Volume Standards for Open AAA Repair Are Not Associated With Improved Clinical Outcomes

Abstract

Abstract Background Volume-outcome relationships exist for many complex surgical procedures, prompting institutions to adopt surgical volume standards for credentialing. The current Leapfrog Group hospital volume standard for open abdominal aortic aneurysm repair (OAR) is 15 per year. However, this is primarily based off data from the 1990’s and may not be appropriate given the dramatic decline in OAR. We sought to quantify the proportion of hospitals meeting volume standards, the difference in perioperative outcomes between low-volume and high-volume hospitals, and the potential travel burden of volume credentialing on patients. Methods We identified Medicare beneficiaries age > 65 years undergoing OAR in 2013-2014. Hospital “all-payer” annual volume was estimated based on the national proportion of patients undergoing OAR covered by Medicare in the Vascular Quality Initiative. Hospital annual OAR volume was characterized as > 15/year (high-volume). Adjusted rates of postoperative morbidity, reoperation, failure to rescue and mortality in 2014 were compared across volume cohorts. Distance between patients’ home zip code and high-volume hospitals was calculated. Results 21,191 OAR were performed at 1,445 hospitals between 2013-2014. The average hospital OAR annual volume was 7.8 (SD +/-9.3) with a median of 4.5. Amongst the 1,445 hospitals, only 190 (13.1%) performed > 15 OAR per year while756 hospitals (53.3%) performed p =0.817). One quarter of patients who received care at a low-volume hospital would be required to travel more than 60 miles to reach a high-volume hospital. Conclusions By conservative estimates, only 13% of hospitals performing OAR meet current volume standards. Triaging all patients to high-volume hospitals would requiring shifting over 5,000 patients annually with no associated improvement in perioperative outcomes. Implementation of the current OAR hospital volume standard may significantly burden patients and hospitals without improving surgical outcomes.