ARF among Indigenous Australians

The incidence rate for ARF among Indigenous Australians has increased over time from 53 per 100,000 population (200 diagnoses) in 2010 to 111 per 100,000 population (484 diagnoses) in 2017 (Figure 2).

Figure 2: Incidence of ARF among Indigenous Australians, 2010 to 2017

The line graph shows an increase in the rate of ARF among Indigenous Australians, from 53 per 100,000 population (200 diagnoses) in 2010 to 111 per 100,000 population (484 diagnoses) in 2017.

Note: ARF diagnoses includes all diagnostic categories and first and recurrent episodes. Refer to box 2 and 3 for more information.

Source: AIHW analysis of National Rheumatic Heart Disease data collection. 

In 2013–2017, the age and sex distribution of ARF diagnoses among Indigenous Australians follows the pattern described above for all Australians. Children aged 5–14 years had the highest rates of ARF diagnosis and constituted one-third of all people diagnosed (602 diagnoses).

More Indigenous females were diagnosed with ARF than Indigenous males, with 57% of reported Indigenous diagnoses being in females (1,006 diagnoses). ARF rates in adults were generally higher among females than males, but in children the rates were higher in males. 

Table 2: Number and rate of ARF diagnoses per 100,000 population among Indigenous Australians by sex and age, 2013–2017

Age group
(years)

Males
(number)

Males
(per 100,000)

Females (number)

Females
(per 100,000)

Total
(number)

Total
(per 100,000)

0–4

32

25.5

30

25.1

62

25.3

5–14

478

203.1

424

185.9

602

194.6

15–24

151

70.6

274

134.2

425

101.6

25–44

104

37.6

256

90.9

360

64.5

45 and over

5

2.6

22

10.3

27

6.7

Total

770

73.8

1,006

96.1

1,776

85.0

Notes

  1. ARF diagnoses include all episode types and confirmation statuses. Refer to box 2 and 3 for more information.
  2. Rates are crude rates per 100,000 population

Source: AIHW analysis of National Rheumatic Heart Disease data collection.

ARF diagnoses by state and territory and region

Numbers and rates of ARF amongst Indigenous Australians during 2013–2017 were consistently highest in the Northern Territory. Fifty-three per cent (954) of all diagnoses were from NT.  

The rate generally increased over time in each jurisdiction, apart from in WA, where there was no clear pattern. In the NT in 2017, 268 diagnoses were recorded, more than twice the number recorded in 2013 (127). The number of diagnoses made in QLD almost tripled over the period (from 43 to 124).

Table 3: Rate of ARF diagnoses per 100,000 population among Indigenous Australians, by state and territory, 2013–2017

Year

Qld
(per 100,000)

WA
(per 100,000)

SA
(per 100,000)

NT
(per 100,000)

Total
(per 100,000)

2013

21.7

80.5

25.7

178.6

63.5

2014

36.0

57.6

37.7

200.7

70.2

2015

32.7

63.7

22.1

241.2

75.4

2016

59.6

59.4

33.7

318.0

102.1

2017

56.8

75.2

40.1

354.1

110.9

Total rate

41.8

67.3

32.0

260.0

85.0

Notes

1. ARF diagnoses includes all diagnostic categories and first and recurrent episodes. Refer to box 2 and 3 for more information.

2. Rates are crude rates per 100,000 population.

Source: AIHW analysis of National Rheumatic Heart Disease data collection.

For each ARF diagnosis, the RHD registers record the region of onset (where the patient was diagnosed with ARF) and the region of management (where the patient receives the majority of their primary health care). The place where GAS infection was acquired is not captured.

Regions which were more remote often had higher rates of ARF onset than non-remote areas. In 2013–2017, the region with the highest rate of ARF onset was Rural Darwin (391 per 100,000 population, 252 diagnoses). Urban Alice Springs (371 per 100,000 population or 124 diagnoses) and East Arnhem in the NT (357 per 100,000 population, 207 diagnoses) also had high rates.

Figure 3: Rate of ARF diagnoses per 100,000 population among Indigenous Australians, by region of onset, 2013–2017 

The map of Australia shows the distribution of where patients were diagnosed with ARF among Indigenous Australians in Qld, WA, SA and NT. the region with the highest rate of ARF onset was Rural Darwin (391 per 100,000 population, 252 diagnoses). Metropolitan areas in Qld, WA and SA have the lowest rates. More information is located in the data tables, ARF Table 5.

Notes

  1. There are 33 regions across the 4 states and territories. Each state and territory define regions uniquely, based on their own specific health services boundaries.  
  2. Rates are crude rates per 100,000 population.
  3. ARF diagnoses include all episode types and confirmation statuses. Refer to box 2 and 3 for more information.
  4. No data are available for jurisdictions not included in the National Rheumatic Heart Disease data collection.
  5. For Queensland regions, the 2016 population estimates were used to calculate rates for 2016 and 2017.
  6. Perth Metro North and South in WA have been combined. Torres Strait and Cape York in Qld have been combined.

Source: AIHW analysis of National Rheumatic Heart Disease data collection.

Over the period 2013–2017, Rural Darwin in the NT (387 per 100,000 population; 249 diagnoses) managed the greatest number of Indigenous Australians with recently diagnosed ARF. (Note that primary health care services manage cases diagnosed prior to 2013 as well.) Rates in East Arnhem in the NT (366 per 100,000; 212 diagnoses) and the Kimberley in WA (180 diagnoses or 200 per 100,000) were also high.

