Purpose: Surveillance biopsies can detect subclinical T cell mediated rejection (SC-TCMR) or subclinical borderline rejection (SC-B-TCMR) in patients with normal/stable creatinine, but the impact on long-term outcomes is unclear, particularly in centers enriched for high immune risk populations such as black recipients. We hypothesized that SC-B-TCMR, which is frequently not treated, will behave similarly as SC-TCMR with worse outcomes than those with no major surveillance abnormality (NOMOA).

Methods: We reviewed all kidney transplant biopsies (N=601) performed at our center from May 2015 to December 2016, immediately following inception of 6-month surveillance biopsies in post-transplant management. The primary exposure was SC-B-TCMR or SC-TCMR by Banff 2013 criteria. The primary outcome was a composite endpoint of acute rejection after surveillance and death-censored graft loss.

Results: We identified 166 (28%) biopsies performed for 6-month surveillance. Our cohort was 55% black and 61% were recipients of deceased donor kidneys. We detected SC-B-TCMR in 48 (29%) and SC-TCMR in 9 (5%) of recipients. All SC-TCMR and 42% of SC-B-TCMR were treated with increased immunosuppression, while 58% of SC-B-TCMR were managed expectantly. The composite endpoint occurred in 10/166 (6%) overall, including 15% of SC-B-TCMR and 20% of SC-TCMR versus only 1% of NOMOA (P<0.001). In SC-B-TCMR, the composite endpoint occurred in 10% that were treated with increased maintenance or pulse corticosteroid therapy (clinician's discretion) compared to 18% in those expectantly managed (P=0.001 compared to NOMOA). Despite similar SC-B-TCMR rates by race, black recipients with SC-B-TCMR had worse outcomes compared to non-black SC-B-TCMR and all-race NOMOA (P<0.0001, Figure).

Conclusions: SC-B-TCMR and SC-TCMR were detected in 34% of recipients and had similar outcomes that were worse than for those with NOMOA. Black recipients had the worst outcomes after SC-B-TCMR. The impact of treating subclinical borderline rejection must be validated in prospective studies to personalize immunosuppression in high-risk populations.

CITATION INFORMATION: Bernard M., Agarwal G., Fatima H., Julian B., Kew C., Kumar V., Mehta S., Ong S., Patel A., Towns G., Seifert M., Mannon R. Subclinical Borderline Rejection: More Than Meets the Eye? Am J Transplant. 2017;17 (suppl 3).

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