Abdominal aortic aneurysm (AAA) diagnosis and repair occurs among women almost 10 years later than in men—with similar age-adjusted mortality—the 2023 Society for Clinical Vascular Surgery (SCVS) annual meeting in Miami (March 25–29) is set to be told. The finding is part of a rare U.S. population-based study of AAA trends, spanning nearly 40 years, carried out by researchers at the Mayo Clinic in Rochester, Minnesota, underscoring already established evidence showing that incidence of ruptured AAAs and aortic-related mortality have decreased significantly in the population over time.
The epidemiological analysis was conducted by first-named author Indrani Sen, MBBS, an assistant professor of surgery in the Mayo Clinic Health System, senior researcher Manju Kalra, MBBS, a professor of surgery in Mayo’s division of vascular and endovascular surgery, and colleagues. They used the Rochester Epidemiology Project—which captures population-based data, not merely hospital-based datasets—to track changes over the four-decade-long study period (1980–2017), a stretch of time that includes the coming of the endovascular revolution at the turn of the century, and the institution in 2007 of AAA screening for men at the age of 65 who have ever smoked.
The study included 1,537 patients, 75% of them male and with a median age of 74 years. Diagnosis of AAA was made at presentation with rupture in 95 patients, the research team found—with 75% presenting before and 66% after Medicare established ultrasound screening criteria. “Overall, only 16% AAAs were detected on screening, 23% after 2007, with no significant change per year,” they report. “Patients with incidentally detected AAAs were older, had larger AAAs, more likely female, and to present with rupture, but had similar incidence of progression to and type of repair.”
Overall survival in AAA patients was 94%, 72% and 34% at one, five and 15 years—“significantly lower than age and sex-matched controls throughout the study,” Sen et al established.
“Traditionally, it has been believed that based upon single-center series, VQI registry studies, hospital-based data, that outcomes in women are poorer than in men,” says Kalra in an interview with Vascular Specialist ahead of SCVS 2023. “Traditionally, aneurysms have been picked up much less frequently in women than in men. We also know that the actual incidence is lower per 100,000 [patient years], which is what we have confirmed yet again with this population-based study.”
Sen points to the finding around the disparity involving female diagnosis and repair as breaking new ground in this area of AAA. “All the rest of the findings are supportive data for a lot of trends we already see, but nobody has ever actually put it down on paper that aneurysms are diagnosed and repaired in women almost a decade later than men with similar age-adjusted mortality,” she says. “What additionally came to light from this study was that, even though the screening guidelines came in over a decade ago, incidental detection is still the commonest [avenue].”
They now have a new baseline to address these issues, Sen continues. She points to newly initiated research in the UK set to look into AAAs in women. The multinational collaboration of researchers received endorsement from the Global Cardiovascular Research Funders Forum (GCRFF) Multinational Clinical Trials Initiative for the WARRIORS (Women’s abdominal aortic aneurysm research: repair immediately or routine surveillance) trial. It aims to answer the question: Should women have their aneurysms repaired electively using endovascular aneurysm repair (EVAR) at smaller diameters than men to improve their survival and quality of life? Imperial College London in London, England, is co-ordinating the study, but it will include collaboration with vascular surgeons from Canada, Denmark, The Netherlands, and Sweden, as well as the U.S.
The investigators behind WARRIORS have noted that the rationale and need for this trial, which seeks to recruit nearly 1,200 women, stems from the poor outcomes suffered by women with AAAs. Although women contribute 15–20% of total AAA burden, and one-third of ruptures, they have been significantly underrepresented in trials which guide current AAA repair, the WARRIORS investigators detailed, adding that women have smaller arteries, a four-fold higher rupture risk, and lose eligibility for EVAR at smaller AAA diameters.
“We have learnt that women worry a lot about their AAA, and modeling has suggested that repair of AAA at 4cm for women might result in improved quality of life and reduced overall cost,” the WARRIORS investigators recently commented. “These potential benefits as well as reduction in aneurysm-related mortality, would need to be balanced against the operative risk of early repair.” They state that these areas of uncertainty, regarding the optimal strategy for AAA repair in women, are what the trial seeks to answer.
The Mayo epidemiological study provides timely data pointing to the fact that these and similar questions regarding aneurysms in women are relevant, Sen adds. The need for a population-based study to highlight these was great, Sen and Kalra relate.
“We don’t have good natural history data, or epidemiology, of aortic aneurysms in the U.S.,” remarks Sen. “Everything that we use, we take from studies performed in Europe and Australia. Among the few studies performed in the U.S., one of them was from this same Rochester epidemiology data—which was in the 1980s. Since the 80s, the two major changes that have happened are the introduction of endovascular repair, which has become the commonest way of repairing these AAAs, and the introduction of a screening protocol for men.”
The questions that the research team were looking to answer were: Do advances in screening really work? How comprehensive is the adoption of the program, and who is being screened? “Are we identifying more aneurysms in women as a side effect?” adds Sen. “A lot has changed in clinical practice, and the outcomes of this are being reported using large hospital-based treatment datasets.” The impact of these developments and changes at a population level was not known, Kalra chimes in, nodding toward the questions around potential benefits of early detection of these aneurysms in women, “although data exists that screening for them has been shown not to be cost-effective.” She says the chief finding was actually something of a surprise. “It’s not that women do poorly with AAA repair, it’s because they are nearly a decade older by the time you are fixing them,” adds Kalra.
As they concentrate their efforts on this particular area of the dataset, Sen informs of future efforts and analysis to get to the bottom of factors that lead to later diagnosis and repair of aneurysms in women.