title: Outcome of mitral valve repair or replacement: a comparison by propensity score analysis.
abstract: BACKGROUND
  There are no randomized trials comparing outcomes after mitral valve (MV) repair and replacement. Propensity scoring is a powerful tool that has the potential to reduce selection bias in nonrandomized studies.
  
  
  METHODS
  From the BC Cardiac Registries, 2,060 patients presented for MV surgery, with or without CABG between 1991 and 2000. We then identified 322 MV repairs who were then matched by propensity score to an equal number of MV replacement patients. We compared survival and freedom from re-operation outcomes using Cox proportional hazards model analysis. Multivariable analysis was then used to compare outcomes in 358 MV repair patients with 352 MV replacement patients who had undergone chordal sparing surgery.
  
  
  RESULTS
  The comparison groups generated using propensity scores were well balanced with respect to all collected baseline risk factors. Median follow-up time was 3.4 years. Patients undergoing MV repair had significantly improved survival (RR 0.46; 95% CI, 0.28 to 0.75) but a trend toward more re-operations (RR 2.11; 95% CI, 1.00 to 4.47) compared with patients undergoing replacement. Mitral valve repair patients still had better survival (RR 0.52; 95% CI, 0.32 to 0.85) compared with MV replacement patients who had undergone chordal sparing surgery.
  
  
  CONCLUSIONS
  We used propensity score methods to reduce selection bias in a population-based cohort of patients undergoing MV repair/replacement. Repair was associated with better survival, but a trend to increased re-operation.
authors.affiliation: Division of Cardiology, St. Paul's Hospital, Vancouver, BC, Canada.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Moss
authors.forename: Karin H
authors.initials: KH
authors.lastname: Humphries
authors.forename: Min
authors.initials: M
authors.lastname: Gao
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Thompson
authors.forename: James G
authors.initials: JG
authors.lastname: Abel
authors.forename: Guy
authors.initials: G
authors.lastname: Fradet
authors.forename: Brad I
authors.initials: BI
authors.lastname: Munt
mesh_terms: D018572:Disease-Free Survival; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery*; D015233:Models, Statistical; D012086:Reoperation; D015996:Survival Rate; D016896:Treatment Outcome