Confounding factors.

The GlobalAncova analysis evaluates if the panel protein levels remain significantly differentiated between the acute rejection (AR) and the non-rejection (NR) groups after adjusting for potential confounding factors. A p value below 0.05 provides evidence of significant differentiation. We use the clinical data available at the time closest to the collection time of the plasma sample measured by iTRAQ (additional potential confounders are shown in the Table S5). The correlation between the value of potential confounders and the LDA classifier score was evaluated using a Pearson correlation coefficient. The last two columns show the mean and standard deviation (SD) of the clinical variables for the 6 AR samples and 14 NR samples in the discovery cohort.