title: Hospital volume and surgical mortality in the United States.
abstract: BACKGROUND
  Although numerous studies suggest that there is an inverse relation between hospital volume of surgical procedures and surgical mortality, the relative importance of hospital volume in various surgical procedures is disputed.
  
  
  METHODS
  Using information from the national Medicare claims data base and the Nationwide Inpatient Sample, we examined the mortality associated with six different types of cardiovascular procedures and eight types of major cancer resections between 1994 and 1999 (total number of procedures, 2.5 million). Regression techniques were used to describe relations between hospital volume (total number of procedures performed per year) and mortality (in-hospital or within 30 days), with adjustment for characteristics of the patients.
  
  
  RESULTS
  Mortality decreased as volume increased for all 14 types of procedures, but the relative importance of volume varied markedly according to the type of procedure. Absolute differences in adjusted mortality rates between very-low-volume hospitals and very-high-volume hospitals ranged from over 12 percent (for pancreatic resection, 16.3 percent vs. 3.8 percent) to only 0.2 percent (for carotid endarterectomy, 1.7 percent vs. 1.5 percent). The absolute differences in adjusted mortality rates between very-low-volume hospitals and very-high-volume hospitals were greater than 5 percent for esophagectomy and pneumonectomy, 2 to 5 percent for gastrectomy, cystectomy, repair of a nonruptured abdominal aneurysm, and replacement of an aortic or mitral valve, and less than 2 percent for coronary-artery bypass grafting, lower-extremity bypass, colectomy, lobectomy, and nephrectomy.
  
  
  CONCLUSIONS
  In the absence of other information about the quality of surgery at the hospitals near them, Medicare patients undergoing selected cardiovascular or cancer procedures can significantly reduce their risk of operative death by selecting a high-volume hospital.
authors.affiliation: Veterans Affairs Outcomes Group, Department of Veterans Affairs Medical Center, White River Junction, VT 05009, USA. john.birkmeyer@dartmouth.edu
authors.forename: John D
authors.initials: JD
authors.lastname: Birkmeyer
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Siewers
authors.forename: Emily V A
authors.initials: EV
authors.lastname: Finlayson
authors.forename: Therese A
authors.initials: TA
authors.lastname: Stukel
authors.forename: F Lee
authors.initials: FL
authors.lastname: Lucas
authors.forename: Ida
authors.initials: I
authors.lastname: Batista
authors.forename: H Gilbert
authors.initials: HG
authors.lastname: Welch
authors.forename: David E
authors.initials: DE
authors.lastname: Wennberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D013504:Cardiovascular Surgical Procedures / Q000401:mortality / Q000706:statistics & numerical data; D016208:Databases, Factual; D005260:Female; D017052:Hospital Mortality; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D006278:Medicare; D009369:Neoplasms / Q000601:surgery; D017063:Outcome Assessment, Health Care; D013514:Surgical Procedures, Operative / Q000401:mortality* / Q000592:standards / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology