IgA nephropathy

Recurrent IgA nephropathy after renal transplantation

Recurrence of the original disease is now the third most frequent cause of allograft loss at 10 years after transplantation in patients with underlying glomerulonephritis. IgA nephropathy (IgAN), the most common type of glomerulonephritis, histologically recurs in up to 60% of the patients. Initially considered to be a relatively benign phenomenon, several studies, which included a total of almost 1200 patients with underlying IgAN, have now established that after a mean follow up of 5 years, approximately 13% of the patients will exhibit some recurrence-related renal graft dysfunction and approximately 5% will have lost their graft as a result of recurrent IgAN. The only established predictor of graft loss is the time elapsed since renal transplantation. The risk of recurrence-associated graft loss increases to approximately 25% if a prior graft has already been lost as a result of recurrent IgAN. Whether living, related donor kidneys are at higher risk for recurrence is controversial. Despite all these issues, graft survival in patients with underlying IgAN compared with patients with other renal diseases is excellent. In patients with recurrent IgAN, no specific therapy other than optimal supportive care has been established.

Use of corticosteroids, other immunosuppressive therapies, and tonsillectomy in the treatment of IgA nephropathy

Because IgA nephropathy (IgAN) was originally regarded as a benign condition, the indication of corticosteroids or other immunosuppressive therapies have been highly restricted because of potential side effects, and such drugs have been used for a specific subgroup of patients with IgAN, taking the risk/benefit ratio into consideration. During the last decade, however, with the recognition that the overall long-term prognosis of IgAN is a nonbenign condition, more aggressive treatments, including high-dose corticosteroids, various immunosuppressive agents, and tonsillectomy, have been used for wider subgroups of patients with IgAN. Moreover, recent studies have suggested that clinical remission as well as histopathologic regression of the nephropathy could be obtained by such treatments if treatment is initiated in its relatively early stage. Thus, the possibility has now been raised that the goal of treatment for patients with IgAN will shift from "slowing the progression of nephropathy" to "remission of nephropathy."

Gene expression profiles of circulating leukocytes correlate with renal disease activity in IgA nephropathy

BACKGROUND

The goal of these studies was to explore the possibility of using gene expression profiles of circulating leukocytes as a functional fingerprint of nephritic disease activity.

METHODS

This feasibility study utilized IgA nephropathy (IgAN) as a model system. Genes differentially expressed in IgAN patients were identified by Affymetrix GeneChip microarrays, and compared with gene expression of focal segmental glomerulosclerosis (FSGS), minimal change disease, antineutrophil cytoplasmic antibody (ANCA) glomerulonephritis, and with healthy volunteers. Of the genes identified, 15 transcriptionally up-regulated were validated in a larger cohort of patients using TaqMan polymerase chain reaction (PCR). To test whether increased expression of these genes correlated with disease activity, cluster analyses were performed utilizing the TaqMan PCR values. Taking a mathematical approach, we tested whether gene expression values were correlative with kidney function, as reflected by serum creatinine and creatinine clearance values.

RESULTS

We identified 15 genes significantly correlative with disease activity in IgAN. This gene signature of IgAN patients' leukocytes reflected kidney function. This was demonstrated in that mathematically generated theoretical values of serum creatinine and creatinine clearance correlated significantly with actual IgAN patient values of serum creatinine and creatinine clearance. There was no apparent correlation with hematuria and proteinuria. The expression levels of this same gene set in ANCA glomerulonephritis or Lupus nephritis patients were not correlative with serum creatinine or creatinine clearance values.

CONCLUSION

These data indicate that leukocytes carry informative disease-specific markers of pathogenic changes in renal tissue.

Race/ethnicity and disease severity in IgA nephropathy

BACKGROUND

Relatively few U.S.-based studies in chronic kidney disease have focused on Asian/Pacific Islanders. Clinical reports suggest that Asian/Pacific Islanders are more likely to be affected by IgA nephropathy (IgAN), and that the severity of disease is increased in these populations.

METHODS

To explore whether these observations are borne out in a multi-ethnic, tertiary care renal pathology practice, we examined clinical and pathologic data on 298 patients with primary glomerular lesions (IgAN, focal segmental glomerulosclerosis, membranous nephropathy and minimal change disease) at the University of California San Francisco Medical Center from November 1994 through May 2001. Pathologic assessment of native kidney biopsies with IgAN was conducted using Haas' classification system.

RESULTS

Among individuals with IgAN (N = 149), 89 (60%) were male, 57 (38%) white, 53 (36%) Asian/Pacific Islander, 29 (19%) Hispanic, 4 (3%) African American and 6 (4%) were of other or unknown ethnicity. The mean age was 37 +/- 14 years and median serum creatinine 1.7 mg/dL. Sixty-six patients (44%) exhibited nephrotic range proteinuria at the time of kidney biopsy. The distributions of age, gender, mean serum creatinine, and presence or absence of nephrotic proteinuria and/or hypertension at the time of kidney biopsy were not significantly different among white, Hispanic, and Asian/Pacific Islander groups. Of the 124 native kidney biopsies with IgAN, 10 (8%) cases were classified into Haas subclass I, 12 (10%) subclass II, 23 (18%) subclass III, 30 (25%) subclass IV, and 49 (40%) subclass V. The distribution of Haas subclass did not differ significantly by race/ethnicity. In comparison, among the random sample of patients with non-IgAN glomerular lesions (N = 149), 77 (52%) patients were male, 51 (34%) white, 42 (28%) Asian/Pacific Islander, 25 (17%) Hispanic, and 30 (20%) were African American.

CONCLUSIONS

With the caveats of referral and biopsy biases, the race/ethnicity distribution of IgAN differs significantly from that of other major glomerulonephridities. However, among individuals undergoing native kidney biopsy, we see no evidence of a race/ethnicity association with severity of disease in IgAN by clinical and IgAN-specific histopathologic criteria. Further studies are needed to identify populations at higher risk for progressive disease in IgAN.

Inhibition of B cell death causes the development of an IgA nephropathy in (New Zealand white x C57BL/6)F(1)-bcl-2 transgenic mice

Little is known about the pathogenic mechanisms of IgA nephropathy, despite being the most prevalent form of glomerulonephritis in humans. We report in this study that in (New Zealand White (NZW) x C57BL/6)F(1) mice predisposed to autoimmune diseases, the expression of a human bcl-2 (hbcl-2) transgene in B cells promotes a CD4-dependent lupus-like syndrome characterized by IgG and IgA hypergammaglobulinemia, autoantibody production, and the development of a fatal glomerulonephritis. Histopathological analysis of glomerular lesions reveals that the glomerulonephritis observed in these animals resembles that of human IgA nephropathy. The overexpression of Bcl-2 in B cells selectively enhances systemic IgA immune responses to T-dependent Ags. Significantly, serum IgA purified from (NZW x C57BL/6)F(1)-hbcl-2 transgenic mice, but not from nontransgenic littermates, shows reduced levels of galactosylation and sialylation and an increased ability to deposit in the glomeruli, as observed in human patients with IgA nephropathy. Our results indicate that defects in the regulation of B lymphocyte survival associated with aberrant IgA glycosylation may be critically involved in the pathogenesis of IgA nephropathy, and that (NZW x C57BL/6)F(1)-hbcl-2 Tg mice provide a new experimental model for this form of glomerulonephritis.

