive breastfeeding

No other food or drink, not even water, except breast milk (including milk expressed) for 6 months of life, but allows the infant to receive oral rehydration solutions, drops and syrups (vitamins, minerals and medicines).

Extremely low birth weight

Birth weight less than 1,000 grams.


Fertility rate

Number of live births in an area during a year, divided by the mid-year female population aged 15-44 in the same area in the same year.

Fetal death

Delivery of a child who did not, at any time after delivery, breathe or show any other evidence of life, such as a heartbeat.


General fertility rate

The least refined measure of fertility in a given population, used when the specific ages of mothers are not known. The numerator is the number of live births in a year and the denominator is the number of females of childbearing age.

Gestational age

The duration of pregnancy in completed weeks from the first day of the last normal menstrual period. Where accurate information on the date of the last menstrual period is not available, a clinical estimate of gestational age may be obtained from ultrasound during the first half of pregnancy or by examination of the newborn infant.


A sexually transmissible infection caused by Neisseria gonorrhoeae bacteria.


Health-adjusted life expectancy (HALE)

Life expectancy adjusted for disease and disability. This is the average number of years a person can expect to live in 'full health' by taking into account years lived in less than full health due to disease and/or injury.

Hepatitis A

A viral infection of the liver. The illness is usually mild, lasting one to three weeks. It is almost always followed by complete recovery. Occasionally it is more severe and symptoms can last longer, particularly in people with chronic liver disease. Small children who become infected usually have no symptoms. It does not cause long-term liver disease and deaths caused by hepatitis A do occur but are very rare. Occasionally people are hospitalised for the disease and can have relapsing symptoms after the disease has seemed to have cleared.

The virus is spread by the faecal-oral route, including contaminated food or water or direct contact with an infected person. Vaccination and good hygiene prevents infection.

Hepatitis B

A viral disease that causes symptoms such as fever, jaundice and feeling generally unwell and can lead to cirrhosis or cancer of the liver.

Hepatitis B virus is transmitted through contact with blood or body fluid of an infectious person, and is commonly acquired either perinatally, by sexual contact, by sharing injecting equipment or by exposure to infectious fluids.

Most adults who get infected with hepatitis B virus recover or clear the infection without specific treatment. They are no longer infectious, and have lifelong immunity. However, about five to ten percent of infected adults do not clear the virus, and remain infectious for many years. They have chronic (long-term) hepatitis B infection.

Hepatitis C

A viral disease that is spread when the blood of an infected person enters the bloodstream of an uninfected person.

Hepatitis C lives in liver tissue and blood and can cause severe scarring and damage to the liver. This can have long-lasting health effects. Around 80% of people who are infected with hepatitis C virus will remain infected for the rest of their lives, unless they receive treatment. Without treatment, some people eventually develop liver failure or cancer of the liver.

Hospital peer group

Groups that define and delineate hospitals with similar structural and patient characteristics, predominantly fused or comparative reporting and service planning.

Human Immunodeficiency Virus (HIV)

A virus that damages the immune system. It is transmitted through body fluids. Treatments are available for HIV, but there is no vaccine and no cure. AIDS (Acquired Immune Deficiency Syndrome) is a late stage of HIV infection.


Illicit substances

Used for non-medicinal purposes: speed, cocaine, sleeping pills or tranquilisers, marijuana, analgesics, heroin, petrol and other inhalants, hallucinogens, designer drugs, and injecting of any illegal drug.


The rate at which new cases of a disorder occur in the population: that is, the number of new cases in a specified period, divided by the population at risk of the disorder in that period.

Infant death

The death of a child before its first birthday.

Infant mortality rate

The number of deaths in children aged up to 1 year per 1,000 live births.


A contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. It can cause mild to severe illness. Symptoms include fever, aching muscles, chills and sweats, headache, dry, persistent cough, shortness of breath, tiredness and weakness, runny or stuffy nose, sore throat and eye pain.

Intentional self-harm

Any event of purposely self-inflicted poisoning or injury or attempted suicide with intent based on notes recorded by the treating clinician.

Interpersonal violence

Injuries from assaults inflicted by another person with intent to injure by any means, including bodily force (such as punching, pushing or submersion), weapons, objects or substances. Both perpetrators (i.e. those with intent to injure) and victims (ie those who are the target of the assault or are uninvolved bystanders) may be hospitalised for injuries related to interpersonal violence.

Invasive meningococcal disease

An uncommon but very serious infection that occurs when the meningococcal bacteria invades the body from the throat or nose.


Labour augmentation

Artificial rupture of the membranes or use of oxytocic drugs after spontaneous onset of labour.

Life expectancy

Life expectancy measures how long, on average, a person is expected to live based on current age and sex-specific death rates. It is a measure of population health and indicates overall mortality of the population.

Live birth

The birth of a child who, after delivery, breathes or shows any other evidence of life, such as a heartbeat. For calculation of perinatal death rates, includes only infants weighing at least 400 grams at birth or, where birth-weight is unknown, of at least 20 weeks gestation.

Local Government Area (LGA)

A geographical area under the responsibility of an incorporated local government council.

Local Health District (LHD)

Health administration structures applicable in NSW since January 2011.



Also known as the arithmetic average. It tells where the values for a group (sample) are centred.


A highly contagious viral disease that is easily spread through the air. The first symptoms are fever, tiredness, cough, runny nose, sore red eyes and feeling unwell. A few days later a rash appears. Young children (especially infants) may also experience diarrhoea. Up to a third of people with measles have complications. These include ear infections, diarrhoea, and pneumonia, and may require hospitalisation. About one in every 1000 people with measles develops encephalitis (swelling of the brain).


