title: Is there a minimum caseload that achieves acceptable operative mortality in abdominal aortic aneurysm operations?
abstract: BACKGROUND
  Studies have shown correlation between operative workload and mortality for major operations. Is there a threshold for case volume that predicts an acceptable mortality for abdominal aortic aneurysm surgery?
  
  
  METHODS
  Hospital Episode Statistics (HES) Data for England between 1997-2002 was analysed using ICD-10 codes I71.x and OPCS-4 codes L16.x-L26.x. Mortality was identified by the method of discharge.
  
  
  RESULTS
  31,078 operations on abdominal aortic aneurysms were studied in 223 NHS Trusts. 6,007 in-hospital deaths were identified in both elective and emergency cases (overall mortality rates 7.7% and 40%, respectively). Trusts with large elective workloads had reduced mortality for both elective and emergency operations. Using parabolic regression and logarithmic transformation, 14 elective operations per Trust per year was identified as a cut-off point above which the decrease in mortality rate with increasing case volume was relatively small. A similar effect was not seen with increasing emergency workload alone.
  
  
  CONCLUSIONS
  HES data analysis suggests increasing elective workload correlates with lower in-hospital mortality for elective and emergency operations on abdominal aortic aneurysm. Data suggests a range of hospital caseload that correlate with an acceptable elective and emergency mortality rate.
authors.affiliation: The Mid Cheshire Hospitals NHS Trust, Leighton Hospital, Crewe, UK. abdjibawi@doctors.net.uk
authors.forename: A
authors.initials: A
authors.lastname: Jibawi
authors.forename: M
authors.initials: M
authors.lastname: Hanafy
authors.forename: A
authors.initials: A
authors.lastname: Guy
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000401:mortality* / Q000601:surgery*; D002983:Clinical Competence; D017558:Elective Surgical Procedures; D004632:Emergency Medical Services; D017052:Hospital Mortality; D006779:Hospitals, Public / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D017063:Outcome Assessment, Health Care; D013222:State Medicine; D006113:United Kingdom; D014656:Vascular Surgical Procedures / Q000401:mortality* / Q000706:statistics & numerical data*; D016526:Workload / Q000706:statistics & numerical data