Review Article. Immunosuppressive treatments for immunoglobulin A nephropathy: A meta-analysis of randomized controlled trials

Immunoglobulin A (IgA) nephropathy is a worldwide disease that causes end-stage kidney disease (ESRD) in up to 15-20% of affected patients within 10 years from the apparent onset of disease and in up to 30-40% of individuals within 20 years from diagnosis. No specific treatment has been established and there is wide variation in current practice. This systematic review evaluates the use of immunosuppressive agents to treat patients with IgA nephropathy. The Cochrane Renal Group Specialized Register, Cochrane Controlled Trial Registry, MEDLINE, EMBASE and article reference lists were searched for randomized or quasi randomized trials. Two independent reviewers assessed studies for inclusion criteria (biopsy proven IgA nephropathy, randomized trial, use of immunosuppressive agents) and extracted data regarding the effects of immunosuppressive agents on ESRD, doubling of serum creatinine, glomerular filtration rate, urinary protein excretion and side-effects. Data were analysed with a random effects model. The published trials were few (13 trials, 623 patients) and were generally of poor quality. Compared with placebo, steroids were associated with a lower risk of progression to ESRD (six trials, 341 patients, RR 0.44, 95% CI 0.25-0.80) and lower end-of-trial proteinuria (six trials, 263 patients, weighted mean difference (WMD) -0.49 g/day, 95% CI -0.25 to -0.72). Treatment with alkylating agents significantly reduced end of treatment proteinuria (two trials, 122 patients, WMD -0.94, 95% CI -0.46 to -1.43). Although the optimal management of patients with IgA nephropathy remains uncertain because of limitations with the existing published data, immunosuppressive agents are a promising strategy and should be investigated further.

G protein β3 subunit C825T polymorphism in primary IgA nephropathy

BACKGROUND

The T allele of the G protein beta3 subunit (GNB3) C825T polymorphism has been associated with increased signal transduction, increased activity of the kidney Na+/H+ exchanger, and also with late-onset essential hypertension. Hypertension is a strong independent risk factor for progression in IgA nephropathy (IgAN).

METHODS

We have studied this polymorphism in a regularly followed cohort of 299 biopsy-proven incident cases of IgAN, collected from 1989 to 1999 [208 males (70%)] and compared the genotypes and alleles distributions to 303 local Caucasian controls matched for the male predominance (214 males). The technique used was a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with BseDI as restriction enzyme and specific primers, followed by gel electrophoresis.

RESULTS

The TT, CT, and CC genotype frequencies were 13.7%, 45.8%, and 40.5% in IgAN, respectively, versus 7.6%, 47.2%, and 45.2% in controls, respectively (chi(2)= 6.16; P= 0.05). The excess of TT patients versus non-TT was significant in IgAN versus controls (chi(2)= 5.94; P= 0.015). The T allele frequency was 0.366 in IgAN versus 0.312 in controls (chi(2)= 3.97; P= 0.05). This data indicated that this polymorphism had a significant but mild influence on the occurrence/initiation of IgAN (RR = 1.81; 95% CI 1.07-3.07). In contrast, we could not demonstrate any significant and sustained difference in the clinical presentation and evolution of the homozygous TT patients compared to non-TT patients (CC + CT) despite a mean and median follow-up about 10 years. The progression to arterial hypertension or to chronic renal failure or to end-stage renal failure (ESRF) was not significantly different. In addition, multivariate Cox regression analysis excluded a significant independent role of C825T polymorphism on progression.

CONCLUSION

The C825T GNB3 polymorphism had a mild influence on occurrence/initiation of IgAN, but played no significant role in the progression of the disease.

IgA nephropathy associated with X-linked thrombocytopenia

X-Linked thrombocytopenia (XLT) is characterized by congenital thrombocytopenia with small platelets and absence of immunodeficiency; XLT is an allelic variant of Wiskott-Aldrich syndrome (WAS). Both entities are caused by mutations in the same gene. This study presents the case of an 8-year-old boy with XLT. He developed immunoglobulin A (IgA) nephropathy at the age of 4 years. Genetic analysis confirmed the XLT diagnosis. His maternal uncle also had thrombocytopenia from early infancy and developed end-stage renal failure as a result of IgA nephropathy. The maternal uncle was inferred to be affected with XLT because of the carrier status of the patient's mother. Abnormal glycosylation has a role in pathogenesis in IgA nephropathy; moreover, sialophorin glycosylation is defective in WAS. Altered glycosylation may contribute to renal involvement in patients with WAS/XLT despite different defective glycosylation patterns in IgA nephropathy and WAS/XLT.

The role of fish oil/omega-3 fatty acids in the treatment of IgA nephropathy

Beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) have been reported in recent epidemiologic studies and randomized clinical trials in a variety of cardiovascular and autoimmune diseases. Fish and marine oils are the most abundant and convenient sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the two major n-3 fatty acids that serve as substrates for cyclooxygenase and lipoxygenase pathways leading to less potent inflammatory mediators than those produced through the n-6 PUFA substrate, arachidonic acid. N-3 PUFA can also suppress inflammatory and/or immunologic responses through eicosanoid-independent mechanisms. Although the pathophysiology of IgA nephropathy is incompletely understood, it is likely that n-3 PUFA prevents renal disease progression by interfering with a number of effector pathways triggered by mesangial immune-complex deposition. In addition, potential targets of n-3 PUFA relevant to renal disease progression could be similar to those involved in preventing the development and progression of cardiovascular disease by lowering blood pressure, reducing serum lipid levels, decreasing vascular resistance, or preventing thrombosis. In IgA nephropathy, efficacy of n-3 PUFA contained in fish oil supplements has been tested with varying results. The largest randomized clinical trial performed by our collaborative group provided strong evidence that treatment for 2 years with a daily dose of 1.8 g of EPA and 1.2 g of DHA slowed the progression of renal disease in high-risk patients. These benefits persisted after 6.4 years of follow up. With safety, composition, and dosing convenience in mind, we can recommend two products that are available as pharmaceutical-grade fish-oil concentrates, Omacor (Pronova Biocare, Oslo, Norway) and Coromega (European Reference Botanical Laboratories, Carlsbad, CA).

TNF deficiency fails to protect BAFF transgenic mice against autoimmunity and reveals a predisposition to B cell lymphoma

TNF is well characterized as a mediator of inflammatory responses. TNF also facilitates organization of secondary lymphoid organs, particularly B cell follicles and germinal centers, a hallmark of T-dependent Ab responses. TNF also mediates defense against tumors. We examined the role of TNF in the development of inflammatory autoimmune disorders resembling systemic lupus erythematosus and Sjögren's syndrome induced by excess B cell-activating factor belonging to the TNF family (BAFF), by generating BAFF-transgenic (Tg) mice lacking TNF. TNF(-/-) BAFF-Tg mice resembled TNF(-/-) mice, in that they lacked B cell follicles, follicular dendritic cells, and germinal centers, and have impaired responses to T-dependent Ags. Nevertheless, TNF(-/-) BAFF-Tg mice developed autoimmune disorders similar to that of BAFF-Tg mice. Disease in TNF(-/-) BAFF-Tg mice correlates with the expansion of transitional type 2 and marginal zone B cell populations and enhanced T-independent immune responses. TNF deficiency in BAFF-Tg mice also led to a surprisingly high incidence of B cell lymphomas (>35%), which most likely resulted from the combined effects of BAFF promotion of neoplastic B cell survival, coupled with lack of protective antitumor defense by TNF. Thus, TNF appears to be dispensable for BAFF-mediated autoimmune disorders and may, in fact, counter any proneoplastic effects of high levels of BAFF in diseases such as Sjögren's syndrome, systemic lupus erythematosus, and rheumatoid arthritis.

Is IgA nephropathy induced by hyperproduction of interferon-α?

