South Australia: ARF and RHD facts

Introduction

In South Australia, while acute rheumatic fever (ARF) is rare among non-Indigenous Australians, Aboriginal and Torres Strait Islander people are over-represented among people with ARF and rheumatic heart disease (RHD), especially in remote communities.

In South Australia, the collection of ARF and RHD notifications is funded by the Australian Government Department of Health. Both ARF and RHD have been notifiable in South Australia since 2016. The RHD control program was established in 2010 and the register established in 2012.

Overview

At 31 December 2020, there were 353 people living with a diagnosis of ARF and/or RHD in South Australia, representing 3.9% of the total 9,158 people recorded across all 5 jurisdictional registers. Of these 353 people in South Australia, 129 people (37%) had only ARF recorded on the register, 126 people (36%) had only RHD recorded and 98 people (28%) had both ARF and RHD recorded (Supplementary Overview Table 1).

Region of management

For each person recorded on a register, the region of management is recorded. This is the area where the patient was most recently reported to receive the majority of the primary health care for their ARF or RHD. The region of management may differ from the person’s region of diagnosis and the notifying jurisdiction. Each state or territory defines regions uniquely, based on its own specific health services boundaries. There are 33 regions spread over Queensland, Western Australia, South Australia, and the Northern Territory. NSW is considered as a whole. Regions do not cross state and territory boundaries.

Remote South Australia had a higher management rate than the Regional and Urban regions (311 cases per 100,000 population, compared with 16 and 8.5, respectively) (Figure 2.1) (Supplementary Overview Table 4).

Acute rheumatic fever

All Australians

In 2016–2020 in South Australia:

• 100 diagnoses of ARF were recorded in 93 people (1.1 per 100,000 population over the 5 years combined) (Supplementary ARF tables 1 and 2)
• no clear trend over time was apparent, with the annual diagnosis rate varying from 0.9 to 1.5 per 100,000 population (Figure 3.1) (Supplementary ARF Table 2)

• the most common age at diagnosis was 5–14, with 41 diagnoses (4.0 per 100,000 population). Females accounted for 67 (67%) diagnoses (Figure 3.2) (Supplementary ARF Table 3a)

Indigenous Australians

In 2016–2020 in South Australia:

• 95 ARF episodes were diagnosed among Aboriginal and Torres Strait Islander people, a rate of 43 per 100,000 population (Supplementary ARF Table 2)
• there was no clear trend in the annual diagnosis rate, which varied between 34 and 57 per 100,000 population (Figure 3.3) (Supplementary ARF Table 2)

• the highest rate of diagnosis was among those aged 5–14, accounting for 40% of all diagnoses (77 per 100,000 population, or 38 diagnoses). Females accounted for 67% of diagnoses (64 diagnoses) (Figure 3.4) (Supplementary ARF Table 3b)

• there were 22 recurrent ARF episodes recorded among Indigenous Australians (Supplementary ARF Table 7)
• Remote South Australia had the highest incidence of ARF (Figure 3.5) (Supplementary ARF Table 4).

Rheumatic heart disease

Prevalence

At 31 December 2020, 220 people living with RHD were recorded on the South Australia register (Supplementary RHD Table 1).

Incidence

In 2016–2020 in South Australia:

• there were 69 reports of new RHD diagnoses (0.8 per 100,000 population) with no clear trend in annual diagnosis rates, which varied from 0.6 to 1.0 per 100,000 population (Figure 4.1) (Supplementary RHD Table 4)

• 56 new RHD diagnoses among Indigenous Australians were reported to the jurisdictional register (26 per 100,000 population) (Supplementary RHD Table 4)
• the annual rate has fluctuated between 21 and 28 per 100,000 population, with no clear trend (Figure 4.2) (Supplementary RHD Table 4)

• new RHD diagnoses were more common among Indigenous females than males (32 and 19 diagnoses per 100,000 population, respectively) (Figure 4.3) (Supplementary RHD Table 5)
• 50% of new diagnoses were among Indigenous Australians aged under 25 (28 diagnoses) (Supplementary RHD Table 5).

Indigenous Australians with no documented previous ARF episode

RHD occurs only in someone who has had ARF, but some people with RHD have no recorded previous ARF episode on state and territory registers. ARF might not be notified to a register for various reasons, such as being diagnosed before the relevant register began; being diagnosed prior to the condition being notifiable; the person being in a jurisdiction that does not have a register; or the episode never being diagnosed.

Among Indigenous Australians in South Australia with a new RHD diagnosis in 2016–2020, 45 (80%) did not have a previous ARF episode recorded on the registers. Of these:

• the proportion was similar in males (81%) and females (80%)
• there was no clear relationship between age and the proportion of people who had no previous ARF recorded. People aged 45 and over at RHD diagnosis were the most likely to have a previous ARF episode recorded.
• the proportion with no previous ARF diagnosis recorded was higher in the non-Indigenous population (92%) than the Indigenous population (80%)
• there was no clear annual trend. This may partially be due to small numbers (Supplementary RHD tables 7 and 8).

Heart surgery for RHD

In 2016–2020 in South Australia, 21 people underwent 23 RHD surgical events. Most of these people were Indigenous Australians, comprising 91% (19) of patients and 91% (21) of events (Supplementary RHD Table 9). Most surgical events occurred among those aged 25–34, who had 10 surgical events (48%), followed by those aged 35-44, with 5 surgical events (24%) (Figure 4.4) (Supplementary RHD Table 11).

Secondary prophylaxis

Delivery of secondary prophylaxis

In 2020, 157 people in South Australia were prescribed a treatment regimen to prevent recurrences of ARF, and progression to RHD, involving regular intramuscular injections of BPG every 21 or 28 days. Of these, 148 were Indigenous Australians (Supplementary Secondary Prophylaxis Table 1).

In 2020, among Indigenous Australians in South Australia prescribed 3- or 4-weekly BPG:

• 22% (33 people) received 100% or more of their prescribed doses
• 35% (52) received 80% to 99% of their prescribed doses
• 21% (31) received 50% to 79% of their prescribed doses
• 22% (32) received less than 50% of their prescribed doses, including 7 people who received no doses (Supplementary Secondary Prophylaxis Table 1)
• similar proportions of males and females received at least 80% of doses (57% and 58%, respectively) (Figure 5.1) (Supplementary Secondary Prophylaxis Table 2) 

• delivery was highest among people aged 5–14, with 87% receiving at least 80% of doses (Figure 5.2) (Supplementary Secondary Prophylaxis Table 3).

Time trend

The proportion of Indigenous Australians receiving at least 80% of their prescribed doses increased from 51% in 2016 to 60% in 2019, before slightly dropping to 57% in 2020. In 2020, 5% of people did not receive any of their prescribed doses. The decrease in those receiving at least 80% of their prescribed doses could be due to the impacts of COVID-19 on health services and health service use (Figure 5.3) (Supplementary Secondary Prophylaxis Table 4).

ARF recurrence rate among people on BPG

Between 2016 and 2020, the ARF recurrence rate per 100 patient-years among Indigenous Australians who had been prescribed BPG decreased from 3.4 to 1.5, however the very small numbers of recurrences preclude meaningful interpretation (Figure 5.4) (Supplementary Secondary Prophylaxis Table 5).