Decision Tree to Determine Impact of Pathology on Kidney Discard Determinations

Presenting results at the American Transplant Congress 2024, Kathryn Sarullo, PhD, and others developed a decision tree to determine the impact of histopathology in kidney discard determinations.

The researchers posited that healthy donor kidneys are being discarded due to inaccurate biopsy interpretation. Machine learning can aid in improving the accuracy of histopathologic examination, potentially lowering the rate of discarded kidneys.

The team trained a decision tree on histopathologic data, evaluating 2681 kidney biopsy referrals between 2015 and 2020 (n=5168 slides). At the start, the classes were unbalanced (keep, n=4339; discard, n=829); discard data were duplicated until the classes were balanced (keep, n=4339; discard, n=4145).

Pathology findings informing decisions to discard included global glomerulosclerosis above 20%, interstitial fibrosis, arteriosclerosis, necrosis, and fibrin thrombi. The decision tree found that the number of additional criteria met was more important than global glomerulosclerosis. If one or more criteria were met, the kidney was categorized as discarded. If no criteria were met, any biopsy with global glomerulosclerosis above 5.1% was categorized as discarded. Of the kidney biopsies labeled for discard, 55% (n=455) did not demonstrate significant histopathologic findings.

Large decision trees have higher accuracy and a higher F1 score (harmonic mean of precision and recall) than histopathology alone. Including histopathologic criteria in addition to global glomerulosclerosis increases the F1 score significantly.

The researchers concluded that, “Although all histologic data is used in the discard decision, there are other unknown factors leading to organ discard. Future studies are warranted to determine the nature of other discard factors and their rationale, especially in cases where kidneys appear transplantable by histology.”

Source: Sarullo K, Gaut JP, Swamidass J. Does pathology impact decisions to discard or keep donor kidneys? Abstract #C150. Presented at the American Transplant Congress 2024; June 1-5, 2024; Philadelphia, Pennsylvania.