New RHD diagnoses among Indigenous Australians

The NT had the highest rate and greatest number of new RHD diagnoses among Indigenous Australians each year, with overall rates around 3 times that in the other jurisdictions. 

Table 3: Rate of new RHD diagnoses per 100,000 population among Indigenous Australians by jurisdiction, 2013–2017

Year

Qld

WA

SA

NT

2013

35.8

46.8

35.9

104.1

2014

37.9

29.9

40.2

128.7

2015

32.7

29.3

34.4

121.3

2016

34.2

48.1

31.3

95.2

2017

30.7

42.1

23.6

138.7

Total rate

34.2

39.3

32.9

117.7

Total number

356

188

67

432

Note: Rates are crude rates per 100,000 population.

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

Age and sex of new RHD diagnoses

The rate of new RHD for Indigenous females was around two times the rate for Indigenous males. Females had higher rates compared to males in all age groups apart from those aged 0–4.

Nearly 60% of cases diagnosed in 2013–2017 were less than 25 years old at diagnosis. There were 15 children aged less than 5 when diagnosed with RHD. 

Table 4: Number and rate per 100,000 population of new RHD diagnoses among Indigenous Australians by sex and age, 2013–2017
Age group
(years)
Male
(number)
Male
(rate per  100,000)
Female
(number)
Female
(rate per 100,000) 
Total
(number)
Total
(rate per  100,000)

0–4

8

6.4

7

5.9

15

6.1

5–14

164

69.7

195

85.5

359

77.5

15–24

71

33.2

167

81.8

238

56.9

25–44

79

28.5

218

77.4

297

53.2

45 +

36

18.8

98

45.9

134

33.1

Total

358

34.3

685

65.4

1,043

49.9

Note: Rates are crude rates per 100,000 population.

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

Region of management of new RHD diagnoses

For each RHD diagnosis reported to a register, the region of management (where the patient receives the majority of the primary health care for their RHD) is recorded. The region of management may be different to the region of diagnosis.

For new RHD diagnoses in Indigenous Australians between 2013 and 2017, the region with the highest rate of RHD management was East Arnhem in the NT (179 per 100,000 population, 104 diagnoses), followed by Northwest, Qld (145 per 100,000 population, 64 diagnoses). The rates of new RHD management in Urban Alice Springs (46 diagnoses), Rural Darwin (87 diagnoses) and Katherine (73 diagnoses) in the NT were all between 130 and 140 diagnoses per 100,000 population.

Each region also manages RHD diagnoses which were diagnosed prior to 2013, so the total number of cases being managed within each region may be greater than shown here.

Figure 1: Rate of new RHD diagnoses among Indigenous Australians per 100,000 by region of management, 2013–2017

The map of Australia shows the distribution of RHD diagnoses among Indigenous Australians in Queensland, Western Australia, South Australia and Northern Territory. The areas with the greatest rates are East Arnhem in NT and North West Qld.  Metropolitan areas in Qld, WA and SA have the lowest rates. More information is located in the data tables, RHD Table 12.

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. No data are available for jurisdictions not included in the National Rheumatic Heart Disease data collection.
  4. For Queensland regions, the 2016 population estimates were used to calculate rates for 2016 and 2017.
  5. 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.

Prior ARF episodes among Indigenous Australians with RHD

RHD cannot occur without a preceding ARF episode. However, some people diagnosed with RHD have not had a previous ARF episode recorded. While it is possible that some of these individuals will have had an appropriately managed ARF episode which was not captured in a relevant register, it is likely many had undiagnosed ARF with no preventative treatment. There are a range of reasons why ARF might not have been diagnosed or notified to the Register. Possible explainations include — mild or subclinical ARF not causing symptoms servere enough to present to a health service, challenges in diagnosing ARF and challenges in upskilling the workforce in a setting of high turnover of primary health care staff.

Among all Indigenous Australians with a new RHD diagnosis between 2013 and 2017, 4 in 5 (838 diagnoses) did not have a prior ARF episode recorded on the registers. This proportion varied between 71% and 85% each year, but did not vary by sex. There was some variation between states and territories, with 91% of newly registered RHD diagnoses in Qld, 85% in SA, 77% in NT and 67% in WA not having a previous ARF episode documented. In Queensland, the proportion of RHD diagnoses with no previous ARF recorded is overestimated due to the timing of notification legislation.

Children (0–14 years) and older Indigenous Australians were more likely to have had no prior ARF at the time of RHD diagnosis compared to those aged 15–34 years.

Table 5: Number and proportion of new RHD diagnoses among Indigenous Australians where no prior ARF was recorded, by age, 2013–2017

Age group (years)

Number of new RHD diagnoses

Number with no prior ARF recorded

Per cent with no prior ARF recorded

0–4

15

15

100.0

5–14

363

298

82.1

15–24

235

176

74.9

25–34

182

132

72.5

35–44

115

99

86.1

45 +

133

118

88.7

Total

1,043

838

80.4

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

Severity classification (priority level) among Indigenous Australians with new RHD diagnoses

Patients on the RHD Registers are categorised as having mild, moderate, or severe RHD (Priority level 3, 2, and 1, respectively), as outlined in the Australian RHD guidelines (Box 4). In this report, severity status and priority level are used interchangeably.

Severity classification is based on clinical symptoms. Classification also determines the frequency of clinical assessment and echocardiography. Patients with ARF on prophylaxis (but no RHD diagnosis) are routinely assigned a priority level of mild.

Box 4: Severity classification (priority level)

Priority 1 (Severe): Severe damage to the heart valves or moderate to severe heart valve damage with symptoms of heart failure

Priority 2 (Moderate): Any moderate heart valve damage without symptoms, and with normal left ventricle function

Priority 3 (Mild): Mild heart valve disease

Priority 4 (Inactive): Patients with a history of ARF (no RHD) for whom secondary prophylaxis has been ceased

Source: RHD Australia 2017.

Severity at diagnosis

In 2013–2017, of the 1,043 Indigenous Australians with new RHD, 53% (552 diagnoses) had mild RHD when first diagnosed, while 28% (288 diagnoses) had moderate RHD and 19% (196 diagnoses) had severe disease. A very small proportion of cases (7 diagnoses) did not have RHD status recorded at diagnosis. This distribution was similar across states and territories.

Figure 2: Severity status at diagnosis among Indigenous Australians newly diagnosed with RHD, by age at 31 December 2017, 2013–2017

This vertical bar charts shows the severity status at diagnosis among Indigenous Australians diagnosed with RHD by age group. Across age groups, most of new RHD diagnoses were mild RHD. Severe status at diagnosis increased with age.  More information is located in the data tables, RHD Table 13.

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

The majority of the 196 diagnoses with severe RHD at diagnosis were Indigenous females (65%, 128 diagnoses) and in those aged 25–44 years (39%, 77 diagnoses). Those who were diagnosed as adults were more likely than those diagnosed as children to have severe RHD at first diagnosis.