title: Influence of patient age and implantation technique on the probability of re-replacement of the homograft aortic valve.
abstract: OBJECTIVE
  Results of valve rereplacement (reoperation) in 898 patients undergoing aortic valve replacement with cryopreserved homograft valves between 1975 and 1998 are reported. The study aim was to provide estimates of unconditional probability of valve reoperation and cumulative incidence function (actual risk) of reoperation.
  
  
  METHODS
  Valves were implanted by subcoronary insertion (n = 500), inclusion cylinder (n = 46), and aortic root replacement (n = 352). Probability of reoperation was estimated by adopting a mixture model framework within which estimates were adjusted for two risk factors: patient age at initial replacement, and implantation technique.
  
  
  RESULTS
  For a patient aged 50 years, the probability of reoperation in his/her lifetime was estimated as 44% and 56% for non-root and root replacement techniques, respectively. For a patient aged 70 years, estimated probability of reoperation was 16% and 25%, respectively. Given that a reoperation is required, patients with non-root replacement have a higher hazard rate than those with root replacement (hazards ratio = 1.4), indicating that non-root replacement patients tend to undergo reoperation earlier before death than root replacement patients.
  
  
  CONCLUSIONS
  Younger patient age and root versus nonroot replacement are risk factors for reoperation. Valve durability is much less in younger patients, while root replacement patients appear more likely to live longer and hence are more likely to require reoperation.
authors: Department of Mathematics, The University of Queensland, St. Lucia, Australia.
authors: Shu K
authors: SK
authors: Ng
authors: Mark F
authors: MF
authors: O'Brien
authors: Susan
authors: S
authors: Harrocks
authors: Geoffrey J
authors: GJ
authors: McLachlan
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000637:transplantation*; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000401:mortality / Q000601:surgery; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D015994:Incidence; D007223:Infant; D008875:Middle Aged; D011336:Probability; D012086:Reoperation; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome