Pre-discharge, post-transplant kidney biopsy does not predict rejection

Rejection and function and chronic allograft dysfunction

Despite the impressive reduction in early acute rejection rates over the past decades, chronic allograft dysfunction remains a key issue after renal transplantation. A number of factors, such as the quality of the original organ, ischemia/reperfusion injury, and/or (treated) acute rejection, will adversely affect renal structure, causing early (but often mild) tubular atrophy and interstitial fibrosis. It remains, however, controversial whether subclinical acute rejection or borderline changes imply a different functional prognosis with longer times of follow-up, if cases with late clinical acute rejection, inadequate dosing, and/or incompliance with drug prescription are excluded. Serum creatinine and immunosuppressant trough levels constitute the current standard biomarkers for assessing and renal function and systemic drug exposure, respectively. Serum creatinine is a notoriously unreliable marker for the glomerular filtration rate; changes in creatinine concentration occur late in disease progression and do not accurately represent the ongoing underlying renal damage. Trough level monitoring without information on the patient's absorption profile or the related systemic drug exposure is equally unreliable for guiding initial calcineurin inhibitor dosing or for controlling systemic drug exposure while tapering. Until more sophisticated biomarkers to guide clinical immunosupprression become available, protocol biopsies may prove to be most useful in patients with an increased risk for (late) acute rejection.

Protocol biopsies in renal transplantation: prognostic value of structural monitoring

The natural history of renal allograft damage has been characterized in serial protocol biopsies. The prevalence of subclinical rejection (SCR) is maximal during the first months and it is associated with the progression of interstitial fibrosis/tubular atrophy (IF/TA) and a decreased graft survival. IF/TA rapidly progress during the first months and constitutes an independent predictor of graft survival. IF/TA associated with transplant vasculopathy, SCR, or transplant glomerulopathy implies a poorer prognosis than IF/TA without additional lesions. These observations suggest that protocol biopsies could be considered a surrogate of graft survival. Preliminary data suggest that the predictive value of protocol biopsies is not inferior to acute rejection or renal function. Additionally, protocol biopsies have been employed as a secondary efficacy variable in clinical trials. This strategy has been useful to demonstrate a decrease in the progression of IF/TA in some calcineurin-free regimens. Quantification of renal damage is associated with graft survival suggesting that quantitative parameters might improve the predictive value of protocol biopsies. Validation of protocol biopsies as a surrogate of graft survival is actively pursued, as the utility of classical surrogates of graft outcome such as acute rejection has become less useful because of its decreased prevalence with actual immunosuppression.

Risk factors for chronic allograft nephropathy after renal transplantation: a protocol biopsy study

BACKGROUND

Chronic allograft nephropathy (CAN) leads to chronic allograft dysfunction and loss. Regular renal transplant biopsies may be useful to find risk factors for CAN.

METHODS

We carried out 688 protocol biopsies in 258 patients at 6, 12, and 26 weeks after renal transplantation. Patients with signs of CAN in the biopsy 3 (N= 70, CAN group), and those without (N= 120, non-CAN group), were compared.

RESULTS

Chronic tubulointerstitial changes increased from biopsy 1 to 3 (5% vs. 37%, P < 0.0001). Fifty-six of 190 patients had acute rejection within 6 months (30%), 33 of which were found in protocol biopsies (17%). On univariate analysis, the CAN group had CAN more often at biopsy 2 than the non-CAN group (23% vs. 4%, P < 0.0001), had a lower calculated creatinine clearance at biopsy 1 and 2 (49.4 +/- 25.8 vs. 57 +/- 20.2 mL/min, P= 0.01; 47.3 +/- 21.2 vs. 57.9 +/- 19.5 mL/min, P= 0.001, respectively), had a living donor less often than a brain dead donor (7% vs. 18%, P= 0.045), had a longer cold ischemia time (17.4 +/- 7 vs. 14.9 +/- 8.1 hours, P= 0.04), and had arterionephrosclerosis more often (24% vs. 12%, P= 0.02). On multivariate analysis, the differences in CAN at biopsy 2 (P= 0.001) and lower GFR at biopsy 2 (P= 0.002) were confirmed; in addition, nephrocalcinosis (P= 0.006) and acute rejection (P= 0.046) were found to occur more often.

CONCLUSION

Chronic tubulointerstitial changes develop early after renal transplantation and are associated with reduced kidney function. Risk factors for CAN are arterionephrosclerosis (donor-related), nephrocalcinosis (related to preexisting hyperparathyroidism), a long cold-ischemia time (ischemia-perfusion-related), and acute rejection. Renal functional decline precedes morphologic changes of CAN, expressed as tubular atrophy and interstitial fibrosis.

