Simple score to assess the risk of rejection after orthotopic heart transplantation.

BACKGROUND The aim of this study was to derive and validate a risk score for rejection after orthotopic heart transplantation. METHODS AND RESULTS The United Network for Organ Sharing registry was used to identify patients undergoing orthotopic heart transplantation between 1998 and 2008. A total of 14 265 eligible patients were randomly divided into derivation (80%; n=11 412) and validation (20%; n=2853) cohorts. The primary outcome was drug-treated rejection within 1 year of orthotopic heart transplantation. Covariates found to be associated (exploratory univariate P<0.2) with rejection were entered into a multivariable logistic regression model. Inclusion of each variable in the model was assessed by improvement in the McFadden pseudo-R(2), likelihood ratio test, and c index. A risk score was then generated through the use of relative magnitudes of the odds ratios from the derivation cohort, and its ability to predict rejection was tested independently in the validation cohort. A 13-point risk score incorporating 4 variables (age, race, sex, HLA matching) was created. The mean scores in the derivation and validation cohorts were 8.3±2.2 and 8.4±2.1, respectively. Predicted 1-year rejection rates based on the derivation cohort ranged from 16.2% (score=0) to 50.7% (score=13; P<0.001). In weighted regression analysis, there was a strong correlation between these predicted rates of rejection and actual, observed rejection rates in the validation cohort (r(2)=0.96, P<0.001). Logistic regression analysis also demonstrated a significant association (odds ratio, 1.13; P<0.001). The c index of the composite score was equivalent in both the derivation and validation cohorts (c=0.67). CONCLUSIONS This novel 13-point risk score is highly predictive of clinically significant rejection episodes within 1 year of orthotopic heart transplantation. It has potential utility in tailoring immunosuppressive regimens and in research stratification in orthotopic heart transplantation.