Figure 4.

Predicted probability of ACR from the 10-fold cross-validation of the five-gene urinary cell diagnostic signature. After the differentiation of AR from ATI in the first step (Figure 1), in the second step and among patients diagnosed with AR biopsies, we derived (using the same assay results) another urinary cell diagnostic signature to better differentiate ACR biopsies (n=26 patients) from AMR biopsies (n=26 patients) than any single mRNA measure. By quadratic discriminant function analysis, a linear combination of four mRNAs (CD3ε, CD105, CD14, and CD46) and 18S rRNA emerged as the parsimonious model and yielded a discriminant score that constituted the diagnostic signature. We did 10-fold cross-validation to internally validate the five-gene diagnostic signature. The left panel shows the box plot of predicted probability of ACR biopsies from the cross-validation. The right panel shows the ROC curve of the five-gene urinary cell diagnostic signature to diagnose ACR. The AUC is the estimate of the expected value in an independent sample not used for deriving the diagnostic signature.