title: Hospital volume, mitral repair rates, and mortality in mitral valve surgery in the elderly: an analysis of US hospitals treating Medicare fee-for-service patients.
abstract: BACKGROUND
  The volume-outcome relationship has been suggested as a quality metric in mitral valve surgery and would be particularly relevant in the elderly because of their greater burden of comorbidities and higher perioperative risk.
  
  
  RESULTS
  The study included 1239 hospitals performing mitral valve surgery on Medicare beneficiaries from 2000 through 2009. Only 9% of hospitals performed more than 40 mitral operations per year, 29% performed 5 or less, and 51% performed 10 or less. Mitral repair rates were low; 22.7% of hospitals performed 1 or less, 65.1% performed 5 or less, and only 5.6% performed more than 20 mitral repairs per year in those aged 65 years or more. Repair rates increased with increasing volume of mitral operations per year: 5 or less, 30.5%; 6 to 10, 32.9%; 11 to 20, 34.9%; 21 to 40, 38.8%; and more than 40, 42.0% (P = .0001). Hospitals with lower volume had significantly higher adjusted operative mortality compared with hospitals performing more than 40 cases per year: 5 or less cases per year, odds ratio (OR) 1.58 (95% confidence interval [CI], 1.40-1.78); 6 to 10 cases per year, OR 1.29 (95% CI, 1.17-1.43); 11 to 20 cases per year, OR 1.17 (95% CI, 1.07-1.28); 21 to 40 cases per year, OR 1.15 (95% CI, 1.05-1.26). Hospitals with lower mitral repair rates had an increased likelihood of operative mortality relative to the top quartile: lowest quartile, OR 1.31 (95% CI, 1.20-1.44); second quartile, OR 1.18 (95% CI, 1.09-1.29); and third quartile, OR 1.14 (95% CI, 1.05-1.24). Long-term mortality beyond 6 months was also higher in low-volume hospitals: 5 or less cases year, hazard ratio (HR) 1.11 (95% CI, 1.06-1.18); 6 to 10 cases per year, OR 1.06 (95% CI, 1.02-1.10) compared with hospitals performing more than 40 cases per year.
  
  
  CONCLUSIONS
  Most hospitals perform few mitral valve operations on elderly patients. Greater volume of mitral procedures was associated with higher repair rates. Both greater volume of mitral procedures and increasing mitral repair rates were associated with decreased mortality.
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Ill. Electronic address: cvassileva@siumed.edu.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Vassileva
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Ill.
authors.forename: Christian
authors.initials: C
authors.lastname: McNeely
authors.affiliation: Saint Luke's Mid America Heart Institute, University of Missouri - Kansas City, Kansas City, Mo.
authors.forename: John
authors.initials: J
authors.lastname: Spertus
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Ill.
authors.forename: Stephen
authors.initials: S
authors.lastname: Markwell
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, Southern Illinois University School of Medicine, Springfield, Ill.
authors.forename: Stephen
authors.initials: S
authors.lastname: Hazelrigg
mesh_terms: D000367:Age Factors; D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000401:mortality* / Q000639:trends; D016009:Chi-Square Distribution; D015897:Comorbidity; D018588:Fee-for-Service Plans / Q000639:trends; D005260:Female; D006349:Heart Valve Diseases / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D017052:Hospital Mortality; D061847:Hospitals, High-Volume / Q000639:trends; D061846:Hospitals, Low-Volume / Q000639:trends; D006801:Humans; D016015:Logistic Models; D008297:Male; D006278:Medicare / Q000639:trends; D008943:Mitral Valve / Q000503:physiopathology / Q000601:surgery*; D016017:Odds Ratio; D016016:Proportional Hazards Models; D019984:Quality Indicators, Health Care / Q000639:trends; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States
keywords: hospital volume; mitral valve; outcome research; surgery