title: Endovascular abdominal aortic aneurysm repair is more profitable than open repair based on contribution margin per day.
abstract: BACKGROUND
  Earlier studies have reported that endovascular abdominal aortic aneurysm (EAAA) repair yields lower total profit margins than open AAA (OAAA) repair. This study compared EAAA versus OAAA based on contribution margin per day, which may better measure profitability of new clinical technologies. Contribution margin equals revenue less variable direct costs (VDCs). VDCs capture incremental resources tied directly to individual patients' activity (eg, invoice price of endograft device, nursing labor). Overhead costs factor into total margin, but not contribution margin.
  
  
  METHODS
  The University of Michigan Health System's cost accounting system was used to extract fiscal year 2002-2003 information on revenue, total margin, contribution margin, and duration of stay for Medicare patients with principal diagnosis of AAA (ICD-9 code 441.4).
  
  
  RESULTS
  OAAA had revenues of $37,137 per case versus $28,960 for EAAA, similar VDCs per case, and thus higher contribution margin per case ($24,404 for OAAA vs $13,911 for EAAA, P < .001). However, OAAA had significantly longer mean duration of stay per case (10.2 days vs 2.2 days, P < .001). Therefore, mean contribution margin per day was $2948 for OAAA, but $8569 for EAAA ( P < .001).
  
  
  CONCLUSIONS
  On the basis of contribution margin per day, EAAA repair dominates OAAA repair. The shorter duration of stay with EAAA allows higher throughput, fuller overhead amortization, better use of scarce inpatient beds, and higher health system profits. Surgeons must understand overhead allocation to devices, especially when new technologies cut duration of stay markedly.
authors.affiliation: Department of Surgery and Radiology, University of Michigan Health System, USA.
authors.forename: Barry L
authors.initials: BL
authors.lastname: Rosenberg
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Comstock
authors.forename: David A
authors.initials: DA
authors.lastname: Butz
authors.forename: Paul A
authors.initials: PA
authors.lastname: Taheri
authors.forename: David M
authors.initials: DM
authors.lastname: Williams
authors.forename: Gilbert R
authors.initials: GR
authors.lastname: Upchurch
mesh_terms: D000046:Academic Medical Centers / Q000191:economics*; D000368:Aged; D001012:Aorta, Abdominal / Q000601:surgery; D017544:Aortic Aneurysm, Abdominal / Q000191:economics* / Q000601:surgery*; D003362:Cost-Benefit Analysis; D004469:Economics, Hospital; D004730:Endothelium, Vascular / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D006278:Medicare / Q000191:economics; D008824:Michigan; D014656:Vascular Surgical Procedures / Q000191:economics* / Q000379:methods