Evaluation of the Oxford Classification of IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

The Oxford Classification of the pathology of immunoglobulin A (IgA) nephropathy, developed in 2009, is highly predictive of renal prognosis. It has been validated in different populations, but the results remain inconsistent.

STUDY DESIGN

Systematic review and meta-analysis.

SETTING & POPULATION

Patients with biopsy-proven primary IgA nephropathy.

SELECTION CRITERIA FOR STUDIES

Studies assessing the Oxford Classification of IgA nephropathy published between January 2009 and December 2012 were included following systematic searching of the MEDLINE and EMBASE databases.

PREDICTOR

4 pathologic lesions of the Oxford Classification: mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental glomerulosclerosis (S), and tubular atrophy/interstitial fibrosis (T).

OUTCOME

Kidney failure defined as doubled serum creatinine level, 50% decline in estimated glomerular filtration rate, or end-stage kidney disease.

RESULTS

16 retrospective cohort studies with 3,893 patients and 570 kidney failure events were included. In a multivariate model, HRs for kidney failure were 0.6 (95% CI, 0.5-0.8; P < 0.001), 1.8 (95% CI, 1.4-2.4; P < 0.001), and 3.2 (95% CI, 1.8-5.6; P < 0.001) for scores of M0 (mesangial hypercellularity score ≤0.5), S1 (presence of segmental glomerulosclerosis), and T1/2 (>25% tubular atrophy/interstitial fibrosis), respectively, without evidence of heterogeneity. Pooled results showed that E lesions were not associated with kidney failure (HR, 1.4; 95% CI, 0.9-2.0; P = 0.1), with evidence of heterogeneity (I(2) = 54.1%; P = 0.01). Crescent (C) lesions were associated with kidney failure (HR, 2.3; 95% CI, 1.6-3.4; P < 0.001), with no evidence of heterogeneity (I(2) = 14.7%; P = 0.3).

LIMITATIONS

All studies were retrospective. This was not an individual-patient-data meta-analysis.

CONCLUSIONS

This study suggests that M, S, T, and C lesions, but not E lesions, are associated strongly with progression to kidney failure and thus should be included in the Oxford Classification system.

Design of the Nephrotic Syndrome Study Network (NEPTUNE) to evaluate primary glomerular nephropathy by a multidisciplinary approach

The Nephrotic Syndrome Study Network (NEPTUNE) is a North American multicenter collaborative consortium established to develop a translational research infrastructure for nephrotic syndrome. This includes a longitudinal observational cohort study, a pilot and ancillary study program, a training program, and a patient contact registry. NEPTUNE will enroll 450 adults and children with minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy for detailed clinical, histopathological, and molecular phenotyping at the time of clinically indicated renal biopsy. Initial visits will include an extensive clinical history, physical examination, collection of urine, blood and renal tissue samples, and assessments of quality of life and patient-reported outcomes. Follow-up history, physical measures, urine and blood samples, and questionnaires will be obtained every 4 months in the first year and biannually, thereafter. Molecular profiles and gene expression data will be linked to phenotypic, genetic, and digitalized histological data for comprehensive analyses using systems biology approaches. Analytical strategies were designed to transform descriptive information to mechanistic disease classification for nephrotic syndrome and to identify clinical, histological, and genomic disease predictors. Thus, understanding the complexity of the disease pathogenesis will guide further investigation for targeted therapeutic strategies.

A pilot study of reduced dose cyclosporine and corticosteroids to reduce new onset diabetes mellitus and acute rejection in kidney transplant recipients

Background

New onset diabetes mellitus (NODM) and acute rejection (AR) are important causes of morbidity and risk factors for allograft failure after kidney transplantation.

Methods

In this multi-center, open label, single-arm pilot study, 49 adult (≥18 years of age), low immunologic risk, non-diabetic recipients of a first deceased or living donor kidney transplant received early steroid reduction to 5 mg/day combined with Thymoglobulin® (Genzyme Transplant, Cambridge, MA, USA) induction, low dose cyclosporine (2-hour post-dose (C2) target of 600 to 800 ng/ml) and mycophenolic acid (MPA) therapy.

Results

Six months after transplantation, two patients (4%) developed NODM and one patient (2%) developed AR. Four patients had impaired fasting glucose tolerance based on 75-g oral glucose tolerance testing (OGTT). There was one patient death. There were no episodes of cytomegalovirus (CMV) infection or BK virus nephritis. In contrast, in a historical cohort of n = 27 patients treated with Thymoglobulin induction, and conventional doses of cyclosporine and corticosteroids, the incidence of NODM and AR was 18% and 15%.

Conclusions

The pilot study results suggest that Thymoglobulin induction combined with early steroid reduction, reduced cyclosporine exposure and MPA, may reduce the incidence of both NODM and AR in low immunological risk patients. A future controlled study enriched for patients at high risk for NODM is under consideration.

Trial registration

ClinicalTrials.gov: http://NCT00706680

Low- and high-molecular-weight urinary proteins as predictors of response to rituximab in patients with membranous nephropathy: a prospective study

BACKGROUND

Selective urinary biomarkers have been considered superior to total proteinuria in predicting response to treatment and outcome in patients with membranous nephropathy (MN).

METHODS

We prospectively tested whether urinary (U) excretion of retinol-binding protein (RBP), α1-microglobulin (α1M), albumin, immunoglobulin IgG and IgM and/or anti-phospholipase 2 receptor (PLA(2)R) levels could predict response to rituximab (RTX) therapy better than standard measures in MN. We also correlated changes in antibodies to PLA(2)R with these urinary biomarkers.

RESULTS

Twenty patients with MN and proteinuria (P) >5 g/24 h received RTX (375 mg/m(2) × 4) and at 12 months, 1 patient was in complete remission (CR), 9 were in partial remission (PR), 5 had a limited response (LR) and 4 were non-responders (NR). At 24 months, CR occurred in 4, PR in 12, LR in 1, NR in 2 and 1 patient relapsed. By simple linear regression analysis, UIgG at baseline (mg/24 h) was a significant predictor of change in proteinuria at 12 months (Δ urinary protein) (P = 0.04). In addition, fractional excretion (FE) of IgG, urinary alpha 1 microglobulin (Uα1M) (mg/24 h) and URBP (μg/24 h) were also predictors of response (P = 0.05, 0.04, and 0.03, respectively). On the other hand, UIgM, FEIgM, albumin and FE albumin did not predict response (P = 0.10, 0.27, 0.22 and 0.20, respectively). However, when results were analyzed in relation to proteinuria at 24 months, none of the U markers that predicted response at 12 m could predict response at 24 m (P = 0.55, 0.42, 0.29 and 0.20). Decline in anti-PLA(2)R levels was associated with and often preceded urinary biomarker response but positivity at baseline was not a predictor of proteinuria response.

CONCLUSIONS

The results suggest that in patients with MN, quantification of low-, medium- and high-molecular-weight urinary proteins may be associated with rate of response to RTX, but do not correlate with longer term outcomes.

Glomerular disease search filters for Pubmed, Ovid Medline, and Embase: a development and validation study

BACKGROUND

Tools to enhance physician searches of Medline and other bibliographic databases have potential to improve the application of new knowledge in patient care. This is particularly true for articles about glomerular disease, which are published across multiple disciplines and are often difficult to track down. Our objective was to develop and test search filters for PubMed, Ovid Medline, and Embase that allow physicians to search within a subset of the database to retrieve articles relevant to glomerular disease.

METHODS

We used a diagnostic test assessment framework with development and validation phases. We read a total of 22,992 full text articles for relevance and assigned them to the development or validation set to define the reference standard. We then used combinations of search terms to develop 997,298 unique glomerular disease filters. Outcome measures for each filter included sensitivity, specificity, precision, and accuracy. We selected optimal sensitive and specific search filters for each database and applied them to the validation set to test performance.

