A BLINDED RETROSPECTIVE ANALYSIS OF RENAL ALLOGRAFT PATHOLOGY USING THE BANFF SCHEMA

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Abstract
We sought to determine whether diagnoses established through the Banff schema for evaluation of renal allograft pathology have implications for clinical management, compared with diagnoses established using descriptive terminology. All patients included in this study had mild to severe allograft rejection diagnosed, and, as part of a therapeutic protocol, they received OKT3 as primary anti-rejection therapy. We conducted a retrospective review of their renal allograft biopsy specimens and reclassified them, using the Banff schema, without knowledge of clinical information, laboratory data, or previous biopsy interpretation. Although there is no strict correspondence between descriptive diagnostic terminology and the criteria used in the Banff schema, for the purpose of comparisons, the following approximation was used: mild and mild to moderate rejection=Banff borderline and Banff grade 1, moderate and moderate to severe rejection=Banff grades 2A and 2B, and severe rejection=Banff grade 3. The diagnosis was considered concordant when the diagnosis by descriptive terminology and Banff grading were within the adopted approximation. Of 96 biopsies specimens with mild to severe allograft rejection, 10 were insufficient for diagnosis, and three had changes of chronic allograft rejection. Of the remaining 83 biopsy specimens, 34 (41%) were concordant in interpretation of rejection grades, whereas 49 (59%) were discrepant. The greatest degree of concordance was in grades 2A (66.7%, 18 of 27) and 2B (64.7% 11 of 17), and the lowest was in the borderline category (11.8%, 2 of 17). The greatest degree of discrepancy was in normal and grade 3 (100%, 3 of 3 and 2 of 2, respectively), and the lowest was in grade 2A (33.3%, 9 of 27). Although primary anti-rejection therapy with OKT3 resulted in a high reversal rate of rejection (98%), there were 5 deaths, 12 graft loses, six episodes of serious infections, and three malignancies in this group of patients during a mean follow-up period of approximately 38 months. Because patients with borderline changes and grades 1 and 2A rejection may be treated differently from patients with higher grades (2B and 3), the use of the Banff schema may allow for better adjustment of immunosuppressive therapy in response to specific grades of acute allograft rejection and may result in decreased complications of immunosuppressive therapy.