Through a glass darkly: seeking clarity in preventing late kidney transplant failure

A common lament is that long-term kidney transplant outcomes remain the same despite improvements in early graft survival. To be fair, progress has been made-in both our understanding of chronic injury and modestly, graft survival. However, we are still a long way from actually solving this important and difficult problem. In this review, we outline recent data supporting the existence of several causes of renal allograft loss, the incidences of which peak at different time points after transplantation. On the basis of this broadened concept of chronic renal allograft injury, we examine the challenges of clinical trial design in long-term studies, including the use of surrogate end points and biomarkers. Finally, we suggest a path forward that, ultimately, may improve long-term renal allograft survival.

Kidney allograft function and histology in recipients dying with a functioning graft

Death with function (DWF) is a major cause of kidney allograft failure. Allograft dysfunction may contribute to DWF. The aim of this study was to examine the relationship between DWF and allograft function using estimated GFR (eGFR) and histology. We retrospectively analyzed 1842 kidney allografts transplanted at our center from 1996 to 2010. eGFR was estimated using the MDRD equation. Biopsies obtained 12 months posttransplant and within 1 year of DWF were analyzed. Proportional hazards models were used to examine the relationship between eGFR and DWF. During 68 ± 43 months of follow-up, 14% (n = 256) of recipients experienced DWF. Risk factors of DWF included increasing recipient age (hazard ratio [HR] = 2.07, confidence interval [CI] 1.77-2.43, p < 0.0001), diabetes (HR = 2.58, CI 1.81-3.69, p < 0.0001), prior dialysis (HR = 1.47, CI 1.05-2.06, p = 0.03) and eGFR <40 mL/min/1.73 m(2) (HR 2.26 per 10 mL/min/1.73 m(2) decrease in eGFR, CI 1.82-2.81, p < 0.0001). Prior to death, only 15.9% (n = 39) of DWF recipients had stage 4 chronic kidney disease (CKD) and only 4.9% (n = 12) had stage 5 CKD. Most biopsies performed within 1 year of DWF (68%) demonstrated benign histology and were comparable to biopsies from matched controls. In conclusion, allograft dysfunction is independently associated with DWF. However, the majority of DWF recipients have well-preserved allograft function and histology prior to death.

Impact of urinary tract infection on allograft function after kidney transplantation

OBJECTIVES

Urinary tract infection (UTI) is the most common infectious complication after kidney transplantation. We aim to determine its impact on allograft function as indicated by several measures such as iothalamate glomerular filtration rate (iGFR), estimated glomerular filtration rate (eGFR), and creatinine value.

METHODS

We performed a single-center retrospective cohort study to determine the impact of UTI on kidney allograft outcome.

RESULTS

The study population consisted of 301 kidney transplant recipients; 84% were living donor transplants. One hundred and one patients (34%) developed at least one episode of UTI and the incidence of UTI during the first year after transplantation was 25%. At the end of the follow-up, the iGFR was lower among patients who had developed at least one UTI (p = 0.044). However, eGFR and creatinine values were not significantly different between UTI and non-UTI groups.

CONCLUSION

When kidney function was measured by eGFR and creatinine, there was no significant difference in allograft function between kidney recipients with or without UTI. However, when kidney function was measured by nuclear studies, there was a tendency toward impairment in allograft function among patients who developed atleast one UTI after transplantation.

Clinical findings, pathology, and outcomes of C3GN after kidney transplantation

C3 glomerulonephritis (C3GN) results from abnormalities in the alternative pathway of complement, and it is characterized by deposition of C3 with absent or scant Ig deposition. In many patients, C3GN progresses to ESRD. The clinical features, pathology, and outcomes of patients with C3GN receiving kidney transplantation are unknown. Between 1996 and 2010, we identified 21 patients at our institution who received a kidney transplant because of ESRD from C3GN. The median age at the time of initial diagnosis of C3GN at kidney biopsy was 20.8 years. The median time from native kidney biopsy to dialysis or transplantation was 42.3 months. Of 21 patients, 14 (66.7%) patients developed recurrent C3GN in the allograft. The median time to recurrence of disease was 28 months. Graft failure occurred in 50% of patients with recurrent C3GN, with a median time of 77 months to graft failure post-transplantation. The remaining 50% of patients had functioning grafts, with a median follow-up of 73.9 months. The majority of patients had hematuria and proteinuria at time of recurrence. Three (21%) patients were positive for monoclonal gammopathy and had a faster rate of recurrence and graft loss. Kidney biopsy at the time of recurrence showed mesangial proliferative GN in eight patients and membranoproliferative GN in six patients. All allograft kidney biopsies showed bright C3 staining (2-3+), with six biopsies also showing trace/1+ staining for IgM and/or IgG. To summarize, C3GN recurs in 66.7% of patients, and one half of the patients experience graft failure caused by recurrence.

Kidney allograft survival after acute rejection, the value of follow-up biopsies

Kidney allografts are frequently lost due to alloimmunity. Still, the impact of early acute rejection (AR) on long-term graft survival is debated. We examined this relationship focusing on graft histology post-AR and assessing specific causes of graft loss. Included are 797 recipients without anti-donor antibodies (DSA) at transplant who had 1 year protocol biopsies. 15.2% of recipients had AR diagnosed by protocol or clinical biopsies. Compared to no-AR, all histologic types of AR led to abnormal histology in 1 and 2 years protocol biopsies, including more fibrosis + inflammation (6.3% vs. 21.9%), moderate/severe fibrosis (7.7% vs. 13.5%) and transplant glomerulopathy (1.4% vs. 8.3%, all p < 0.0001). AR were associated with reduced graft survival (HR = 3.07 (1.92-4.94), p < 0.0001). However, only those AR episodes followed by abnormal histology led to reduced graft survival. Early AR related to more late alloimmune-mediated graft losses, particularly transplant glomerulopathy (31% of losses). Related to this outcome, recipients with AR were more likely to have new DSA class II 1 year posttransplant (no-AR, 11.1%; AR, 21.2%, p = 0.039). In DSA negative recipients, early AR often leads to persistent graft inflammation and increases the risk of new DSA II production. Both of these post-AR events are associated with increased risk of graft loss.

Oral paricalcitol reduces the prevalence of posttransplant hyperparathyroidism: results of an open label randomized trial

Postkidney transplant hyperparathyroidism is a significant problem. Vitamin D receptor agonists are known to suppress parathyroid hormone (PTH) secretion. We examined the effect of oral paricalcitol on posttransplant secondary hyperparathyroidism by conducting an open label randomized trial in which 100 incident kidney transplant recipients were randomized 1:1 to receive oral paricalcitol, 2 μg per day, for the first year posttransplant or no additional therapy. Serial measurements of serum PTH, calcium and bone alkaline phosphatase, 24-h urine calcium and bone density were performed. The primary endpoint was the frequency of hyperparathyroidism 1-year posttransplant. Eighty-seven patients completed the trial. One-year posttransplant, 29% of paricalcitol-treated subjects had hyperparathyroidism compared with 63% of untreated patients (p = 0.0005). Calcium supplementation was discontinued in two control and 15 treatment patients due to mild hypercalcemia or hypercalcuria. Paricalcitol was discontinued in four patients due to hypercalcuria/hypercalcemia and in one for preference. Two subjects required decreasing the dose of paricalcitol to 1 μg daily. Hypercalcemia was asymptomatic and reversible. Incidence of acute rejection, BK nephropathy and renal function at 1 year were similar between groups. Moderate renal allograft fibrosis was reduced in treated patients. Oral paricalcitol is effective in decreasing posttransplant hyperparathyroidism and may have beneficial effects on renal allograft histology.

