Regional variation in the incidence of end-stage renal disease in
Alan Cass, Joan Cunningham, Zhiqiang Wang and Wendy Hoy
MJA 2001; 175: 24-27
More articles on Aboriginal health
Objective: To evaluate regional variation in the
incidence of end-stage renal disease (ESRD) in Indigenous
Australians, and to examine the proximity to ESRD treatment
facilities of Indigenous patients.|
Design: Secondary data review, with collection of
primary data regarding patients' place of residence before
beginning ESRD treatment.
Participants: Indigenous ESRD patients who
commenced treatment in Australia during 1993-1998.
Methods: We obtained data from the Australian and New
Zealand Dialysis and Transplant Registry regarding 719 Indigenous
patients who started ESRD treatment between 1 January 1993 and 31
December 1998. We obtained primary data from the treating renal units
to determine the place of residence before beginning renal
replacement therapy. We calculated the average annual incidence of
ESRD for each of the 36 Aboriginal and Torres Strait Islander
Commission regions using population estimates based on the 1996
Census, and calculated standardised incidence ratios with 95%
confidence intervals for each region. We compared the number of cases
with the treatment facilities available in each region.
Main outcome measure: Regional standardised ESRD
incidence for Indigenous Australians referenced to the total
resident population of Australia.
Results: Standardised ESRD incidence among
Indigenous Australians is highest in remote regions, where it is up to
30 times the national incidence for all Australians. In urban regions
the standardised incidence is much lower, but remains significantly
higher than the national incidence. Forty-eight per cent of
Indigenous ESRD patients come from regions without dialysis or
transplant facilities and 16.3% from regions with only satellite
Conclusions: There is marked regional variation in
the incidence of ESRD among Indigenous Australians. Because of the
location of treatment centres, there is inequitable access to ESRD
treatment services for a significant proportion of Indigenous
In Australia, geographical differences in morbidity and mortality
have been demonstrated.1-4 In general, people living
in rural and remote areas have higher death and hospital separation
rates, which have been attributed to differences in socioeconomic
status,1,3-5 access to health
services,2,6,7 ethnicity4 and racial
discrimination.8 Indigenous Australians
constitute a disproportionate number of new patients commencing
end-stage renal disease (ESRD) treatment:9 in 1997, the incidence rate
(adjusted for age and sex) for Indigenous Australians beginning ESRD
treatment was nearly nine times that of non-Indigenous
Australians.10 Although epidemics of
renal disease among Indigenous Australians in defined
areas11 have been documented,
there have been no systematic reports of the regional patterns of ESRD
incidence in Australia. In this study we have attempted to determine
these patterns and to examine the accessibility of ESRD treatment
facilities for Indigenous people.
The Australia and New Zealand Dialysis and Transplant Registry
(ANZDATA) maintains a database of patients treated by maintenance
dialysis or renal transplantation in Australia. All renal units that
provide ESRD treatment in Australia participate in the Registry.
Postcode of residence at the start of treatment is collected for all
new patients entered into the ANZDATA Registry. ANZDATA maintains a
list of hospital renal transplant services, tertiary referral units
and satellite dialysis units. Satellite units are defined as
dialysis facilities, generally staffed by specialist nurses, that
are geographically separate from hospital nephrology services.
Postcode of residence at the start of treatment is an imperfect
indicator of the usual place of residence before starting treatment.
In remote areas of Australia a single postcode may apply to many
communities across a vast area. Furthermore, patients may be
required to relocate to a major regional centre to access dialysis
services; thus, their postcode at the start of treatment may not
reflect their previous usual place of residence. To determine the
usefulness of postcode data, we reviewed 104 Indigenous patients who
commenced ESRD treatment from 1993 to 1998 at Royal Darwin Hospital,
Northern Territory. For these patients the previous usual place of
residence was known. Fifty-one patients (49%) had postcodes in the
Darwin region, but only nine of these 51 patients previously lived in
this region. The other 42 had relocated to Darwin to commence dialysis
and were from communities across the "Top End", extending from the
Torres Strait in Queensland to Geraldton in Western Australia. As a
result of this audit, we decided to collect primary data from each
treating renal unit regarding the previous place of usual residence
of their Indigenous patients.
Indigenous identification was based upon self-identification and
discussion with the treating physician. There is often significant
concern about the quality of Indigenous identification in
morbidity, mortality and demographic data sets. However, we believe
that racial identification in the ANZDATA registry is good. A survey
form is completed every six months for all patients on maintenance
dialysis or with functioning renal transplants. In this survey,
question five is about "Racial origin" and includes a prompt
regarding Indigenous status. ESRD patients have regular contact
with renal services from the time of diagnosis, through intensive
maintenance therapy until death. There is heightened awareness of
renal disease in Indigenous Australians and multiple opportunities
exist to reconfirm data accuracy.
From 1 January 1993 to 31 December 1998, 719 Indigenous patients
started treatment for ESRD in Australia. We determined the previous
place of usual residence for 680 (94.6%). For 38 patients (5.3%) we
used the postcode at entry as an indicator of previous place of usual
residence. No geographical data were obtainable for one patient.
We used the 36 Aboriginal and Torres Strait Islander Commission
(ATSIC) regions (Boxes 1 and 2) as our geographic units for analysis.
These are legally prescribed administrative areas and the smallest
geographical areas for which accurate resident population
estimates for the Indigenous population are available.12 We assigned
the place of usual residence for Indigenous patients to the
appropriate ATSIC regions. We assigned the 38 patients for whom we
could not obtain exact information on previous place of residence to
ATSIC regions according to their postcode at the time of beginning
Using population estimates based on the 1996 Census, we calculated
the average annual incidence of ESRD in the 36 ATSIC regions. We used
ABS estimates of the Indigenous population, derived using Census
information on place of usual residence. These estimates are
adjusted for net Census undercount and non-response to the Census
question about Indigenous status.13 We used indirect
standardisation to calculate an age- and sex-standardised
incidence ratio with 95% confidence intervals for each region. Rates
for the total Australian resident population were used as the
reference (standardised incidence ratio equals incidence in the
Indigenous population divided by incidence in the total Australian
population, after adjusting for differences in the age and sex
composition of both populations). Statistical analysis was
performed using Stata.14
We obtained ANZDATA approval to analyse geographic data for
Indigenous patients starting treatment for ESRD between 1 January
1993 and 31 December 1998. We also obtained approval for the study from
the joint institutional ethics committee of Royal Darwin Hospital
and the Menzies School of Health Research. The head of each renal unit
gave written consent for us to access potentially identifying
patient data in order to determine the previous place of usual
residence for Indigenous ESRD patients.
Mapping reveals significant variation in the incidence of ESRD among
Indigenous Australians. The areas of highest incidence (up to 1300
cases per million per year) were the remote regions of Tennant Creek,
Aputula and Jabiru in the Northern Territory, Warburton and
Kalgoorlie in Western Australia, and Ceduna in South Australia (Box
1). The areas of lowest incidence (less than 100 per million per year)
were the regions of Rockhampton and Brisbane in Queensland, Sydney
and Queanbeyan in NSW/ACT, Wangaratta (which includes much of
eastern Victoria) and Hobart (which encompasses all of Tasmania)
(Box 1). The standardised incidence ratio for ESRD (compared with the
total national population incidence) ranged from less than two in
Rockhampton, Sydney, Queanbeyan and Wangaratta to more than 25 in
Aputula, Kalgoorlie and Tennant Creek (Box 2). There were no ESRD
patients identified as Indigenous in Tasmania in the six-year
Tertiary renal services, particularly transplant services, are
located within significant population centres such as capital
cities. Three hundred and forty-five (48.0%) of the 719 Indigenous
ESRD patients lived in ATSIC regions without ESRD treatment
facilities (Box 2). A further 117 (16.3%) lived in regions with only
satellite dialysis facilities (Box 2). Most Indigenous patients
must travel hundreds of kilometres to access transplant services,
which are located in Perth, Adelaide, Melbourne, Sydney, Newcastle
In this study we have demonstrated a large gradient in Indigenous ESRD
incidence from urban to remote regions and highlighted inequitable
access for remote patients to treatment facilities. However, even in
urban regions, the Indigenous ESRD incidence was high after age and
sex standardisation. Poor Indigenous health outcomes are not
confined to the most disadvantaged or most remote regions, but exist
across the Indigenous population.
The quality of Indigenous identification is a potential concern in
our study. ANZDATA relies upon self-identification and discussion
with the treating physician. Self-identification is the method used
by the Australian Bureau of Statistics in census collections and is
generally used in health-related data collection. We believe that
the quality of identification in our study is high owing to the ongoing
intensive interaction of ESRD patients with medical and nursing
staff, Indigenous status being a prominent question in the
six-monthly survey form, and the strong awareness of Indigenous ESRD
among nephrologists. The most likely error would be the failure to
identify all urban Indigenous ESRD patients. This would result in an
underestimate of the true Indigenous ESRD incidence in urban areas
and an overestimate of the gradient from urban to remote Indigenous
ESRD incidence. Yet, as this gradient is so large, representing an
almost 20-fold variation in standardised ESRD incidence, it can not
be entirely explained by problems with Indigenous identification.
The very high standardised incidence ratios for Indigenous people in
remote areas would not change.
These results have significant implications for the delivery of
services to Indigenous people with ESRD. Satellite facilities
opened in the Jabiru region in 1999 and the Katherine region in 2000
(after the patients in this study commenced treatment). Of the 16
regions with the highest Indigenous ESRD incidence, at the beginning
of 2001 only Kalgoorlie, Jabiru (Tiwi Islands), Geraldton,
Katherine and South Hedland had satellite dialysis units. A
satellite unit is scheduled to open soon in Broome and
recommendations have been accepted to establish a satellite
haemodialysis service in the Torres Strait as part of the recent
Queensland Renal Strategy.15 We recognise the
significant difficulties related to the establishment and
maintenance of renal treatment facilities in remote locations.
These include high construction costs, poor reliability of
electricity and water supply, variable water quality, difficulties
in training and retaining specialised nursing staff, infrequent
access to medical staff and provision of housing for patients
returning to live in their local community. Despite these
difficulties, treatment facilities have been established in some of
the most remote communities in Australia.
Even with the availability of satellite units, initiation of ESRD
treatment usually requires a prolonged stay in a major urban centre.
During this stay, vascular or peritoneal access for dialysis is
created, the patient starts and is stabilised on treatment and learns
skills required for self-care in order to return to a remote satellite
dialysis unit. We should develop more innovative methods of patient
education, training for self-care and delivery of treatment to allow
patients to remain within their communities whenever possible.
Improving prevention and treatment services in high-incidence
areas should be a priority.
Indigenous people living in remote communities demand more
equitable access to dialysis services,16 regardless of practical
problems related to the establishment of remote treatment
facilities. The need to relocate to distant urban areas to access
treatment affects the patient, patient's family and community. A
recent study of ESRD among Aboriginal people of central Australia
concluded: "This level of illness and death [due to ESRD] represents
Aboriginal family trauma and loss on a shocking scale, described
without exaggeration as sorrows nearly every year [because] the
young and the old are dying". 17
The data reported here have been supplied by the Australia and New
Zealand Dialysis and Transplant Registry. The interpretation of
these data is the responsibility of the authors and should not be seen
as an official policy or interpretation of the Australia and New
Zealand Dialysis and Transplant Registry. Dr Alan Cass receives
postgraduate research scholarship funding from the Colonial
Foundation. Dr Joan Cunningham is supported by a fellowship from the
Menzies Foundation. We thank Dr Mark Thomas, Dr Paul Snelling, Dr
Meshak Kirubakaran, Dr Tim Furlong, Dr Peter de Jersey and the heads of
renal units for providing information regarding the place of usual
residence for their patients.
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(Received 13 Sep 2000, accepted 22 Mar 2001)
Menzies School of Health Research, Casuarina, NT.
Alan Cass, GradDipClinEpi, FRACP, PhD Student and
Joan Cunningham, ScD, Epidemiologist and Menzies Fellow.
Zhiqiang Wang, PhD, Biostatistician.
Wendy Hoy, MB BS, FRACP, Head of Renal Unit.
No reprints will be available from the authors.
Alan Cass, Menzies School of Health Research, PO Box 41096,
Casuarina, NT, 0811.
|Map numbers refer to Aboriginal and Torres Strait Islander Commission regions as specified in Box 2
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|2: End-stage renal disease among Indigenous
Australians from 1993 to 1998
ratio* (95% CI)
|Tennant Creek (35)
||31.05 (20.96 - 44.33)
||27.75 (17.60 - 41.64)
||25.03 (19.01 - 32.36)
||22.77 (13.91 - 35.17)
||22.48 (10.78 - 41.34)
||21.87 (15.95 - 29.26)
||18.20 (11.78 - 26.86)
|Mount Isa (11)
||17.74 (12.21 - 24.91)
||16.85 (10.56 - 25.51)
||15.64 (10.56 - 22.33)
|Torres Strait (15)
||14.99 (9.96 - 21.66)
|South Hedland (25)
||14.75 (8.74 - 23.30)
||13.40 (7.66 - 21.76)
||11.74 (7.27 - 17.94)
||11.61 (7.19 - 17.75)
||11.47 (5.73 - 20.53)
| Port Augusta (19)
||10.45 (6.09 - 16.74)
||10.16 (6.29 - 15.53)
||9.41 (6.55 - 13.08)
||8.71 (6.07 - 12.12)
|Alice Springs (30)
||8.55 (4.27 - 15.30)
||8.20 (4.37 - 14.02)
||7.02 (4.09 - 11.24)
||Tx, T, S
||6.70 (4.48 - 9.61)
||Tx, T, S
||4.62 (2.58 - 7.61)
||4.18 (2.16 - 7.30)
||3.70 (1.60 - 7.28)
|Coffs Harbour (3)
||Tx, T, S
||3.68 (2.36 - 5.47)
||Tx, T, S
||3.42 (1.64 - 6.28)
|Wagga Wagga (6)
||2.98 (1.63 - 5.00)
||Tx, T, S
||2.51 (1.46 - 4.02)
||1.78 (0.58 - 4.16)
||Tx, T, S
||1.77 (1.01 - 2.88)
||1.75 (0.48 - 4.48)
||Tx, T, S
||1.39 (0.38 - 3.55)
||0.00 (0.00 - 1.03)
|* Indirectly standardised to the rates for
the total Australian resident population.
†Tx = transplant service, T = tertiary renal unit, S = satellite dialysis
Geographical data were unobtainable for one patient.
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