Large study shows continued and quickening decline in AAA mortality

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Lead author Edward Choke

According to a new, population-based analysis, abdominal aortic aneurysm (AAA) mortality has continued to decline and “at a faster rate than ever” in the second decade of the 21st century. Authors C Y Maximilian Png (Massachusetts General Hospital, Boston, USA), Edward Choke (Sengkang General Hospital, Singapore), and colleagues attribute this continued and accelerating decline to multiple factors, highlighting in particular the impact of sustained reductions in smoking and hypertension.

The authors describe their work, published as an Editor’s Choice Paper in the June edition of the European Journal of Vascular and Endovascular Surgery (EJVES), as the largest population-based analysis of AAA mortality to date, incorporating data from 17 countries across four continents. Despite the evidence showing a strong general trend, Png, Choke, et al do acknowledge and detail heterogeneity among countries included in the study and notable geographical limitations.

It is known that the early 21st century witnessed a decrease in mortality from AAA, the authors begin, noting an association with “variations in the prevalence of cardiovascular risk factors”. The aim of this study was to investigate whether this trend had continued into the second decade of the century by looking at data from 2001 through 2015.

The researchers first extracted the International Classification of Disease codes for AAAs, thoracoabdominal aortic aneurysms, and aortic aneurysms of unspecified site (both ruptured and without rupture) from the World Health Organisation (WHO) mortality database. In addition, they collected data on risk factors from the Institute of Health Metrics and Evaluation and WHO InfoBase, as well as data on population from the World Development Indicators database.

In order to be included in the analysis, countries had to meet the following criteria: <30% of mortality data missing and at least 10 annual AAA-related deaths, the authors communicate. Out of the 17 countries included in total, 11 were European, and two each were Australasian, North American, and Asian.

Writing in EJVES, Png, Choke, and colleagues report that male AAA mortality decreased in 13 countries (population weighted average, -2.84%), while female AAA mortality decreased in 11 countries (population weighted average, -1.64%). Looking at the specifics, they detail that the USA (-5.24%), the UK (-4.53%), and The Netherlands (-4.27%) had the largest annual decreases. Of note, the researchers highlight that four countries—Hungary, Israel, Japan, and Romania—actually witnessed an overall increase in male AAA over the time period. Of these four countries, Hungary experienced the largest increase.

In addition, the authors reveal that the decrease in AAA mortality was seen in both younger (<65 years) and older (>65 years) patients, and that the decrease in AAA mortality was more marked in the second decade of the 21st century (2011–2015) compared with the first decade (2001–2005 and 2006–2010).

Considering the reasons behind these findings, Png, Choke, et al note that trends in AAA mortality positively correlated with smoking and hypertension, while AAA mortality negatively correlated with obesity. There was no significant correlation with diabetes, they add.

The authors recognise that the study has some limiting factors. For example, they acknowledge that “while the epidemiological study design allowed for large-scale comparisons across countries, relationships may not be generalisable to the individual”. They add that data collection disparities between countries “may affect interpretation of mortality and risk factor data”.

They also identify a limitation regarding the included geographies. “Despite the original intent of this study,” they write, “the resulting pool of included countries sorely lacked representation from South American, African, and Asian countries”. They note in particular that China and India, the two most populous countries, did not meet the inclusion criterion regarding available mortality data and as such could not be included in the present analysis. Furthermore, Png, Choke, and colleagues remark that Israel and Japan were the only non-Western countries to meet the inclusion criteria. “This is significant because white people have been shown to have a 10-fold higher incidence of AAA than Asian people, and whether their mortality and risk profiles would be representative of non-white populations as well remains to be proven”, they comment.

Considering future research, the authors advance that “a greater understanding of the epidemiology and risk factors at a population level will be helpful in informing future AAA-related healthcare policy strategies”.


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