Acute pancreas allograft rejection is associated with increased risk of graft failure in pancreas transplantation

The effect of acute allograft rejection (AR) on long-term pancreas allograft function is unclear. We retrospectively studied 227 consecutive pancreas transplants performed at our institution between January 1, 998 and December 31, 2009 including: 56 simultaneous pancreas and kidney (SPK), 69 pancreas transplantation alone (PTA); and 102 pancreas after kidney (PAK) transplants. With a median follow-up of 6.1 (IQR 3-9) years, 57 patients developed 79 episodes of AR, and 19 experienced more than one episode. The cumulative incidence for AR was 14.7%, 19.7%, 26.6% and 29.1% at 1, 2, 5 and 10 years. PTA transplant (hazards ratio [HR]=2.28, p=0.001) and donor age (per 10 years) (HR=1.34, p=0.006) were associated with higher risk for AR. The first AR episode after 3 months post PT was associated with increased risk for complete loss (CL) (HR 3.79, p<0.001), and the first AR episode occurring during 3- to 12-month and 12- to 24-month periods after PT were associated with significantly increased risk for at least partial loss (PL) (HR 2.84, p=0.014; and HR 6.25, p<0.001, respectively). We conclude that AR is associated with increased risk for CL and at least PL. The time that the first AR is observed may influence subsequent graft failure.

A prospective controlled study of kidney donors: baseline and 6-month follow-up

BACKGROUND

Most previous studies of living kidney donors have been retrospective and have lacked suitable healthy controls. Needed are prospective controlled studies to better understand the effects of a mild reduction in kidney function from kidney donation in otherwise healthy individuals.

STUDY DESIGN

Prospective, controlled, observational cohort study.

SETTING & PARTICIPANTS

Consecutive patients approved for donation at 8 transplant centers in the United States were asked to participate. For every donor enrolled, an equally healthy control with 2 kidneys who theoretically would have been suitable to donate a kidney also was enrolled.

PREDICTOR

Kidney donation.

MEASUREMENTS

At baseline predonation and at 6 months after donation, medical history, vital signs, measured (iohexol) glomerular filtration rate, and other measurements were collected. There were 201 donors and 198 controls who completed both baseline and 6-month visits and form the basis of this report.

RESULTS

Compared with controls, donors had 28% lower glomerular filtration rates at 6 months (94.6 ± 15.1 [SD] vs 67.6 ± 10.1 mL/min/1.73 m(2); P < 0.001), associated with 23% greater parathyroid hormone (42.8 ± 15.6 vs 52.7 ± 20.9 pg/mL; P < 0.001), 5.4% lower serum phosphate (3.5 ± 0.5 vs 3.3 ± 0.5 mg/dL; P < 0.001), 3.7% lower hemoglobin (13.6 ± 1.4 vs 13.1 ± 1.2 g/dL; P < 0.001), 8.2% greater uric acid (4.9 ± 1.2 vs 5.3 ± 1.1 mg/dL; P < 0.001), 24% greater homocysteine (1.2 ± 0.3 vs 1.5 ± 0.4 mg/L; P < 0.001), and 1.5% lower high-density lipoprotein cholesterol (54.9 ± 16.4 vs 54.1 ± 13.9 mg/dL; P = 0.03) levels. There were no differences in albumin-creatinine ratios (5.0 [IQR, 4.0-6.6] vs 5.0 [IQR, 3.3-5.4] mg/g; P = 0.5), office blood pressures, or glucose homeostasis.

LIMITATIONS

Short duration of follow-up and possible bias resulting from an inability to screen controls with kidney and vascular imaging performed in donors.

CONCLUSIONS

Kidney donors have some, but not all, abnormalities typically associated with mild chronic kidney disease 6 months after donation. Additional follow-up is warranted.

