Long-term renal survival and undetected risk factors of IgA nephropathy in Chinese children-a retrospective 1243 cases analysis from single centre experience

IPNA clinical practice recommendations for the diagnosis and management of children with IgA nephropathy and IgA vasculitis nephritis

IgA nephropathy and IgA vasculitis with nephritis, albeit rare, represent two relatively frequent glomerular conditions in childhood. Compared to adults, pediatric IgA nephropathy has a more acute presentation, most frequently with synpharyngitic macrohematuria and histologically with more intense inflammation and less intense chronic damage. Management of these conditions is controversial and supported by little high-quality evidence. The paucity of evidence is due to the disease heterogeneity, its inter-ethnic variability, and the difficulty of extrapolating data from adult studies due to the peculiarities of the condition in children. IgA vasculitis with nephritis is a kidney manifestation of a systemic disorder, typical of the pediatric age, in which both the diagnosis of kidney involvement and its management are poorly defined, and an interdisciplinary approach is crucial. Both conditions can have a profound and long-lasting impact on kidney function and the global health of affected children. The International Pediatric Nephrology Association has therefore convened a diverse international group of experts from different disciplines to provide guidance on the recommended management of these conditions in children and to establish common definitions and define priorities for future high-quality, evidence-based collaborative studies for the benefit of children.

Predictive role of Oxford Classification for prognosis in children with IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

The Oxford Classification was proposed as an independent prognostic indicator in IgA nephropathy (IgAN). However, most studies on the subject focus on adults instead of children.

OBJECTIVES

Using a meta-analysis to appraise the predictive roles of the Oxford classification for the prognosis of pediatric patients with IgAN.

METHODS

All cohort studies regarding the analysis of the association between poor kidney-related prognosis (GFR categories G2-G5) according to the Kidney Disease Improving Global Outcomes (KDIGO) Guideline in pediatric patients with IgAN and five pathologic lesions in the Oxford Classification were included. Hazard ratios (HRs) regarding the association between the Oxford classification and prognosis of pediatric patients with IgAN were synthesized using random effect models. The risk of bias in studies was assessed based on the Newcastle-Ottawa scale.

RESULTS

Fourteen articles were included with 5679 IgAN patients and 710 endpoint outcome events occurred. M1 was associated with a higher risk of poor kidney-related prognosis compared with M0, pooled HR (1.79; 95%CI, 1.46-2.19; p < 0.001, random effect model). S1 and T1 or T2 increased the risk of poor kidney-related prognosis (pooled HR, 2.13; 95%CI, 1.68-2.70; p < 0.001; pooled HR, 2.64; 95%CI, 1.81-3.86; p < 0.001, respectively, estimated by random effect model). Compared with C0, C1, or C2 was also associated with an increased risk of poor kidney-related prognosis in the subgroup analysis of Asian and other populations. Evidence to indicate that E1 increased the risk of poor kidney-related prognosis was marginal.

IgA Vasculitis and IgA Nephropathy: Two Sides of the Same Coin?

IgA vasculitis (IgAV) is considered a systemic form of IgA nephropathy (IgAN). The two diseases share similar geographic and ethnic distribution, along with common variants in genetic association studies. The pathophysiology of IgAN and IgA vasculitis nephritis (IgAVN) can be explained by the four-hit hypothesis. Key molecules involved at each step in both diseases were evaluated as diagnostic and prognostic biomarkers with many common factors, most prominently serum galactose-deficient IgA1. On kidney biopsy, the two diseases are indistinguishable, and the established histological Oxford classification for IgAN will soon be validated for IgAVN. Chronic lesions (segmental glomerulosclerosis and tubular atrophy / interstitial fibrosis) seem more frequent in IgAN, while proliferative lesions (endocapillary hypercellularity and crescents) are more frequent in IgAVN, which could explain the worse IgAN renal prognosis. Due to characteristic skin rash, IgAVN patients are diagnosed precociously. Conversely, the frequent absence of overt clinical signs in IgAN leads to a delayed diagnostic kidney biopsy in the disease evolution, which explains the chronic pathologic lesions. From a therapeutic perspective, while impressive advances have been made in recent years for IgAN, there is a glaring lack of evidence-based guidelines for the treatment of IgAVN. Large therapeutic clinical studies are required, and future IgAN trials should include IgAVN.

Are children with IgA nephropathy different from adult patients?

BACKGROUND

Previously, several studies have indicated that pediatric IgA nephropathy (IgAN) might be different from adult IgAN, and treatment strategies might be also different between pediatric IgAN and adult IgAN.

