OVER Study Shows Similar Long-Term Survival for EVAR Versus Open Repair


May 30, 2019—Long-term findings from the OVER study of open repair (OR) versus endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA) were published in The New England Journal of Medicine (NEJM) by Frank A. Lederle, MD, et al for the OVER Veterans Affairs Cooperative Study Group (2019;380:2126–2135).

The study demonstrated similar long-term overall survival among patients who underwent EVAR and patients who underwent OR. These results were not consistent with the findings of worse performance of EVAR with respect to long-term survival that were seen in two studies conducted in Europe, noted the investigators in NEJM.

The OVER study was funded by the United States Department of Veteran Affairs (VA) Office of Research and Development. Dr. Lederle, who served as Study Chair, died in January 2018. He was Core Investigator for the Center for Chronic Disease Outcomes Research at the Minneapolis VA Health Care System and previously Director of the Minneapolis VA Center for Epidemiology and Clinical Research in Minneapolis, Minnesota.

According to the investigators, although elective EVAR of AAA has shown lower perioperative mortality than OR, this survival advantage was not seen after 4 years. In this publication, the OVER investigators report on the long-term results of a study conducted more than a decade ago.

In OVER, patients with asymptomatic AAA were randomly assigned to either EVAR or OR for aneurysm treatment and were followed for up to 14 years. As summarized in NEJM, the study was composed of 881 patients who were candidates for either procedure, with 444 assigned to EVAR and 437 to OR. The primary outcome was all-cause mortality.

The OVER investigators found the following, although none of these trends were significant:

  • 302 patients (68%) in the EVAR group and 306 patients (70%) in the OR group died (hazard ratio [HR], 0.96; 95% confidence interval [CI], 0.82–1.13).
  • In the first 4 years of follow-up, overall survival appeared to be higher with EVAR versus OR.
  • In year 4 through year 8, overall survival was higher in the OR group.
  • After 8 years, overall survival was higher in the EVAR group (HR for death, 0.94; 95% CI, 0.74–1.18).

Additionally, the investigators reported in NEJM:

  • There were 12 aneurysm-related deaths (2.7%) in the EVAR group and 16 (3.7%) in the OR group (between-group difference, -1.0 percentage point; 95% CI, -3.3–1.4) with most deaths occurring during the perioperative period.
  • Aneurysm rupture occurred in seven patients (1.6%) in the EVAR group, and rupture of a thoracic aneurysm occurred in one patient (0.2%) in the OR group (between-group difference, 1.3 percentage points; 95% CI, 0.1–2.6).
  • Death from chronic obstructive lung disease was approximately 50% more common in OR patients than EVAR patients (8.2% vs 5.4%) with a between-group difference of -2.8 percentage points (95% CI, -6.2–0.5).
  • More patients in the EVAR group underwent secondary procedures.

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