RESULTS

High performance filters achieved at least 93.8% sensitivity and specificity in the development set. Filters optimized for sensitivity reached at least 96.7% sensitivity and filters optimized for specificity reached at least 98.4% specificity. Performance of these filters was consistent in the validation set and similar among all three databases.

CONCLUSIONS

PubMed, Ovid Medline, and Embase can be filtered for articles relevant to glomerular disease in a reliable manner. These filters can now be used to facilitate physician searching.

Venous thromboembolism in patients with membranous nephropathy

BACKGROUND AND OBJECTIVES

The aims of this study were to determine the frequency of venous thromboembolic events in a large cohort of patients with idiopathic membranous nephropathy and to identify predisposing risk factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied patients with biopsy-proven membranous nephropathy from the Glomerular Disease Collaborative Network (n=412) and the Toronto Glomerulonephritis Registry (n=486) inception cohorts. The cohorts were pooled after establishing similar baseline characteristics (total n=898). Clinically apparent and radiologically confirmed venous thromboembolic events were identified. Potential risk factors were evaluated using multivariable logistic regression models.

RESULTS

Sixty-five (7.2%) subjects had at least one venous thromboembolic event, and this rate did not differ significantly between registries. Most venous thromboembolic events occurred within 2 years of first clinical assessment (median time to VTE = 3.8 months). After adjusting for age, sex, proteinuria, and immunosuppressive therapy, hypoalbuminemia at diagnosis was the only independent predictor of a venous thromboembolic event. Each 1.0 g/dl reduction in serum albumin was associated with a 2.13-fold increased risk of VTE. An albumin level <2.8 g/dl was the threshold below which risk for a venous thromboembolic event was greatest.

CONCLUSIONS

We conclude that clinically apparent venous thromboembolic events occur in about 7% of patients with membranous nephropathy. Hypoalbuminemia, particularly <2.8 g/dl, is the most significant independent predictor of venous thrombotic risk.

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.

Historical aspects of proteinuria

Historical aspects in the investigation, evaluation, and management of patients with proteinuria, in large part, as they relate to patients with glomerulonephritis, are reviewed. This evaluation has been a long and complex process with many divergent and cross pathways. Although the history covers more than 2000 years, it is only in the past 2 centuries, with the more advanced experimental methods that have developed in science, that the growth has been exponential. With these advances, the knowledge between kidney structure and function evolved, and the subsequent links determined between physiology and pathology of kidney disease, and the clinical phenotypes of glomerular disease have revealed the overwhelming importance of proteinuria as both an indicator of kidney involvement and a marker of disease progression.

Have we changed the outcome in membranous nephropathy? A propensity study on the role of immunosuppressive therapy

BACKGROUND AND OBJECTIVES

The long-term effect of immunosuppressive therapy (IS) on kidney survival in idiopathic membranous nephropathy (MGN) is debated. The introduction of renin angiotensin blockade, rigorous BP control, and the increasing age at presentation of patients with MGN adds further uncertainty. Given these important changes, we sought to determine whether implementation of IS has altered outcome.

DESIGN, SETTING, PARTICIPANTS, & METHODS

We prospectively evaluated 280 incident MGN patients from three distinct 10-year periods starting from 1975.

RESULTS

We found expected changes in treatment regimens but also variations in age, renal function, severity of proteinuria, and BP at presentation over this time. Outcomes did not differ over time if these significant variations in clinical characteristics were not accounted for across the eras. The effect of IS in the 57 patients treated with currently recommended regimens was assessed using propensity adjustment to address selection bias and the effect of newer, conservative therapies. A propensity score estimating the probability of receiving IS permitted the pairing of 39 treated patients with controls with similar high risk of progression of clinical features. Using this approach, IS was associated not only with remissions in proteinuria but also with substantially improved renal survival.

CONCLUSIONS

The study confirms that patient presenting characteristics and management regimens have changed significantly over time and the natural history of MGN has been altered. A study of propensity-matched patients confirms that current recommendations for IS have improved outcomes in MGN patients at high risk of progression.

Validation of the Oxford classification of IgA nephropathy

The Oxford classification of IgA nephropathy (IgAN) identified four pathological elements that were of prognostic value and additive to known clinical and laboratory variables in predicting patient outcome. These features are segmental glomerulosclerosis/adhesion, mesangial hypercellularity, endocapillary proliferation, and tubular atrophy/interstitial fibrosis. Here, we tested the Oxford results using an independent cohort of 187 adults and children with IgAN from 4 centers in North America by comparing the performance of the logistic regression model and the predictive value of each of the four lesions in both data sets. The cohorts had similar clinical and histological findings, presentations, and clinicopathological correlations. During follow-up, however, the North American cohort received more immunosuppressive and antihypertensive therapies. Identifying patients with a rapid decline in the rate of renal function using the logistic model from the original study in the validation data set was good (c-statistic 0.75), although less precise than in the original study (0.82). Individually, each pathological variable offered the same predictive value in both cohorts except mesangial hypercellularity, which was a weaker predictor. Thus, this North American cohort validated the Oxford IgAN classification and supports its utilization. Further studies are needed to determine the relationship to the impact of treatment and to define the value of the mesangial hypercellularity score.

Persistent proteinuria and dyslipidemia increase the risk of progressive chronic kidney disease in lupus erythematosus

Advances in immunotherapy have improved survival of patients with systemic lupus erythematosus who now face an increasing burden of chronic diseases including that of the kidney. As systemic inflammation is also thought to contribute directly to the progression of chronic kidney disease (CKD), we assessed this risk in patients with lupus, with and without a diagnosis of nephritis, and also identified modifiable risk factors. Accordingly, we enrolled 631 patients (predominantly Caucasian), of whom 504 were diagnosed with lupus within the first year and followed them an average of 11 years. Despite the presence of a chronic inflammatory disease, the rate of decline in renal function of 238 patients without nephritis was similar to that described for non-lupus patient cohorts. Progressive loss of kidney function developed exclusively in patients with lupus nephritis who had persistent proteinuria and dyslipidemia, although only six required dialysis or transplantation. The mortality rate was 16% with half of the deaths attributable to sepsis or cancer. Thus, despite the presence of a systemic inflammatory disease, the risk of progressive CKD in this lupus cohort was relatively low in the absence of nephritis. Hence, as in idiopathic glomerular disease, persistent proteinuria and dyslipidemia (modifiable risks) are the major factors for CKD progression in lupus patients with renal involvement.

A molecular signature of proteinuria in glomerulonephritis

Proteinuria is the most important predictor of outcome in glomerulonephritis and experimental data suggest that the tubular cell response to proteinuria is an important determinant of progressive fibrosis in the kidney. However, it is unclear whether proteinuria is a marker of disease severity or has a direct effect on tubular cells in the kidneys of patients with glomerulonephritis. Accordingly we studied an in vitro model of proteinuria, and identified 231 “albumin-regulated genes” differentially expressed by primary human kidney tubular epithelial cells exposed to albumin. We translated these findings to human disease by studying mRNA levels of these genes in the tubulo-interstitial compartment of kidney biopsies from patients with IgA nephropathy using microarrays. Biopsies from patients with IgAN (n = 25) could be distinguished from those of control subjects (n = 6) based solely upon the expression of these 231 “albumin-regulated genes.” The expression of an 11-transcript subset related to the degree of proteinuria, and this 11-mRNA subset was also sufficient to distinguish biopsies of subjects with IgAN from control biopsies. We tested if these findings could be extrapolated to other proteinuric diseases beyond IgAN and found that all forms of primary glomerulonephritis (n = 33) can be distinguished from controls (n = 21) based solely on the expression levels of these 11 genes derived from our in vitro proteinuria model. Pathway analysis suggests common regulatory elements shared by these 11 transcripts. In conclusion, we have identified an albumin-regulated 11-gene signature shared between all forms of primary glomerulonephritis. Our findings support the hypothesis that albuminuria may directly promote injury in the tubulo-interstitial compartment of the kidney in patients with glomerulonephritis.