METHODS

We analyzed two prospective cohorts established by pediatric and adult nephrologists, respectively. A comprehensive analysis was performed investigating the difference in clinical and pathological characteristics, treatment, and prognosis between children and adults with IgAN.

RESULTS

A total of 1015 children and 1911 adults with IgAN were eligible for analysis. More frequent gross hematuria (88% vs. 20%, p < 0.0001) and higher proteinuria (1.8 vs. 1.3 g/d, p < 0.0001) were seen in children compared to adults. In comparison, the estimated glomerular filtration rate (eGFR) was lower in adults (80.4 vs. 163 ml/min/1.73 m2, p < 0.0001). Hypertension was more prevalent in adult patients. Pathologically, a higher proportion of M1 was revealed (62% vs. 39%, p < 0.0001) in children than in adults. S1 (62% vs. 28%, p < 0.0001) and T1-2 (34% vs. 8%, p < 0.0001) were more frequent in adults. Adjusted by proteinuria, eGFR, and hypertension, children were more likely to be treated with glucocorticoids than adults (87% vs. 45%, p < 0.0001). After propensity score matching, in IgAN with proteinuria > 1 g/d, children treated with steroids were 1.87 (95% CI 1.16-3.02, p = 0.01) times more likely to reach complete remission of proteinuria compared with adults treated with steroids.

CONCLUSIONS

Children present significantly differently from adults with IgAN in clinical and pathological manifestations and disease progression. Steroid response might be better in children.

Corticosteroids in the treatment of IgA nephropathy: lessons from the TESTING trial

IgA nephropathy (IgAN), the most common form of primary glomerulonephritis, is mainly observed in young adults and children. Clinical and basic studies indicate the role of immunity in IgAN pathogenesis; however, corticosteroid therapy has been controversial in past decades. The TESTING study, initiated in 2012, is an international, multicenter, double-blinded, randomized, placebo-controlled trial that aimed to evaluate oral methylprednisolone's safety and long-term efficacy under conditions of optimized supportive treatment in patients with IgAN whose risk of progression is high. After a decade of effort, the successful completion of the TESTING study showed that a 6- to 9-month course of oral methylprednisolone is an effective regimen to protect kidney function in high-risk patients with IgAN, but also demonstrated safety concerns. Compared with the full-dose regimen, the reduced-dose regimen was reported to be beneficial, with successfully increased safety. Overall, the TESTING trial provided more data regarding the treatment dosage and safety of corticosteroids, a cost-effective therapy, in IgAN, which have important implications for pediatric patients with IgAN. With a deeper understanding of the disease pathogenesis of IgAN, ongoing studies of novel therapeutic regimens would help further optimize the benefit-risk ratio.

Hyperuricemia is associated with the progression of IgA nephropathy in children

BACKGROUND

The objective of the study was to explore the potential biomarkers and risk factors in children with immunoglobulin A nephropathy (IgAN).

METHODS

Untargeted metabolomics analysis was performed on children with IgAN before and after treatment. Subsequently, a retrospective study involving the past 15 years and a follow-up study were performed to verify the role of hyperuricemia in IgAN children.

RESULTS

Serum metabolomics analyses showed that levels of serum xanthosine were closely related to the outcome of IgAN, and KEGG analyses showed that differential metabolites were significantly enriched in purine metabolism. Furthermore, retrospectively analyses of 252 children with IgAN showed that hyperuricemia was associated with poorer renal outcome. Logistic regression analysis showed that BMI, serum creatinine, eGFR, Lee's grade III, and crescents were risk factors of hyperuricemia in children with IgAN. Kaplan-Meier analysis revealed that kidney progression-free survival in IgAN children with hyperuricemia was lower than that without hyperuricemia, especially in females.

CONCLUSIONS

We first performed a dynamic metabolomics study to reveal that hyperuricemia is closely related to the progression of IgAN in children. Then retrospective and follow-up studies confirmed that hyperuricemia is an important risk factor for poor renal outcomes. We need to pay more attention to the hyperuricemia in children with IgAN.

IMPACT

We first performed a dynamic metabolomics study to reveal that hyperuricemia was closely related to the progression of IgAN in children. Retrospective analyses in past 15 years confirmed that IgAN children with hyperuricemia had poorer renal function and worse renal pathology. The BMI, Scr, eGFR, Lee's grade III, and crescents were risk factors of hyperuricemia in children with IgAN. The long-term follow-up study showed that hyperuricemia was an important risk factor for poor renal outcome in children with IgAN. We need to pay more attention to hyperuricemia in children with IgAN, especially in females.