Clinical significance of renal allograft biopsies with "borderline changes," as defined in the Banff Schema

BACKGROUND

The Banff Schema suggests the term "borderline changes" for biopsies showing changes insufficient for a diagnosis of mild acute rejection. The appropriate clinical management for patients showing such changes on biopsy is controversial.

METHODS

We reviewed the clinical course and response to antirejection therapy of 24 patients with borderline changes, and compared our findings with those obtained from 14 patients with mild acute rejection. Patients were classified as showing complete response, partial response, or no response to antirejection treatment, depending on whether the posttreatment fall in serum creatinine was >70%, 30-70%, or <30% of the pretreatment rise, respectively. Renal allograft biopsies were systematically evaluated in accordance with the Banff schema.

RESULTS

Complete response to antirejection therapy was seen in 15/24 (63%), partial response in 3/24 (13%), and nonresponse in 6/24 (25%) patients with borderline change. Compared with patients showing complete response, nonresponse was associated with higher scores of acute tubular necrosis and chronic allograft nephropathy (P<0.05). By comparison, 12/14 (86%) cases of mild acute rejection showed complete response to antirejection therapy (P=0.25 vs. patients with borderline change), and lack of response was associated with a higher score for chronic allograft nephropathy.

CONCLUSION

When biopsies are done in the context of renal allograft dysfunction, borderline changes frequently require increased immunosuppression. These findings should not be extrapolated to protocol biopsies performed in the setting of stable graft function.

Significance of the Banff borderline biopsy

In the Banff classification of kidney transplant pathology the "borderline changes" category falls short of a diagnosis of mild acute rejection, with the recommendation that no treatment is a possible clinical approach. We reviewed the clinical course of patients whose renal allograft biopsies showed "borderline changes" to determine how often these histologic findings actually represented acute rejection. Between January 1992 and June 1994, 351 biopsy specimens were obtained from 170 renal allografts and graded according to the Banff criteria. Eighty-one biopsy specimens were classified as "borderline changes" (23%). Of these, 59 had Banff scores of i1, t1, and vO; the remaining 22 had scores of i2, t1, and vO (i = interstitial infiltrate, t = tubulitis, and v = vasculitis). Medical record review showed that nearly all the "borderline" biopsies had been performed because of an elevated creatinine (Cr; 78 of 81 [96%]), with a mean increase of 1.1 +/- 0.1 mg/dL (+/- SE) over baseline. Most of the patients with "borderline changes" and elevated Cr were treated for acute rejection (61 of 78 [78%]); some with pulse steroids alone (29 of 61 [48%]), the rest with antilymphocyte antibody (32 of 61 [52%]). Among all 61 patients with "borderline" biopsies treated for rejection, 26 had a complete response (43%), 17 had a partial response (28%), and 18 had no response (30%). Interpretation of these changes in Cr, however, was confounded by intercurrent conditions in 28 of the patients. A group of 33 patients was therefore identified in whom a "borderline changes" biopsy was obtained, who were treated for rejection, and in whom all other identifiable causes of elevated Cr other than possible acute rejection had been systematically eliminated from consideration. In this group the mean Cr was 2.0 +/- 0.1 mg/dL at baseline, 3.3 +/- 0.2 mg/dL at the time of biopsy, and 2.2 +/- 0.1 mg/dL 1 month after treatment (P < 0.001 Cr at biopsy v Cr 1 month later). Among these 33 patients, 19 had a complete response (58%), 10 had a partial response (30%), and four had no response (12%). Therefore, the Cr in 88% of the patients in this group was lower 1 month after treatment for rejection than it was at the time of the biopsy. Follow-up biopsies were performed within 1 month of the "borderline" biopsy in 24 cases; these showed "borderline changes" (five of 24 [21%]), mild acute rejection (eight of 24 [33%]), or moderate to severe acute rejection (11 of 24 [46%]). We conclude that in the clinical setting of deteriorating renal graft function with mild elevation of serum Cr, the "borderline changes" biopsy frequently represents acute rejection. Antirejection treatment is therefore appropriate in the majority of cases. The reader should bear in mind that the current study is retrospective, with no control group. The risk of loosely interpreting these data is that some patients will be treated without due cause. Banff "borderline changes" should be used as part of an algorithm, but not the sole criterion, for therapeutic decision making.

