Health Statistics New South Wales - Acute respiratory infection hospitalisations by Aboriginality and sex, NSW

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Methods: Aboriginal peoples

Identification of Aboriginal people in data collections

Estimating the size and composition of the Aboriginal population is difficult for a range of reasons, in particular the incomplete and differential identification of Aboriginal people in administrative data collections. The Aboriginal population is generally under-identified in administrative data collections for reasons such as staff reluctance to ask about Aboriginality and Aboriginal people’s reluctance to identify as Aboriginal in some circumstances. Identification is usually better in rural and remote regions than in major cities.

Identification of Aboriginal people in the Admitted Patient Data Collection

The quality of identification of Aboriginal people in health administrative datasets in NSW varies and may affect these rates. The estimated level of enumeration of Aboriginal people in hospital data (Admitted Patient Data Collection) in NSW was 88% in 2007 (Statistical Information Management Committee 2007).

Differences in population composition

The Aboriginal population is relatively young, with a median age of 21 years, compared with 36 years for the non-Aboriginal population. As age is closely related to health, care should be taken when comparing information for these two populations, except where rates have been age-standardised.

Standardisation by age allows comparing rates of disease in Aboriginal and non-Aboriginal populations. Comparisons are often limited, however, by very low numbers of Aboriginal persons in age groups of 55 years and older.

For example, in NSW in 2008 the proportion of Aboriginal young persons aged below 20 years was 47.6% while persons aged 55 years and older were 9.0% (estimated as 14,064 persons) of the total Aboriginal population. The corresponding proportions in non-Aboriginal population in NSW in 2008 were 25.3% and 34.3% (estimated as 1,733,605 persons). In NSW in 2008, there were estimated 1,613 Aboriginal persons and 458,987 non-Aboriginal persons aged 75 years and older.

These differences in age distribution result in a situation where chronic diseases of the old age may be relatively underrepresented in the Aboriginal older population and cases of rarer diseases may even be absent, leading to falsely favourable results in Aboriginal people when compared with non-Aboriginal people.

To ensure a substantial number of older people in the Aboriginal population for comparison, the older age groups in both Aboriginal and non-Aboriginal populations are often amalgamated starting already from the age 55 years. In this report, the amalgamation from the age 75 years is used in indicators with Aboriginal population data, while in indicators not illustrating Aboriginal population the amalgamation from the age 85 years is used.

Amalgamating older ages allows results in the Aboriginal and non-Aboriginal populations to be compared, but it is not suitable for analysis of a disease distribution in the total population, because information concerning older ages from 55 to 85 years and over is lost.

References

Statistical Information Management Committee. Hospital under-identification for Aboriginal and Torres strait Islander peoples. Out of session agenda item No 4/2007. Canberra: AIHW, 2007.

Australian Bureau of Statistics. Experimental estimates and projections, Aboriginal and Torres Strait Islander Australians 1991-2021. Cat no 3238.0. Canberra: ABS, 2009. Available at http://www.abs.gov.au/ausstats/abs@.nsf/Products/946D4BC28DB92E1BCA25762A001CBF38?opendocument

Description	ICD-9 & ICD-9-CM	ICD-10 & ICD-10-AM	Comments
Acute respiratory infections	460-466, 480-487	J00-J22	All records are included, NSW residents only, all ages.

Key points: Respiratory disease

• In 2009 in NSW, around 9% of adult males and 13% of adult females had asthma, and in 2007 and 2008, just under 16% of boys and almost 12% of girls aged 2-15 years had asthma. Asthma was responsible for 130 deaths in 2007 and around 13,000 hospitalisations in 2009-10.

• Chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema, was responsible for over 1,700 deaths in 2007 in NSW and over 19,000 hospitalisations in 2009-10.

• In 2007, 75% of all deaths from chronic obstructive pulmonary disease in NSW and 91% of all lung cancer deaths were attributable to smoking. In 2009-10, smoking caused around 80% of all hospitalisations for chronic obstructive pulmonary disease and lung cancer.

• Asbestosis is a chronic lung disease that is associated with occupational exposure to asbestos. Total hospitalisations due to asbestos in NSW have decreased in the past five years.

• Death rates from respiratory tuberculosis have remained low and stable since 1994 in NSW.

• The rate of new cases of malignant mesothelioma (a cancer that is associated with past exposure to asbestos) more than doubled in NSW between 1986 and 2003. It has been slowly decreasing since then.

Introduction: Respiratory disease

Respiratory diseases

Respiratory diseases include acute diseases, such as influenza and pneumonia, and chronic respiratory diseases (specifically asthma, chronic obstructive pulmonary disease, asbestosis, and respiratory tuberculosis), where preventive measures and better management of conditions can reduce the burden of disease and reduce associated healthcare costs. Respiratory diseases, including lung cancer, were together responsible for around 14% of all deaths in NSW in the period 2003 to 2007, and about 5% of hospital separations in 2008-09.

Chronic respiratory diseases were responsible for 7.1% of total burden of disease and injury in Australia in 2003, with chronic obstructive pulmonary disease and asthma accounting for 46% and 34% of this burden, respectively (Begg et al. 2007).

Influenza and pneumonia

Influenza and pneumonia are acute respiratory diseases that can be very severe and, in persons at high risk, can lead to death. Influenza and pneumonia cause around 1.8% of all deaths and around 0.9% of hospital separations and are an important cause of hospitalisations in the very young, and of death and hospitalisations among older age groups.

Asthma

Asthma is a significant public health problem in Australia and it is estimated that Australian prevalence rates are among the highest in the world. Fortunately, recent studies in children show no further increase in prevalence. The overall prevalence of asthma reported in Australia was 9.9%, down from 11.6% in the 2001 ((ABS Cat. no. 4364.0 2009). Among children asthma is the most prevalent long term condition in Australia. In Australia in 2003, asthma was estimated to account for 2.3% of the disease burden (Begg et al. 2007).

Chronic obstructive pulmonary disease

Chronic bronchitis and emphysema are the two main conditions comprising chronic obstructive pulmonary disease (COPD). In Australia in 2003, COPD was estimated to account for 2.9% of the disease burden.

Tuberculosis

Tuberculosis (TB) is caused by the bacterial organism Mycobacterium tuberculosis. Despite the increasing burden from respiratory tuberculosis globally, it is not a major public health problem in NSW. In fact the mortality and morbidity from all types of tuberculosis in NSW is one of the lowest in the world.

Lung cancer

Lung cancer is excluded from analyses of respiratory diseases, as it is classified with cancers, and not with respiratory diseases, in the International Classification of Diseases (the coding system used for health data in NSW). However, some indicators analysing respiratory diseases explicitly include lung cancer to provide a more appropriate measure of the burden of respiratory disease from a clinical and health services planning perspective.

Risk factors

Cigarette smoking is the main risk factor for both COPD and lung cancer and the current incidence rates of these conditions reflect smoking rates 20 years and more in the past. Lung cancer is one of the leading causes of death in Australia.