Raj C. Thuraisingham

Pretransplant Donor-Specific Antibodies in Cytotoxic Negative Crossmatch Kidney Transplants: Are They Relevant?

Background. The corresponding antigens of alloantibodies identified in patients awaiting kidney transplantation are often listed as unacceptable for transplantation. The use of solid phase testing, being more sensitive and accurate than conventional complement-dependent cytotoxicity (CDC) assays, has resulted in increased identification of alloantibodies. We aimed to study the clinical importance of alloantibodies defined solely by solid phase techniques. Methods. All patients transplanted between 1999 and 2001 at our center with available day-of-transplant sera (D0) were included (121 patients). All had negative CDC crossmatches. Results. Thirty-eight patients (31%) had detectable alloantibodies using high-definition assays with 16 having donor-specific antibodies (DSA) and 22 non-DSA. There were no cases of hyperacute rejection in any of the groups. Biopsy-proven acute rejection rates in the DSA and non-DSA were similar to the unsensitized group. Delayed graft function and 1-year graft survival rates were also similar for the three groups as were median 1-year serum creatinine levels. Multivariate analysis, however, showed that DSA were associated with an increased relative risk of longer-term graft failure (relative risk, 6.5; P<0.05). Conclusions. These data show that in the context of a CDC-negative crossmatch, the presence of D0 DSA has little impact on any early graft parameters. DSA, however, are associated with poorer longer-term graft outcomes in kidney transplantation.

Predictors of Renal Outcome in HIV-Associated Nephropathy

BACKGROUND Human immunodeficiency virus (HIV)-associated nephropathy (HIVAN) is an important cause of end-stage renal disease among African American patients. This study was performed to study the epidemiology of HIVAN in a predominantly black African population and the impact of highly active antiretroviral therapy and other factors on the development of end-stage renal disease. METHODS We retrospectively identified all patients with HIVAN, defined by biopsy or strict clinical criteria, in 8 clinics in the United Kingdom. Baseline renal function, HIV parameters, renal pathological index of chronic damage, and responses to highly active antiretroviral therapy were analyzed, and factors associated with adverse renal outcome were identified. RESULTS From 1998 through 2004, we studied 16,834 patients, 61 of whom had HIVAN. HIVAN prevalence in black patients was 0.93%, and HIVAN incidence in those without renal disease at baseline was 0.61 per 1000 person-years. After a median of 4.2 years, 34 patients (56%) had developed end-stage renal disease. There were no significant differences in renal function and HIV parameters at baseline, time to initiation of highly active antiretroviral therapy, and rates of HIV RNA suppression between the 20 patients who developed end-stage renal disease >3 months after receiving the HIVAN diagnosis and the 23 patients who maintained stable renal function. However, the index of chronic damage score was significantly higher in those who developed end-stage renal disease (P < .001), and an index of chronic damage score >75 was associated with shorter renal survival (P < .001). CONCLUSIONS Whereas overall patient survival suggested an important benefit of highly active antiretroviral therapy, no additional renal benefit of early initiation of highly active antiretroviral therapy or viral suppression could be demonstrated in this large cohort of patients with established HIVAN. Severity of chronic kidney damage, as quantified by biopsy, was the strongest predictor of renal outcome.

Blood Pressure Control and Symptomatic Intradialytic Hypotension in Diabetic Haemodialysis Patients: A Cross-Sectional Survey

Background:Cardiovascular disease remains the most common cause of mortality in end-stage kidney failure patients with diabetes. To improve blood pressure control, and reduce cardiovascular risk, in 2002 the UK Renal Association Standards’ Committee introduced pre- and post-dialysis target blood pressures of <140/90 and <130/80 mm Hg, respectively. Methods: We audited blood pressure control and symptomatic intradialytic hypotension during 1 week in the eleven renal centres in the Greater London Urban Area in 2,193 patients, capturing 6,579 haemodialysis sessions. Results: Although 73.9% of the 658 diabetic patients were prescribed antihypertensive medications, compared to 57.8% of the 1,535 non-diabetic patients (p < 0.001), both the mean pre- and post-dialysis blood pressures were greater in the diabetic patients: before dialysis 152 ± 23/77 ± 13 versus 144 ± 23/79 ± 13 mm Hg and after dialysis 138 ± 24/71 ± 12 versus 132 ± 26/73 ± 13 mm Hg, and fewer diabetic patients achieved the pre- and post-dialysis blood pressure targets: 28.6 versus 40.8% and 37.9 versus 46.3%, respectively (p < 0.01). In addition, more diabetic patients suffered symptomatic intradialytic hypotension, 20.3 versus 14.9% (p < 0.01), associated with greater interdialytic weight gains. Conclusion: Diabetic haemodialysis patients had higher blood pressures, both before and after dialysis, associated with greater interdialytic weight gains and more frequent symptomatic intradialytic hypotension.

Long-term graft outcome with mycophenolate mofetil and azathioprine : A paired kidney analysis

Background. Randomized controlled trials and U.S. Registry data have demonstrated that mycophenolate mofetil (MMF) reduces acute rejection rates and improves graft survival. We undertook the first paired kidney analysis comparing the effects of MMF and azathioprine on graft outcome in the United Kingdom. Methods. In all, 238 deceased donors from 1999 to 2002 who donated one kidney to a patient treated with MMF and the other kidney to a patient treated with azathioprine were identified from the national transplant database held by U.K. Transplant. Graft function and rates of change of graft function were compared using multiple linear regression analyses adjusting for covariates on an intention-to-treat basis. Incidence of acute rejection and delayed graft function were studied using logistic regression. Patient and graft survival censored for death were evaluated with Cox regression analyses. Results. The MMF-treated patients exhibited a nonsignificant trend towards improved graft function but with increased rejection rates (44% versus 31%, P<0.01). Treatment with MMF did not reduce delayed graft function rates. Univariate analysis showed that graft survival was inferior in MMF-treated patients (90% versus 95%, log-rank, P=0.02) but in multivariate Cox regression models, MMF treatment was not a significant factor. Surprisingly, in the first year 32% of patients achieved daily doses of less than 2 g of MMF compared to 18% of patients who received less than 100 mg of azathioprine (P<0.01). Conclusion. In this real-life study, there was no difference in patient or graft outcome between MMF and azathioprine treated groups despite increased rejection rates in patients receiving MMF therapy.

Allosensitization Rate of Male Patients Awaiting First Kidney Grafts After Leuko-Depleted Blood Transfusion

Background. Blood transfusions are generally avoided for potential renal transplant recipients due to risk of human leukocyte antigen (HLA) allosensitization. Despite the near universal use of erythropoiesis-stimulating agents, there are still occasions when patients require blood transfusions for reasons such as resistance to erythropoiesis-stimulating agents or cardiovascular instability. The risk of allosensitization in renal patients is believed to be lower with leuko-depleted blood. We sought to quantify the risk of blood transfusion per se in male renal patients on the transplant waiting list for their first kidney graft, using sensitive solid phase antibody detection. Method. Cross-sectional survey looking at the prevalence of HLA antibody detected using single antigen Luminex beads in male patients awaiting first renal transplantation. Results. One hundred sixteen male patients awaiting their first kidney transplant were identified on our waiting list. Seven of the 42 patients (16.7%) who received at least one unit of leuko-depleted blood developed HLA antibody (HLAab). Of the remaining 74 patients without a history of transfusion, 3 (4.1%) were found to have HLAab. All the antibodies identified were directed against class I antigens. A history of blood transfusion gave a relative risk of 4.1 of developing HLAab (P=0.02). Conclusion. Male patients awaiting their first organ transplant had a fourfold increased risk of developing HLA antibody if they had been previously transfused when compared with those who did not have a history of a transfusion. Transfusion even in the postleukodepletion era continues to pose a significant risk of sensitization.

Creatinine reduction ratio: a useful marker to identify medium and high-risk renal transplants.

Introduction. Delayed graft function (DGF) has a major impact on long-term renal transplant survival. However, it is a diagnosis made retrospectively with little opportunity to modify treatment protocols. A classification based on creatinine reduction ratio between days 1 and 2 (CRR2) suggests that patients with CRR2 less than or equal to 30% (nondialysis requiring DGF [ND-DGF]) have similar outcomes to those with dialysis-requiring delayed graft function (D-DGF). We retrospectively applied this definition in our cohort of patients to examine outcomes. Methods. We studied the association between CRR2 and graft outcomes in all 367 patients transplanted between 1996 and 2004 at our center. Patients were divided into the following three groups: IGF (immediate graft function; CRR2 >30%), D-DGF, and ND-DGF. Mean follow-up was 4.2 years. Results. IGF accounted for 36% of patients, D-DGF for 22%, and ND-DGF for 42%. CRR2 was inversely correlated with serum creatinine on days 7, 30, 90, and 365 (r ranging from −0.65 to −0.22, P<0.001). Graft survival at 5 years was 98% (IGF), 74% (D-DGF), and 89% (ND-DGF). There was a significant difference in graft survival between IGF and D-DGF (P<0.001) and IGF and ND-DGF (P=0.005). In a multivariate analysis adjusting for recipient age and sex, donor age and sex, and human leukocyte antigen mismatch, graft failure was 2.4 times more likely to occur in patients with D-DGF than those with ND-DGF(P=0.02). Conclusions. Our study shows CRR2 influences long-term graft outcomes. Unlike the original description, patients with ND-DGF carry an intermediate risk and perhaps should be considered on day 2 for alternative treatment protocols.

Acute reversal of cyclosporine nephrotoxicity by neutral endopeptidase inhibition in stable renal transplant recipients.

BACKGROUND Atrial natriuretic peptide and cyclosporine have opposing effects on renal hemodynamics and excretory function. METHODS Twelve male stable cyclosporine-treated renal transplant recipients received a single 100-mg i.v. dose of the neutral endopeptidase EC 24.11 inhibitor candoxatrilat in a double-blind, placebo-controlled cross-over study. Each study day consisted of 2 hr of baseline and 7 hr of postdose evaluation. RESULTS After administration of candoxatrilat, plasma atrial natriuretic factor rose from 12.8+/-1.6 (mean +/- SEM) to 44.1+/-6.8 pmol/L (P<0.001) in association with a threefold increase in urine cGMP excretion (573+/-195 pmol/min baseline to 1823+/-545 pmol/ min; P<0.001), marked natriuresis (207+/-34 micromol/min baseline to 416+/-62 micromol/min; P<0.001), fractional sodium excretion (3.3+/-0.5% baseline to 5.6+/-0.7%; P<0.01), and diuresis (3.4+/-0.5 ml/min baseline to 7.4+/-1 ml/min; P<0.001). All parameters remained elevated above baseline for the remaining 7-hr study period. In response to candoxatrilat, the glomerular filtration rate rose by 19% (P=0.01), renal plasma flow by 7% (P=0.04), renal blood flow by 13% (P=0.03) in association with an increase in filtration fraction from 24+/-2% to 28+/-2% (P=0.002) and small fall in renal vascular resistance from 0.38+/-0.04 to 0.30+/-0.04 mmHg x min x 1.73 m2 x ml(-1) (P=0.02). There was a fall in plasma angiotensin II without a change in plasma renin concentration or plasma aldosterone. Median urinary albumin excretion increased after candoxatrilat administration from 48 (3-131) to 114 (32-641) microg/min (P<0.01). CONCLUSIONS Acute neutral endopeptidase inhibition with candoxatrilat appears to reverse the adverse renal hemodynamic and renal excretory effects of cyclosporine in stable renal transplant recipients.

Blood Pressure Guidelines in Chronic Kidney Disease: A Critical Review

The primary purpose of guidelines should be to improve patient care by providing an avenue for healthcare professionals to participate in the assessment of appropriate care, based on sound medical reasoning and robust scientific knowledge. Guidelines are usually meant to be evidence-based when they are derived from systemic reviews of the relevant literature. Nephrology as a medical subspeciality lags behind other clinical disciplines when it comes to availability of high-quality clinical studies with hard clinical outcomes. In the absence of robust clinical evidence, recommendations in renal guidelines are overwhelmingly opinion-based and reflect the experience of the various experts. Unfortunately, no guidelines are detailed enough to provide recommendations for individual patients with different types and severity of co-morbidities. We propose that guidelines should be viewed as desirables and should not replace a common sense clinical approach to patient care by an autonomously practicing competent clinician.