ABS levels correlate well with cfdDNA and endomyocardial biopsy results.

<p>(A) ABS levels plotted for all study participants. Acute rejection events as diagnosed by endomyocardial biopsy (ACR, violet; acute antibody-mediated rejection [AMR], green) or cfdDNA level (pink) are shown in color. (B) Samples are classified by rejection status diagnosed by biopsy as no evidence of rejection, mild ACR (biopsy grade 1R), or moderate-to-severe ACR (biopsy grade ≥ 2R), and by rejection status diagnosed by the cfdDNA assay. Samples are colored as in (A) if at any point the organ recipient experienced a serious rejection event. As biopsy grades are independent of cfdDNA measurements, there is overlap between samples in the elevated cfdDNA and biopsy-proven rejection bins. The groups were compared using a one-sided Mann-Whitney U test, which has high efficiency for both normally and non-normally distributed datasets. (C) Receiver operating characteristic (ROC) curves for ABS levels compared to cfdDNA (pink) and endomyocardial biopsy (violet) results. FPR, false rejection rate; TPR, true positive rate. (D) ABS levels measured before and after rejection diagnosis. The black line shows the single-exponent fit of ABS levels measured prior to rejection, <i>y</i> = <i>a</i> × (exp[<i>b</i> × <i>t</i>]), with best fit values (least squares) of <i>a</i> = 0.0317 and <i>b</i> = 0.00468. The gray line shows the single-exponent fit of ABS levels after diagnosis and during treatment of rejection: <i>y</i> = <i>a</i> × (exp[<i>b</i>× <i>t</i>]), with best fit values (least squares) of <i>a</i> = 0.0344 and <i>b</i> = −0.0324. Green lines show the median ABS levels in the covered time periods.