The relative influence of delayed graft function and acute rejection on renal transplant survival

Three hundred and eight cadaveric renal transplants were analysed to establish the effects of acute rejection in the first 90 days and delayed graft function (DGF) on graft outcome. There were 120 patients (39%) with no DGF and no rejection (group 1), 101 patients (33%) with rejection but no DGF (group 2), 41 patients (13%) with DGF but no rejection (group 3) and 46 patients (15%) with both rejection and DGF (group 4). The actuarial 4-year graft survival rates for groups 1,2,3 and 4 were 78.3%, 65.4%, 60.1% and 40.4%, respectively. The acute rejection rate was 101/221 (46%) in patients with initial graft function compared with 46/87 (53%) for those with DGF (chi 2 = 1.02, P = 0.31). Cox stepwise logistic regression analysis demonstrated that DGF was a more powerful predictive factor for poor graft survival (P = 0.001) than acute rejection occurring in the first 90 days post-transplant (P = 0.034). Further efforts at improving graft outcome should concentrate on reducing the incidence of DGF.

The correlation of Banff scoring with reversibility of first and recurrent rejection episodes

Recurrent acute rejection remains a significant problem for recipients of renal allografts, with a large proportion of patients progressing to graft loss. The newly introduced Banff schema was used to determine whether the histologic pattern of acute rejection (severity and renal compartment scoring) could discriminate recurring from nonrecurring rejections and to examine whether objective rejection scoring had predictive value for rejection reversal and outcome. A total of 67 biopsies obtained from 50 patients with acute rejection were examined for the occurrence of recurrent allograft rejection. All patients were maintained on a cyclosporine-based triple immunosuppressive protocol and had biopsy-proven acute rejection without chronic changes. Rejection recurred in 13 patients (26%), of whom 4 further developed a third rejection. The majority of the patients developed this first rejection within 2 months posttransplantation. Demographics, prebiopsy renal function, immunosuppression, and peak serum creatinine level at the time of biopsy were similar in patients with multiple and single rejection. Peak levels of reactivity to panel of lymphocytes seemed higher in the group of patients with recurrent rejection, whereas HLA matching was similar for all patients. Banff scores for acute rejection did not discriminate patients at risk of rejection recurrence who had lower vascular (0.6 vs. 1.2), tubular (0.6 vs. 1.1), and lower cumulative SUM (3.0 vs. 4.5) scores on their first rejection when compared with patients with one rejection. Histological scoring was, however, significantly different when first and third episodes were compared in the same patient, indicating increased rejection severity with recurrence. Moreover, the rate of reversal of recurrent rejection by anti-lymphocyte therapy was significantly less than that of first rejection (P<0.05). In conclusion, these data demonstrate that Banff scoring correlated with rejection reversal and steroid responsiveness, yet rejection recurrence was independent of histological score of the first rejection. Furthermore, Banff schema provided an objective histological correlation to the poor clinical outcome seen with recurrent rejection. The data also suggest that patients with early mild rejection continue to be at risk for recurrence and graft loss.

Correlation between Banff classification, acute renal rejection scores and reversal of rejection

The Banff classification of acute rejection is based on histologic grades and scores for borderline changes, glomerular, vascular, interstitial and tubular lesions. We reviewed 56 episodes of acute rejection occurring in 44 kidney allograft recipients (30 cadaveric and 14 living donor transplants), comparing Banff classification to degree of reversibility of rejection. Rejection reversal was defined as complete if serum creatinine returned < or = 25% of baseline, partial if creatinine was > 25% to < 75% of baseline, and irreversible if creatinine was > or = 75% of baseline or graft loss occurred. Eight biopsies were classified as borderline (SUM score 1.6 +/- 0.5), 14 grade I (SUM score 3.3 +/- 0.4), 19 grade II (SUM score 4.2 +/- 0.3), and 15 grade III (SUM score 8.5 +/- 0.4). SUM distinguished borderline and grade III rejections, but not grades I and II. Clinically, grade and SUM score correlated with rejection reversal. Complete reversal of rejection occurred in 93% of patients with grade I rejection, while 47% of patients with grade III had irreversible rejection. The mean SUM for complete reversal was 3.9 +/- 0.34 and was different from SUM of partial (6.0 +/- 0.86) and irreversible (8.5 +/- 0.93), P < 0.006. Meanwhile, vascular scores were similar for rejections with complete (0.9 +/- 0.2) or partial (1.0 +/- 0.4) reversal, but significantly higher in those with irreversible rejection (3.0 +/- 0.4, P < 0.000). Likewise, mean scores for tubulitis and interstitial inflammation were significantly higher for irreversible rejection. Resolution of rejection by steroids was correlated to low vascular score (steroid sensitive 0.65 +/- 0.25 vs. steroid resistant 1.42 +/- 0.18, P < 0.01), and low SUM score (steroid sensitive 3.7 +/- 0.5 vs. steroid resistant 5.22 +/- 0.43, P < 0.04). Neither scores for tubulitis nor interstitial cellular inflammation were predictive of steroid sensitivity. These data demonstrate that Banff scoring has clinical relevance in predicting rejection reversal and has implications to first-line therapy of rejection episodes.