Neonatal death

Death within 28 days of birth of any child who, after delivery, breathed or showed any other evidence of life, such as a heartbeat.


Certification in an approved form of a disease listed in Schedule 3 of Notifiable Diseases in the NSW Public Health Act 2010. In HealthStats NSW, notifications concern cases of communicable diseases reported by general practitioners, hospitals and pathology laboratories to the Secretary of the NSW Ministry of Health.



The total number of live births and stillbirths of the mother before the pregnancy or birth under consideration.

Perinatal death

A fetal or neonatal death (i.e. still births and death within 28 days of birth).

Perineal status

The perineum's condition immediately after birth (post partum). 1st degree tear: a perineal graze; laceration; tear involving: the fourchette, hymen, labia, skin, vagina, or vulva. 2nd degree tear: a perineal laceration or tear involving the pelvic floor or perineal muscles or vaginal muscles. 3rd degree tear: a perineal laceration; tear involving the anal sphincter or rectovaginal septum. 4th degree tear: a third degree perineal laceration or tear which also involves the anal mucosa or rectal mucosa. Episiotomy is a surgical incision of the perineum that enlarges the birth canal.


The pelvic floor and associated structures occupying the pelvic outlet. It is bounded anteriorly by the pubic symphysis, laterally by ischial tuberosities and posteriorly by the coccyx.


Also known as whooping cough. A highly infectious bacterial disease that causes bouts of coughing. Adolescents and adults can have an annoying cough for up to 3 months. Severe bouts of coughing can cause vomiting, rib fractures, rupture of small blood vessels and hernias. About 1 in 200 babies aged less than 6 months who catch whooping cough from an infected person die from pneumonia or brain damage.

Physical activity

Any bodily movement produced by skeletal muscles, that requires energy expenditure.


The number of fetuses in utero at 20 weeks pregnancy gestation that are subsequently born separately.

Pneumococcal disease

Infection caused by the bacteria Streptococcus pneumoniae. Infection can cause a variety of diseases including: pneumonia (infection of the lungs), otitis media (infection of the middle ear) and meningitis (infection of the membranes around the brain and spinal cord). Infections are more common in winter and spring. Small children, and the elderly are most at risk. Infection is treated with antibiotics. Immunisation can prevent infection.


An infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus, causing cough with phlegm or pus, fever, chills, and difficulty breathing. A variety of organisms, including bacteria, viruses and fungi, can cause pneumonia.

Postnatal average length of stay

The average number of days mothers spend in hospital following the birth of their babies.

Potentially avoidable deaths

Deaths occurring before the age 75 years, which could be avoided by clinical or other healthcare interventions.

Potentially preventable hospitalisations

Hospitalisations for certain conditions for which hospitalisation is considered potentially avoidable or preventable if earlier preventive care and disease management was provided upstream of the hospitalisation. Usually delivered through primary health care.


The number of people with a disease at a given time (point prevalence) or in a specified period (period prevalence), divided by the number of people at risk from that disease.

Primary Health Network (PHN)

A regional network governed by a Board and consisting of general practitioner-led Clinical Councils and Community Advisory Committees which report to the Board on issues to ensure services across the primary, community and specialist sectors in the region work together. Geographical boundaries of Primary Health Networks (PHNs) are formalised by the Australian Government Department of Health. There are nine Primary Health Networks in NSW. Primary Health Networks replace Medicare Locals.

Principal diagnosis

The first ICD-9 or ICD-10 coding variable reported on the hospital separation form. It means the final diagnosis that best accounts for inpatient care.


Rate ratio

The ratio of two rates: for example, the rate of disease in one population group divided by the rate in another population group.


Scheduled medical condition

Medical conditions to be notified under the provisions of the NSW Public Health Act 2010.

Secure Analytics for Population Health Research and Intelligence (SAPHaRI)

Data warehouse and analysis tool. It is managed by the Centre for Epidemiology and Evidence, NSW Ministry of Health, and employs sophisticated business intelligence technology to enable analysis of key health datasets. SAPHaRI replaced HOIST (Health Outcomes Information Statistical Toolkit) in 2012.


The formal process whereby an inpatient leaves a hospital or other district health service facility after completing an episode of care (e.g. discharge to home, discharge to another hospital or nursing home, or death).

Standard deviation

Measures the scatter in a group of observations. While the mean tells where the values for a group (sample) are centred, the standard deviation is a summary of how widely distributed the values are around the centre. Standard deviation describes how widely individuals within the survey sample differ from the sample mean. It may be unaffected by the increased sample size.

Standard error (of the mean)

An estimate of how closely a sample mean is likely to be to the true mean (i.e. the mean of the population from which the sample was drawn). In other words, it is the standard deviation of an estimate of the mean. It is used to calculate confidence intervals. The larger the standard error, the less confident we are that the estimate from the sample is close to the true value. The bigger the sample (that is the closer the sample is to the total population) the smaller the standard error because the estimate of the population mean improves.


The complete expulsion or extraction from its mother of a product of conception of at least 20 weeks gestation or 400 grams birth weight who did not - at any time after birth - breathe or show any evidence of life such as a heartbeat.


Ischemic stroke is the blood flow to the brain being suddenly blocked preventing the brain from getting oxygen and nutrients from the blood. Without oxygen and nutrients, brain cells quickly begin to die. Hemorrhagic stroke is sudden bleeding in the brain that can also cause a stroke if it damages brain cells

Strokes may cause sudden weakness, loss of sensation, or difficulty with speaking, seeing, or walking.


Underlying cause of death

The primary disease or injury causing the death. It is listed on a death certificate together with other diseases or injuries, which are classified as associated causes. These are all other conditions, diseases or injuries that were considered to have contributed to the death.