HIV and AIDS in Aboriginal and Torres Strait Islander Australians: 1992-1998

Abstract

Objective: To describe the epidemiological pattern of newly diagnosed HIV infection and AIDS among Indigenous Australians.
Design and setting: National surveillance for newly diagnosed HIV infection and AIDS in Australia. Information on Indigenous status was sought at HIV/AIDS notification in all State/Territory health jurisdictions, except the Australian Capital Territory, and Victoria before June 1998.
Main outcome measures: Number of people with newly diagnosed HIV per year and population rate of HIV diagnosis; demographic characteristics of people with HIV and AIDS diagnoses by Indigenous status.
Results: From 1992 to 1998, 127 Indigenous Australians were newly diagnosed with HIV infection and 55 were diagnosed with AIDS. The population rate of HIV diagnosis among Indigenous Australians (5.23/100 000 per year) was similar to that among non-Indigenous Australians (5.51/100 000 per year). The annual number of HIV diagnoses among Indigenous people was relatively stable, but among non-Indigenous people it declined steadily over time. A higher proportion of Indigenous people diagnosed with HIV were women (26.8% v 8.9%; P < 0.001). Although male homosexual contact was the predominant source of exposure for both Indigenous (46.7%) and non-Indigenous (75.0%) people with HIV infection, exposure by heterosexual contact (36.7% v 15.3%; P < 0.001) was reported more frequently among Indigenous people.
Conclusion: Although HIV incidence was similar among Indigenous and non-Indigenous Australians, the lack of a recent decline in incidence and the higher proportion of Indigenous people exposed to HIV by heterosexual contact indicate the need to intensify interventions to prevent HIV transmission among Indigenous people.

Introduction

The epidemic of HIV transmission peaked in Australia in the mid 1980s, and there was a subsequent peak in AIDS incidence of nearly 1000 cases in 1994.¹ The estimated number of people diagnosed with HIV infection in Australia to the end of 1998 was 16 714, with an estimated 11 800 living with HIV infection. Although the peaks of both the HIV and AIDS epidemics in Australia have passed, HIV infection continues to be transmitted, predominantly through male homosexual contact, at an estimated level of 450 cases per year.¹

Despite evidence of a relatively well-controlled HIV epidemic in Australia, evaluation of the Third National HIV/AIDS Strategy noted an increase in the reported number of Indigenous Australians diagnosed with HIV infection in the early 1990s.¹ Furthermore, high rates of other sexually transmissible infections in some Indigenous communities indicate the potential for HIV transmission.¹

To define the pattern of HIV infection among Indigenous Australians, and to assess time trends in new diagnoses of HIV infection and AIDS, we examined national HIV and AIDS notification data by Indigenous status for the years 1992-1998. National Health and Medical Research Council guidelines on ethical matters in Aboriginal and Torres Strait Islander health research were followed.²

Methods

National surveillance procedures
Surveillance procedures for newly diagnosed HIV infection and AIDS have been described previously.^3,4 Briefly, newly diagnosed HIV infection and AIDS are notifiable conditions in each State or Territory health jurisdiction in Australia. Information sought at national notification of newly diagnosed HIV infection includes the State or Territory of diagnosis, postcode of residence, namecode (based on the first two letters of the family name and the first two letters of the first given name), sex, date of birth, Indigenous status, date of HIV diagnosis, CD4 cell count at HIV diagnosis, evidence of newly acquired HIV infection, and patient-reported source of exposure to HIV. Information sought at AIDS notifications also includes the date of AIDS diagnosis, AIDS-defining illnesses, and use of antiretroviral therapy before AIDS diagnosis.

People with newly diagnosed HIV infection with evidence of newly acquired HIV infection (ie, a negative or indeterminate HIV antibody test result or a diagnosis of HIV seroconversion illness within 12 months of HIV diagnosis) were defined as having "newly acquired HIV infection". People with AIDS were classified as having "late HIV diagnosis" if HIV infection was newly diagnosed within three months of AIDS diagnosis.

Indigenous status
From 1985, information on Indigenous status, obtained through self-identification as Aboriginal or Torres Strait Islander, was routinely sought at notification of HIV infection and AIDS for people newly diagnosed in the Northern Territory, Queensland, South Australia, Tasmania and Western Australia. In New South Wales, Indigenous status has been sought for newly diagnosed cases of HIV infection and AIDS since 1992. Indigenous status was not available for people with HIV infection or AIDS diagnosed in the Australian Capital Territory, or from Victoria before June 1998. Information on Indigenous status has been sought nationally from 1995; available information on Indigenous status for cases diagnosed before 1995 was obtained retrospectively through State or Territory health authorities.

Exposure category
HIV exposure was classified as male homosexual contact, male homosexual contact plus injecting drug use, injecting drug use, heterosexual contact only, haemophilia/coagulation disorder, receipt of blood or tissue, mother with or at risk for HIV infection, and other or undetermined exposure.