The frequent occurrence of tonsillitis or upper respiratory tract infections preceeding exacerbations of haematuria in IgA nephropathy (IgAN) suggests a relationship to the pathogenesis. Since it has been shown that release of type I interferon (IFN-alpha) can promote the release of BAFF which aids maturation of B lymphocytes, and IFN-alpha is released as part of innate immunity to pathogens of the upper respiratory tract, it is suggested than IFN-alpha may trigger the pathogenic process of IgAN. How cells in the tonsils contribute and whether Il-6 formation in the lungs also helps development of Th.2 lymphocytes are to be considered.

Pathogenesis of IgA nephropathy

Immunoglobulin A (IgA) nephropathy is an immune-complex-mediated glomerulonephritis characterized by the presence of immunoglobulin A deposits in mesangial and paramesangial regions. The patients with IgA nephropathy present with varying clinical symptoms (eg, microhematuria with preserved renal function or progressive deterioration of renal functions resulting in end-stage renal disease). The factors involved in the pathogenetic mechanisms of IgA nephropathy include (1). environmental factors, (2). genetic factors, (3). abnormality of the IgA1 molecule, and (4). various inflammatory mediators. The gene polymorphism studies for human leukocyte antigen (HLA), renin-angiotensin-aldosterone system, and selectin gene clusters, suggest a certain degree of genetic predisposition in patients for IgA nephropathy. Also, the genome-wide screening in familial IgA nephropathy showed linkage of IgA nephropathy to the 6q22-23 chromosome. Besides genetic influence in its pathogenesis, aberrant galactosylation in serum IgA and IgA1 eluted from kidneys with IgA nephropathy has been observed, and conceivably such abnormalities induce the expression of various cytokines, interleukin (IL)-6, platelet-derived growth factor (PDGF), tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-beta1 in the renal cells, which contributes to further glomerular injury. Despite an enormous amount of information available in the literature, further studies are needed to delineate the precise pathogenetic mechanisms involved in primary IgA nephropathy and also to facilitate the development of newer therapeutic interventions.

Effects of co-administration of urokinase and benazepril on severe IgA nephropathy

BACKGROUND

The availability of treatment for IgA nephropathy (IgAN) is limited. Method. A prospective randomized controlled clinical trial was performed to evaluate the effects of therapy with urokinase (UK) and benazepril (BZ, an angiotensin-converting enzyme inhibitor) or BZ alone on severe IgAN. We divided 71 cases of IgAN, Lee's grade >/=III and with fibrinogen deposits, into two groups to be treated for 12 months with either UK + BZ or BZ alone.

RESULTS

There was no significant difference between the two groups in baseline clinical and histopathological data. After 12 months of treatment, 25 of 35 patients (71.4%) in the UK + BZ group and 16 of 36 (44.4%) in the BZ-alone group had a >/=50% decrease in 24-h urinary protein excretion compared with the baseline (chi(2) test, P<0.05). Proteinuria significantly decreased at 6 and 12 months of treatment in both groups compared with baseline (P<0.01 in the UK + BZ group, P<0.05 in the BZ group), and the therapeutic efficiency of UK + BZ was better than that of BZ alone (P<0.05 at 6 and 12 months). The endogenous creatinine clearance rate (Ccr) was stable in the UK + BZ group, while Ccr declined significantly at 6 and 12 months in the BZ-alone group compared with baseline (P<0.05, respectively). The Ccrs of the two groups at 12 months of treatment were statistically different (P<0.05).

CONCLUSIONS

Combined therapy with UK and BZ was more effective than with BZ alone in reducing proteinuria and protecting renal function in patients with severe IgAN.

Immunomodulation by polyunsaturated fatty acids: mechanisms and effects

Polyunsaturated fatty acids (PUFAs) modulate immune responses, thereby exerting beneficial effects in a variety of inflammatory disorders. PUFAs of the n-3 series that are found in marine fish oils are particularly effective. A variety of molecular mechanisms have been found to explain how PUFAs could interfere with immune cell function. PUFAs alter eicosanoid (prostaglandin, leukotriene) synthesis, orphan nuclear receptor activation (e.g. peroxisome proliferator-activated receptors, liver X receptors) and T lymphocyte signaling by changing the molecular composition of special signaling platforms called lipid rafts. This review discusses these mechanisms in detail with respect to their probable relevance in vivo. In addition, the effects of PUFAs on the immune system in general are summarized, as are clinical effects in rheumatoid arthritis, inflammatory bowel disease and sepsis.

