UK AAA screening results show “considerable” local variation in proportion of patients undergoing endovascular repair

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abdominal aortic aneurysmThe first detailed surgical results from the UK National Health Service (NHS) Abdominal Aortic Aneurysm Screening Programme (NAAASP) show that, over a seven-year period, the turn down rate after referral for treatment with a screen-detected AAA and perioperative mortality were low. However, the data also reveal that there remains “considerable” variation between local screening programmes in the proportion undergoing endovascular repair. These findings were published in the February edition of the European Journal of Vascular and Endovascular Surgery (EJVES).

Authors Lewis Meecham (Heart of England NHS Foundation Trust, Birmingham, UK) and colleagues detail that the NAAASP began implementation in 2009, and became fully operational in 2013. Since that time, all men in England with a large aneurysm >54mm, either at first screen or during surveillance, are referred for intervention.

In order to see whether there has been any local variation in treatment rates and types of repair, the investigators aimed in this study to explore the outcomes of all men referred to a vascular network with a large AAA diagnosed through screening between 1 April and 31 December 2016. Meecham et al relay that basic demographic information, nurse assessment details, as well as outcome data were extracted from the national NAAASP IT system, AAA SMaRT, for analysis.

In the seven-year study period, the authors note that 3,026 men were referred for possible intervention (48% first screen, 52% surveillance). They specify that while 448 men (13.3%) either declined (63; 2.1%) or were turned down for early intervention for various reasons (385; 12.7%), 8% were declined for medical reasons (true turn down rate). Men referred for surveillance were older, and more likely not to have had elective surgery within three months (16 vs. 11.2%; hazard ratio [HR], 1.37; 95% confidence interval [CI], 1.07–1.75, p=0.011), Meecham and colleagues write in the EJVES. In addition, the authors report that turn down rates did not vary among local programmes, when men under surveillance were taken into account.

Regarding mortality, the investigators report that 2,624 (87%) men had planned AAA repair, with a perioperative mortality of 1.3%. They add that 30-day surgical mortality was lower after endovascular aneurysm repair (EVAR): 0.4% compared with 2.1% after open repair.

The method of repair remained consistent year on year, Meecham et al communicate, with roughly equal numbers undergoing endovascular (50%) and open surgical repair (48%); 2% unknown. However, the “striking finding” of the study was that there was variation among local screening programmes in the proportion treated by endovascular repair: from 20% to 97%.

Wide range of EVAR use points to variations in local uptake of the technology

In the discussion of their findings, the investigators consider possible explanations behind this “very wide range” of EVAR use for screen-detected AAA. “This proportion should not have been affected by the number of complex endovascular repair,” they write, noting that procedures done in tertiary centres are still counted in their originating programme.

They add that the differences do not seem to be related to patient factors either, leading them to conclude that it is likely to represent variations in local uptake of EVAR technology. “The question is what to do with this information,” they write, “as by definition, variation results in inequity”.

NICE guidelines may precipitate reduction in EVAR procedures

Meecham et al also remark on how the recent publication of the UK National Institute for Health and Care Excellent (NICE) guidelines on the management of AAA might influence future outcomes. “The draft version of the document suggested that EVAR was not a cost-effective elective intervention,” they state, adding that this approach has been “softened” in the definitive document.

“It is possible there may be a reduction in the number of EVAR procedures as a result,” the authors posit, going so far as to say that there may even be a decrease in all elective surgical procedures for AAA. They write that this would have “a number of significant consequences” for AAA screening. For example, they suggest that it would increase population risks of death from AAA rupture, and, by definition, make the screening programme less effective.


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