title: Volume and process of care in high-risk cancer surgery.
abstract: BACKGROUND
  Although relations between procedure volume and operative mortality are well established for high-risk cancer operations, differences in clinical practice between high-volume and low-volume centers are not well understood. The current study was conducted to examine relations between hospital volume, process of care, and operative mortality in cancer surgery.
  
  
  METHODS
  Using the Medicare claims database (2000-2002), we identified all patients undergoing major resections for lung, esophageal, gastric, liver, or pancreatic cancer (n=71,558). Preoperative, intraoperative, and postoperative processes of care potentially related to operative mortality were identified from inpatient, outpatient, and physician claims files using appropriate International Classification of Diseases--Clinical Modification (ICD-9) and Current Procedural Terminology (CPT) codes. We then assessed variation in the use of each process according to hospital volume, adjusting for patient characteristics and procedure type. Study Participants were US Medicare patients. The main outcome measure was specific processes of care.
  
  
  RESULTS
  Relative to those at low-volume centers (lowest 20th by volume), patients at high-volume hospitals (highest 20th) were significantly more likely to undergo stress tests (odds ratio [OR]: 1.51, 95% confidence interval [CI]: 1.21-1.87), but not other preoperative imaging tests. They were more likely to see medical or radiation oncologists (OR: 1.37, 95% CI: 1.16-1.62), but not other specialists, preoperatively. Although blood transfusions and use of epidural pain management did not vary significantly by volume, patients at high-volume hospitals had significantly longer operations and were more likely to receive perioperative invasive monitoring (OR: 2.56, 95% CI: 1.82-3.60). Differences in measurable processes of care did not explain volume-related differences in operative mortality to any significant degree.
  
  
  CONCLUSIONS
  Although high-volume and low-volume hospitals differ with regard to many aspects of perioperative care, mechanisms underlying volume-outcome relations in high-risk cancer surgery remain to be identified.
authors.affiliation: Michigan Surgical Collaborative for Outcomes Research and Evaluation (M-SCORE), Department of Surgery, University of Michigan, Ann Arbor, Michigan 48109, USA. jbirkmey@umich.edu
authors.forename: John D
authors.initials: JD
authors.lastname: Birkmeyer
authors.forename: Yating
authors.initials: Y
authors.lastname: Sun
authors.forename: Aaron
authors.initials: A
authors.lastname: Goldfaden
authors.forename: Nancy J O
authors.initials: NJ
authors.lastname: Birkmeyer
authors.forename: Therese A
authors.initials: TA
authors.lastname: Stukel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000601:surgery*; D010043:Outcome and Process Assessment, Health Care / Q000706:statistics & numerical data*; D012307:Risk Factors; D013503:Surgery Department, Hospital / Q000706:statistics & numerical data*