Comparative study on clinicopathological features and prognosis of IgA vasculitis nephritis and IgA nephropathy in children

BACKGROUND

IgA vasculitis nephritis (IgAVN) and IgA nephropathy (IgAN) share several clinical and pathological characteristics, though distinctions also exist. Their interrelation, however, remains undefined. This study investigates the clinicopathological divergences and prognostic disparities in pediatric patients with IgAVN and IgAN.

METHODS

Our study encompasses 809 pediatric patients with IgAVN and 236 with IgAN, all of whom underwent kidney biopsy. We utilized the Semiquantitative Classification (SQC) scoring system to juxtapose the pathologies of the two conditions, and performed a COX regression analysis to examine factors influencing their prognoses.

RESULTS

Both patient groups demonstrated a predominance of males. A seasonality was observed, with a higher incidence of IgAN in the summer, and IgAVN in the fall (P < 0.0001). Patients with IgAN exhibited more severe tubulointerstitial injury, higher chronicity index, and total biopsy scores compared to those with IgAVN (P < 0.0001). Mesangial deposition intensity of complement C3, and the rate of pure IgA deposition, were found to be greater in patients with IgAVN compared to those with IgAN (P < 0.0001). The intensity of IgA deposition was also significantly higher in IgAVN patients (P = 0.003). IgAVN demonstrated a superior prognosis, with a higher rate of kidney remission (P < 0.0001). COX regression analysis indicated that interstitial fibrosis, as identified in the SQC pathology system, was associated with the prognosis of both conditions. Furthermore, the findings suggest that IgA deposition levels (IgA +  + and IgA +  + +) could potentially influence the prognosis of IgAVN.

CONCLUSIONS

Compared to IgAVN, IgAN manifests more severely with regard to renal impairment, interstitial damage, and prognosis. The disparities in immune complex deposition levels and locations within the kidneys support the hypothesis of IgAVN and IgAN as distinct diseases. Interstitial fibrosis may serve as a key pathological indicator within the SQC system associated with kidney prognosis in children with IgAVN and IgAN. The degree of IgA deposition could also be linked with the prognosis of IgAVN.

Diagnosis and treatment of IgA nephropathy and IgA vasculitis nephritis in Chinese children

IgA nephropathy (IgAN) and IgA vasculitis-associated nephritis (IgAVN) are among the most frequent childhood glomerular diseases and are characterized by significant variability in clinical manifestations, pathological presentation and long-term outcomes. IgAVN, alternatively called purpura nephritis, is pathologically indistinguishable from kidney-limited IgAN. In Chinese children, the clinical presentations and pathological manifestations of IgAN and IgAVN are variable. The severity of proteinuria and abnormalities in kidney function and blood pressure of children in China are comparable to those of children in Europe, the USA, and Japan. Compared to Caucasian children and Japanese children, crescents were more common in Chinese children with IgAN or IgAVN. Approximately 10-20% of childhood IgAN or IgAVN progresses to impaired kidney function in China. Since 2007, a series of guidelines on the diagnosis and treatment of pediatric kidney diseases has been published following the principles of evidence-based medicine. However, a large difference exists between the Chinese evidence-based guidelines and the guidelines developed by Kidney Disease: Improving Global Outcomes (KDIGO) in 2021. Chinese children with IgAN or IgAVN were more likely to be treated with steroids or immunosuppressive agents. Further studies exploring the optimal treatment regimen for childhood IgAN or IgAVN are needed in the future.

Association between glomerular C4d deposition, proteinuria, and disease severity in children with IgA nephropathy

BACKGROUND

C4d may be used as a marker to evaluate the condition and prognosis of adults with IgA nephropathy, but there have been few studies of children with IgA nephropathy.

METHODS

C4d immunohistochemical staining was performed on samples from children with IgA nephropathy with C1q-negative immunofluorescence. The clinical and pathological treatment and prognostic characteristics of children in the C4d-positive and -negative groups were compared.

RESULTS

A total of sixty-five children with IgA nephropathy were included in the study and were followed up for an average of 37 months. C4d was mainly deposited along the capillary loops. The urinary protein-to-creatinine ratio (UPCR) in the C4d-positive group was significantly higher than that in the C4d-negative group (3.97 vs. 0.81, P < 0.001), and the average integrated optical density value of each child was positively correlated with the UPCR (r = 0.441, P < 0.001). There was a significant difference in the proportions of children with mesangial hypercellularity (M1) (68.97% vs. 44.44%, P = 0.048) and segmental glomerulosclerosis (S1) (65.52% vs. 33.33%, P = 0.010) between the C4d-positive group and the C4d-negative group. The proportion of children who received immunosuppressants in the C4d-positive group was higher than that in the C4d-negative group (86.21% vs. 36.11%, P < 0.001). There was no significant difference in the proportion of children developing kidney failure between the two groups.