Figure 4: Rate of ARF diagnoses per 100,000 population among Indigenous Australians, by region of management, 2013–2017  

The map of Australia shows the distribution of where patients received majority of their primary health care. Over the period 2013–2017, Rural Darwin in the NT (387 per 100,000 population; 249 diagnoses) managed the greatest number of Indigenous Australians with recently diagnosed ARF. More information is located in the data tables, ARF Table 6.

Notes

  1. There are 33 regions across the 4 states and territories. Each state and territory define regions uniquely, based on their own specific health services boundaries. 
  2. For Queensland regions, the 2016 population estimates were used to calculate rates for 2016 and 2017.
  3. Rates are crude rates per 100,000 population.
  4. ARF diagnoses includes all diagnostic categories and first and recurrent episodes. Refer to box 2 and 3 for more information.
  5. No data are available for jurisdictions not included in the National Rheumatic Heart Disease data collection.
  6. Perth Metro North and South in WA have been combined. Torres Strait and Cape York in Qld have been combined.

Source: AIHW analysis of National Rheumatic Heart Disease data collection.

ARF among Indigenous Australians by diagnostic category

Nearly three-quarters of all ARF diagnoses among Indigenous Australians in 2013–2017 (1,284 diagnoses, 72%) were for definite ARF (see Box 2). Probable diagnoses made up 17% (296 diagnoses) and 11% of diagnoses were possible (195 diagnoses).

Between 2013 and 2017, rates for definite or probable ARF increased from 59 per 100,000 population (234 diagnoses) to 106 per 100,000 population (424 diagnoses), in line with overall increases in ARF regardless of diagnostic category. However, the proportion of definite or probable ARF diagnoses decreased from 92% in 2013 to 88% in 2017, with a corresponding increase in possible diagnoses. Older Indigenous Australians were more likely to have a definite or probable ARF diagnosis and the patterns in diagnostic category were similar in males and females.

Box 2: ARF diagnostic categories

There is no specific diagnostic test for ARF. Instead, it is diagnosed based on medical history and a pattern of clinical features (‘manifestations’) as follows:

  • Definite ARF: 2 major or 1 major and 2 minor manifestations plus evidence of preceding GAS infection. Long–term preventive penicillin should commence.
  • Probable ARF: clinical presentation falls short by either one major or one minor manifestation, or the absence of streptococcal serology results, but where ARF is the most likely diagnosis. Long-term preventive penicillin should commence.
  • Possible ARF: Strong clinical suspicion of ARF, but insufficient signs and symptoms for diagnosis of definite or probable ARF. Preventive penicillin should commence, with a clinical review scheduled for 12 months later, to determine if it should continue long-term.

This classification applies to both first known and recurrent episodes.

Source: RHD Australia 2012.

ARF diagnoses by recurrence category 

Both first known ARF episodes and recurrent episodes (see Box 3) are preventable. After the first known ARF episode, adherence to secondary prophylaxis reduces the likelihood of a recurrence.

In 2013–2017, three-quarters of ARF diagnoses (74%, 1,316 diagnoses) were recorded as the first known diagnosis for that individual while one-quarter of diagnoses were for recurrent disease (26%, 460 diagnoses). The number and rate of first known ARF episodes increased from 49 per 100,000 population in 2013 (197 diagnoses) to 72 per 100,000 population in 2017 (348 diagnoses), in line with an overall increase in diagnoses. The proportion of ARF diagnoses categorised as first known ARF was relatively stable over this period, ranging between 72% and 78% of diagnoses each year.

Figure 5: Number of ARF diagnoses among Indigenous Australians by recurrence category, 2013–2017

This stacked vertical bar chart shows that the annual increases in the overall number of ARF diagnoses from 2013–2017, is due to increases in both first known diagnoses and recurrent cases. More information is located in the data tables, ARF table 8.

Note: ARF diagnoses includes all diagnostic categories and first and recurrent episodes. Refer to box 2 and 3 for more information.

Source: AIHW analysis of National Rheumatic Heart Disease data collection.

Recurrent ARF episodes

Around one-quarter of ARF diagnoses reported were for recurrent disease. Recurrent episodes were more common in females and in older people.

In each state and territory, the majority of ARF diagnoses were categorised as the first known diagnosis. In 2013–2017, the proportion of first known ARF diagnoses in Qld was 82% (356 diagnoses). WA reported 76% of ARF diagnoses as first known (246 diagnoses) overall, though the proportion varied from year to year. In SA, 75% of diagnoses were categorised as first known (49 diagnoses). There was greater annual variation in SA, because of a smaller number of diagnoses. In NT, 70% were first known ARF diagnoses (665 diagnoses), and this was stable over the 5 years.

Figure 6: Proportion of ARF diagnoses among Indigenous Australians by recurrence category and state and territory, 2013–2017

Four vertical stacked bar chart of Queensland, Western Australia, South Australia and Northern Territory. They show the distribution of first known and recurrent ARF diagnoses, as a proportion of the total, annually for 2013–2017. For all states and territories, there was a higher proportion of first known ARF diagnoses. More information is located in the data tables, ARF Table 9.

Note: ARF diagnoses includes all diagnostic categories and first and recurrent episodes. Refer to box 2 and 3 for more information.

Source: AIHW analysis of National Rheumatic Heart Disease data collection.

The proportion of episodes categorised as recurrent increased with age. In 2013–2017, 5% of 0–4 year olds had a recurrent diagnosis compared to 48% of those aged over 45 years. Females were more likely to have recurrent episodes, both overall (28% of diagnoses in females compared with 23% of those in males) and in all age groups except 15–24 year olds.

Box 3: ARF recurrence status definitions

  • First known episode: A reported ARF episode (definite, probable or possible) in an individual with no known past ARF or RHD.
  • Recurrence status: A reported ARF episode (definite, probable or possible) in an individual with known past ARF or RHD.