Mortality rates for women undergoing surgery for abdominal aortic aneurysms are nearly twice those for men, a study by Imperial College and the University of Cambridge found.
The findings show women fare worse than men at every stage of treatment, leading to the study’s authors to call for urgent improvement in how the condition is managed in women.
The researchers, from Imperial College London and the University of Cambridge, found that women are less likely than men to be deemed suitable for keyhole surgery for the condition, which is associated with better outcomes. They are also more likely to be offered no surgical treatment at all. The findings are based on a review of international research into the condition, carried out since 2000.
An abdominal aortic aneurysm is caused by a weakening in the wall of the aorta, the body’s largest blood vessel, which carries blood from the heart through the abdomen to the rest of the body. Degenerative changes in the aortic wall cause weakening and ballooning of the blood vessel, sometimes to more than three times its normal diameter, with a risk of a potentially life-threatening rupture.
Surgical repair for these aneurysms is offered only when the swelling is large enough to make the risk of rupture greater than the risks of the operation, with two types of surgery available.
Open surgery involves cutting into the abdomen and replacing all of the ballooning section of the aorta with a tube-like graft. The second procedure, endovascular repair, is a minimally invasive ‘keyhole’ technique which involves inserting a tube-like graft through the leg artery into the swollen section of the aorta to reinforce the blood vessel’s weakened wall. It is associated with better early outcomes than open surgery, but can only be offered when the aneurysm meets certain criteria, due to the shape and size of the grafts.
For some patients with large aneurysms, the risk of both of these options are deemed to outweigh the risk of rupture and no treatment is offered unless patient fitness can be improved.
The study, funded by the National Institute for Health Research, found that only a third of women were deemed suitable for keyhole surgery, compared with just over half of men. Less than a fifth of men were not offered surgery, compared with a third of women.
Mortality rates for women for the 30 days after keyhole surgery were 2.3% compared with 1.4% for men. For open surgery, this rose to 5.4% for women and 2.8% for men. Women tend to develop aneurysms at an older age than men, and their aortas are smaller. Given the current technologies available, both of these factors can affect which type of surgery is deemed suitable, or whether surgery is an option at all.
The researchers say that while these factors will form the basis of future research, age and physical fitness are not enough to account for the differences seen in mortality between men and women.
Professor Janet Powell, from Imperial’s department of surgery & cancer and who led the research, said: “Our findings show that despite overall improvement in mortality rates for this condition, there is a huge disparity between outcomes for men and women, which is not acceptable.
“The way abdominal aortic aneurysm is managed in women needs urgent improvement. We need to see if the devices used for keyhole surgery can be made more flexible to enable more women to be offered this option. We also need more grafts designed to fit women, who have smaller aortas, as all the grafts currently available have been designed for men.”
In the UK, abdominal aortic aneurysm is more prevalent in men, with men over 65 regularly screened for the condition. The condition often has no symptoms and many women are only diagnosed when the aneurysm ruptures, at which point the likelihood of survival can be less than 20%.
Powell added: “Abdominal aortic aneurysm is still seen as mainly a male condition, and as a result, the way we manage the condition – from screening to diagnosis and treatment – has been developed with men in mind. Our study shows that this needs to change.”
Summary
Background: Prognosis for women with abdominal aortic aneurysm might be worse than the prognosis for men. We aimed to systematically quantify the differences in outcomes between men and women being assessed for repair of intact abdominal aortic aneurysm using data from study periods after the year 2000.
Methods: In these systematic reviews and meta-analysis, we identified studies (randomised, cohort, or cross-sectional) by searching MEDLINE, Embase, CENTRAL, and grey literature published between Jan 1, 2005, and Sept 2, 2016, for two systematic reviews and Jan 1, 2009, and Sept 2, 2016, for one systematic review. Studies were included if they were of both men and women, with data presented for each sex separately, with abdominal aortic aneurysms being assessed for aneurysm repair by either endovascular repair (EVAR) or open repair. We conducted three reviews based on whether studies reported the proportion morphologically suitable (within manufacturers' instructions for use) for EVAR (EVAR suitability review), non-intervention rates (non-intervention review), and 30-day mortality (operative mortality review) after intact aneurysm repair. Studies had to include at least 20 women (for the EVAR suitability review), 20 women (for the non-intervention review), and 50 women (for the operative mortality review). Studies were excluded if they were review articles, editorials, letters, or case reports. For the operative review, studies were also excluded if they only provided hazard ratios or only reported in-hospital mortality. We assessed the quality of the studies using the Newcastle–Ottawa scoring system, and contacted authors for the provision of additional data if needed. We combined results across studies by random-effects meta-analysis. This study is registered with PROSPERO, number CRD42016043227.
Findings: Five studies assessed the morphological eligibility for EVAR (1507 men, 400 women). The overall pooled proportion of women eligible (34%) for EVAR was lower than it was in men (54%; odds ratio [OR] 0·44, 95% CI 0·32–0·62). Four single-centre studies reported non-intervention rates (1365 men, 247 women). The overall pooled non-intervention rates were higher in women (34%) than men (19%; OR 2·27, 95% CI 1·21–4·23). The review of 30-day mortality included nine studies (52 018 men, 11 076 women). The overall pooled estimate for EVAR was higher in women (2·3%) than in men (1·4%; OR 1·67, 95% CI 1·38–2·04). The overall estimate for open repair also was higher in women (5·4%) than in men (2·8%; OR 1·76, 95% CI 1·35–2·30).
Interpretation: Compared with men, a smaller proportion of women are eligible for EVAR, a higher proportion of women are not offered intervention, and operative mortality is much higher in women for both EVAR and open repair. The management of abdominal aortic aneurysm in women needs improvement.
Authors
Pinar Ulug, Michael J Sweeting, Regula S von Allmen, Simon G Thompson, Janet T Powell
[link url="http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_25-4-2017-15-53-5"]Imperial College London material[/link]
[link url="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)30639-6/fulltext?rss=yes"]The Lancet article summary[/link]