Study Indicates Shortcomings of United Kingdom's AAA Screening Program for Women

August 15, 2018—An analysis of the United Kingdom's screening program for abdominal aortic aneurysm (AAA) in women was published by Michael J. Sweeting, PhD, et al in The Lancet (2018;392:487–495). The aim of the study was to formally assess the benefits, harms, and cost-effectiveness in offering a similar program to women as the one for men.

The investigators found that by United Kingdom standards, a AAA screening program for women that is designed to be similar to the one used to screen men is unlikely to be cost-effective. "Further research on the aortic diameter distribution in women and potential quality-of-life decrements associated with screening are needed to assess the full benefits and harms of modified options," concluded the investigators in The Lancet.

The background of the study is that national screening programs for men reduce deaths from AAA and are cost-effective. In the United Kingdom, one-third of deaths from ruptured AAAs occur in women.

As summarized in The Lancet, the investigators developed a decision model to assess predefined outcomes of death caused by AAA, including life-years, quality-adjusted life-years, costs, and the incremental cost-effectiveness ratio for a population of women invited to AAA screening versus a population who were not invited to screening.

The investigators set up a discrete event simulation model for AAA screening, surveillance, and intervention. Relevant female-specific parameters were obtained from sources including systematic literature reviews, national registry or administrative databases, major AAA surgery trials, and United Kingdom National Health Service reference costs.

In the United Kingdom, screenings for men are offered at 65 years of age, with a AAA diagnosis at an aortic diameter of ≥ 3.0 cm and elective repair considered at ≥ 5.5cm. With these same criteria, AAA screening for women for a period of 30 years provided an estimated incremental cost-effectiveness ratio of £30,000 (95% confidence interval [CI], £12,000–87,000) per quality-adjusted life-year gained. It required 3,900 invitations to screening to prevent one AAA-related death with an overdiagnosis rate of 33%.

The investigators found that a modified option for women (screening at 70 years of age, diagnosis at 2.5 cm, and repair at 5.0 cm) was estimated to have an incremental cost-effectiveness ratio of £23,000 (95% CI, £9,500–71,000) per quality-adjusted life-year with 1,800 invitations to screening required to prevent one AAA death but had an overdiagnosis rate of 55%.

There was considerable uncertainty in the cost-effectiveness ratio, largely driven by uncertainty about AAA prevalence, the distribution of aortic sizes for women at different ages, and the effect of screening on quality of life, reported the investigators in The Lancet.