International standardization of criteria for the histologic diagnosis of renal allograft rejection: the Banff working classification of kidney transplant pathology

A group of renal pathologists, nephrologists, and transplant surgeons met in Banff, Canada on August 2-4, 1991 to develop a schema for international standardization of nomenclature and criteria for the histologic diagnosis of renal allograft rejection. Development continued after the meeting and the schema was validated by the circulation of sets of slides for scoring by participant pathologists. In this schema intimal arteritis and tubulitis are the principal lesions indicative of acute rejection. Glomerular, interstitial, tubular, and vascular lesions of acute rejection and "chronic rejection" are defined and scored 0 to 3+, to produce an acute and/or chronic numerical coding for each biopsy. Arteriolar hyalinosis (an indication of cyclosporine toxicity) is also scored. Principal diagnostic categories, which can be used with or without the quantitative coding, are: (1) normal, (2) hyperacute rejection, (3) borderline changes, (4) acute rejection (grade I to III), (5) chronic allograft nephropathy ("chronic rejection") (grade I to III), and (6) other. The goal is to devise a schema in which a given biopsy grading would imply a prognosis for a therapeutic response or long-term function. While the clinical implications must be proven through further studies, the development of a standardized schema is a critical first step. This standardized classification should promote international uniformity in reporting of renal allograft pathology, facilitate the performance of multicenter trials of new therapies in renal transplantation, and ultimately lead to improvement in the management and care of renal transplant recipients.

Timing of cyclosporine administration in patients with delayed graft function

Cyclosporine in renal transplant recipients with delayed graft function (DGF) has been reported to decrease graft survival and prolong both DGF and hospitalization. In some centers, antilymphocyte globulin (ALG) has been used perioperatively to obviate these problems, but ALG is associated with increased viral infections. In this study, first cadaver transplant recipients with a fall in serum creatinine level of greater than or equal to 30% in the first 24 hr were started on prednisone (P) and cyclosporine (Group 1, n = 18). Those whose creatinine level did not fall were started on P and azathioprine (Group 2, n = 23) and switched to P and cyclosporine when serum creatinine fell 30%. One-year patient survival was 98%. One-year graft survival was 83% for both Groups 1 and 2 (NS). Results were compared to historical controls with DGF who received P and cyclosporine (Group 3, n = 19). Patients with DGF and requiring dialysis had fewer dialyses (P less than 0.05) and a shorter hospital stay (P less than 0.05) if started on azathioprine, as compared to those started on cyclosporine. Patients with DGF had a higher serum creatinine at 12 months than those with immediate function (P less than 0.05). We conclude that withholding cyclosporine until DGF is resolving decreases the duration of dialysis, decreases hospital stay, and without the use of prophylactic ALG, is associated with graft survival equivalent to that in patients with immediate function.

Endomyocardial biopsy in the cardiac allograft recipient. A review of 570 biopsies

The morphologic abnormalities present in 570 endomyocardial biopsies from 39 cardiac allograft recipients and 16 autopsy hearts are described, and criteria pertinent to the diagnosis of rejection discussed. Entirely normal myocardium was apparent in 16% of the biopsies. Abnormalities related to biopsy of previous biopsy site occurred in 69%, and mononuclear infiltrates of varying intensity were present in 64% of the biopsies. Acute rejection was diagnosed in 17 (43.6%) patients in 32 (5.6%) of the biopsies and five hearts at autopsy. Seven of the biopsies with acute rejection were follow-up biopsies after a previous diagnosis of acute rejection and represented ongoing acute rejection. Similarly, three patients with rejection at autopsy died with ongoing rejection. The overall frequency of acute rejection was thus 0.70 episodes per patient. The most reliable histologic feature in the diagnosis of acute rejection in cyclosporine immunosuppressed recipients was a diffuse mononuclear infiltrate, apparent at low magnification. Myocyte necrosis, said to be critical in the diagnosis of rejection in cyclosporine-treated patients, was not a reliable indicator in the authors' experience.