Epidemiology, baseline characteristics and risk of progression in the first South-Asian prospective longitudinal observational IgA nephropathy cohort

To evaluate the utility of Oxford classification in predicting renal outcome in IgA nephropathy patients

BACKGROUND

Immunoglobulin A Nephropathy (IgAN) is a heterogeneous disorder. Multiple ethnicities conducted studies to assess the effectiveness of the Oxford classification of IgAN in prognostication. However, there is no study on the Pakistani population. We aim to identify its prognostic effectivity in our patients.

METHODS

We retrospectively reviewed the medical records of 93 biopsy-proven cases of primary IgAN. We collected the clinical and pathological data at baseline and on follow-ups. The median follow-up period was 12 months. We defined the renal outcome as a ≥ 50% decline in eGFR or end-stage renal disease (ESRD).

RESULTS

Of 93 cases, 67.7% were males with a median age of 29. Glomerulosclerosis was the most prevalent lesion (71%). The median MEST-C was 3. On follow-up, median serum creatinine worsened from 1.92 to 2.2 mg/dL, and median proteinuria reduced from 2.3 g/g to 1.072 g/g. The reported renal outcome was 29%. T and C scores and MEST-C scores above 2 were significantly associated with pre-biopsy eGFR. On Kaplan-Meier analysis, the T and C scores' association was significant with the renal outcome (p-value 0.000 and 0.002). In univariate and multivariate analyses, the association of T-score (p-value 0.000, HR 4.691), total MEST-C score (p-value 0.019), and baseline serum creatinine (p-value 0.036, HR 1.188) were significant with the outcome.

CONCLUSION

We validate the prognostic significance of the Oxford classification. T and C scores, baseline serum creatinine, and total MEST-C score significantly affect the renal outcome. Furthermore, we recommend the inclusion of the total MEST-C score in determining the IgAN prognosis.

Clinicopathological Characteristics of Adult IgA Nephropathy in the United States

Introduction

IgA nephropathy (IgAN) is a progressive autoimmune kidney disease and a leading cause of glomerular disease that can result in kidney failure (KF). The median age at diagnosis is 35 to 37 years and approximately 50% of patients will progress to KF within 20 years. We aimed to enhance the understanding of renal histology and chronic kidney disease (CKD) stage at the time of IgAN diagnosis using a large real-world biopsy cohort.

Methods

This retrospective cohort study evaluated biopsy data and clinical characteristics from adult patients within the US who were diagnosed with IgAN between January 1, 2016 to May 31, 2020. Descriptive statistics were summarized and relationship(s) between each Oxford Classification (MEST-C) component score with 24-hour proteinuria or CKD stage were examined using regression analysis.

Results

A total of 4375 patients (mean age 47.7 years, 62.7% male) met eligibility criteria. Mild to moderate mesangial hypercellularity (47.3%), segmental sclerosis (65.0%), tubular atrophy ≥25% (57.4%), and crescents (18.5%) were identified; and 74.6% of patients were at CKD stage ≥3. Proteinuria ≥1 g/d was associated with higher MEST-C scores, and the odds of mesangial hypercellularity, segmental sclerosis, tubular atrophy, and crescents increased with CKD stage.

Conclusion

Most patients with IgAN in our US cohort were diagnosed at CKD stage ≥3 and had high MEST-C scores and proteinuria that are suggestive of significant disease burden at the time of kidney biopsy. Strategies are required to raise awareness and promote earlier detection of asymptomatic urinary abnormalities before extensive irreversible kidney damage has occurred.

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.

Indian TrANslational GlomerulonephrItis BioLogy nEtwork (I-TANGIBLE): Design and Methods

Background and Aim

Primary glomerular disease accounts for one-sixth of all chronic kidney diseases (CKDs) in India. We remain limited in our ability to effectively treat these conditions because of lack of understanding of the disease mechanisms and lack of predictors to identify the clinical course and therapeutic responsiveness. We propose to develop a network of investigators in glomerular diseases, collect information in a systematic fashion to understand the clinical outcomes, answer translational research questions better, and identify and recruit patients for clinical trials.