Urine high and low molecular weight proteins one-year post-kidney transplant: relationship to histology and graft survival

Increased urinary protein excretion is common after renal transplantation and portends worse outcome. In this study we assessed the prognostic contribution of several urinary proteins. Urinary total protein, albumin, retinol binding protein (RBP), α-1-microglobulin, IgG and IgM were measured in banked urine samples from 221 individuals 1 year after renal transplantation (age 52 ± 13 years, 55% male, 93% Caucasian and 82% living donor). Levels of all proteins measured were higher than in normal nontransplant populations. Patients with glomerular lesions had higher urinary albumin than those with normal histology, while those with interstitial fibrosis and tubular atrophy plus inflammation (ci>0, cg = 0, i>0) had higher levels of IgG, IgM, α-1-microglobulin and RBP. Concomitant normal levels of urinary albumin, IgM and RBP identified normal histology (specificity 91%, sensitivity 15%,). Urinary levels of the specific proteins were highly correlated, could not differentiate among the histologic groups, and appeared to result from tubulointerstitial damage. Increased urinary excretion of the low molecular weight protein RBP was a sensitive marker of allografts at risk, predicting long-term graft loss independent of histology and urinary albumin. This study highlights the prognostic importance of tubulointerstitial disease for long-term graft loss.

Cardiac troponin T before and after kidney transplantation: determinants and implications for posttransplant survival

Pretransplant cardiac troponin T(cTnT(pre) ) is a significant predictor of survival postkidney transplantation. We assessed correlates of cTnT levels pre- and posttransplantation and their relationship with recipient survival. A total of 1206 adult recipients of kidney grafts between 2000 and 2010 were included. Pretransplant cTnT was elevated (≥0.01 ng/mL) in 56.4%. Higher cTnT(pre) was associated with increased risk of posttransplant death/cardiac events independent of cardiovascular risk factors. Elevated cTnT(pre) declined rapidly posttransplant and was normal in 75% of recipients at 3 weeks and 88.6% at 1 year. Elevated posttransplant cTnT was associated with reduced patient survival (cTnT(3wks) : HR = 5.575, CI 3.207-9.692, p < 0.0001; cTnT(1year) : 3.664, 2.129-6.305, p < 0.0001) independent of age, diabetes, pretransplant dialysis, heart disease and allograft function. Negative/positive predictive values for high cTnT(3wks) were 91.4%/50% respectively. Normalization of cTnT posttransplant was associated with reduced risk. Variables related to elevated cTnT posttransplant included pretransplant diabetes, older age, time on dialysis, high cTnT(pre) and lower graft function. Patients with delayed graft function and those with GFR < 30 mL/min at 3 weeks were more likely to have an elevated cTnT(3wks) and remained at high risk. When allografts restore sufficient kidney function cTnT normalizes and patient survival improves. Lack of normalization of cTnT posttransplant identifies a group of individuals with high risk of death/cardiac events.

Desensitization in the era of kidney paired donation: the Mayo Foundation 3-site experience

Sensitized renal allograft candidates face significant barriers to transplantation. While several options exist, including: kidney paired donation (KPD), desensitization, or pursuing a deceased donor kidney transplant, it is unclear from existing data what is the appropriate protocol for an individual patient. In this study, we seek to devise a balance between waiting for a paired donor and combining desensitization with KPD.

Cellular and physiological mechanisms of new-onset diabetes mellitus after solid organ transplantation

New-onset diabetes after transplantation is recognized as one of the metabolic consequences which may increase the risk of morbidity and mortality after solid organ transplantation. The pathophysiology of new-onset diabetes after transplantation has not been clearly defined and may resemble that of Type 2 diabetes, characterized by predominantly insulin resistance or defective insulin secretion, or both. This review aims to summarize the current state of knowledge regarding the prevalence, consequences, pathogenesis, and management of new-onset diabetes after transplantation, with a major focus on the possible mechanisms involved in the pathogenesis of the disorder. The aetiology of new-onset diabetes after transplantation is multifactorial, with diabetogenic immunosuppressive drugs playing a major role. Multiple cellular and physiologic mechanisms are involved in the process. Selection of an appropriate maintenance immunosuppressive regimen should involve balancing the risk of patient and graft survival vs. the potential for new-onset diabetes after transplantation.

