title: Creation of a quantitative recipient risk index for mortality prediction after cardiac transplantation (IMPACT).
abstract: BACKGROUND
  No recipient risk index exists predicting short-term mortality after orthotopic heart transplantation (OHT). We utilized United Network for Organ Sharing (UNOS) data to develop a novel quantitative recipient risk score for use in OHT.
  
  
  METHODS
  A prospectively collected open cohort of 21,378 primary OHT patients (1997 to 2008) was randomly divided into subgroups. The training cohort (n=17,079) was used for score derivation and the test cohort (n=4,299) was used for independent validation. Recipient specific variables associated with 1-year mortality (exploratory p value<0.2) were incorporated stepwise into a multivariable logistic regression model. The final model contained variables which maximized explanatory power (assessed by pseudo R2, area under the curve, and likelihood-ratio test). A risk index was created by apportioning points approximating the relative impact of variables on 1-year mortality. The Kaplan-Meier method was used to assess impact of risk score on short-term survival.
  
  
  RESULTS
  The 50-point scoring system incorporated 12 recipient specific variables. Derivation and validation cohort scores ranged from 0 to 33 and 0 to 27, respectively (mean 6.1±3.7 and 6.1±3.7). Each point increased the odds of 1-year death by 14% in the derivation cohort (odds ratio 1.14 [1.13 to 1.15], p<0.001) and 15% in the validation cohort (odds ratio 1.15 [1.12 to 1.17], p<0001). One-year survivals in the validation cohort (by increments of 3 points) were the following: 0 to 2 (92.5%); 3 to 5 (89.9%); 7 to 9 (86.3%); and 10 or greater (74.9%); p<0.001. Patients transplanted with risk scores of 20 or higher had 1-year mortality rates greater than 50%.
  
  
  CONCLUSIONS
  We present a novel internally validated OHT recipient risk score, which is highly predictive of 1-year mortality. This risk index may prove valuable for patient prognosis, organ allocation, and research stratification in OHT.
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Weiss
authors.forename: Jeremiah G
authors.initials: JG
authors.lastname: Allen
authors.forename: George J
authors.initials: GJ
authors.lastname: Arnaoutakis
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: George
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Russell
authors.forename: Ashish S
authors.initials: AS
authors.lastname: Shah
authors.forename: John V
authors.initials: JV
authors.lastname: Conte
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000401:mortality / Q000601:surgery*; D016027:Heart Transplantation / Q000401:mortality*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008396:Maryland / Q000453:epidemiology; D008875:Middle Aged; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends