IMPORTANCE OF ALLOGRAFT BIOPSY IN RENAL-TRANSPLANT RECIPIENTS - CORRELATION BETWEEN CLINICAL AND HISTOLOGICAL DIAGNOSIS

Renal allograft dysfunction after transplantation may be caused by acu te rejection (AR), chronic rejection (CR), cyclosporine (CyA) or tacro limus (FK) toxicity, and other causes such as recurrence of renal dise ase. Allograft biopsy is the ''gold standard'' to establish the correc t diagnosis. However, many transplant centers routinely do not conside r graft biopsy at the onset of renal dysfunction; instead, empirical s teroid therapy or CyA dose reduction is the initial response to graft dysfunction. In this study, we prospectively predicted the histologica l findings prior to renal biopsy and correlated the clinical and histo logical diagnoses after the final report was issued by the pathologist . Patients with renal dysfunction after transplantation (increased ser um creatinine >20% from baseline) were submitted to allograft biopsy. Three clinicians (C1, C2, and C3) involved in the care of these patien ts independently predicted the histological findings prior to the biop sy. A total of 100 cases (62 men, 38 women; 71 whites, 29 blacks) with a mean age of 41 years (21 to 70 years) were included in this study. Biopsy samples were taken after a mean period of 1.6 +/- 0.32 years (m edian, 0.25 years; range, 4 days to 17 years) after transplantation. T wo patients with en bloc pediatric kidneys required postbiopsy blood t ransfusions for self-limiting bleeding; all other patients had no comp lications. Al patients received azathioprine and prednisone; additiona lly, 74 received CyA and 19 FK. Final histopathologic diagnoses were A R (30), CyA/FK toxicity (36), AR plus CyA/FK toxicity (17), CR (11), r ecurrent disease (11), and other (6). In 28 cases (28%), the results o f the biopsies showed more than one diagnosis. A completely correct di agnosis was predicted by C1, C2, and C3 in 47%, 42%, and 41% (mean, 43 %) of the cases, incorrect diagnosis in 25%, 27%, and 25% (mean, 26%) of the cases, and partially correct diagnosis in 28%, 31%, and 34% (me an, 31%) of the cases, respectively. AR was confirmed histologically i n 26 of 47 cases (55%) in the presence of therapeutic or high CyA/FK b lood levels, whereas in 41 of 53 cases (77%), the histology showed CyA /FK toxicity in the presence of therapeutic or low CyA/FK blood levels . The mean serum creatinine at the time of the biopsy was 2.92 +/- 0.3 0 mg/dL, compared with the baseline of 1.76 +/- 0.10 mg/dL (P < 0.0001 ). After appropriate treatment, mean serum creatinine was 2.38 +/- 0.3 3 mg/dL (P < 0.0001). These data show that clinical prediction was poo r, with totally correct diagnosis in only 43% of the cases. In 26%, th e diagnosis was incorrect. We conclude that the renal biopsy is essent ial for establishing the correct diagnosis of renal allograft dysfunct ion and the appropriate management thereof. (C) 1998 by the National K idney Foundation, Inc.