High-volume Hospitals Demonstrate Better Survival After AAA Repair

Dr. McKinsey 

PHILADELPHIA -- Patients with ruptured abdominal aortic aneurysms had markedly better survival rates when they were treated at higher-volume centers than when treated at lower-volume centers, according to a review of more than 43,000 patients from the Medicare data set.

Patients who underwent endovascular aneurysm repair (EVAR) for a ruptured aneurysm had better short-term survival and reduced perioperative morbidity than did patients who had open surgical repair, but after 2 years of follow-up, the survival advantage from EVAR disappeared.

The early national experience with EVAR for ruptured abdominal aortic aneurysms (AAAs) "is promising, especially in high-volume centers, with improved short-term survival and decreased morbidity," Dr. James F. McKinsey said at the Vascular Annual Meeting, sponsored by the Society for Vascular Surgery.

The improved survival at higher-volume centers was seen both in patients treated with EVAR and in those who had open surgical repairs, added Dr. McKinsey, chief of vascular surgery at Columbia-Presbyterian Medical Center in New York.

The cases reviewed by Dr. McKinsey and his associates were drawn from the 41 million patients in the Medicare data set for 1995-2004. The data set included more than 700,000 patients with a diagnosis of AAA, more than 400,000 who underwent some type of surgical repair, and more than 60,000 who were diagnosed with a ruptured AAA at the time of hospitalization. The data set included 42,645 patients who had open surgical repair of a ruptured AAA and 1,035 who had EVAR.

In patients treated with EVAR, the incidence of postoperative complications included bleeding complications in 22%, respiratory complications in 21%, cardiac complications in 8%, and infections in 2%. The rate of each complication was significantly lower with EVAR than in the open-surgery group, which had rates of 38%, 27%, 11%, and 4%, respectively.

The average length of hospital stay was 11.7 days in the EVAR group and 13.1 days in the open-surgery group, also a statistically significant difference.

Survival rates were significantly better in the EVAR group at 30 and 90 days after surgery. At 30 days, the EVAR mortality rate was 39%, compared with 47% in the open-surgery group; at 90 days, the death rates were 46% and 51%, respectively. But by 1 year, death rates were 53% with EVAR and 56% with open-surgery, not a significant difference; and after 2 years, the rate was 59% in both groups, Dr. McKinsey said.

A second analysis examined the impact of hospital volume on mortality rates for all repairs of ruptured AAA, and for EVAR and open repairs separately. All analyses showed a significant survival advantage in the higher-volume hospitals (see box).