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Kidney Week

Abstract: PO2195

Diagnostic Performance of Donor-Derived Cell-Free DNA Assay (AlloSure®) in Kidney Transplant Recipients with Graft Dysfunction: A Single-Center Study

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Naseer, Muhammad Saad, Willis Knighton Medical Center, Shreveport, Louisiana, United States
  • Singh, Ayush, Willis Knighton Medical Center, Shreveport, Louisiana, United States
  • Singh, Neeraj, Willis Knighton Medical Center, Shreveport, Louisiana, United States
Background

Circulating donor-derived cell-free DNA (dd-cf-DNA) is a non-invasive biomarker of kidney allograft injury with a high negative predictive value for ruling out active rejection in patients with evidence of graft dysfunction. At our center, we compared the AlloSure® test (CareDx®) for the dd-cfDNA assays using >1% as the cut-off value suggested by the DART study or an increase of >30% from the previous value against the gold standard biopsy results and calculated its performance metrics.

Methods

From Dec 2019 to Oct 2020, we found 16 patients who had their 21 AlloSure® assays drawn which were within 4 weeks of for-cause biopsy sampling. In assessing the cause of 21 biopsy samples, 20 had AKI, 5 had proteinuria, and 3 had clinical symptoms of volume overload.

Results

AlloSure® and biopsy results were concordant in 14/21 (66.7%) samples [Table 1]. Of the 21 for-cause biopsies, 8 biopsies were positive for rejection (2 borderline, 1 TCMR, 3 AMR, 1 mixed AMR/TCMR, 1 chronic). AlloSure® was positive in 2 of these rejections (1 TCMR, 1 mixed AMR/TCMR). However, it was false-negative in the other 6 rejections (2 borderline, 3 AMR, 1 chronic). Out of the 13 negative biopsy results, AlloSure® was negative in 12 samples and false-positive in one sample. The performance metrics in this patient population were: sensitivity 25%, specificity 92.3%, positive and negative predictive values of 66.7%, and accuracy of 66.7%.

Conclusion

Although we had a sample size, it can be concluded from this study that AlloSure® has a high specificity to diagnose active graft rejection in kidney transplant recipients.

Table 1: 2 x 2 Table
 Biopsy
PositiveNegativeTotal
AlloSure®Positive213
Negative61218
Total81321