No association of the -2518 MCP-1 A/G promoter polymorphism with incidence and clinical course of IgA nephropathy

BACKGROUND

The clinical course of IgA nephropathy is highly variable, ranging from complete remission to progression with end-stage renal disease. Although the mechanisms involved in disease progression are not characterized in detail, loss of renal function is positively correlated with mononuclear cell infiltration. In general, chemokines play an important role in the directional recruitment of inflammatory cells. Recently, a polymorphism in the distal 5' regulatory region of the chemokine monocyte chemoattractant protein-1 (MCP-1), which affects gene expression, has been described (A/G at position -2518). The aim of our study was to evaluate a possible association of this polymorphism with disease progression in patients with IgA nephropathy, as well as susceptibility to this form of glomerulonephritis.

METHODS

Blood samples from 207 patients with biopsy proven IgA nephropathy and 140 ethnically, age and sex-matched healthy controls were collected and genomic DNA was extracted. MCP-1 -2518 genotype was assessed by PCR, followed by restriction fragment length polymorphism analysis. Genotype distribution between the two groups was compared by chi(2) test. Cumulative renal survival was assessed by Kaplan-Meier plot and log-rank analysis.

RESULTS

111 (53.6%) patients had the MCP-1 -2518 wild-type A/A, 83 (40.1%) were heterozygous for the G allele and 13 (6.3%) patients showed homozygosity. The allelic distribution was not significantly different in the control group of 140 healthy blood donors (P = 0.71). Renal survival analysis of patients did not reveal statistically significant differences in cumulative survival (P = 0.32), median survival time and 5 year survival rate between the wild-type group and carriers of the G allele. Furthermore, the number of infiltrating CD68-positive monocytes/macrophages into the kidneys of patients with IgA nephropathy was not statistically different between the groups.

CONCLUSION

Our data indicate that no association exists between the -2518 A/G polymorphism and susceptibility to IgA nephropathy or its clinical course.

Clinical features of thin basement membrane disease and associated glomerulopathies

BACKGROUND

Thin basement membrane disease (TBMD) occurs in 5-11% of renal biopsy series, and can be associated with other glomerulopathies (GNs). Data on the prevalence, clinical features, and prognosis of TBMD with other GNs are limited.

METHODS AND RESULTS

From June 1990 to May 2001, findings from 658 native kidney biopsies were retrospectively studied. The overall prevalence of TBMD was 7.9% (52 of 658). The mean glomerular basement membrane (GBM) thickness was 206 +/- 30 nm. Clinicopathological features were compared for patients with TBMD only (n = 14) and in those with TBMD and GN (n = 38). Focal segmental glomerulosclerosis, mesangial proliferative GN, and minimal change disease were the most common GNs associated with TBMD. After a mean follow-up period of 44.9 +/- 42.5 months, the group who only had TBMD revealed a relatively benign disease with microscopic haematuria and trivial proteinuria, a low prevalence of hypertension, and no renal progression. In the group who had both TBMD and GN, heavy proteinuria (6.1 +/- 5.2 g/day), hypoalbuminaemia (26 +/- 12 g/L) and renal insufficiency (76 +/- 25 mL/min) might develop.

CONCLUSION

We suggested that the TBMD is a developmental abnormality of little or no significance and that it is the underlying associated GN rather than TBMD, which has the relevance to the outcome of renal disease.

