Uncovering the treatable burden of severe aortic stenosis in Australia: current and future projections within an ageing population

Abstract

Background We aimed to address the paucity of information describing the treatable burden of disease associated with severe aortic stenosis (AS) within Australia’s ageing population. Methods A contemporary model of the population prevalence of symptomatic, severe AS and treatment pathways in Europe and North America was applied to the 2019 Australian population aged ≥ 55 years (7 million people) on an age-specific basis. Applying Australian-specific data, these estimates were used to further calculate the total number of associated deaths and incident cases of severe AS per annum. Results Based on an overall point prevalence of 1.48 % among those aged ≥ 55 years, we estimate that a minimum of 97,000 Australians are living with severe AS. With a 2-fold increased risk of mortality without undergoing aortic valve replacement (AVR), more than half of these individuals (∼56,000) will die within 5-years. From a clinical management perspective, among those with concurrent symptoms (68.3 %, 66,500 [95 % CI 59,000–74,000] cases) more than half (58.4 %, 38,800 [95 % CI 35,700 − 42,000] cases) would be potentially considered for surgical AVR (SAVR) - comprising 2,400, 5,400 and 31,000 cases assessed as high-, medium- or low peri-operative mortality risk, respectively. A further 17,000/27,700 (41.6 % [95 % CI 11,600 − 22,600]) of such individuals would be potentially considered to a transthoracic AVR (TAVR). During the subsequent 5-year period (2020–2024), each year, we estimate an additional 9,300 Australians aged ≥ 60 years will subsequently develop severe AS (6,300 of whom will experience concurrent symptoms). Of these symptomatic cases, an estimated 3,700 and 1,600 cases/annum, will be potentially suitable for SAVR and TAVR, respectively. Conclusions These data suggest there is likely to be a substantive burden of individuals living with severe AS in Australia. Many of these cases may not have been diagnosed and/or received appropriate treatment (based on the evidence-based application of SAVR and TAVR) to reduce their high-risk of subsequent mortality.

Uncovering the treatable burden of severe aortic stenosis in the UK

“… 17 The same broad methods were also applied to an equivalent study of the treatable burden of AS in Australia. 7 The primary basis for this study (in respect to providing AS-specific data) was two meta-analyses of AS that systematically reviewed and analysed the relevant public health to clinical literature to build contemporary models of the likely burden and treatment of severe AS. 15 16 The most recent of these reports synthesised data from 9723 cases of severe AS from 7 studies (predominantly from North America and Europe/UK).…”

“…A pragmatic approach to estimate the treatable burden of disease imposed by severe AS in the UK was applied using similar methods previously used to derive what proved to be an accurate forecast of the contemporary and projected burden of heart failure in the UK 17. The same broad methods were also applied to an equivalent study of the treatable burden of AS in Australia 7. The primary basis for this study (in respect to providing AS-specific data) was two meta-analyses of AS that systematically reviewed and analysed the relevant public health to clinical literature to build contemporary models of the likely burden and treatment of severe AS 15 16.…”

“…Of concern, in the context of a probable ‘iceberg’ of largely undetected and untreated cases of AS within progressively ageing high-income countries like the UK,7 is the high mortality associated with untreated severe AS, especially once symptoms develop 8. The mortality in such patients is reported to be as high as 50% at 2 years and 97% at 5 years 9.…”

Increasing risk of mortality across the spectrum of aortic stenosis is independent of comorbidity & treatment: An international, parallel cohort study of 248,464 patients

“…Specifically, we demonstrated a high risk of short- and longer-term mortality associated with moderate AS that warrants further research to understand how to optimally monitor and, if necessary, intervene, in affected individuals. The urgency to apply a more nuanced and cost-effective approach to AS management will only increase as the number of individuals living with this deadly condition inevitably rises in many countries [ 14 ].…”

“…Regardless of the causal mechanism, the high risk of mortality amongst those with moderate AS suggests the need for closer surveillance in this subgroup and referral to a Heart Valve Clinic when indicated: noting the resource implications for such management [ 14 ]. Furthermore, these results support a role for ongoing prospective trials in those with moderate AS to assess the role of AVR in mitigating the observed risk.…”