Screening women aged 65 years or over for abdominal aortic aneurysm: A modelling study and health economic evaluation

Simon G. Thompson, Matthew J. Bown, Matthew J. Glover, Edmund Jones, Katya L. Masconi, Jonathan A. Michaels, Janet T. Powell, Pinar Ulug, Michael J. Sweeting

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Background: Abdominal aortic aneurysm (AAA) screening programmes have been established for men in the UK to reduce deaths from AAA rupture. Whether or not screening should be extended to women is uncertain. Objective: To evaluate the cost-effectiveness of population screening for AAAs in women and compare a range of screening options. Design: A discrete event simulation (DES) model was developed to provide a clinically realistic model of screening, surveillance, and elective and emergency AAA repair operations. Input parameters specifically for women were employed. The model was run for 10 million women, with parameter uncertainty addressed by probabilistic and deterministic sensitivity analyses. Setting: Population screening in the UK. Participants: Women aged ≥ 65 years, followed up to the age of 95 years. Interventions: Invitation to ultrasound screening, followed by surveillance for small AAAs and elective surgical repair for large AAAs. Main outcome measures: Number of operations undertaken, AAA-related mortality, quality-adjusted life-years (QALYs), NHS costs and cost-effectiveness with annual discounting. Data sources: AAA surveillance data, National Vascular Registry, Hospital Episode Statistics, trials of elective and emergency AAA surgery, and the NHS Abdominal Aortic Aneurysm Screening Programme (NAAASP). Review methods: Systematic reviews of AAA prevalence and, for elective operations, suitability for endovascular aneurysm repair, non-intervention rates, operative mortality and literature reviews for other parameters. Results: The prevalence of AAAs (aortic diameter of ≥ 3.0 cm) was estimated as 0.43% in women aged 65 years and 1.15% at age 75 years. The corresponding attendance rates following invitation to screening were estimated as 73% and 62%, respectively. The base-case model adopted the same age at screening (65 years), definition of an AAA (diameter of ≥ 3.0 cm), surveillance intervals (1 year for AAAs with diameter of 3.0–4.4 cm, 3 months for AAAs with diameter of 4.5–5.4 cm) and AAA diameter for consideration of surgery (5.5 cm) as in NAAASP for men. Per woman invited to screening, the estimated gain in QALYs was 0.00110, and the incremental cost was £33.99. This gave an incremental cost-effectiveness ratio (ICER) of £31,000 per QALY gained. The corresponding incremental net monetary benefit at a threshold of £20,000 per QALY gained was –£12.03 (95% uncertainty interval –£27.88 to £22.12). Almost no sensitivity analyses brought the ICER below £20,000 per QALY gained; an exception was doubling the AAA prevalence to 0.86%, which resulted in an ICER of £13,000. Alternative screening options (increasing the screening age to 70 years, lowering the threshold for considering surgery to diameters of 5.0 cm or 4.5 cm, lowering the diameter defining an AAA in women to 2.5 cm and lengthening the surveillance intervals for the smallest AAAs) did not bring the ICER below £20,000 per QALY gained when considered either singly or in combination. Limitations: The model for women was not directly validated against empirical data. Some parameters were poorly estimated, potentially lacking relevance or unavailable for women. Conclusion: The accepted criteria for a population-based AAA screening programme in women are not currently met.

Original languageEnglish
Pages (from-to)V-141
JournalHealth Technology Assessment
Volume22
Issue number43
DOIs
Publication statusPublished - Aug 2018
Externally publishedYes

Bibliographical note

Funding Information:
The research reported in this issue of the journal was funded by the HTA programme as project number 14/179/01. The contractual start date was in April 2015. The draft report began editorial review in April 2017 and was accepted for publication in December 2017. The authors have been wholly responsible for all data collection, analysis and interpretation, and for writing up their work. The HTA editors and publisher have tried to ensure the accuracy of the authors’ report and would like to thank the reviewers for their constructive comments on the draft document. However, they do not accept liability for damages or losses arising from material published in this report.

Funding Information:
Declared competing interests of authors: Jonathan A Michaels reports grants outside the submitted work from the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme (grant number RP-PG-1210-12009). Janet T Powell report grants from NIHR (HTA 07/37/64) outside the submitted work.

Funding Information:
This report presents independent research funded by the National Institute for Health Research (NIHR). The views and opinions expressed by authors in this publication are those of the authors and do not necessarily reflect those of the NHS, the NIHR, NETSCC, the HTA programme or the Department of Health and Social Care. If there are verbatim quotations included in this publication the views and opinions expressed by the interviewees are those of the interviewees and do not necessarily reflect those of the authors, those of the NHS, the NIHR, NETSCC, the HTA programme or the Department of Health and Social Care.

Publisher Copyright:
© Queen’s Printer and Controller of HMSO 2018.

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