Predicting progression in IgA nephropathy

External Validation of the International IgA Nephropathy Prediction Tool in Older Adult Patients

Purpose

The International IgA Nephropathy Prediction Tool (IIgAN-PT) can predict the risk of End-stage renal disease (ESRD) or estimated glomerular filtration rate (eGFR) decline ≥ 50% for adult IgAN patients. Considering the differential progression between older adult and adult patients, this study aims to externally validate its performance in the older adult cohort.

Patients and Methods

We analyzed 165 IgAN patients aged 60 and above from six medical centers, categorizing them by their predicted risk. The primary outcome was a ≥50% reduction in estimated glomerular filtration rate (eGFR) or kidney failure. Evaluation of both models involved concordance statistics (C-statistics), time-dependent receiver operating characteristic (ROC) curves, Kaplan-Meier survival curves, and calibration plots. Comparative reclassification was conducted using net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

Results

The study included 165 Chinese patients (median age 64, 60% male), with a median follow-up of 5.1 years. Of these, 21% reached the primary outcome. Both models with or without race demonstrated good discrimination (C-statistics 0.788 and 0.790, respectively). Survival curves for risk groups were well-separated. The full model without race more accurately predicted 5-year risks, whereas the full model with race tended to overestimate risks after 3 years. No significant reclassification improvement was noted in the full model without race (NRI 0.09, 95% CI: -0.27 to 0.34; IDI 0.003, 95% CI: -0.009 to 0.019).

Conclusion

: Both models exhibited excellent discrimination among older adult IgAN patients. The full model without race demonstrated superior calibration in predicting the 5-year risk.

IgA nephropathy in children with minimal proteinuria: to biopsy or not to biopsy?

BACKGROUND

Tubulointerstitial lesions and glomerular inflammation severity have been shown to correlate with proteinuria in children with IgA nephropathy (cIgAN). However, there is a lack of data regarding severity of histopathologic findings in cIgAN in patients with minimal to absent proteinuria since kidney biopsy indications are not well defined in these cases.

METHODS

Twenty-eight cIgAN patients with kidney biopsy from 4 different centers in Paris (France) and Montreal (Canada) with a urine protein/creatinine ratio (UPCr) ≤ 0.03 g/mmol and a normal estimated glomerular filtration rate (eGFR > 90 ml/min/1.73 m2) on the day of kidney biopsy prior to treatment were included.

RESULTS

Median age was 11.82 (9.32-13.45) years, and median follow-up was 4 years (2.87-6.53). At time of biopsy, median eGFR was 116 (102.3-139.7) ml/min/1.73 m2, and median UPCr was 0.02 (0.011-0.03) g/mmol. Microscopic or macroscopic hematuria was present in 35.7% and 64.3% of cases, respectively. Kidney biopsy microscopy analysis showed mesangial (M1), endocapillary (E1), or extracapillary (C1) hypercellularity in 53.5%, 32.1%, and 7.1% of patients, respectively. Chronic histological lesions were also present: glomerulosclerosis (S1) in 42.8% and tubular atrophy/interstitial fibrosis in 7.1%. Podocytopathic features were detected in 21.4%. An ACE inhibitor or immunosuppressive therapy (IS) was prescribed in 42.8% and 21.4% of these patients respectively. One-third (35.7%) received no treatment. At last follow-up, median eGFR was 111.9 (90.47-136.1) ml/min/1.73 m2, and median UPCr was 0.028 (0.01-0.03) g/mmol.

CONCLUSION

cIgAN with minimal proteinuria at time of biopsy might be linked with acute and chronic glomerular lesions.

Examining the association between serum galactose-deficient IgA1 and primary IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

IgA nephropathy (IgAN) is a common primary glomerular disease. The O-glycosylation status of IgA1 plays a crucial role in disease pathophysiology. The level of poorly-O-galactosylated IgA1, or galactose-deficient IgA1 (Gd-IgA1), has also been identified as a potential biomarker in IgAN. We sought to examine the value of serum Gd-IgA1 as a biomarker in IgAN, by investigating its association with clinical, laboratory, and histopathological features of IgAN.

METHODS

The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations and was registered in PROSPERO (CRD42021287423). The literature search was conducted in PubMed, Web of Science, Cochrane, and Scopus, and the selected articles were evaluated for eligibility based on predefined criteria. The methodological quality of the studies was assessed using the Newcastle-Ottawa Scale. Statistical analysis was performed to calculate effect sizes and assess heterogeneity among the studies.

RESULTS

This review analyzed 29 out of 1,986 studies, conducted between 2005 and 2022, with participants from multiple countries. Gd-IgA1 levels were not associated with age and gender, while associations with hypertension, hematuria, and proteinuria were inconsistent. In the meta-analyses, a correlation between serum Gd-IgA1 and estimated glomerular filtration rate was identified, however, the relationships between Gd-IgA1 levels and chronic kidney disease (CKD) stage and progression to kidney failure were inconsistent.

CONCLUSIONS

Serum Gd-IgA1 levels were not associated with validated prognostic risk factors, but were negatively correlated with kidney function. Further research in larger studies using standardized assays are needed to establish the value of Gd-IgA1 as a prognostic risk factor in IgAN.

Oral glucocorticoids with intravenous cyclophosphamide or oral glucocorticoids alone in the treatment of IgA nephropathy present with nephrotic syndrome and mesangioproliferative glomerulonephritis

Background

Few studies have evaluated the treatment of immunoglobulin A nephropathy (IgAN) patients with nephrotic syndrome (NS) and mesangioproliferative glomerulonephritis (MPGN). The aim of this study was to compare the therapeutic effects of oral glucocorticoids (GCS) combined with intravenous cyclophosphamide (CTX) and oral GCS alone in the treatment of the MPGN-IgAN patients with NS.

Methods

Biopsy-proven primary IgAN patients who were aged ≥14 years at diagnosis, had coexistent NS and MPGN and estimated glomerular filtration rate (eGFR) ≥15 mL/min/1.73 m2, and were treated by oral GCS combined with intravenous CTX or oral GCS alone for 6-12 months were retrospectively included. The patients in the GCS + CTX (prednisone 0.6-0.8 mg/kg/day and intravenous CTX 0.6-1.0 g monthly) or GCS (prednisone 0.8-1 mg/kg/day) group were rather matched at a 1:1 ratio on key characteristics by propensity score matching. The primary outcome was defined as either complete remission or partial remission at Month 24. The secondary outcome was a composite renal endpoint defined as a 50% decline in eGFR, doubling of serum creatinine or progression to end-stage kidney disease.

Results

Among the 146 IgAN patients who met the inclusion criteria, 42 patients were enrolled in the GCS + CTX group, and 42 patients were enrolled in the GCS group after propensity score matching. The clinical and histological parameters were similar between the two groups. Remission occurred more frequently in the GCS + CTX group at Month 6 (88.1% vs 52.4%, P < 0.001), Month 12 (88.1% vs 56.1%, P = 0.001) and Month 24 (85.0% vs 47.5%, P < 0.001) than in the GCS group. Moreover, subgroup analysis revealed that the higher response rate at Month 24 in the GCS + CTX group than in the GCS group was also present in different subgroups defined by sex, age, eGFR or Oxford MEST-C. Notably, we found that eGFR decreased at a lower rate in patients from the GCS + CTX group than in patients from the GCS group [eGFR slope: 0.05(-3.09, 3.67) vs -2.56 (-11.30, 0.86) mL/min/1.73 m2/year, P = 0.03]. Based on multivariate Cox regression analysis, GCS + CTX treatment was found to be independently associated with a decrease in risk for the composite endpoint after adjusted by the International Risk Prediction Score with race (hazard ratio = 0.17, 95% confidence interval 0.04-0.83, P = .03). There was no significant difference in adverse events (50.0% vs 42.9%, P = 0.51) or serious adverse events (7.1% vs 11.9%, P = .71) between the two groups.

Conclusions

Oral GCS combined with intravenous CTX is superior to GCS alone in treating MPGN-IgAN patients combined with NS. As the retrospective design and small sample size, our findings need to be validated by a prospective study.

Potential benefits and related treatment effects of calcineurin inhibitors combined with steroid for IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

IgA nephropathy is not uncommon for clinical practice. Within multiple options of treatment, it is alternatively to consider less well-studied immunosuppressants such as calcineurin inhibitors (CNI). The knowledge of CNI with steroid in the treatment of IgA nephropathy can be clarified via a systematic review and meta-analysis of randomized clinical trials.

METHODS

We performed the systematic search and meta-analysis for the randomized clinical trials of the CNI treatment in IgA nephropathy. The comparison between CNI combined with steroid and steroid-alone treatment was performed to find if the CNI combined with steroid can achieve more complete remission for IgA nephropathy. In addition, the related treatment effects were analyzed. After restricted selection, 16 studies with a total of 998 subjects with IgA nephropathy were enrolled. The focused outcome was complete remission, proteinuria, serum creatinine, and estimated glomerular filtration rate.

RESULTS

The meta-analysis showed higher odds ratio of complete remission if the patients received CNI with steroid combined treatment. The proteinuria can be significantly reduced under the combined treatment of CNI and steroid. However, the CNI with steroid combined treatment showed a non-superior effect on the parameters of serum creatinine and estimated glomerular filtration rate.

CONCLUSIONS

In current meta-analysis, the CNI combined with steroid treatment might show a trend to achieve complete remission status and reduce the proteinuria of IgA nephropathy when compared to steroid-alone treatment. However, no significant effects were observed in parameters of serum creatinine and estimated glomerular filtration rate.

Treatment and outcome of IgA nephropathy in children from one single center experience

BACKGROUND

There is no standard recommendation for IgA nephropathy treatment in children.

METHODS

This is a retrospective study. From 2012 to 2020, newly diagnosed primary IgAN followed up for at least 1 year were enrolled. The correlation of MESTC scores and clinical index including proteinuria, gross hematuria and renal dysfunction was analyzed. Treatment and clinical response of 6 month, 1year and 3 year at follow up were also analyzed. Complete renal remission was calculated with Kaplan-Meier analysis.

RESULTS

The median follow up was 36 months, from 12 months to 87months in 40 IgAN children. Angiotensin-converting enzyme inhibitor (ACEI) was applied to all patients. 30% received ACEI alone; 15% received glucocorticoids; 37.5% received glucocorticoids plus cyclophosphamide, 17.5% received glucocorticoids plus mycophenolate mofetil. Individuals with diffuse mesangial hypercellularity (M1) were more likely to have nephrotic range proteinuria compared to patients with M0 (80% vs. 20%, P < 0.01). Complete renal remission at 6-month, 1-year and 3-year follow up is 50.25%, 70% and 87.5% respectively. Five-year complete renal remission calculated by Kaplan-Meier analysis is 58.4%. Although without significant difference, there is trend of better survival with complete renal remission in group of nephrotic range proteinuria onset. There is no severe adverse effect.

CONCLUSION

This study supports the use of glucocorticoids plus immunosuppressive in addition to ACEI in IgA nephrology pediatric patients with proteinuria. We suggest proactive immunosuppressive treatment in IgA nephropathy in children. This is from a single center in China as may not same results in other population.

Validation of the children international IgA nephropathy prediction tool based on data in Southwest China

Background

Immunoglobulin A nephropathy (IgAN) is one of the most common kidney diseases leading to renal injury. Of pediatric cases, 25%-30% progress into end-stage kidney disease (ESKD) in 20-25 years. Therefore, predicting and intervening in IgAN at an early stage is crucial. The purpose of this study was to validate the availability of an international predictive tool for childhood IgAN in a cohort of children with IgAN treated at a regional medical centre.

Methods

An external validation cohort of children with IgAN from medical centers in Southwest China was formed to validate the predictive performance of the two full models with and without race differences by comparing four measures: area under the curve (AUC), the regression coefficient of linear prediction (PI), survival analysis curves for different risk groups, and R₂D.

Results

A total of 210 Chinese children, including 129 males, with an overall mean age of 9.43 ± 2.71 years, were incorporated from this regional medical center. In total, 11.43% (24/210) of patients achieved an outcome with a GFR decrease of more than 30% or reached ESKD. The AUC of the full model with race was 0.685 (95% CI: 0.570-0.800) and the AUC of the full model without race was 0.640 (95% CI: 0.517-0.764). The PI of the full model with race and without race was 0.816 (SE = 0.006, P < 0.001) and 0.751 (SE = 0.005, P < 0.001), respectively. The results of the survival curve analysis suggested the two models could not well distinguish between the low-risk and high-risk groups (P = 0.359 and P = 0.452), respectively, no matter the race difference. The evaluation of model fit for the full model with race was 66.5% and without race was 56.2%.

Conclusions

The international IgAN prediction tool has risk factors chosen based on adult data, and the validation cohort did not fully align with the derivation cohort in terms of demographic characteristics, clinical baseline levels, and pathological presentation, so the tool may not be highly applicable to children. We need to build IgAN prediction models that are more applicable to Chinese children based on their particular data.

COSMC expression as a predictor of remission in IgA nephropathy

PURPOSE

The impact of core 1,3-galactosyltransferase-specific molecular chaperon (COSMC) gene expression and methylation profile on clinical progression of IgA nephropathy (IgAN) is unclear. The aim of this study was to determine the clinical significance and the relation of the COSMC gene expression and methylation pattern with the progression of IgAN.

METHODS

Thirty-nine biopsy-confirmed IgAN patients, 11 healthy relatives and 20 healthy controls were recruited. The COSMC mRNA levels and methylation profile of COSMC gene promoter were measured using the quantitative real-time PCR. The galactose-deficient IgA1 (Gd-IgA1) levels were measured using ELISA in serum and cell culture supernatant. The effect of IL-4 and AZA on COSMC expression and methylation and the correlation of COSMC gene expression and methylation levels with baseline kidney function tests, histology and long-term outcomes were examined.

RESULTS

The mean COSMC mRNA level was significantly lower, and serum Gd-IgA1 level was higher in IgAN patients compared with the control groups (p < 0.001, and p =  < 0.001, respectively). The COSMC mRNA levels were correlated with intensity of hematuria (r = - 0.41, p = 0.009), serum creatinine level (r = - 0.37, p = 0.002) and eGFR (r = 0.36, p = 0.002). The COSMC methylation levels were correlated with age (r = 0.25, p = 0.04) and baseline eGFR (r = - 0.326, p = 0.006). Twenty IgAN patients (51.3%) reached to complete (5, 12.8%) or partial remission (15, 38.5%) after a median of 34.5 months (IQR, 13.75-71). In multivariable Cox regression analysis, COSMC mRNA expression (adjusted HR (aHR) 1.871, 95% CI 1.287-2.722, p = 0.001) and Oxford T score (aHR 0.355, 95% CI 0.146-0.859, p = 0.022) predicted the remission.

CONCLUSION

COSMC mRNA level is a novel biomarker candidate to predict the remission in IgAN patients.

Validation of two IgA nephropathy risk-prediction tools using a cohort with a long follow-up

BACKGROUND

Recently, two immunoglobulin A nephropathy prediction tools were developed that combine clinical and histopathological parameters. The International IgAN Prediction Tool predicts the risk for 50% declines in the estimated glomerular filtration rate or end-stage renal disease up to 80 months after diagnosis. The IgA Nephropathy Clinical Decision Support System uses artificial neural networks to estimate the risk for end-stage renal disease. We aimed to externally validate both prediction tools using a Norwegian cohort with a long-term follow-up.

