title: Hospital volume of thoracoabdominal aneurysm repair does not affect mortality in California.
abstract: OBJECTIVE
  Open thoracoabdominal aneurysm repair (TAAR) is a rarely performed but a complicated and morbid procedure. This study compares the morbidity and mortality of open TAAR at high- versus low-volume hospitals.
  
  
  METHODS
  Included patients from California Office of Statewide Health Policy and Development patient discharge database who underwent an open TAAR between 1995 and 2010. High volume was ≥ 9 cases per year. Outcomes included mortality and postoperative complications. Multivariate analyses compared patients at high- versus low-volume hospitals.
  
  
  RESULTS
  A total of 122 hospitals were included, with 5 designated as high volume. Adjusted analysis found no difference in the odds ratio (OR) of mortality or morbidity at high-volume hospitals compared to low-volume hospitals (OR 0.37, P = .077; OR 0.94, P = .834, respectively). However, there was a decreased OR of mortality in high- versus low-volume hospitals when a high-volume hospital was defined as each year after meeting the initial threshold of 9 cases (OR 0.40, P = .040).
  
  
  CONCLUSIONS
  We found no difference in mortality between low- and high-volume institutions in California, until high-volume hospitals were defined as each year after meeting initial threshold case volume. This may suggest that the benefits of high-volume hospitals on outcomes are maintained after reaching the requisite case volume.
authors: University of California San Diego, San Diego, CA, USA a3weiss@ucsd.edu.
authors: Anna
authors: A
authors: Weiss
authors: University of California San Diego, San Diego, CA, USA.
authors: Jamie A
authors: JA
authors: Anderson
authors: University of California San Diego, San Diego, CA, USA.
authors: Amanda
authors: A
authors: Green
authors: University of California San Diego, San Diego, CA, USA.
authors: David C
authors: DC
authors: Chang
authors: St. Elizabeth's Medical Center, Boston, MA, USA.
authors: Nikhil
authors: N
authors: Kansal
mesh_terms: D000368:Aged; D017545:Aortic Aneurysm, Thoracic / Q000401:mortality* / Q000601:surgery*; D002140:California / Q000453:epidemiology; D016009:Chi-Square Distribution; D016208:Databases, Factual; D005260:Female; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects / Q000401:mortality*
keywords: thoracoabdominal aneurysm; vascular surgery outcomes; volume outcomes relationship