Delayed graft function and the risk of death with graft function in living donor kidney transplant recipients

BACKGROUND

The link between delayed graft function (DGF) and death with graft function (DWGF) in living donor kidney transplant recipients presently is unknown.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

44,630 adult living donor kidney recipients (first transplants only) in the US Renal Data System from January 1, 1994, to December 31, 2004.

PREDICTOR

DGF, defined as the need for dialysis therapy in the first week after transplant.

OUTCOME

Time to DWGF.

MEASUREMENTS

Kaplan-Meier curves were constructed to assess the impact of DGF on DWGF. Recipients with DGF were 1:1 propensity score matched to those without DGF, and time-dependent Cox proportional hazards models were used to examine factors associated with DWGF. Subgroup and sensitivity analyses also were conducted.

RESULTS

DWGF occurred in 3,878 patients during 3.9 years' (median) follow-up. In patients with DGF, survival with graft function at 1, 3, 5, and 10 years was 91.9%, 86.8%, 81.6%, and 61.7%, respectively (in patients without DGF, these values were 98.0%, 95.2%, 91.6%, and 80.1%, respectively; P < 0.001 compared with the DGF group). In a fully adjusted time-dependent Cox model, HRs for DWGF in patients with DGF (vs without DGF) were 6.55 (95% CI, 4.78-8.97), 3.55 (95% CI, 2.46-5.11), 2.07 (95% CI, 1.53-2.81), and 1.48 (95% CI, 1.26-1.73) at 0-1, 1-3, 3-12, and longer than 12 months posttransplant, respectively. Propensity score analysis showed similar results. Inferences were unchanged after adjustment for kidney function and acute rejection at 6 months and 1 year posttransplant. Cardiovascular and infectious causes of DWGF were more prevalent in patients with DGF. The association was more marked in female recipients and robust to various sensitivity analyses.

LIMITATIONS

The impact of lesser decreases in early graft function could not be evaluated.

CONCLUSIONS

DGF is associated with an increased risk of DWGF in living donor kidney recipients. The mechanisms underlying this relation require further study.

Rituximab therapy in idiopathic membranous nephropathy: a 2-year study

BACKGROUND AND OBJECTIVES

It was postulated that in patients with membranous nephropathy (MN), four weekly doses of Rituximab (RTX) would result in more effective B cell depletion, a higher remission rate, and maintaining the same safety profile compared with patients treated with RTX dosed at 1 g every 2 weeks. This hypothesis was supported by previous pharmacokinetic (PK) analysis showing that RTX levels in the two-dose regimen were 50% lower compared with nonproteinuric patients, which could potentially result in undertreatment.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Twenty patients with MN and proteinuria >5 g/24 h received RTX (375 mg/m(2) × 4), with re-treatment at 6 months regardless of proteinuria response. PK analysis was conducted simultaneously with immunological analyses of T and B cells to ascertain the effect of RTX on lymphocyte subpopulations.

RESULTS

Baseline proteinuria of 11.9 g/24 h decreased to 4.2 and 2.0 g/24 h at 12 and 24 months, respectively, whereas creatinine clearance increased from 72.4 ml/min per 1.73 m(2) at baseline to 88.4 ml/min per 1.73 m(2) at 24 months. Of 18 patients who completed 24-month follow-up, 4 are in complete remission, 12 are in partial remission, 1 has a limited response, and 1 patient relapsed. Serum RTX levels were similar to those obtained with two doses of RTX.

CONCLUSIONS

Four doses of RTX resulted in more effective B cell depletion, but proteinuria reduction was similar to RTX at 1 g every 2 weeks. Baseline quantification of lymphocyte subpopulations did not predict response to RTX therapy.

Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial

CONTEXT

Hyperhomocysteinemia is frequently observed in patients with diabetic nephropathy. B-vitamin therapy (folic acid, vitamin B(6), and vitamin B(12)) has been shown to lower the plasma concentration of homocysteine.

OBJECTIVE

To determine whether B-vitamin therapy can slow progression of diabetic nephropathy and prevent vascular complications.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter, randomized, double-blind, placebo-controlled trial (Diabetic Intervention with Vitamins to Improve Nephropathy [DIVINe]) at 5 university medical centers in Canada conducted between May 2001 and July 2007 of 238 participants who had type 1 or 2 diabetes and a clinical diagnosis of diabetic nephropathy.

INTERVENTION

Single tablet of B vitamins containing folic acid (2.5 mg/d), vitamin B(6) (25 mg/d), and vitamin B(12) (1 mg/d), or matching placebo.

MAIN OUTCOME MEASURES

Change in radionuclide glomerular filtration rate (GFR) between baseline and 36 months. Secondary outcomes were dialysis and a composite of myocardial infarction, stroke, revascularization, and all-cause mortality. Plasma total homocysteine was also measured.

RESULTS

The mean (SD) follow-up during the trial was 31.9 (14.4) months. At 36 months, radionuclide GFR decreased by a mean (SE) of 16.5 (1.7) mL/min/1.73 m(2) in the B-vitamin group compared with 10.7 (1.7) mL/min/1.73 m(2) in the placebo group (mean difference, -5.8; 95% confidence interval [CI], -10.6 to -1.1; P = .02). There was no difference in requirement of dialysis (hazard ratio [HR], 1.1; 95% CI, 0.4-2.6; P = .88). The composite outcome occurred more often in the B-vitamin group (HR, 2.0; 95% CI, 1.0-4.0; P = .04). Plasma total homocysteine decreased by a mean (SE) of 2.2 (0.4) micromol/L at 36 months in the B-vitamin group compared with a mean (SE) increase of 2.6 (0.4) micromol/L in the placebo group (mean difference, -4.8; 95% CI, -6.1 to -3.7; P < .001, in favor of B vitamins).

CONCLUSION

Among patients with diabetic nephropathy, high doses of B vitamins compared with placebo resulted in a greater decrease in GFR and an increase in vascular events.

TRIAL REGISTRATION

isrctn.org Identifier: ISRCTN41332305.

Delayed graft function and the risk for death with a functioning graft

Delayed graft function (DGF) associates with an increased risk for graft failure, but its link with death with graft function (DWGF) is unknown. We used the US Renal Data System to assemble a cohort of all first, adult, deceased-donor kidney transplant recipients from January 1, 1998, through December 31, 2004. In total, 11,542 (23%) of 50,246 recipients required at least one dialysis session in the first week after transplantation. Compared with patients without DGF, patients with DGF were significantly more likely to die with a functioning graft (relative hazard 1.83 [95% confidence interval 1.73 to 1.93] and 1.53 [95% CI 1.45 to 1.63] for unadjusted and fully adjusted models, respectively). The risk for DWGF was slightly higher among women with DGF than among men. There was no significant heterogeneity among other subgroups, and the results were robust to sensitivity analyses. Acute rejection within the first year attenuated the DGF-DWGF association. Cardiovascular and infectious deaths were slightly more prevalent in the DGF group, but the relative hazards of cause-specific death were similar between DWGF and deaths during total follow-up. In summary, DGF associates with an increased risk for DWGF; the mechanisms underlying the negative impact of DGF require further study.

The natural history of the non-nephrotic membranous nephropathy patient

BACKGROUND AND OBJECTIVES

Although early studies suggest that patients with idiopathic membranous nephropathy (MGN) and subnephrotic range proteinuria overall do well, these studies were small and follow-up was short or difficult to discern.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Three hundred ninety-five cases of idiopathic MGN with at least 12 mo of follow-up from the Toronto Glomerulonephritis Registry were reviewed to determine the outcome of the subgroup of patients that presented with subnephrotic range proteinuria. Onset and follow-up data included mean arterial pressure (MAP) and creatinine clearance (CrCl) as determined by the Cockcroft-Gault equation. Outcome variables included the rate of progression (slope of CrCl), 50% reduction in initial CrCl, and end-stage renal disease (ESRD).

