The Impact of Late Surveillance Biopsy and Importance of “Borderline Rejection” On Allograft Outcome in Kidney Transplant Recipients.

Abstract

Listen

Translate article

Background: Our aim was to examine the impact of early and late surveillance biopsy findings on kidney allograft functional outcome. Many inflamed biopsies with changes insufficient to be called T-Cell-mediated rejection are labeled “borderline “and its implication on graft outcome remains uncertain. Methods: We studied 158 renal transplant recipients between 2004 to 2012; mean follow up was 5.2 (standard deviation: 0.24) yrs. Early protocol biopsy (B1) and late protocol biopsy (B2) were performed between 3-12 and 13-24 months (m) respectively. There were 102 patients who had both biopsies. Biopsies were classified as: interstitial fibrosis and/or tubular atrophy only (IFTA), normal histology (NML), acute rejection (AR), borderline rejection (BDR). Baseline graft function by estimated glomerular filtration rate (eGFR) was fixed at 12m while changes were evaluated up to last follow up eGFR. Univariate and multivariable linear mixed effect models were developed to examine the effects of surveillance biopsies on changes in the eGFR. Random intercepts and random time effects were considered in linear mixed model analysis. All statistical analyses were carried out using SAS 9.3. Results: The eGFR rate declined from 12m to last visit was found to be -1.26 ± 0.40(standard error) per year. Multivariate analysis revealed that eGFR at 3 m, donor age, and delayed graft function were associated with baseline eGFR while B1 and B2 findings were significantly associated with both baseline eGFR and change in eGFR over time. Final multivariate analysis of both B1 and B2 taken together showed that the change in eGFR was found to be associated with findings of IFTA in B1 (p=0.0038), AR in B2 (p=0.0605) and BDR in B2 (p=0.049) when compared to NML. All three abnormal histology groups had lower eGFR (AR=25.65 ±14.28 ml/min; p=0.1029), (BDR=42.17±19.24; p=0.016), (IFTA 45.26±16.13; p=0.016), than those with (NML=51.77±16.96 ml/min) at last follow up (p<0.05). Conclusion: Early biopsy results correlate with baseline GFR at 12m; while abnormal late surveillance biopsy results significantly impact GFR decline over long-term. In addition, the diagnosis of borderline inflammation on surveillance biopsy affected graft functional status on long-term follow up.