Thresholds in women with abdominal aortic aneurysm

www.thelancet.com Published online April 25, 2017 http://dx.doi.org/10.1016/S0140-6736(17)31110-8 1 Past studies have found that women have a lower prevalence of abdominal aortic aneurysm, develop abdominal aortic aneurysm at later ages, have higher rates of rupture, and have higher 30-day mortality and more complications from either open abdominal aortic aneurysm repair or endovascular repair (EVAR) than do men. These sex differences have raised questions about thresholds in women: what aortic diameter should be labelled an abdominal aortic aneurysm, and at what diameter should surgical intervention be considered? These were among the questions addressed for men by the UKSAT and ADAM trials, but these trials included only 198 women in total. In The Lancet, Pinar Ulug and colleagues’ systematic reviews with meta-analysis adds to our understanding of abdominal aortic aneurysm in women, as they report on sex differences among patients being assessed for intact abdominal aortic aneurysm. They found that a smaller proportion of women than men were eligible for EVAR (34% vs 54%; odds ratio [OR] 0·44, 95% CI 0·32–0·62), a higher proportion of women than men were not offered intervention (34% vs 19%; OR 2·27, 95% CI 1·21–4·23), and 30-day mortality was higher in women than in men for both EVAR (2·3% vs 1·4%; OR 1·67, 95% CI 1·38–2·04) and open repair (5·4% vs 2·8%; OR 1·76, 95% CI 1·35–2·30). Ulug and colleagues highlight the need to design an endograft for women or refer women to centres with endovascular sealing technology or with specialists in open repair. They also point out that women have smaller aortas than men and suggest that “if a smaller threshold for both diagnosis and intervention were introduced, compared with those recommended for men, women might have a better chance of being offered and surviving intervention at a younger age”. As Ulug and colleagues note, the evidence they examined has limitations. Only five studies evaluated morphological eligibility for EVAR and only four single-centre studies addressed non-intervention rates. The results of these studies had considerable heterogeneity, and adjustments for important variables such as age, comorbidity, and smoking history were inconsistent. Although the evidence base is stronger for 30-day mortality after EVAR and open repair—women clearly have higher mortality than men—their review again found important variation in actual rates. Important considerations exist when assessing sex differences in abdominal aortic aneurysm. First, most studies on this topic are from countries where most of the screening for abdominal aortic aneurysm occurs among men rather than women. Generally, screen-detected abdominal aortic aneurysms have a better prognosis than clinically detected abdominal aortic aneurysms, partly because screening results in a higher rate of detection and surgery of abdominal aortic aneurysms that would never have ruptured even without surgery (ie, overdiagnosis and overtreatment). Therefore, comparisons of a screened and a non-screened cohort can be misleading. Second, although abdominal aortic aneurysm is less frequent in women, the natural history of abdominal aortic aneurysms that occurs in women might be worse, which does not mean, however, that earlier or more aggressive intervention would reduce mortality. It could, in fact, increase mortality. Third, that women have a higher non-intervention rate than men does not necessarily mean that women have too high a non-intervention rate. Many patients considered unfit for surgery have high competing risks and a short remaining lifespan, with or without surgery. Mortality is not the only measure to consider and future research should include patient-relevant outcomes—eg, unnecessary treatment, physical and cognitive loss after surgery, and ability to return to an independent life after surgery. The suggestion of lowered thresholds for diagnosis and intervention in women is supported by the fact that women in general have smaller aortas than men. However, the higher rate of complications and operative mortality in women instead argues for a higher threshold for elective surgery, since the higher risk of surgery might outweigh any incremental additional benefit from earlier intervention. Aneurysm diameter is a better predictor of rupture in men than in women, where diameter indexed to body size seems superior. However, a change in the definition of the diagnosis for women might result in increased harm due to overdiagnosis and overtreatment of abdominal aortic aneurysms that would never have caused symptoms. Indeed, studies using alternative definitions (eg, aortic maximum diameter ≥1·5 times normal infrarenal aortic diameter) have shown a prevalence of abdominal aortic aneurysm of up to 10% in women, which appears to constitute an Thresholds in women with abdominal aortic aneurysm