RESULTS

One hundred eight (27% of the total) patients presented with subnephrotic proteinuria and almost 40% (42 of 108) of this subgroup remained subnephrotic. Their long-term slope was -0.93 ml/min/yr. In contrast, those who subsequently developed nephrotic range proteinuria had a progression rate almost four times faster (-3.52 ml/min/yr). The majority who developed nephrotic syndrome did so within the first year of follow-up. The only distinguishing baseline feature between the two groups was a higher level of urine protein in the group that subsequently developed nephrotic syndrome (1.98 [0.3 to 3.4] versus 2.43 [0.5 to 3.4] g/d).

CONCLUSIONS

Patients with MGN and sustained subnephrotic range proteinuria have an excellent prognosis. Conservative management with close monitoring is recommended given the difficulty predicting which patients will develop nephrotic range proteinuria and then progress more rapidly.

The Oxford classification of IgA nephropathy: rationale, clinicopathological correlations, and classification

IgA nephropathy is the most common glomerular disease worldwide, yet there is no international consensus for its pathological or clinical classification. Here a new classification for IgA nephropathy is presented by an international consensus working group. The goal of this new system was to identify specific pathological features that more accurately predict risk of progression of renal disease in IgA nephropathy, thus enabling both clinicians and pathologists to improve individual patient prognostication. In a retrospective analysis, sequential clinical data were obtained on 265 adults and children with IgA nephropathy who were followed for a median of 5 years. Renal biopsies from all patients were scored by pathologists blinded to the clinical data for pathological variables identified as reproducible by an iterative process. Four of these variables: (1) the mesangial hypercellularity score, (2) segmental glomerulosclerosis, (3) endocapillary hypercellularity, and (4) tubular atrophy/interstitial fibrosis were subsequently shown to have independent value in predicting renal outcome. These specific pathological features withstood rigorous statistical analysis even after taking into account all clinical indicators available at the time of biopsy as well as during follow-up. The features have prognostic significance and we recommended they be taken into account for predicting outcome independent of the clinical features both at the time of presentation and during follow-up. The value of crescents was not addressed due to their low prevalence in the enrolled cohort.

Validation of the Toronto formula to predict progression in IgA nephropathy

BACKGROUND/AIM

Predicting outcome in IgA nephropathy (IgAN) is difficult. The Toronto formula uses average mean arterial blood pressure and proteinuria during the first 2 years of follow-up (MAP(0-2), UP(0-2)) to predict the subsequent slope of estimated creatinine clearance (eCrCl). We aimed to validate the Toronto formula in a Scottish cohort and test the hypothesis that adding the slope eCrCl over the first 2 years of follow-up (eCrCl(0-2)) would improve the predictive utility of a similar multivariate model.

METHODS

Adultsfrom our centre with biopsy-proven IgAN (n = 169) and at least 2 years of follow-up (median 129.4 months) were included. Clinical data were used to calculate MAP(0-2),UP(0-2),slope eCrCl(0-2 )and predicted slope eCrCl (using the Toronto formula).

RESULTS

There was a significant correlation between predicted slope eCrCl using the Toronto formula and actual slope eCrCl (R(2 =) 0.21; p < 0.001). The formula predicted the actual rate of progression to within 4 ml/min/year in 75% of subjects, predicting patients with the most rapid deterioration with the greatest accuracy. The multivariate linear regression model created in our cohort using the same independent variables as the Toronto formula to predict the overall slope eCrCl had an R(2) of 0.22 (p < 0.001) and adding the slope CrCl(0-2) only increased this to 0.25.

