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Survival at 3 years among patients who underwent endovascular abdominal aortic aneurysm repair was superior to patients who had open surgery in a statewide, population-based study from California.

The study was the first to compare the two elective procedures for the repair of abdominal aortic aneurysms (AAA) in a real-world surgical setting, and it is also the first to show a long-term survival advantage for endovascular repair over open surgery, of Massachusetts General Hospital in Boston, and colleagues reported online in .

Clinical trials comparing the two procedures showed a survival advantage for endovascular repair at 30-days post surgery, but not at 1 year and beyond.

The large population study, which included all patients undergoing endovascular repair in California over an 8 year period, better reflects outcomes in a non-research setting, Chang noted in an email exchange with 麻豆传媒.

"Our study highlights the importance of looking at real-world data in evaluating surgical options," he wrote. "Clinically, our study found that the survival advantage for endovascular (EVAR) repairs is maintained until 3 years, after which mortality was (slightly) higher for patients who had EVAR repairs. This is different from data from clinical trials."

The increase in deaths among EVAR repair patients after 3 years could be explained by the fact that older, sicker patients may be more likely to get the less-invasive procedure, the researchers noted.

They used the California Office of Statewide Health Planning and Development database to examine outcome among all residents of the state undergoing AAA repair between 2001 and 2009.

In all, 23,670 patients were identified and they were followed for a median of 3.3 years (IQR 1.4-5.7 years). Endovascular repair was done in 51.7% of the patients, and these patients were significantly more likely to be older, non-white, male, and to receive treatment at a teaching hospital.

As seen in clinical trials, all-cause mortality was significantly higher at 30 days among patients undergoing open AAA repair (4.74% versus 1.54%), and this trend remained at 6 months post surgery (8.71% versus 5.04%), 1 year (10.91% versus 8%), and 3 years (19.93% versus 19.84%).

The trend reversed at 4 and 5 years, with open repair patients having a lower rate of all cause mortality than EVAR repair patients (24.82% versus 26.31% at 4 years and 29.69% versus 32.05% at 5 years).

"Given that the major risk factor for AAA is smoking, this (survival) advantage would inevitably erode as cardiovascular disease, emphysema, and pulmonary malignancy exact their toll," the researches wrote. "After 3 years, mortality was higher for patients who had EVAR repair. We believe this is explained by the willingness of the surgeon to undertake EVAR repair in older patients knowing that the less invasive procedure is safer than open aortic repair."

Endovascular repair was associated with a significantly higher rate of reintervention and AAA late rupture, but study co-author of the University of California Irvine Medical Center, said technological advances in EVAR repair should make reintervention less of an issue in the future.

"30-day mortality with endovascular repair was approximately a quarter of that seen with open repair, and there were fewer early complications," Wilson told 麻豆传媒. "Moving forward, I believe the vast majority of AAA repairs will be endovascular."

In an editorial published with the study,, and of UC Davis Medical Center, Sacramento, Calif., wrote that the development of more sophisticated health databases from data derived from electronic medical records should allow medical research to "move beyond research focused on a snapshot of information."

They concluded that the study by Chang, Wilson, and colleagues "offers a glimpse into the future of population-based health services research."

"With the dawn of electronic medical records and big data, we should be able to develop surgical outcomes research that can complete with and complement the randomized trial," they wrote.

Wilson agreed, but he added that both big data research and clinical trials will be needed moving forward to optimize medical treatment.

"The big data studies will allow us to look at what is happening with a population in general, and that is important," he said. "But clinical trials will still define more sharply the comparable effectiveness of different treatments."

From the American Heart Association:

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