METHODS

We included 306 patients with biopsy-proven primary immunoglobulin A nephropathy in this study. Histopathologic samples were retrieved from the Norwegian Kidney Biopsy Registry and reclassified according to the Oxford classification. We used discrimination and calibration as principles for externally validating the prognostic models.

RESULTS

The median patient follow-up was 17.1 years. A cumulative dynamic time-dependent receiver operating characteristic analysis showed area under the curve values of ranging from 0.90 at 5 years to 0.83 at 20 years for the International IgAN Prediction Tool, while time-naive analysis showed an area under the curve value at 0.83 for the IgA Nephropathy Clinical Decision Support System. The International IgAN Prediction Tool was well calibrated, while the IgA Nephropathy Clinical Decision Support System tends to underestimate risk for patients with higher risk, and overestimates risk in the lower risk categories.

CONCLUSIONS

We have externally validated two prediction tools for IgA nephropathy. The International IgAN Prediction Tool performed well, while the IgA Nephropathy Clinical Decision Support System has some limitations.

Galactose-Deficient IgA1 as a Candidate Urinary Marker of IgA Nephropathy

In patients with IgA nephropathy (IgAN), circulatory IgA1 and IgA1 in the mesangial deposits contain galactose-deficient IgA1 (Gd-IgA1). Some of the Gd-IgA1 from the glomerular deposits is excreted in the urine and thus urinary Gd-IgA1 may represent a disease-specific marker. We recruited 338 Japanese biopsy-proven IgAN patients and 120 patients with other renal diseases (disease controls). Urine samples collected at the time of renal biopsy were used to measure Gd-IgA1 levels using a specific monoclonal antibody (KM55 mAb). Urinary Gd-IgA1 levels were significantly higher in patients with IgAN than in disease controls. Moreover, urinary Gd-IgA1 was significantly correlated with the severity of the histopathological parameters in IgAN patients. Next, we validated the use of urinary Gd-IgA1 levels in the other Asian cohorts. In the Korean cohort, urinary Gd-IgA1 levels were also higher in patients with IgAN than in disease controls. Even in Japanese patients with IgAN and trace proteinuria (less than 0.3 g/gCr), urinary Gd-IgA1 was detected. Thus, urinary Gd-IgA1 may be an early disease-specific biomarker useful for determining the disease activity of IgAN.

Urinary Epidermal Growth Factor: A Promising "Next Generation" Biomarker in Kidney Disease

BACKGROUND

The epidermal growth factor (EGF) is a globular protein that is generated in the kidney, especially in the loop of Henle and the distal convoluted tubule. While EGF is nonexistent or hardly detectable in plasma, it is present in normal people's urine. Until now, risk stratification and chronic kidney disease (CKD) diagnosis have relied on estimated glomerular filtration rate (eGFR) and urine albumin/creatinine ratio (uACR), both of which reflect glomerular function or impairment. Tubular dysfunction, on the other hand, may also be associated with renal failure.

SUMMARY

Because decreased urine EGF (uEGF) indicates tubular atrophy and interstitial fibrosis, this biomarker, together with eGFR and uACR, may be employed in the general population for risk assessment and diagnosis of CKD. uEGF levels have been shown to correlate with intrarenal EGF mRNA expression and have been found to decrease in a variety of glomerular and non-glomerular kidney disorders.

KEY MESSAGE

uEGF, uEGF/creatinine, or uEGF/monocyte chemotactic peptide-1 are possible "new generation" biomarkers linked to a variety of kidney diseases that deserve further investigation as a single biomarker or as part of a multi-biomarker panel.

External validation of the International Prediction Tool in Korean patients with immunoglobulin A nephropathy

Background

The International IgA Nephropathy Prediction Tool (International IgA Nephropathy Prediction Tool) has been recently developed to estimate the progression risk of immunoglobulin A nephropathy (IgAN). This study aimed to evaluate the clinical performance of this prediction tool in a large IgAN cohort in Korea.

Methods

The study cohort was comprised of 2,064 patients with biopsy-proven IgAN from four medical centers between March 2012 and September 2021. We calculated the predicted risk for each patient. The primary outcome was occurrence of a 50% decline in estimated glomerular filtration rate (eGFR) from the time of biopsy or end-stage kidney disease. The model performance was evaluated for discrimination, calibration, and reclassification. We also constructed and tested an additional model with a new coefficient for the Korean race.

Results

During a median follow-up period of 3.8 years (interquartile range, 1.8–6.6 years), 363 patients developed the primary outcome. The two prediction models exhibited good discrimination power, with a C-statistic of 0.81. The two models generally underestimated the risk of the primary outcome, with lesser underestimation for the model with race. The model with race showed better performance in reclassification compared to the model without race (net reclassification index, 0.13). The updated model with the Korean coefficient showed good agreement between predicted risk and observed outcome.

Conclusion

In Korean IgAN patients, International IgA Nephropathy Prediction Tool had good discrimination power but underestimated the risk of progression. The updated model with the Korean coefficient showed acceptable calibration and warrants external validation.

Late Presentation for Kidney Biopsy: Clinical Presentations and Laboratory Findings

Although the number of patients reaching end-stage kidney disease without a biopsy- proven diagnosis is increasing, kidney biopsies play a key role in diagnosing kidney disease. We analyzed prospective data from patients with kidney disease who underwent percutaneous native kidney biopsies from January 2006 to December 2017. Demographic data, clinical presentations, and the laboratory and radiological findings at the time of biopsy were analyzed. Of 530 patients, 42.8% were male. The mean age was 33.9 (32.8-34.9.2) years; 66.3% were aged 25-64 years. Edema was the main clinical presentation (61.9%), with clinical urine changes seen in 66.7%. Most (89.6%) were nondiabetic; 46.8% had high blood pressure or were on antihypertensive therapy. Most patients (77.5%) were in Stages I, II, and III, and 12.3% underwent hemodialysis at the time of admission. Most (54.4%) were obese. Low hemoglobin (31.8%), high triglycerides (30%), high total cholesterol (58.2%), low serum albumin (73.9%), nephrotic proteinuria (61.8.6%), and microscopic hematuria (79.8%) were the main laboratory findings. The immunological investigations showed that antinuclear antibodies, positive anti-double-stranded DNA (anti-dsDNA), and extractable nuclear antigens were positive in 29.6%, 20.7%, and 19.7%, respectively. Perinuclear antineutrophil cytoplasmic antibodies (ANCA) were positive in 9.6% and cytoplasmic ANCA were positive in 5.4%, whereas immunoglobulin A was detected in 4.6%. More than one- third of the patients had reached advanced chronic kidney disease (CKD) Stages IIIB, IV, and V. This indicates the need to increase awareness about CKD, greater utilization of kidney biopsies, and earlier investigations to enable accurate diagnoses, and proper and timely management.

Efficacy and limitations of additional steroid pulse therapy in IgA nephropathy patients whose hematuria did not remit on tonsillectomy and protocol steroid pulse therapy

BACKGROUND

Hematuria is the essential symptom of IgA nephropathy that has been suggested to be associated with long-term renal prognosis, Tonsillectomy and steroid pulse therapy (TSP), which is widely practiced in Japan, is effective for achieving hematuria remission. However, some cases are refractory to TSP, and additional steroid pulse therapy (SP) administered to these cases to achieve remission of hematuria. Nonetheless, the clinical significance of additional SP is unknown.

METHODS

In this retrospective study, we enrolled 99 patients from Okubo Hospital whose hematuria persisted following TSP. Patients were divided into the hematuria remission and non-remission groups. A multivariate regression analysis was performed on the factors that contributed to hematuria remission.

