Modelling the impact of changes to abdominal aortic aneurysm screening and treatment services in England during the COVID-19 pandemic.

Lois G Kim,Michael J Sweeting,Morag Armer,Seamus C Harrison,Jo Jacomelli,Akhtar Nasim,Janet Powell

doi:10.1371/journal.pone.0253327

Abstract

The National Health Service (NHS) abdominal aortic aneurysm (AAA) screening programme (NAAASP) in England screens 65-year-old men. The programme monitors those with an aneurysm, and early intervention for large aneurysms reduces ruptures and AAA-related mortality. AAA screening services have been disrupted following COVID-19 but it is not known how this may impact AAA-related mortality, or where efforts should be focussed as services resume. We repurposed a previously validated discrete event simulation model to investigate the impact of COVID-19-related service disruption on key outcomes. This model was used to explore the impact of delayed invitation and reduced attendance in men invited to screening. Additionally, we investigated the impact of temporarily suspending scans, increasing the threshold for elective surgery to 7cm and increasing drop-out in the AAA cohort under surveillance, using data from NAAASP to inform the population. Delaying invitation to primary screening up to two years had little impact on key outcomes whereas a 10% reduction in attendance could lead to a 2% lifetime increase in AAA-related deaths. In surveillance patients, a 1-year suspension of surveillance or increase in the elective threshold resulted in a 0.4% increase in excess AAA-related deaths (8% in those 5-5.4cm at the start). Longer suspensions or a doubling of drop-out from surveillance would have a pronounced impact on outcomes. Efforts should be directed towards encouraging men to attend AAA screening service appointments post-COVID-19. Those with AAAs on surveillance should be prioritised as the screening programme resumes, as changes to these services beyond one year are likely to have a larger impact on surgical burden and AAA-related mortality.

Highlights

In March 2020 the initiation of the nationwide “lockdown” to protect against transmission of COVID-19 had a profound effect upon the delivery of routine services provided by the UK National Health Service (NHS)
Ruptured Abdominal Aortic Aneurysms (AAA) carries a high mortality [2] and screening for AAA is offered to men in their 65th year throughout England via the NHS Abdominal Aortic Aneurysm Screening Program (NAAASP) [3]
The results suggest that the impact is additive, with a 10% increase in AAA-related deaths in a scenario with a one year suspension of surveillance scans combined with an increase to 10% drop-out/annum applied for two years and use of a 7 cm threshold for two years

Summary

Introduction

In March 2020 the initiation of the nationwide “lockdown” to protect against transmission of COVID-19 had a profound effect upon the delivery of routine services provided by the UK National Health Service (NHS). This included a substantial reduction in the number of cardiovascular procedures performed including repair of Abdominal Aortic Aneurysms (AAA) [1]. Ruptured AAA carries a high mortality [2] and screening for AAA is offered to men in their 65th year throughout England via the NHS Abdominal Aortic Aneurysm Screening Program (NAAASP) [3] Those with small and medium AAA (3.0–5.4 cm) are offered ultrasound surveillance quarterly or annually depending on size, whilst those with large AAA ( 5.5 cm) are referred for consideration of elective surgical repair, before the risk of rupture becomes too high. AAA screening services have been disrupted following COVID-19 but it is not known how this may impact AAA-related mortality, or where efforts should be focussed as services resume

Results

Discussion

Conclusion