Relationships of race and ethnicity to progression of kidney dysfunction and clinical outcomes in patients with chronic kidney failure

In the United States, the incidence of end-stage renal disease (ESRD) is much higher for blacks, Native Americans, and Asians than for whites. The incidence of kidney disease is also higher for populations of Hispanic ethnicity. ESRD attributed to diabetes (ESRD-DM), hypertension (ESRD-HT), and glomerulonephritis (ESRD-GN), in this order of frequency, are the major categories of ESRD in the United States for all race/ethnic groups. By using the incidence rates of ESRD, during the period from 1997 through 2000, and with whites as reference, the highest rate ratio (RR) was observed for ESRD-HT in blacks (RR = 5.96), ESRD-DM in Native Americans (RR = 5.11), and ESRD-GN in Asians (RR=2.20). The data suggest that the excess of ESRD observed for racial/ethnic minorities may be reduced by interventions aimed at prevention/control of hypertension and diabetes. The data suggest that before developing ESRD, patients with chronic renal failure from minority groups have to face more barriers to receive high-quality health care. This may explain why they see nephrologists later and are less likely to receive renal transplantation at initiation of renal replacement therapy (RRT). Improvements in quality of care after initiating RRT may explain the lower mortality and higher scores in heath-related quality of life observed for patients from racial/ethnic minorities.

IgA nephropathy presenting clinical features of poststreptococcal glomerulonephritis

IgA nephropathy and poststreptococcal glomerulonephritis are common forms of primary glomerulonephritis in children. This paper reports a 5-year-old Omani boy who had a chance occurrence of these two different glomerular diseases. Our patient presented with clinical features of poststreptococcal glomerulonephritis and then developed recurrent macroscopic hematuria, polyarthritis, bloody diarrhea, and erythematous swelling of the penis. Renal biopsy revealed diffuse mesangial hypercellularity, with focal glomerular sclerosis, fibrous crescents, and mesangial IgA and C3 deposits, consistent with IgA nephropathy. The clinical features and differential diagnosis are outlined.

Prevalence of hematuria among Zuni Indians with and without diabetes: The Zuni kidney Project

BACKGROUND

There is an epidemic of kidney disease among the Zuni Indians. In contrast to other American Indian tribes, the epidemic among the Zuni Indians is attributable to diabetic and nondiabetic renal disease.

METHODS

The Zuni Kidney Project, established to reduce the burden of renal disease, conducted a population-based cross-sectional survey of Zuni Indians aged 5 years or older to precisely estimate the prevalence of hematuria. The survey used neighborhood household clusters as the sampling frame to maximize ascertainment and minimize bias. During the survey, we administered a questionnaire; collected blood and urine samples; and measured blood pressure, height, and weight.

RESULTS

Age and sex distributions in our sample (n = 1,469) were similar to those of the eligible Zuni population (n = 9,228). Prevalences of hematuria, defined as dipstick of trace or greater and 50 red blood cells/microL or greater, age- and sex-adjusted to the Zuni population aged 5 years or older, were 33.2% (95% confidence interval [CI], 30.7 to 35.6) and 17.8% (95% CI, 15.8 to 19.8), respectively. Hematuria of trace or greater was more common among females (40.6%; 95% CI, 37.0 to 44.1) than males (25.1%; 95% CI, 21.8 to 28.4). Hematuria of trace or greater was common among Zuni Indians without diabetes (females, 39.7%; 95% CI, 35.7 to 43.8; males, 22.7%; 95% CI, 19.4 to 26.1) and with diabetes (females, 47.5%; 95% CI, 39.8 to 55.2; males, 45.8%; 95% CI, 34.3 to 57.3). Diabetes and alcohol use for greater than 10 years were associated with hematuria among males, but not females.

CONCLUSION

The prevalence of hematuria is high among Zuni Indians with and without diabetes. These findings are consistent with the hypothesis that nondiabetic kidney disease is common among Zuni Indians with and without diabetes.