RESULTS

Following TSP, 103 of 403 patients (32.3%) did not achieve hematuria remission. Additional SP were performed in 99 of these patients, and remission of hematuria was achieved in 57 (57.6%). Patients with a greater degree of improvement in hematuria with TSP were significantly more likely to have remission of hematuria with additional SP (p = 0.0084*). Even in the hematuria non-remission group, both hematuria and proteinuria improved after additional SP.

CONCLUSION

In IgA nephropathy, additional SP could induce hematuria remission and reduce proteinuria.

Validation of the International IgA Nephropathy Prediction Tool in the Greek Registry of IgA Nephropathy

Background

Immunoglobulin A nephropathy (IgAN) is among the commonest glomerulonephritides in Greece and an important cause of end-stage kidney disease (ESKD) with an insidious chronic course. Thus, the recently published International IgAN prediction tool could potentially provide valuable risk stratification and guide the appropriate treatment module. This study aimed to externally validate this prediction tool using a patient cohort from the IgAN registry of the Greek Society of Nephrology.

Methods

We validated the predictive performance of the two full models (with or without race) derived from the International IgAN Prediction Tool study in the Greek Society of Nephrology registry of patients with IgAN using external validation of survival prediction models (Royston and Altman). The discrimination and calibration of the models were tested using the C-statistics and stratified analysis, coefficient of determination (RD2) for model fit, and the regression coefficient of the linear predictor (β_PI), respectively.

Results

The study included 264 patients with a median age of 39 (30–51) years where 65.2% are men. All patients were of Caucasian origin. The 5-year risk of the primary outcome (50% reduction in estimated glomerular filtration rate or ESKD) was 8%. The RD2 for the full models with and without race when applied to our cohort was 39 and 35%, respectively, and both were higher than the reported RD2 for the models applied to the original validation cohorts (26.3, 25.3, and 35.3%, respectively). Harrel's C statistic for the full model with race was 0.71, and for the model without race was 0.70. Renal survival curves in the subgroups (<16th, ~16 to <50th, ~50 to <84th, and >84th percentiles of linear predictor) showed adequate separation. However, the calibration proved not to be acceptable for both the models, and the risk probability was overestimated by the model.

Conclusions

The two full models with or without race were shown to accurately distinguish the highest and higher risk patients from patients with low and intermediate risk for disease progression in the Greek registry of IgAN.

The International IgA nephropathy network (IIgANN) prediction tool underestimates disease progression in Indian patients

Introduction

International IgA nephropathy (IgAN) network (IIgANN) prediction tool was developed to predict risk of progression in IgAN. We attempted to externally validate this tool in an Indian cohort because the original study did not include Indian patients.

Methods

Adult patients with primary IgAN were stratified to low, intermediate, higher, and highest risk groups, as per the original model. Primary outcome was reduction in estimated glomerular filtration rate (eGFR) by >50% or kidney failure. Both models were evaluated using discrimination: concordance statistics (C-statistics), time-dependent receiver operating characteristic (ROC) curves, R²d, Kaplan–Meier survival curves between risk groups and calibration plots. Reclassification with net reclassification improvement and integrated discrimination improvement (IDI) was used to compare the 2 models with and without race.

Results

A total of 316 patients with median follow-up of 2.8 years had 87 primary outcome events. Both models with and without race showed reasonable discrimination (C-statistics 0.845 for both models, R²d 49.9% and 44.7%, respectively, and well-separated survival curves) but underestimated risk of progression across all risk groups. The calibration slopes were 1.234 (95% CI: 0.973–1.494) and 1.211 (95% CI: 0.954–1.468), respectively. Both models demonstrated poor calibration for predicting risk at 2.8 and 5 years. There was limited improvement in risk reclassification risk at 5 and 2.8 years when comparing model with and without race.