Kidney allograft inflammation and fibrosis, causes and consequences

This study assessed the development of allograft interstitial fibrosis and inflammation (GIF+"i"), a histologic pattern associated with reduced graft survival. Included are 795 adults, recipients of kidney allografts from 2000 to 2006. GIF+"i" was diagnosed in surveillance and clinical biopsies that had no transplant glomerulopathy. With time, posttransplant increasing number of grafts showed GIF+"i" and these patients had reduced death-censored graft survival (HR = 4.33 (2.49-7.53), p < 0.0001). Development of GIF+"i" was related to prior acute cellular rejection (ACR), BK nephropathy (PVAN), increasing number of HLA mismatches, retransplantation and DGF. However, 46.4% of GIF+"i" cases had no history of ACR or PVAN. Anti-HLA antibodies at transplant did not relate to GIF+"i" and these patients had no increased frequency of new antibody formation posttransplant. Post-ACR biopsies showed that GIF+"i" developed more commonly after clinically and/or histologically more severe ACR. Graft inflammation persisted in 38.7 and 29.6% of grafts 2 and 12 months post-ACR. Twelve months post-ACR, 27.1% of biopsies developed moderate-severe GIF and 51.8% showed GIF and inflammation. Persistent inflammation and progressive GIF is often subclinical but may lead to graft failure. GIF+"i" can be initiated by multiple etiologies but it is often postinfectious or due to persistent cellular immune-mediated injury.

Long-term follow-up of patients with monoclonal gammopathy of undetermined significance after kidney transplantation

INTRODUCTION

Long-term data regarding kidney transplantation (KTx) patients with monoclonal gammopathy of undetermined significance (MGUS) are scarce. We evaluated the long-term outcomes of these patients in a single-center retrospective study from the Mayo Clinic, Rochester, Minn., USA.

METHODS

Patients who had an MGUS before transplant or developed one after KTx were selected. Monoclonal protein was screened as part of the KTx evaluation by serum protein electrophoresis. Screening for posttransplant lymphoproliferative disorder (PTLD) or MGUS after transplant was not required by protocol. Patients with multiple myeloma, dysproteinemia-related kidney disease or no pretransplant serum protein electrophoresis were excluded.

RESULTS

Between 1963 and 2006, 3,518 patients underwent KTx. MGUS was identified in 42 patients, with 23 before transplant and 19 after transplant. Median follow-up for these patients was 8.5 years (range 0.3-37). Four (17.4%) pretransplant MGUS patients developed a hematologic malignancy: 2 smoldering multiple myeloma and 2 PTLD - an Epstein-Barr virus-positive diffuse large cell lymphoma and a Hodgkin lymphoma. None of the 19 patients who developed an MGUS after transplant progressed to multiple myeloma, but 2 (10.5%) developed Epstein-Barr virus-negative T cell lymphoproliferative disorders at 16 and 26 years after transplant. Median survival was 26.1 and 28.0 years for the pretransplant and posttransplant MGUS groups, respectively.

CONCLUSION

Progression from true MGUS to multiple myeloma is rare after KTx. KTx appears safe in true MGUS patients if the monoclonal gammopathy was not the cause of the kidney disease. None of the patients progressed to multiple myeloma, but 2 developed smoldering multiple myeloma and several developed PTLD. Further studies are needed to explain the relationship between MGUS and PTLD.

