Authors: Karthikesalingam A et al., N Engl J Med 2016 Nov 24; 375:2051
Mean abdominal aortic aneurysm diameter at the time of repair was significantly smaller in the U.S.
International guidelines recommend that abdominal aortic aneurysm (AAA) repair be considered for AAAs with diameters ≥5.5 cm in men or ≥5.0 cm in women (Eur J Vasc Endovasc Surg 2011; 41:S1). But clinical practice varies within and across countries. Using national databases in the U.S. and U.K., investigators examined data on AAA outcomes in both countries.
From 2005 through 2012, about twice as many intact AAAs were repaired annually per 100,000 people in the U.S. as in the U.K. During the same period, the rate of hospitalization for AAA rupture was more than twice as high and the rate of AAA-related mortality was more than three times as high in the U.K. as in the U.S. Mean preoperative AAA diameters were significantly higher in the U.K. in 2014 than in the U.S. in 2013 (6.4 cm vs. 5.8 cm). Data from a national AAA screening program conducted in the U.K. in 2009 through 2014 showed that 76 men per 100,000 screened had aneurysms ≥5.8 cm in diameter and 48 per 100,000 had aneurysms ≥6.4 cm in diameter.
This study suggests, but does not prove, that the higher threshold for AAA repair in the U.K. contributed to the greater incidence of AAA ruptures and higher AAA-related mortality in that country compared with the U.S. Currently recommended thresholds are based on studies showing that, for smaller aneurysms (i.e., those <5.5 cm in diameter), observation and surgical intervention yield similar outcomes. But these studies are dated, and new trials might be needed to account for advances in clinical practice.