CONCLUSION

C4d was found to be associated with proteinuria, segmental lesions, and immunosuppressant treatment. Activation of the lectin pathway may reflect the severity of clinical and pathological manifestations of IgA nephropathy in children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Management of IgA Nephropathy in Pediatric Patients

The onset of IgA nephritis in childhood and adolescence often develops into chronic glomerulonephritis with declining renal function. Although these long-term consequences are known, there is still a lack of evidence-based treatment recommendations in this age group. We report data from 22 pediatric patients who were biopsied to confirm the diagnosis of IgAN at our clinical center. 14 of them were treated with corticosteroids according to the recommendations for IgA nephritis vasculitis of the German Society of Pediatric Nephrology (GPN). Improvement was achieved in the majority of all cases, with a significant reduction in proteinuria five months after initiation of therapy. Our data suggest that treatment regimens for acute IgA nephritis and IgA vasculitis nephritis may be unified and are discussed in the context of current studies.

Immunosuppressants or corticosteroids compared with supportive therapy: a systematic review and meta-analysis on the efficacy and safety for IgA nephropathy treatment

Background

Corticosteroids or immunosuppressants and supportive treatment in reducing the risk of proteinuria and end-stage kidney disease (ESKD) in immunoglobulin A (IgA) nephropathy (IgAN) patients were still controversial. The purpose of this meta-analysis was to evaluate the efficacy and safety of immunosuppressants or corticosteroids compared with supportive therapy for treatment of IgAN in order to provide guidance for clinical practice.

Methods

We conducted an online search in PubMed, Embase, Cochrane Library, and Web of Science databases to collect randomized control trials (RCTs) about the efficacy and safety of immunosuppressants or corticosteroids compared with supportive therapy for treatment of IgA for relevant literature published from the databases' inception to August 21, 2021. The Cochrane risk assessment tool was used to assess the risk of bias in the included studies and analyzed by Revman 5.4 software, and Stata 15.0 statistical software was adopted for meta-analysis.

Results

A total of 10,622 related studies were retrieved, and 11 RCTs were finally included in the meta-analysis, with a total sample size of 809 cases. The primary outcome measures for immunosuppressants or corticosteroids were better than those for supportive therapy: proteinuria [weighted mean difference (WMD) =-0.54, 95% confidence interval (CI): -0.63, -0.44, Z =10.79, P<0.001] and ESKD [relative risk (RR) =0.189, 95% CI: 0.059, 0.605, Z =2.81, P=0.005]. The secondary outcome measures were also better than that for supportive treatment: glomerular filtration rate [standardized mean difference (SMD) =0.32, 95% CI: 0.09, 0.54, Z =2.48, P=0.013]. The incidence of adverse reactions was consistent with that of supportive treatment, and the difference was not statistically significant (RR =1.06, 95% CI: 0.71, 1.59, Z =0.28, P=0.777).

Discussion

Current evidence shows that immunosuppressants and corticosteroids can significantly reduce the risk of proteinuria and ESKD in IgAN patients. Due to limited quality and quantity of the included studies, more high-quality studies are need to verify above conclusion. In addition, we hope that more rationally designed multicenter RCTs that are not limited to short-term treatment outcomes will be conducted in the future.

IgA Vasculitis and IgA Nephropathy: Same Disease?

Many authors suggested that IgA Vasculitis (IgAV) and IgA Nephropathy (IgAN) would be two clinical manifestations of the same disease; in particular, that IgAV would be the systemic form of the IgAN. A limited number of studies have included sufficient children or adults with IgAN or IgAV (with or without nephropathy) and followed long enough to conclude on differences or similarities in terms of clinical, biological or histological presentation, physiopathology, genetics or prognosis. All therapeutic trials available on IgAN excluded patients with vasculitis. IgAV and IgAN could represent different extremities of a continuous spectrum of the same disease. Due to skin rash, patients with IgAV are diagnosed precociously. Conversely, because of the absence of any clinical signs, a renal biopsy is practiced for patients with an IgAN to confirm nephropathy at any time of the evolution of the disease, which could explain the frequent chronic lesions at diagnosis. Nevertheless, the question that remains unsolved is why do patients with IgAN not have skin lesions and some patients with IgAV not have nephropathy? Larger clinical studies are needed, including both diseases, with a common histological classification, and stratified on age and genetic background to assess renal prognosis and therapeutic strategies.