The pathology and clinical features of early recurrent membranous glomerulonephritis

We assessed the earliest manifestations of recurrent membranous glomerulonephritis (MGN) in renal allografts. Clinical, laboratory and pathologic data were reviewed in 21 patients at the initial biopsy within 4 months post-transplant with evidence of MGN and on follow-up biopsies, compared to a biopsy control group of eight transplants without recurrent MGN. The mean time of first biopsy with pathologic changes was 2.7 months. In each earliest biopsy, immunofluorescence (IF) showed granular glomerular basement membrane (GBM) staining for C4d, IgG, kappa and lambda. IF for C3 was negative or showed trace staining in 16/21. On each MGN biopsy positive by IF, 14/19 showed absence of deposits or rare tiny subepithelial deposits by electron microscopy (EM). At the earliest biopsy, the mean proteinuria was 1.1 g/day; 16 patients had <1 g/day proteinuria. Follow-up was available in all patients (mean 35 months posttransplant). A total of 13 patients developed >1 g/day proteinuria; 12 were treated with: rituximab (n = 8), ACEI and increased prednisone dose (n = 2), ACEI or ARB only (n = 2). All patients showed reduction in proteinuria after treatment. A total of 11/16 patients showed progression of disease by EM on follow-up biopsy. Recognition of early allograft biopsy features aids in diagnosis of recurrent MGN before patients develop significant proteinuria.

Bilateral native ureteral ligation without nephrectomy in the management of kidney transplant recipients with native proteinuria

The aim of this study was to assess the safety of bilateral native ureteral ligation (BNUL) without nephrectomy in the management of native proteinuria in kidney transplant (KTx) recipients. We retrospectively studied 17 patients who underwent BNUL between 2002 and 2010 with a median preoperative 24 h protein concentration of 2140 (range 1020-25 000) mg/L. Fifteen of the 17 patients had focal segmental glomerulosclerosis as their primary renal disease and ligation was employed to facilitate the diagnosis of early recurrence. The BNUL was performed simultaneously with KTx in 14 patients. Surgical techniques were: open (n = 5), pure laparoscopic (n = 1) and a hybrid of hand-assisted laparoscopic surgical/open approach (n = 12) used at the time of transplantation via the transplant incision. At a median follow-up of 46 months (range 1-59), no patient had a complication related to BNUL and none required interventions associated with their native kidneys. BNUL without nephrectomy seems to be a safe technique to manage native proteinuria in renal transplant candidates.

Terminal complement inhibition decreases antibody-mediated rejection in sensitized renal transplant recipients

Sensitized renal transplant recipients with high levels of donor-specific alloantibody (DSA) commonly develop antibody-mediated rejection (AMR), which may cause acute graft loss or shorten allograft survival. We examined the efficacy of terminal complement inhibition with the humanized anti-C5 antibody, eculizumab, in the prevention AMR in renal transplant recipients with a positive crossmatch against their living donor. The incidence of biopsy-proven AMR in the first 3 months posttransplant in 26 highly sensitized recipients of living donor renal transplants who received eculizumab posttransplant was compared to a historical control group of 51 sensitized patients treated with a similar plasma exchange (PE)-based protocol without eculizumab. The incidence of AMR was 7.7% (2/26) in the eculizumab group compared to 41.2% (21/51) in the control group (p = 0.0031). Eculizumab also decreased AMR in patients who developed high levels of DSA early after transplantation that caused proximal complement activation. With eculizumab, AMR episodes were easily treated with PE reducing the need for splenectomy. On 1-year protocol biopsy, transplant glomerulopathy was found to be present in 6.7% (1/15) eculizumab-treated recipients and in 35.7% (15/42) of control patients (p = 0.044). Inhibition of terminal complement activation with eculizumab decreases the incidence of early AMR in sensitized renal transplant recipients (ClincalTrials.gov number NCT006707).

