Proteinuria: a new marker of long-term graft and patient survival in kidney transplantation

Risk factors and prognosis for proteinuria in renal transplant recipients

INTRODUCTION

Proteinuria in renal transplant recipients has been recognized as a risk factor of progression of chronic allograft nephropathy and for cardiovascular disease, the main causes of transplant failure.

PATIENTS AND METHODS

We analyzed the risk factors for persistent proteinuria (>0.5 g/day) among 337 kidney allograft recipients with a minimum follow-up of 6 months, among a series of 375 transplants performed during a decade, as well as their association with allograft and patient survivals. Patients with proteinuria greater than 0.5 g/d were treated with angiotensin-converting enzyme inhibitors (ACEI) and/or angiotensin-receptor blockers.

RESULTS

After a mean follow-up of 53.35 +/- 52.63 months, 68 patients (20.17%) had persistent proteinuria greater than 0.5 g/d. Female patients (P = .012), body mass index (BMI) >25 (P = .008), pretransplant HLA sensitization (P = .039), and delayed graft function (DGF; P = .001) were associated with proteinuria. Induction treatment with antithymocyte globulin (P = .030) and treatment with tacrolimus instead of cyclosporine (P = .046) were associated with an increased risk of proteinuria. Multivariate analysis confirmed the independent value of DGF (RR = 2.23; 95% confidence interval [CI] 1.22 to 4.07; P = .009) and BMI >25 (RR = 1.968; 95% CI 1.05 to 3.68; P = .035) to predict postransplant proteinuria. The mean values of serum creatinine (P = .000) and systolic blood pressure (P < .05) were persistently higher from the early stages after transplantation in the proteinuric group. Graft survival at 5 years was 69% among patients who developed proteinuria and 93% in those without proteinuria (P = .000), with no differences in patient survival (P = .062).

CONCLUSION

Proteinuria in renal transplant recipients was related to immunological and nonimmunological factors, some of which, such as hypertension and obesity could be modifiable. Proteinuria in renal transplant recipients predicted a worse allograft survival despite of intensive treatment of hypertension including ACEI/angiotensin-receptor blockers.

Early onset proteinuria after renal transplantation: a marker for allograft dysfunction

The objective of this study was to determine whether early proteinuria after renal transplantation affected long-term allograft survival. The 130 patients included 105 men and 25 women of overall mean age, 29.6 +/- 9.6 years. There were 105 living related and, 25 cadaveric donor transplants. Proteinuria was defined as a level in of more than 300 mg/d. Donor and recipient age at transplantation, duration of pretransplant dialysis, donor type (living related or cadaveric), the presence of delayed graft function or acute rejection, panel-reactive antibodies, the number of human leukocyte antigen mismatches, and the systolic blood pressure level were retrospectively recorded for the study subjects. Cox regression analysis was used to determine the effects of proteinuria on allograft survival. Patients with proteinuria demonstrated significantly lower graft survival rates than did those without proteinuria (54.17% vs 82.62%, respectively; P<.002). Proteinuria at the third month after transplantation (P<.004, odds ratio [OR]=3.26, confidence interval [CI]=1.46 to 7.29), donor age (P<.001, OR=1.06, CI=1.02 to 109), and panel-reactive antibodies (P<.041, OR=1.06, CI=1.00 to 1.12) were significantly associated with decreased allograft survival. Early proteinuria after renal transplantation was indicative of a high risk for allograft dysfunction. A reduction of proteinuria may be associated with improved graft survival.

Diagnostic Tools for Monitoring Kidney Transplant Recipients

Recent advancements in immunobiology have introduced several new diagnostic tools for monitoring kidney transplant recipients. These have been added to more established tests that, although imperfect, remain important benchmarks of diagnostic utility. Both new and old tests can be characterized with regard to their practicality, and as to whether they detect aberrant function or define the cause of dysfunction. Unfortunately, no current test is both practical and specific to a particular disease entity. Accordingly, the diagnosis of graft dysfunction remains dependent on the proper use and interpretation of many studies. This article reviews the current assays that have been evaluated in the clinic for the diagnosis of renal allograft-related diseases. These are limited to assays based on routinely obtainable samples such as blood, biopsy tissue, and urine. Newer studies are presented, along with more mundane assays, to highlight the practical use of studies regardless of their degree of mechanistic sophistication.

Impact of Surgical Procedures and Complications on Outcomes of Third and Subsequent Kidney Transplants

BACKGROUND

Surgical procedures and complications have rarely been described in patients receiving a third or subsequent renal transplant.