Statistical analysis
A χ² or Fisher's exact test and odds ratios were used to test for differences between Indigenous and non-Indigenous cases with respect to demographic characteristics (sex, residence), newly acquired HIV 1infection, late HIV diagnosis, HIV exposure category, and individual AIDS-defining illnesses. Residence was divided into "metropolitan" and "non-metropolitan" on the basis of postcode. "Metropolitan" was defined as capital city (including Canberra), and "non-metropolitan" was defined as other than capital city.

In the analyses, cases without information on Indigenous status were grouped with non-Indigenous cases. The population-based rate of HIV diagnosis was calculated by Indigenous status and year (for States and Territories other than Victoria and the ACT) using Australian Bureau of Statistics (ABS) census data for 1996.⁵

Results

Information on Indigenous status was available for 91% of people with newly diagnosed HIV infection. For the period 1992-1998, 5313 cases of newly diagnosed HIV infection were notified to the national HIV surveillance centre, of which 127 (2.4%) were Indigenous cases. For the same period, 3638 AIDS cases were notified, of which 55 (1.5%) were Indigenous cases. The annual number of HIV diagnoses among Indigenous people was relatively stable over this period (Box 1). In contrast, the annual number of HIV diagnoses among non-Indigenous people gradually declined over the years 1992-1998. During this period, the annual HIV diagnosis rate per 100 000 population among Indigenous people (diagnosed in States and Territories other than Victoria and the ACT) (5.23) was similar to that among non-Indigenous people (5.51) (Box 1).

A higher proportion of Indigenous people with HIV were female (26.8% v 8.9%; P < 0.001) (Box 2). The median age at HIV diagnosis (30 years v 33 years; P < 0.001) and AIDS diagnosis (32 v 37 years; P < 0.001) was lower among Indigenous cases. The pattern of exposure to HIV reported by Indigenous people was different from that reported by non-Indigenous people both for newly diagnosed HIV infection and AIDS (Box 2). Although male homosexual contact was the predominant source of exposure to HIV for both Indigenous (46.7%) and non-Indigenous (75.0%) people, a history of heterosexual contact only was reported more frequently by Indigenous people (36.7% v 15.3%; P < 0.001).

The proportion of Indigenous and non-Indigenous people with AIDS with "late HIV diagnosis" was similar (23.6% and 18.3%; P = 0.42), as was the proportion reporting antiretroviral therapy before AIDS diagnosis (56.4% and 62.2%; P = 0.5). No difference between Indigenous and non-Indigenous cases was observed in the median CD4 cell count at diagnosis of HIV and of AIDS.

The spectrum of AIDS-defining illnesses for Indigenous and non-Indigenous people with AIDS is shown in Box 3. Cryptococcal disease (odds ratio [OR], 3.3; 95% CI, 1.4-7.6; P = 0.004), oesophageal candidiasis (OR, 1.8; 95% CI, 0.95-3.38; P = 0.05), and atypical mycobacterium (OR 8.3; 95% CI, 2.4- 25.42; P = 0.002) were more frequent among Indigenous AIDS cases, whereas Kaposi's sarcoma was less frequent (OR, 0.12; 95% CI, 0.01-0.80; P = 0.01).

Among people with HIV, there were more Indigenous than non-Indigenous cases in non-metropolitan locations (36% v 16%) (P < 0.01). Similarly, among people with AIDS, there were more Indigenous than non-Indigenous cases in non-metropolitan locations (37% v 19%) (P = 0.002).

Discussion

The HIV epidemic among Indigenous Australians has been relatively limited to date, with an overall rate of HIV diagnosis comparable with that for non-Indigenous Australians over the years 1992-1998. However, there have been contrasting trends in these rates, with a declining rate of HIV diagnosis among the non-Indigenous population, but a relatively stable rate among Indigenous people. Features that distinguish the Indigenous from the non-Indigenous HIV epidemic are a higher proportion of women affected, a higher proportion with heterosexual exposure to HIV, a younger age at HIV and AIDS diagnosis, and a higher proportion of people with HIV in rural areas.

The low proportion of people with "late HIV diagnosis" among both Indigenous and non-Indigenous AIDS cases would suggest that a large pool of undiagnosed HIV infection is not present in Australia. The very low HIV prevalence among prison entrants in all States and Territories, including those where Indigenous Australians constitute a large proportion of prison inmates, is further confirmation that HIV prevalence among Indigenous Australians remains low.⁶ Our findings also extend those of an earlier study that showed comparable rates of HIV infection in both the Indigenous and the non-Indigenous population in Queensland.⁷

In interpreting our findings, several limitations to the study methods need to be considered. Firstly, the lack of a uniform reporting system for Indigenous status in all States and Territories may result in under-reporting in some jurisdictions. However, there is evidence that in recent years Indigenous status has been more completely reported, with 91% of HIV notifications in those States/Territories other than the ACT and Victoria currently reporting Indigenous status.¹ Secondly, reporting of Indigenous status was based on "self-identification", which may either not be reported correctly by the patient, or not requested by the clinician. If identifying as Indigenous is more likely in a census setting than in clinical practice, our rates of Indigenous HIV diagnosis may be underestimates. Thirdly, reported rates of HIV and AIDS diagnoses are dependent on the level and extent of HIV testing. Poor access to and uptake of confidential testing by some Indigenous people, and fear of possible stigmatisation arising from positive test results, may influence the extent of HIV testing among Indigenous people.

