title: Regionalization of abdominal aortic aneurysm repair: evidence of a shift to high-volume centers in the endovascular era.
abstract: BACKGROUND
  Since the early 1990s, many studies have shown lower mortality for abdominal aortic aneurysm (AAA) repair at high-volume centers compared with low-volume centers. The introduction of endovascular AAA repair (EVAR) also has changed the practice of AAA repair. The goal of this study was to determine if regionalization of AAA repair occurred in the United States. Etiologic factors were examined in addition to any reduction in operative mortality rates.
  
  
  METHODS
  Patient discharges of nonruptured AAA repair were identified from the Nationwide Inpatient Sample between 1998 and 2004. Hospitals were stratified by yearly AAA surgical volume of low (< or =17 cases), medium (18 to 50), and high (>50).
  
  
  RESULTS
  A total of 46,901 patients underwent AAA repair (72.7% open vs 27.3% endovascular). The percentage of AAA repairs performed at both low-volume (36.2% to 24.3%) and medium-volume (51.0% to 44.8%) centers fell; whereas, the percentage performed at high-volume centers nearly tripled (12.9% vs 30.9%). In 1998 there were 10 high-volume centers; by 2004 this had increased to 26. The number of low-volume centers decreased, from 412 to 328. EVAR was more rapidly adopted by high-volume centers compared with low-volume centers. By 2004, 64.3% of AAA repairs at high-volume centers were done with endovascular techniques compared with 31.8% in low-volume centers. A concurrent reduction occurred in patient mortality, from 4.4% in 1998 to 2.5% in 2004 (P < .0001).
  
  
  CONCLUSIONS
  Between 1998 and 2004, a trend towards the regionalization of AAA repair to high-volume centers occurred. Nearly one-third of all AAA repairs were performed at high-volume centers. There was a concurrent increase in the frequency of endovascular AAA repair, especially at high-volume centers. During this period of regionalization of AAA repair to high-volume centers, patient mortality after AAA repair decreased by 23%. Thus, the observed regionalization of AAA repair and the reduction in short-term patient mortality for this operation may be explained by increased utilization of endovascular technologies at high-volume centers.
authors.affiliation: Department of Surgery, University of Massachusetts Medical School, Worcester, MA, USA.
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Hill
authors.forename: James T
authors.initials: JT
authors.lastname: McPhee
authors.forename: Louis M
authors.initials: LM
authors.lastname: Messina
authors.forename: Rocco G
authors.initials: RG
authors.lastname: Ciocca
authors.forename: Mohammad H
authors.initials: MH
authors.lastname: Eslami
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000401:mortality* / Q000601:surgery*; D017558:Elective Surgical Procedures; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care; D016019:Survival Analysis; D014481:United States / Q000453:epidemiology; D014656:Vascular Surgical Procedures / Q000706:statistics & numerical data*