title: Congenital Heart Surgery Case Mix Across North American Centers and Impact on Performance Assessment.
abstract: BACKGROUND
  Performance assessment in congenital heart surgery is challenging due to the wide heterogeneity of disease. We describe current case mix across centers, evaluate methodology inclusive of all cardiac operations versus the more homogeneous subset of Society of Thoracic Surgeons benchmark operations, and describe implications regarding performance assessment.
  
  
  METHODS
  Centers (n = 119) participating in the Society of Thoracic Surgeons Congenital Heart Surgery Database (2010 through 2014) were included. Index operation type and frequency across centers were described. Center performance (risk-adjusted operative mortality) was evaluated and classified when including the benchmark versus all eligible operations.
  
  
  RESULTS
  Overall, 207 types of operations were performed during the study period (112,140 total cases). Few operations were performed across all centers; only 25% were performed at least once by 75% or more of centers. There was 7.9-fold variation across centers in the proportion of total cases comprising high-complexity cases (STAT 5). In contrast, the benchmark operations made up 36% of cases, and all but 2 were performed by at least 90% of centers. When evaluating performance based on benchmark versus all operations, 15% of centers changed performance classification; 85% remained unchanged. Benchmark versus all operation methodology was associated with lower power, with 35% versus 78% of centers meeting sample size thresholds.
  
  
  CONCLUSIONS
  There is wide variation in congenital heart surgery case mix across centers. Metrics based on benchmark versus all operations are associated with strengths (less heterogeneity) and weaknesses (lower power), and lead to differing performance classification for some centers. These findings have implications for ongoing efforts to optimize performance assessment, including choice of target population and appropriate interpretation of reported metrics.
authors.affiliation: Department of Pediatrics and Communicable Diseases, C.S. Mott Children's Hospital, Ann Arbor, Michigan. Electronic address: pasquali@med.umich.edu.
authors.forename: Sara K
authors.initials: SK
authors.lastname: Pasquali
authors.affiliation: Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina.
authors.forename: Amelia S
authors.initials: AS
authors.lastname: Wallace
authors.affiliation: Department of Surgery, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: J William
authors.initials: JW
authors.lastname: Gaynor
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; Division of Cardiovascular Surgery, Department of Surgery, Johns Hopkins All Children's Heart Institute, All Children's Hospital and Florida Hospital for Children, St. Petersburg, Tampa, and Orlando, Florida.
authors.forename: Marshall L
authors.initials: ML
authors.lastname: Jacobs
authors.affiliation: Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina.
authors.forename: Sean M
authors.initials: SM
authors.lastname: O'Brien
authors.affiliation: Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Hill
authors.affiliation: Department of Pediatrics and Communicable Diseases, C.S. Mott Children's Hospital, Ann Arbor, Michigan.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gaies
authors.affiliation: Department of Cardiac Surgery, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Romano
authors.affiliation: Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: David M
authors.initials: DM
authors.lastname: Shahian
authors.affiliation: Department of Cardiovascular Surgery, Boston Children's Hospital, Boston, Massachusetts.
authors.forename: John E
authors.initials: JE
authors.lastname: Mayer
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; Division of Cardiovascular Surgery, Department of Surgery, Johns Hopkins All Children's Heart Institute, All Children's Hospital and Florida Hospital for Children, St. Petersburg, Tampa, and Orlando, Florida.
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Jacobs
mesh_terms: D019985:Benchmarking; D006348:Cardiac Surgical Procedures / Q000401:mortality / Q000706:statistics & numerical data*; D016507:Cardiology Service, Hospital / Q000706:statistics & numerical data; D002675:Child, Preschool; D016208:Databases, Factual; D003953:Diagnosis-Related Groups; D005260:Female; D006330:Heart Defects, Congenital / Q000145:classification / Q000453:epidemiology / Q000601:surgery*; D017052:Hospital Mortality; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017063:Outcome Assessment, Health Care; D018401:Sample Size; D014481:United States / Q000453:epidemiology