title: Procedure-specific Cardiac Surgeon Volume associated with Patient outcome following Valve Surgery, but not Isolated CABG Surgery.
abstract: OBJECTIVE
  Trends towards surgical sub-specialisation to improve patient-outcomes are well-documented and largely supported by evidence. However few studies have examined whether this benefit exists within adult-cardiac surgery. To answer whether sub-specialisation within adult-cardiac surgery improves patient-outcomes, this study assessed the relationship between procedure-specific and total-cardiac surgeon-volume and mortality and morbidity in cardiac-valve and coronary artery bypass grafting (CABG) surgery.
  
  
  METHODS
  Data came from the Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) registry from 2001 to 2010 and included 23 hospitals, 109 surgeons, 20,619 patients with isolated-CABG-surgery and 11,536 patients with a valve-procedure. Hierarchical logistic regression using generalised estimating equations was used to analyse outcomes. Measures included operative-mortality and occurrence of a complication (deep sternal wound infection, new stroke, acute kidney injury).
  
  
  RESULTS
  Crude operative mortality (and complication rates) were 1.7% (4.9%) and 4% (11%) in the isolated-CABG and valve-surgical populations respectively. A greater procedure-specific surgeon volume was associated with reduced mortality and complication rates in valve-surgery but not isolated-CABG. There was a 33% decrease in odds of dying for every additional 50 valve procedures performed [OR 0.67, p=0.003]. Conversely, greater total-cardiac surgical volume for individual surgeons did not result in improved outcomes, for both isolated-CABG and valve populations.
  
  
  CONCLUSIONS
  Our finding of an association between increased valve-specific surgeon volumes with improved valve-surgery outcomes, and absence of an association between these outcomes and annual total-cardiac surgical experience supports the case for sub-specialisation specifically within the field of valve surgery.
authors.affiliation: Monash Medical Centre, Melbourne Australia; Epworth HealthCare, Melbourne, Australia. Electronic address: zlt.chng@gmail.com.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Ch'ng
authors.affiliation: Monash Medical Centre, Melbourne Australia.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Cochrane
authors.affiliation: School of Public Health and Preventive Medicine, Monash University, Melbourne Australia.
authors.forename: Rory
authors.initials: R
authors.lastname: Wolfe
authors.affiliation: School of Public Health and Preventive Medicine, Monash University, Melbourne Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Reid
authors.affiliation: School of Public Health and Preventive Medicine, Monash University, Melbourne Australia.
authors.forename: Catherine I
authors.initials: CI
authors.lastname: Smith
authors.affiliation: Monash Medical Centre, Melbourne Australia.
authors.forename: Julian A
authors.initials: JA
authors.lastname: Smith
mesh_terms: D000328:Adult; D001315:Australia; D002423:Cause of Death; D016000:Cluster Analysis; D001026:Coronary Artery Bypass / Q000379:methods / Q000401:mortality* / Q000706:statistics & numerical data*; D016208:Databases, Factual; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000379:methods / Q000401:mortality* / Q000706:statistics & numerical data*; D017052:Hospital Mortality; D061847:Hospitals, High-Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D011183:Postoperative Complications / Q000401:mortality / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D011786:Quality Control; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D013043:Specialties, Surgical; D016019:Survival Analysis; D016896:Treatment Outcome
keywords: Adult cardiac surgery; Coronary artery bypass; High-volume; Hospital; Specialization; Valve surgery