Materials and Methods

This is a prospective, observational study. The Indian TrANslational GlomerulonephrItis BioLogy nEtwork (I-TANGIBLE) cohort will enroll patients (>18 years) with biopsy-proven minimal change disease (MCD), focal segmental glomerulonephritis (FSGS), membranous nephropathy (MN), IgA nephropathy (IgAN), or membranoproliferative glomerulonephritis (MPGN) (immune complex- and complement-mediated), with first biopsy taken within 2 years of enrollment. Patients with estimated glomerular filtration (eGFR) rate <15 ml/min/1.73 m2 for >3 months at the time of screening, kidney transplant or bone marrow transplant recipients, patients with active malignancy, and patients with active hepatitis B/C replication or human immunodeficiency virus (HIV)-I/II will be excluded. Clinical details including history, medication history and details, and family history will be obtained. Consenting patient's blood and urine samples will be collected and stored, aligned to their clinical follow-up.

Expected Outcomes

The network will allow accurate ascertainment of disease burden of glomerular diseases across study sites, establishment of the treatment pattern of common glomerular diseases, investigation of medium- and long-term outcomes (remission, relapse, rate of eGFR decline), and building a suitable infrastructure to carry out clinical trials in primary glomerular disease.

Prognostic significance of the extent of tubulointerstitial lesions in patients with IgA nephropathy

PURPOSE

IgA nephropathy (IgAN) is the most common type of primary glomerulonephritis worldwide. However, the effect of the degree of tubulointerstitial lesions (TIL) on the renal prognosis of these patients is uncertain.

METHODS

All biopsy-proven primary IgAN patients from a single center (≥ 14 years old) were retrospectively examined from January 2006 to December 2011. According to the Oxford classification for tubulointerstitial lesions in IgAN, eligible patients were assigned to T0 or T1/2 groups. The clinicopathological features of these groups were compared and multivariate models were used to identify the effect of tubulointerstitial lesions on renal prognosis. The composite endpoint was end-stage renal disease or doubling of serum creatinine.

RESULTS

We initially identified 1570 patients with IgAN and examined 988 patients who completed follow-up examinations (mean: 49 months). There were 506 patients in the T0 group (51.2%) and 482 in the T1/2 group (48.8%). The 1-year, 3-year, and 5-year incidences of the composite endpoint were 0.2%, 1.5%, 7.7% in the T0 group, and 1.9%, 9.9%, 18.1% in the T1/2 group. An adjusted multivariate model indicated the hazard ratio for reaching the composite endpoint was 9.3 for patients with T1/2 rather than T0 (reference group). A multivariate logistic analysis of the T1/2 group indicated the independent risk factors for reaching the composite endpoint were decreased eGFR, hypertension, hyperlipidemia, proteinuria, global glomerulosclerosis, and segmental glomerulosclerosis.

CONCLUSION

More severe tubulointerstitial lesions (> 25%, T1/2) were an independent predictor of poor renal prognosis in patients with IgAN.

Clinicopathologic Manifestations of Immunoglobulin A Nephropathy in a Northern Indian Cohort: A Mute Assassin with Delayed Diagnosis

Introduction

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis worldwide, but there is a marked geographic difference in its prevalence and prognosis. IgAN is known to have an aggressive course in Asians. However, its exact prevalence and clinicopathologic spectrum in North India are not well documented.

Materials and Methods

The study included all patients aged above 12 years with primary IgAN on kidney biopsy from January 2007 to December 2018. Clinical and pathological parameters were noted. Two histopathologists independently reviewed all kidney biopsies, and MEST-C score was assigned as per the Oxford classification.

Results

IgAN was diagnosed in 681 (11.85%) out of 5751 native kidney biopsies. The mean age was 32 ± 12.3 years, and the male to female ratio was 2.5:1. At presentation, 69.8% had hypertension, 68% had an estimated glomerular filtration rate (eGFR) of less than 60 ml/min, 63.2% had microscopic hematuria, and 4.6% had gross hematuria. The mean proteinuria was 3.61 ± 2.26 g/day, with 46.8% showing nephrotic range proteinuria and 15.2% showing nephrotic syndrome manifestation. Histopathologically, 34.4% of patients had diffuse global glomerulosclerosis. Oxford MEST-C scoring revealed M1 in 67%, E1 in 23.9%, S1 in 46.9%, T1/T2 in 33%, and crescents in 19.6% of biopsies. The mean serum creatinine was significantly higher in cases with E1, T1/2, and C1/2 scores (P < 0.05). Hematuria and proteinuria were significantly higher (P < 0.05) with E1 and C1/2 scores. Coexisting C3 was associated with higher serum creatinine at presentation (P < 0.05).

Conclusion

IgAN patients with late presentation and advanced disease became less amenable to immunomodulation in our cohort. The implementation of point-of-care screening strategies, early diagnosis, and retarding disease progression should be prioritized in the Indian strategy.