METHODS

Data from 61 consecutive third (n=56), fourth (n=4), and fifth (n=1) renal transplants performed during 1974 to 2005 were analyzed retrospectively.

RESULTS

Actuarial graft survival was 91%, 74%, and 57% at one, five, and 10 years, respectively. Technical failure accounted for the loss of three grafts (5%). A transperitoneal approach was necessary in 41% of patients. Technical difficulties occurred in half of the procedures, mainly due to atheroma or vascular calcifications. Overall, there were 45 surgical complications in 30 patients, of urological (n=11), vascular (n=6), infectious (n=9), hemorrhagic (n=12), digestive (n=3), or wound origin (n=4). The rate of surgical revision was 16%. Univariate analysis showed that among surgical complications, only vascular complications were associated with a poor graft outcome (P=0.02). Urological complications did not influence long-term graft outcome. Multivariate analysis of all surgical procedures and complications that might have influenced graft survival showed that only vascular complications were associated with a poorer graft outcome (relative risk=6.13, P=0.015).

CONCLUSIONS

Despite a high rate of surgical complications and revisions, third and subsequent kidney transplantations may be performed safely by experienced surgeons without surgical complications influencing long-term graft outcome.

Erythropoietin treatment in the sixth posttransplant month as a prognostic factor for renal allograft survival

The purpose of this work was to assess the prognostic value of the need for erythropoietin (EPO) treatment at 6 months after transplantation. We retrospectively reviewed the outcomes of 143 consecutive cadaveric kidney transplants performed between January 2000 and April 2004, functioning at 6 months postransplantation. Patients were divided into two groups: group EPO6m (n = 24) received EPO treatment in the sixth month, and a control group (n = 119) did not receive EPO. Renal function deterioration (RFD) was considered to be a sustained decrease in creatinine clearance (CrCl) greater than 20% between the sixth month postransplant and the last visit. Mean follow-up was 38 +/- 16 months. The mean ages of the donor (57 +/- 9 vs 49 +/- 12 years; P = .001) and the recipient (59 +/- 12 vs 47 +/- 17 years; P = .000) were greater in the EPO6m group. Delayed graft function (83% vs 48%; P = .001) was more frequent in the EPO6m group. At 6 months after transplantation the EPO6m group showed lower hemoglobin (11.52 +/- 1.71 vs 13.32 +/- 1.69 g/dL; P = .000), higher serum creatinine (2.31 +/- 0.72 vs 1.65 +/- 0.53 mg/dL; P = .000), lower CrCl (33.53 +/- 10.83 vs 53.6 +/- 17.58 mL/min; P = .000), and similar proteinuria. RFD was more common in the EPO6m group (38% vs 10%; P = .026), with a different pattern of evolution of CrCl (-0.098 +/- 0.176 vs +0.093 +/- 0.396 mL/min/mo, P = .000). Multivariate analysis demonstrated that treatment with EPO at 6 months was the only predictor of RFD (RR 4.46; 1.58 to 12.58; P = .005). The need for EPO at 6 months postransplant was a good predictor of later renal allograft deterioration, more sensitive than serum creatinine or proteinuria.

Assessment of the risk of chronic allograft dysfunction after renal transplantation in a randomized cyclosporine withdrawal trial

BACKGROUND

We report the two-year follow-up of a trial comparing the three-month postgraft discontinuation of either cyclosporine (CsA) or mycophenolate mofetil (MMF) from a triple-drug regimen after de novo renal transplantation.

METHODS

One hundred and eight patients were enrolled in this study and randomized to be withdrawn from CsA (MMF group, n=54) or MMF (CsA group, n=54).

RESULTS

Despite an increased risk of acute rejection and a lower, but nonsignificant, two-year graft survival, CsA withdrawal induced a sustained improvement of the renal function. At one year, the chronic allograft damage index was similar in both the MMF and CsA groups. However, CsA elimination resulted in a higher incidence of C4d deposits, irrespective of the occurrence of a prior acute rejection. While this finding could suggest a risk of chronic rejection in the MMF group, the outcome did not appear to be related to the C4d status. Moreover, logistic regression analysis showed that only two factors, acute rejection and the one-year glomerular filtration rate level, were predictive of a significant decline of the renal function at two years.

CONCLUSIONS

These results point out the need to secure the minimization of the calcineurin inhibitors after renal transplantation, in order to reduce the risk of acute rejection in these patients, because this strategy allows the improvement of the one-year renal function which is predictive of a chronic allograft dysfunction.

