Abstract: SA-PO475

Magnitude of Pre-Biopsy Decline in Renal Function and Its Association with Allograft Rejection

Session Information

Category: Transplantation

  • 1702 Transplantation: Clinical and Translational

Authors

  • Voora, Santhi, UCSF, San Francisco, California, United States
  • Ahearn, Patrick, UCSF, San Francisco, California, United States
  • Tavakol, Matthew Mehdi, UCSF, San Francisco, California, United States
  • Johansen, Kirsten L., UCSF, San Francisco, California, United States
  • Ku, Elaine, UCSF, San Francisco, California, United States
Background

Acute rejection is a significant cause of morbidity, and transplant biopsy remains the gold standard for the diagnosis of rejection. Guidelines published by KDIGO recommend biopsy for “persistent, unexplained increase in serum creatinine.” To our knowledge there have been few studies defining the magnitude of decline in renal function that should trigger a biopsy to rule out rejection.

Methods

We performed a retrospective analysis of patients at a single center who underwent diagnostic transplant biopsy (excluding surveillance biopsies) between 2006-2016 at least three months post-transplant. We evaluated for association between pre-biopsy decline in renal function (mean of renal function measured between 6 months prior to biopsy and day of biopsy) and pathologic findings of rejection using logistic regression models (adjusted for age, race, sex, diabetes, donor type and transplant year). Absolute rise in serum creatinine and percent change in estimated glomerular filtration rate (eGFR) by CKD-EPI equation were examined as predictors of the outcome of rejection (cellular or antibody-mediated).

Results

1,224 biopsies were included for analysis. Mean age was 46.3 years. 58.3% were men, and 18% were black. Overall, 53.5% of biopsies demonstrated evidence of rejection. Declines in eGFR of ≥20% were associated with higher odds of rejection in both unadjusted and adjusted analyses compared to a <5% decline in eGFR [Table]. Rises in absolute serum creatinine by ≥0.3 mg/dL also corresponded with a higher risk of rejection compared to rises in creatinine by <0.3 mg/dL.

Conclusion

In this single-center study, decline in eGFR ≥20% or rise in serum creatinine by ≥0.3 mg/dL were associated with higher risk of rejection. Changes in renal function of this magnitude may warrant prompt arrangement of biopsy given the high risk of rejection.

Thresholds of decline in renal function and risk of rejection
Percent Change in eGFRNumber of biopsiesUnadjusted
Odds Ratio (95% CI)
P ValueAdjusted Odds Ratio (95% CI)P Value
<5%2301.0ref1.0ref
5-<20%2490.91 (0.63-1.32)0.610.93 (0.64-1.35)0.70
20-40%2021.55 (1.08-2.22)0.021.65 (1.14-2.39)0.02
≥40%5432.43 (1.73-3.42)<0.0012.33 (1.64-3.29)<0.001
Absolute rise in serum creatinine (mg/dL)Number of biopsiesUnadjusted Odds Ratio (95% CI)P ValueAdjusted Odds Ratio (95% CI)P Value
<0.34371.0ref1.0ref
0.3-<0.62011.68 (1.19-2.36)0.0031.67 (1.19-2.37)0.003
≥0.65842.70 (2.09-3.50)<0.0012.55 (1.96-3.32)<0.001

Funding

  • NIDDK Support