Rituximab-induced depletion of anti-PLA2R autoantibodies predicts response in membranous nephropathy

Autoantibodies to the M-type phospholipase A(2) receptor (PLA(2)R) are sensitive and specific for idiopathic membranous nephropathy. The anti-B cell agent rituximab is a promising therapy for this disease, but biomarkers of early response to treatment currently do not exist. Here, we investigated whether levels of anti-PLA(2)R correlate with the immunological activity of membranous nephropathy, potentially exhibiting a more rapid response to treatment than clinical parameters such as proteinuria. We measured the amount of anti-PLA(2)R using Western blot immunoassay in serial serum samples from a total of 35 patients treated with rituximab for membranous nephropathy in two distinct cohorts. Pretreatment samples from 25 of 35 (71%) patients contained anti-PLA(2)R, and these autoantibodies declined or disappeared in 17 (68%) of these patients within 12 months after rituximab. Those who demonstrated this immunologic response fared better clinically: 59% and 88% attained complete or partial remission by 12 and 24 months, respectively, compared with 0% and 33% among those with persistent anti-PLA(2)R levels. Changes in antibody levels preceded changes in proteinuria. One subject who relapsed during follow-up had a concomitant return of anti-PLA(2)R. In summary, measuring anti-PLA(2)R levels by immunoassay may be a method to follow and predict response to treatment with rituximab in membranous nephropathy.

Improving long-term renal allograft survival via a road less traveled by

It has become cliché to state that improvements in early renal allograft survival over the past two decades have not led to increased long-term renal allograft survival. However, it is not clear how long-term graft survival can be improved. Here, we present the viewpoint that the road forward does not involve searching for new and more ideal immunosuppressive regimens, but rather detailed patient follow-up to identify specific causes of late renal allograft loss and the development of new therapy designed to address these problems before allograft damage becomes irreversible.

Living donor age and kidney transplant outcomes

We assessed the relationship between living donor (LD) age and kidney survival in 1063 adults transplanted between 1980 and 2007. Increasing LD age was associated with lower kidney function (GFR) before and after transplantation and loss of GFR beyond 1 year. Increasing LD age was also associated with low-moderate proteinuria posttransplant (151-1500 mg/day, p < 0.0001). By univariate analysis, reduced graft survival related to lower GFR at 1 year [HR = 0.925 (0.906-0.944), p < 0.0001], proteinuria [HR = 1.481 (1.333-1.646), p < 0.0001] and increasing LD age [HR = 1.271 (1.219-1.326), p = 0.001]. The impact of LD age on graft survival was noted particularly >4 years posttransplant and was modified by recipient age. Thus, compared to a kidney graft that was within 5 years of the recipient age, younger kidneys had a survival advantage [HR = 0.600 (0.380-0.949), p = 0.029] while older kidneys had a survival disadvantage [HR = 2.217 (1.507-3.261), p < 0.0001]. However, this effect was seen only in recipients <50 years old. By multivariate analysis, the relationship between LD age and graft survival was independent of GFR but related to proteinuria. In conclusion, LD age is an important determinant of long-term graft survival, particularly in younger recipients. Older kidneys with reduced survival are identifiable by the development of proteinuria posttransplant.

The histology of solitary renal allografts at 1 and 5 years after transplantation

Previous studies suggest that the majority of renal allografts are affected by progressive, severe chronic histologic injury, yet studies using current protocols are lacking. The goal of this study was to examine the prevalence and progression of histologic changes using protocol allograft biopsies at 1 and 5 years after solitary kidney transplantation in patients transplanted between 1998 and 2004. Chronic histologic changes generally were mild at both 1 and 5 years and were similar in deceased and living donor kidneys. The overall prevalence of moderate or severe fibrosis was 13% (60/447) at 1 year and 17% (60/343) at 5 years. In a subgroup of 296 patients who underwent both 1- and 5-year biopsies, mild fibrosis present at 1 year progressed to more severe forms at 5 years in 23% of allografts. The prevalence of moderate or severe arteriolar hyalinosis was similar in tacrolimus and calcineurin inhibitor-free immunosuppression. These results in the recent era of transplantation demonstrate fewer, less severe and less progressive chronic histologic changes in the first 5 years after transplantation than previously reported.