CONCLUSIONS

The Toronto formula is valid in a European population and useful for identifying patients at high risk of future deterioration in renal function. Adding slope eCrCl(0-2) to a predictive model containing MAP(0-2), andUP(0-2 )does not appear to improve prediction of the overall slope of eCrCl.

Rituximab treatment of idiopathic membranous nephropathy

Idiopathic membranous nephropathy is a common cause of nephrotic syndrome whose pathogenesis may involve B-cell functions. Rituximab is a monoclonal antibody that binds to the CD20 antigen on B cells thereby deleting them. We conducted an open-label pilot trial of rituximab treatment in 15 severely nephrotic patients with proteinuria refractory to angiotensin-converting enzyme inhibition and/or receptor blockade but with adequately controlled blood pressure. Rituximab was given 2 weeks apart and, at 6 months, patients who remained proteinuric but had recovered B-cell counts were given a second course of treatment. Proteinuria was significantly decreased by about half at 12 months. Of the 14 patients who completed follow-up, full remission was achieved in two and partial remission in six patients based upon the degree of proteinuria. Side effects were minor; however, we found no relationship between the response and number of B cells in the blood, CD20 cells in the kidney biopsy, degree of tubulointerstitial fibrosis, starting proteinuria or creatinine values. Rituximab appears effective in reducing proteinuria in some patients with idiopathic membranous nephropathy but prospective identification of responsive patients was not possible.

Remission of proteinuria improves prognosis in IgA nephropathy

Proteinuria has been shown to be an adverse prognostic factor in IgA nephropathy. The benefit of achieving a partial remission of proteinuria, however, has not been well described. We studied 542 patients with biopsy-proven primary IgA nephropathy in the Toronto Glomerulonephritis Registry and found that glomerular filtration rate (GFR) declined at -0.38 +/- 0.61 ml/min per 1.73 m2/mo overall, with 30% of subjects reaching end-stage renal disease. Multivariate analysis revealed that proteinuria during follow-up was the most important predictor of the rate of GFR decline. Among the 171 patients with <1 g/d of sustained proteinuria, the rate of decline was 90% slower than the mean rate. The rate of decline increased with the amount of proteinuria, such that those with sustained proteinuria >3 g/d (n = 121) lost renal function 25-fold faster than those with <1 g/d. Patients who presented with > or =3 g/d who achieved a partial remission (<1 g/d) had a similar course to patients who had < or =1 g/d throughout, and fared far better than patients who never achieved remission. These results underscore the relationship between proteinuria and prognosis in IgA nephropathy and establish the importance of remission.

Cyclosporin in idiopathic glomerular disease associated with the nephrotic syndrome : workshop recommendations

Management of idiopathic glomerular disease associated with nephrotic syndrome (INS) remains controversial and one of the most complex areas relates to utilization of the drug cyclosporin. This is despite its demonstrated effectiveness in several histologic types of the INS in randomized controlled trials. Cyclosporin is effective in inducing remission of proteinuria in approximately 80% of steroid-sensitive cases of minimal change disease (MCD). Cyclosporin is also effective in both the induction of remission and long-term preservation of renal function in steroid-dependent/-resistant MCD and steroid-resistant focal segmental glomerulosclerosis (FSGS). The overall response rate in FSGS is lower than in MCD, and long-term therapy (>12 months) may be required to both achieve remission and sustain it. Cyclosporin therapy is also of benefit in reducing proteinuria in 70-80% of patients with steroid-resistant membranous nephropathy (MGN). In MGN, the maximum benefit is often delayed compared to MCD (>12 weeks). Cyclosporin is generally well tolerated and safe. The major concern remains the nephrotoxicity, but with careful monitoring of the patient's renal function; minimizing the maintenance dose and utilizing repeat renal biopsy in those receiving long-term therapy, this risk can be minimized. The algorithms have been developed derived from the best evidence in the literature in each of the histologic types to help provide a guide to the integration of cyclosporin into the management of INS for the practicing nephrologist.