Cardiovascular complications after renal transplantation and their prevention

By the time of renal transplantation, end-stage renal disease patients have a huge burden of cardiovascular disease (CVD) and are heavily saturated with atherosclerotic risk factors. Worsening of preexisting risk factors or new CVD risk factors may develop in the posttransplant period consequent in part to the diabetogenic and atherogenic potential of immunosuppressive drugs. The annual risk of a fatal or non-fatal CVD event of 3.5 to 5% in kidney transplant recipients is 50-fold higher than the general population. Renal allograft dysfunction, proteinuria, anemia, moderate hyperhomocysteinemia and elevated serum C-reactive protein concentrations, each dependently confer greater risk of CVD morbidity and mortality in the posttransplant period. Long-term care of renal transplant recipients should programmatically incorporate the recommendations of the National Kidney Foundation Working Groups and European Best Practice Guidelines Expert Group on Renal Transplantations into the management of hypertension, dyslipidemia, smoking, and posttransplant diabetes mellitus. Timely utilization of coronary revascularization procedures should be undertaken as these treatments are equally effective in the kidney transplant population.

Blood Pressure and Graft Outcome in Renal Transplantation

To investigate the effects of blood pressure (BP) on kidney function, we reviewed 116 patients who had a median follow-up of 40.5 months. Systolic and diastolic hypertension (HTN) at month 6 resulted in significantly higher serum creatinine (SCr) levels at 1 year, compared with patients with normal BP, namely, 2.2 versus 1.4 mg/dL (P = .0001) and 1.87 versus 1.5 mg/dL (P = .04), respectively. Mean systolic and diastolic BP at the end of 1 and 6 months were significantly higher among patients who had returned to hemodialysis or who had an SCr > or =2 mg/dL at their last follow-up. Mean age, mean donor age, donor type, and sex had no significant effect on graft function. Patients receiving Rapamune-based treatment (n = 9) had no graft failure; graft outcomes were similar between cyclosporine-based and tacrolimus-based immunosuppression therapy. Patients with biopsy-proved acute rejection showed significantly lower graft survival. By multivariate analysis, systolic HTN at the end of 1 month (P = .006) and 6 months (P = .01), and diastolic HTN at the end of 6 months (P = .04) were independent risk factors for graft outcome. Actuarial 5-year graft survival was 95%, versus 76% in patients with normal BP versus systolic HTN at 1 month, respectively (P = .02). A significant difference in 5-year graft survival was observed between patients with normal diastolic BP and diastolic HTN at 6 months (95% versus 67%, respectively; P = .001). Since systolic and diastolic BP at different times before and after transplantation correlate with graft function, more attention should be paid to maintain normal BP in patients with renal transplants.

Posttransplant de novo membranous nephropathy in childhood

Posttransplant proteinuria is a recognized, but relatively uncommon, presentation of renal transplant dysfunction. Significant proteinuria occurs in around 10-15% of renal transplant recipients. We present a case of de novo posttransplant membranous nephropathy in childhood complicating renal transplantation for severe congenital obstructive uropathy and review the pathology, pathogenesis, and clinical implications of this condition. In the majority of cases, the cause of posttransplant proteinuria is either related to chronic allograft nephropathy or recurrence of the glomerulonephritis for which transplantation was indicated. In a minority, however, de novo posttransplant membranous nephropathy (DNPMN) is identified on biopsy. The histopathological findings in some cases may either be similar to those of classical membranous nephropathy, or may be more subtle, showing focal segmental variation in severity, often in conjuction with the features of chronic allograft nephropathy. The use of ancillary techniques including immunohistochemistry and electron microscopy may be required to confirm the diagnosis. The presence of posttransplant de novo membranous nephropathy may be associated with an increased risk of graft loss.

Chronic kidney disease progression in native and transplant kidneys

PURPOSE OF REVIEW

The present review addresses the recent literature demonstrating important differences in the rate of progression of kidney function decline between transplant recipients and patients with native kidney disease. It also highlights the need for prospective studies to determine the importance of nonimmune factors that are established risk factors for progression of native kidney disease in the transplant setting.

RECENT FINDINGS

Transplant recipients establish modest levels of kidney function but have rates of kidney function decline that are slower than those in patients with native kidney disease. Continued improvements in long-term graft survival have not been achieved despite significant advances in immunosuppression. There is increasing observational evidence that nonimmune factors that play a causal role in progression of native kidney disease may also be important determinants of allograft decline. There are fundamental differences between transplant recipients and patients with native kidney disease that preclude extrapolation of evidence from native kidney disease to the transplant setting.

SUMMARY

Transplant recipients are a unique group of chronic kidney disease patients. Prospective studies to determine the importance of nonimmune factors such as hypertension, proteinuria, dyslipidemia, diabetes, and anemia in the transplant setting are needed.