Treating ruptured AAA: Clues to improve outcomes

In-hospital survival of patients with a ruptured abdominal aortic aneurysm (AAA) is significantly higher in the U.S. than in England, a study published in the March 15 issue of The Lancet showed. The findings offered insights on hospital-level factors that impact outcomes.

Alan Karthikesalingam, PhD, of St. George’s Vascular Institute in London, and colleagues compared data from two national administrative databases, the Hospital Episode Statistics in England and the Nationwide Inpatient Sample in the U.S., between 2005 and 2010. They identified 11,799 patients in England and 23,838 patients in the U.S. with diagnosed ruptured AAA. Their primary outcome was in-hospital mortality, mortality after open or endovascular aneurysm repair (EVAR) and noncorrective treatment for ruptured AAA.    

In-hospital mortality was significantly lower in the U.S., at 53.05 percent vs. 65.9 percent in England. Patients in the U.S. were more likely to receive an intervention, at 80.43 percent vs. 58.45 percent; and EVAR was much more common in the U.S., at 20.88 percent vs. 8.54 percent. Overall post-intervention mortality rates were similar for both countries, but the post-intervention EVAR mortality was lower in the U.S. than in England (26.84 percent vs. 31.58 percent).

After adjustment, predictors of mortality in both countries included admission on a weekend and treatment in a nonteaching hospital. In England, interhospital transfer was also a predictor of mortality. Patients in England were more likely to receive noncorrective treatment if treated on a weekend or at a nonteaching facility.

Karthikesalingam and colleagues attributed the higher mortality rate in England to greater use of noncorrective treatment and lesser use of EVAR. "The proportion of patients offered intervention … in the USA greatly differed from that in England, and provides important context for the improvement of English practice."

The results highlighted factors in both countries that might inform strategies to improve outcomes. Hospitals with the highest bed capacity, the greatest ruptured AAA volume and with the largest proportion of ruptured AAA managed by EVAR showed the best outcomes.

"The results from our study suggest that service configuration should focus on ensuring that patients with rAAA [ruptured AAA] are treated in a teaching hospital with a high aortic workload, offering both conventional and endovascular repair," they wrote.

Greater use of EVAR might boost survival rates in both countries, they proposed. "About 50% of patients with rAAA are morphologically suitable for rEVAR, yet the use of rEVAR in both countries remained short of this benchmark."

The use of administrative data and an observational design posed limitations, they added. In an accompanying editorial, Martin Bjorck, MD, and Kevin Mani, MD, of Uppsala University in Uppsala, Sweden, added that the assessment of only in-hospital mortality and differing discharge patterns in the U.S. and England also were limitations.

But Bjorck and Mani emphasized that international comparisons can be useful in quality improvement efforts. "Karthikesalingam and colleagues’ study suggests that the main benefit of EVAR for rAAA might be the possibility to treat elderly patients, patients with comorbidities, or both, who would not otherwise be considered candidates for open surgery," they wrote. "This international trend is clear in the elective setting; as an example, the broad introduction of EVAR has resulted in a more than doubled incidence of elective AAA repair among octogenarians in Sweden."