Emerging Biomarkers for Early Detection of Chronic Kidney Disease

Chronic kidney disease (CKD) is a major and serious global health problem that leads to kidney damage as well as multiple systemic diseases. Early diagnosis and treatment are two major measures to prevent further deterioration of kidney function and to delay adverse outcomes. However, the paucity of early, predictive and noninvasive biomarkers has undermined our ability to promptly detect and treat this common clinical condition which affects more than 10% of the population worldwide. Despite all limitations, kidney function is still measured by serum creatinine, cystatin C, and albuminuria, as well as estimating glomerular filtration rate using different equations. This review aims to provide comprehensive insight into diagnostic methods available for early detection of CKD. In the review, we discuss the following topics: (i) markers of glomerular injury; (ii) markers of tubulointerstitial injury; (iii) the role of omics; (iv) the role of microbiota; (v) and finally, the role of microRNA in the early detection of CKD. Despite all novel findings, none of these biomarkers have met the criteria of an ideal early marker. Since the central role in CKD progression is the proximal tubule (PT), most data from the literature have analyzed biomarkers of PT injury, such as KIM-1 (kidney injury molecule-1), NGAL (neutrophil gelatinase-associated lipocalin), and L-FABP (liver fatty acid-binding protein).

Incidence, demographic, biochemical, and clinicopathological profile of primary IgAN in a tertiary care center from Northern India

Background

Primary IgA nephropathy (IgAN) has variable distribution and clinicopathological spectrum throughout the world. We report the incidence, demographic, and clinicopathological profile of primary IgAN from a tertiary care center in Northern India.

Methods

This is a single-center, prospective, observational study conducted at Sheri- Kashmir Institute of Medical Sciences, J&K, India, from January 2015 to December 2018. The study was approved by the hospital ethical committee.

Results

A total of 106 patients were included in this study, accounting for 19% (106/558) of all native kidney biopsies done during the period from January 2015 till December 2018. Males and females accounted for 60.4% (64/106) and 39.6% (42/106), respectively, with a ratio of 1.5:1. The mean age was 31.37±11.60 years. Edema and hypertension were the most common presenting symptoms and signs, seen in 69 (65.1%) and 72 (67.9%) patients, respectively. The baseline 24-h urine protein excretion was 2.32 ±1.34 g, Nephrotic range proteinuria (≥3.5g/day) was seen in 23/106 (21.7%). Average serum creatinine was 1.6±0.80 mg/dl and estimated glomerular filtration rate using CKD-EPI was <60 ml/min/1.73 m2 in 48.1% of patients (51/106). In patients with < 1 g proteinuria, 36.8% had E1, 78.9% had S1, 36.8% had T1, and 42.1% had T2 lesions.

Conclusions

IgAN is common in North India and has a more severe histopathological presentation, characterized by extensive sclerosis and tubulointerstitial fibrosis. Renal dysfunction and nephrotic range proteinuria are common. Hypertension, low eGFR, and proteinuria correlate with the presence of segmental scarring, endocapillary hypercellularity, and IFTA. Screening of asymptomatic individuals might help in early diagnosis and long-term preservation of renal function.

Is IgA nephropathy the same disease in different parts of the world?

Since it was first described in 1968, immunoglobulin A nephropathy (IgAN) is understood to be the most common form of glomerulonephritis worldwide. The diagnosis of IgAN depends on the presence of dominant mesangial IgA1 deposition by renal biopsy. To date, a wide spectrum of clinical and pathologic features of IgAN have been observed, implying that IgAN might not be the same disease across the world. Here, we review the characteristics of IgAN from perspectives of epidemiology, clinical-pathological patterns, disease pathogenesis, and treatment response across different ethnic populations. Overall, IgAN is most prevalent in Asians, followed by Caucasians, and relatively rare in Africans. More severe clinical presentation and higher risk of disease progression have been reported in Asians than Europeans. Moreover, active lesions, such as endocapillary hypercellularity and crescents, are more commonly reported in Asians than Europeans. Response to corticosteroid/immunosuppression therapy is variably reported, with greater apparent efficacy reported in Asian than European studies. Although a multi-hit hypothesis has been suggested for IgAN, the relative importance of each "hit" may vary in different ethnic populations and this variation underlies the differences in presentation of IgAN. In the future, a better understanding of pathogenic pathways operating in different ethnic populations may help provide better biomarkers of disease and more precise targeting of treatment strategies for IgAN.