Western Australia: ARF and RHD facts

Introduction

In Western 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 Western Australia, the collection of ARF and RHD notifications is funded by the Australian Government Department of Health. ARF has been a notifiable disease in Western Australia since 2007. The register and RHD control program were established in 2009. In June 2015, Western Australia became the first jurisdiction in Australia to mandate the reporting of both ARF and RHD by health professionals.

Overview

At 31 December 2020, there were 1,215 people living with a diagnosis of ARF and/or RHD in Western Australia, representing 13% of the total 9,158 people recorded across all 5 jurisdictional registers. Of these 1,215 people in Western Australia, 396 people (33%) had only ARF recorded on the register, 328 people (27%) had only RHD recorded and 491 people (40%) 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.

Kimberley was the region in Western Australia with the highest rate of ARF and/or RHD management (Figure 2.1) (Supplementary Overview Table 4).

Acute rheumatic fever

All Australians

In 2016–2020 in Western Australia:

• 352 diagnoses of ARF were recorded in 324 people (3 per 100,000 population over the 5 years combined) (Supplementary ARF tables 1 and 2)
• the number and rate of ARF diagnoses increased from 55 (2.2 per 100,000 population) in 2016 to 98 (3.7 per 100,000 population) in 2020 (Figure 3.1) (Supplementary ARF Table 2)

• the most common age at diagnosis was 5–14, with 175 diagnoses (11 per 100,000 population). Females accounted for 179 (2.8 per 100,000 population) diagnoses (Figure 3.2) (Supplementary ARF Table 3a)

Indigenous Australians

In 2016–2020 in Western Australia:

• 340 ARF episodes were diagnosed among Aboriginal and Torres Strait Islander people, a rate of 65 per 100,000 population (Supplementary ARF Table 2)
• the diagnosis rate among Indigenous Australians increased between 2016 and 2020—from 55 to 89 per 100,000 population (55 to 96 diagnoses, respectively) (Figure 3.3) (Supplementary ARF Table 2)

• the highest rate of diagnosis among Indigenous Australians was among those aged 5–14, accounting for 49% of all diagnoses (10 per 100,000 population, or 168 diagnoses). Females accounted for 52% of diagnoses (175 diagnoses) (Figure 3.4) (Supplementary ARF Table 3b)

• there were 75 recurrent ARF episodes recorded among Indigenous Australians (Supplementary ARF Table 7)
• the Kimberley had the highest incidence of ARF (183 per 100,000 population) (Figure 3.5) (Supplementary ARF Table 4).

Rheumatic heart disease

Prevalence

At 31 December 2020, 789 people living with RHD were recorded on the Western Australia register (Supplementary RHD Table 1).

Incidence

In 2016–2020 in Western Australia:

• there were 317 reports of new RHD diagnoses (2.4 per 100,000 population). There was no clear trend in annual diagnosis rates, which varied from 2.2 to 3.0 per 100,000 population (Figure 4.1) (Supplementary RHD Table 4)

• 262 new RHD diagnoses among Indigenous Australians were reported to the jurisdictional register (50 per 100,000 population) (Supplementary RHD Table 4)
• the annual rate among Indigenous Australians has fluctuated between 44 and 61 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 (67 and 33 diagnoses per 100,000 population, respectively) (Supplementary RHD Table 5)
• 47% of new diagnoses were among Indigenous Australians aged under 25 (123 diagnoses) (Figure 4.3) (Supplementary RHD Table 5).

Severity of RHD at time of diagnosis

In 2016–2020, of the 260 Indigenous Australians with severity recorded at a new RHD diagnoses:

• 49% had mild RHD when first diagnosed (128 diagnoses)
• 32% had moderate RHD (84)
• 19% had severe RHD (48) (Supplementary RHD Table 6).

By age group:

• people aged 15–24 were more likely to have severe RHD at diagnosis (26%, 13 diagnoses)
• the proportion of mild cases decreased with age with 64% (46 diagnoses) of people aged 5–14 having mild RHD at diagnosis (Figure 4.4) (Supplementary RHD Table 6).

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 Western Australia with a new RHD diagnosis in 2016–2020, 229 (87%) did not have a previous ARF episode recorded on the registers. Of these:

• males were more likely than females to have no recorded history of ARF (92% compared with 85%)
• the youngest and oldest age groups were less likely to have a history of ARF recorded than those aged 25–44
• the proportion of people with no previous ARF episode recorded was higher in the non-Indigenous population (98%) than the Indigenous population (87%)
• there was no clear annual trend (Supplementary RHD tables 7 and 8).

Heart surgery for RHD

In 2016–2020 in Western Australia, 82 people underwent 91 RHD surgical events. Most of these people were Indigenous Australians, comprising 88% (72) of patients and 88% (80) of events (Supplementary RHD Table 9). Most surgical events among Indigenous Australians occurred among those aged 25–34 and those aged 45 and over with 20 surgical events (25%) each (Figure 4.5) (Supplementary RHD Table 11).

Secondary prophylaxis

Delivery of secondary prophylaxis

In 2020, 757 people 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, 720 were Indigenous Australians (Supplementary Secondary Prophylaxis Table 1).

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

• 5.3% (38 people) received 100% or more of their prescribed doses
• 15% (108 people) received 80% to 99% of their prescribed doses
• 30% (219 people) received 50% to 79% of their prescribed doses
• 49% (355 people) received less than 50% of their prescribed doses, including 103 people who received no doses (Supplementary Secondary Prophylaxis Table 1)
• similar proportions of males and females received at least 80% of doses (20% and 21%, respectively) (Figure 5.1) (Supplementary Secondary Prophylaxis Table 2)

• delivery was highest among people aged 5–14, with 37% 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 25% in 2016 to 26% in 2017, before dropping to 23% in 2018 and 20% in 2020. In 2020, 14% of people did not receive any of their prescribed doses. The delivery of prophylaxis in 2020 may have been affected by 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

In 2020, among Indigenous Australians prescribed BPG in Western Australia, there were 23 ARF recurrences and a rate of 3.4 recurrences per 100 patient-years. The rate of recurrence per 100 patient-years generally decreased with age, with the highest risk among those aged 5–14 (6) (Figure 5.4) (Supplementary Secondary Prophylaxis Table 5).

Between 2016 and 2020, the ARF recurrence rate per 100 patient-years among Indigenous Australians prescribed BPG increased from 2.4 to 3.4 (Figure 5.5) (Supplementary Secondary Prophylaxis Table 6).