The relationship between volume and outcome following elective open repair of abdominal aortic aneurysms (AAA) in 131 German hospitals

Eur J Vasc Endovasc Surg. 2007 Sep;34(3):260-6. doi: 10.1016/j.ejvs.2007.05.006. Epub 2007 Jun 29.


Objectives: Several studies indicate that high-volume hospitals have better results in open repair of unruptured abdominal aortic aneurysms (AAA). Up to now no studies had addressed this question in German hospitals.

Design: Post-hoc-analysis from a prospective physician-led registry.

Material and methods: Since 1999, the German Society for Vascular Surgery has conducted a prospective registry for open and endovascular repair of AAAs. This study includes 131 hospitals who conducted n=10163 elective open repairs for unruptured AAA between 1999 to 2004. All perioperative variables including annual volume as a continuous variable were analysed in a step-wise logistic regression model. In order to define a threshold annual volume an additional logistic regression analysis was performed by use of annual volume groups (0-9, 10-19, 20-29, 30-39, 40-49, 50 or more). The relationship between annual volume and further outcome parameters (length of procedure, blood transfusion, length of stay) were also analyzed.

Results: The overall mortality rate was 3.2%. The stepwise logistic regression model identified the following predictors of an increased perioperative mortality: age (OR 1.084, 95% CI 1.066-1.102), AAA diameter (OR 1.008, 95% CI 1.001-1.016), length of procedure (OR 1.008, 95% CI 1.006-1.009), ASA-Score (OR 2.636, 95% CI 2.129-3.264), suprarenal clamping (OR 1.447, 95% CI 1.008-2,078), blood transfusion (OR 1.786, 95% CI 1.268-2.514). Annual volume was moderately predictive (OR 1.003, 95% CI 1-1.006) but failed to reach statistical significance (p=0.07). The analysis of volume groups identified a significantly higher risk for hospitals with an annual volume of 1-9 AAA-repairs by comparison to hospitals with an annual volume of 50 or more AAA-repairs (OR 1.903, 95% CI 1.124-3.222). Operations at low volume hospitals were also longer (p<0.001), with an extended postoperative stay (p<0.001) and a higher transfusion rate (p<0.001).

Conclusions: Patient's age, ASA classification, AAA diameter, length of procedure, suprarenal clamping and blood transfusion are predictive variables for an increased perioperative mortality in elective open AAA repair. Mortality is also increased by a low annual volume. Further studies are needed to examine whether these data are applicable to all German hospitals.

Publication types

  • Evaluation Study
  • Multicenter Study

MeSH terms

  • Age Factors
  • Aged
  • Aortic Aneurysm, Abdominal / mortality*
  • Aortic Aneurysm, Abdominal / pathology
  • Aortic Aneurysm, Abdominal / surgery*
  • Blood Loss, Surgical / statistics & numerical data
  • Blood Transfusion / statistics & numerical data
  • Elective Surgical Procedures
  • Germany / epidemiology
  • Hospitals / statistics & numerical data*
  • Humans
  • Length of Stay / statistics & numerical data
  • Logistic Models
  • Mortality / trends
  • Odds Ratio
  • Prospective Studies
  • Quality of Health Care / statistics & numerical data*
  • Registries / statistics & numerical data
  • Risk Assessment
  • Risk Factors
  • Severity of Illness Index
  • Time Factors
  • Treatment Outcome
  • Vascular Surgical Procedures / statistics & numerical data*