(A) The urine score performed better than eGFR or the urinary protein/creatinine ratio in discriminating AR vs STA. For the entire set of 170 STA and 103 AR, the Q-Score, eGFR, and protein/creatinine (Pr/Cr) ratio were plotted and the AUC calculated. The AUCs were 0.99, 0.86, and 0.76 respectively. (B) Similar performance of the urine score for non-invasive diagnosis of biopsy-confirmed pediatric and adult AR. The urine score performed well for diagnosis of AR in children ≤ 18 yrs. old as well as adult recipients >18 yrs. old: Pediatric AUC = 0.95 (No AR 30, AR 21); Adult AUC = 0.99 (No AR 138, AR 82).