The explanation for the apparently limited HIV epidemic among Indigenous Australians is almost certainly multifaceted. The drop in HIV transmission from the mid 1980s has meant that the extent of the Australian HIV epidemic has been limited compared with many other countries.¹ Behaviour change among homosexual men was largely responsible for the initial reduction in HIV transmission from the mid 1980s,¹ with other measures such as the widespread introduction of harm minimisation programs for injecting drug users,⁸ and high condom use and low rates of sexually transmissible infections among most sex workers⁹ contributing to the ongoing relatively low level of HIV transmission. The absence of substantial levels of HIV infection among injecting drug users and female sex workers¹ may have limited the spread of HIV into the heterosexual population. Despite the fact that the proportion of HIV diagnoses attributed to heterosexual contact has increased in recent years, homosexual contact remains the exposure category for about 85% of new HIV diagnoses.¹

Australia's Indigenous people are not a homogeneous group. There are many hundreds of language groups and a wide diversity of cultural, social, economic and geographical settings within and between Indigenous Australian communities. Most Indigenous Australians suffer a higher burden of illness and die at a younger age than non-Indigenous Australians for almost every type of disease or condition for which information is available.¹⁰ Indigenous Australians are more likely to have lower annual incomes, are less likely to have qualifications beyond secondary school,¹¹ and are 15 times more likely to be imprisoned than non-Indigenous Australians.¹¹ These factors, combined with the remote locations in which many Indigenous Australians live and the resulting poor access to health services, contribute to their vulnerability to sexually transmissible infections.¹² Associations in other industrialised countries between socioeconomic disadvantage and HIV transmission from heterosexual exposure and injecting drug use¹³ highlight the need to provide HIV prevention services which reach all sectors of society.

The higher proportion of Indigenous people with HIV in rural areas should alert policymakers to the need for access to culturally appropriate health services in these locations. Likewise, the higher proportion of Indigenous people with HIV infection who are women, who report heterosexual exposure only and who inject drugs shows a need for broadly focused HIV prevention programs. This demographic pattern, the relatively stable level of HIV diagnoses in Indigenous people, and the continuing high rates of other sexually transmissible infections among some Indigenous communities,¹ highlight the need to strengthen both sexual health and harm-minimisation strategies for Indigenous Australians.

Following the recommendations of the Evaluation of the Third National HIV/AIDS Strategy, several measures have been implemented in an attempt to reduce the higher rates of sexually transmissible infections among Indigenous Australians and the associated risk of HIV infection. These include the establishment of an Indigenous Australians' Sexual Health Working Party and the subsequent implementation of the National Indigenous Australians' Sexual Health Strategy 1996-97 to 1998-99, which proposed a comprehensive approach to HIV prevention through a range of strategies considering treatment and care, partnership agreements and a properly resourced workforce.¹⁴ In particular, the Strategy emphasises the need for access to primary care services for communities without adequate facilities for diagnosing and treating sexually transmissible infections and the provision of information on reducing the risk of acquisition. Strategies aimed at the underlying causes of low socioeconomic status, low levels of education and low levels of employment must also be employed in order to reduce the risk of transmission of HIV and other sexually transmissible infections in Indigenous Australians.

Acknowledgements

The National Centre in HIV Epidemiology and Clinical Research (NCHECR) is funded by the Commonwealth Department of Health and Aged Care.

We would like to acknowledge the valuable input and feedback received from the National Australian Indigenous Sexual Health Working Party during the drafting of this article. We also thank Ms Yueming Li for statistical analyses, Ms Patty Correll (NCHECR) for her assistance in extracting data, and Ms Suzanne Blogg (National Centre for Epidemiology and Population Health [NCEPH]) for her guidance and assistance.

We thank the doctors who reported cases of newly diagnosed HIV infection and AIDS under national surveillance procedures, and the National HIV Surveillance Committee for their collaboration. The National HIV Surveillance Committee comprises Ms Irene Passaris (ACT), Mr Robert Menzies (NSW), Dr Jan Savage (NT), Dr Hugo Ree (QLD), Ms Therese Davey (SA), Mr Neil Cremasco (TAS), Ms Cathy Keenan (VIC), Dr Gary Dowse (WA), Professor John Kaldor (NCHECR), and Ms Ann McDonald (NCHECR).

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Authors' details

Reprints will not be available from the authors.
Correspondence: Professor J M Kaldor, National Centre in HIV Epidemiology and Clinical Research, Level 2, 376 Victoria Street, Darlinghurst, NSW 2010.
jkaldorATnchecr.unsw.edu.au