Treatment of IgA nephropathy with ACE inhibitors: a randomized and controlled trial

Some retrospective studies have suggested a beneficial influence of angiotensin-converting enzyme (ACE) inhibitors on the progression of IgA nephropathy (IgAN), but prospective and controlled studies demonstrating this effect are lacking. Forty-four patients with biopsy-proven IgAN, proteinuria > or = 0.5 g/d, and serum creatinine (SCr) < or = 1.5 mg/dl were randomly assigned either to receive enalapril (n = 23) or to a control group (n = 21) in whom BP was controlled with antihypertensives other than ACE inhibitors. Primary outcome was renal survival estimated by a 50% increase in baseline SCr. Secondary outcomes were the presence of a SCr > 1.5 mg/dl at the last visit and the evolution of proteinuria. Baseline clinical findings were similar at baseline between enalapril-treated and control group, and there were no differences in BP control during follow-up. Mean follow-up was 78 +/- 37 mo in the enalapril group and 74 +/- 36 mo in the control group. Three patients (13%) in the enalapril group and 12 (57%) in the control group reached the primary end point (P < 0.05). Kaplan-Meier renal survival was significantly better in enalapril group than in control group: 100% versus 70% after 4 yr and 92% versus 55% after 7 yr (P < 0.05). Three patients in the enalapril group (13%) and 11 (52%) in the control group showed SCr > 1.5 mg/dl at the last visit (P < 0.05). Proteinuria significantly decreased in the enalapril group, whereas it tended to increase in the control group (P < 0.001 between groups). In conclusion, ACE inhibitors significantly improve renal survival in proteinuric IgAN with normal or moderately reduced renal function.

Immunosuppressive agents for treating IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is a world-wide disease and the cause of end-stage renal failure (ESRF) in 15 to 20% of patients within 10 years and in 30 to 40% of individuals within 20 years from the apparent onset of disease. No specific treatment has yet been established but many approaches have been investigated.

OBJECTIVES

To assess the benefits and harms of immunosuppressive treatment for IgAN.

SEARCH STRATEGY

We searched The Cochrane Renal Group's specialized register (May 2003), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 3, 2002) MEDLINE (1966 - September 2002), EMBASE (1988 - September 2002) and handsearched reference lists of retrieved articles and conference proceedings.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and quasi-RCTs comparing treatment of IgAN with immunosuppressive agents against placebo, no treatment, other immunosuppressive or non-immunosuppressive agents.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) for dichotomous outcomes and weighted mean difference (WMD) for continuous outcomes, with 95% confidence intervals (CI).

MAIN RESULTS

Thirteen eligible RCTs involving 623 patients were identified. All identified RCTs had a placebo, no treatment or warfarin/dipyridamole control group. Seven trials used steroids, three used alkylating agents/cyclosporin and three used combinations of steroids and alkylating agents/cyclosporin. No trial directly compared steroids versus alkylating agents/cyclosporin. Quality was sub-optimal. Steroids were associated with a lower risk of progression to ESRF (RR 0.44, 95% CI 0.25 to 0.80) and lower urinary protein excretion (WMD -0.49 g/24h, 95% CI -0.72 to -0.12). Urinary protein excretion was lower for patients treated with alkylating agents/cyclosporin compared to placebo/no treatment (WMD -0.94 g/24h, 95% CI -1.43 to -0.46). There was no significant reduction of urinary protein excretion with combination treatment of steroids and alkylating agents compared with placebo/no treatment.

REVIEWER'S CONCLUSIONS

The optimal management of IgAN remains uncertain. The RCTs identified were small, of sub-optimal methodological quality and tended to only report favorable and surrogate outcomes without a thorough reporting of treatment harms. All outcomes favor the use of immunosuppressive interventions, with steroids appearing to be the most promising. Further study, in the form of RCTs, is necessary to ascertain which patients would benefit from these interventions, whether they are the ones with early signs of renal dysfunction or those with more advanced renal impairment.