Conclusion

IIgANN prediction tool showed reasonable discrimination of risk in Indian patients but underestimated the trajectory of disease progression across all risk groups.

Oxidative stress and macrophage infiltration in IgA nephropathy

BACKGROUND

The aim of this study was to evaluate the interactions among serum levels of galactose-deficient IgA1 (Gd-IgA1), oxidative stress and macrophage infiltration and their clinical correlates in patients with IgA Nephropathy (IgAN).

METHODS

A total of 47 patients with biopsy-proven primary IgAN, aged between 16 and 79 years, with a follow-up period ≥ 1 year or who showed progression to end stage kidney disease (ESKD) regardless the duration of follow-up were included. Study endpoint was the progression to ESKD. Serum Gd-IgA1 and advanced oxidation protein product (AOPP) levels were measured using ELISA assays. Kidney biopsies were evaluated according to the Oxford MEST-C scoring, with C4d and CD68 staining.

RESULTS

Seventeen patients (36%) experienced ESKD during a median follow-up time of 6 years (IQR 3.7-7.5). Serum AOPP levels were correlated with the intensity of glomerular C3 deposition (r = 0.325, p = 0.026), glomerular (r = 0.423, p = 0.003) and interstitial CD68 + cell count (r = 0.298, p = 0.042) and Gd-IgA1 levels (r = 0.289, p = 0.049). Serum Gd-IgA1 levels were correlated with the intensity of C3 deposition (r = 0.447, p = 0.002). eGFR at biopsy (adjusted HR (aHR) 0.979 p = 0.011), and E score (aHR, 8.305, p = 0.001) were associated with progression to ESKD in multivariate analysis. 5-year ESKD-free survival rate was significantly lower in patients with higher E score compared to patients with E score 0 [p = 0.021].

CONCLUSIONS

An increased number of macrophages in the glomerular and tubulointerstitial area may play a role in oxidative stress and complement system activation. Endocapillary hypercellularity is a predictive factor for poor prognosis in IgAN.

A Validation Study Comparing Risk Prediction Models of IgA Nephropathy

We aimed to validate three IgAN risk models proposed by an international collaborative study and another CKD risk model generated by an extended CKD cohort with our multicenter Chinese IgAN cohort. Biopsy-proven IgAN patients with an eGFR ≥15 ml/min/1.73 m² at baseline and a minimum follow-up of 6 months were enrolled. The primary outcomes were a composite outcome (50% decline in eGFR or ESRD) and ESRD. The performance of those models was assessed using discrimination, calibration, and reclassification. A total of 2,300 eligible cases were enrolled. Of them, 288 (12.5%) patients reached composite outcome and 214 (9.3%) patients reached ESRD during a median follow-up period of 30 months. Using the composite outcome for analysis, the Clinical, Limited, Full, and CKD models had relatively good performance with similar C statistics (0.81, 0.81, 0.82, and 0.82, respectively). While using ESRD as the end point, the four prediction models had better performance (all C statistics > 0.9). Furthermore, subgroup analysis showed that the models containing clinical and pathological variables (Full model and Limited model) had better discriminatory abilities than the models including only clinical indicators (Clinical model and CKD model) in low-risk patients characterized by higher baseline eGFR (≥60 ml/min/1.73 m²). In conclusion, we validated recently reported IgAN and CKD risk models in our Chinese IgAN cohort. Compared to pure clinical models, adding pathological variables will increase performance in predicting ESRD in low-risk IgAN patients with baseline eGFR ≥60 ml/min/1.73 m².

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.

The association of microhematuria with mesangial hypercellularity, endocapillary hypercellularity, crescent score and renal outcomes in immunoglobulin A nephropathy

BACKGROUND

Microhematuria is common in immunoglobulin A nephropathy (IgAN). However, current prognostication is based on proteinuria and mesangial hypercellularity, endocapillary hypercellularity, segmental sclerosis, tubulointerstitial fibrosis and crescent (MEST-C) scores.

METHODS

In this retrospective study, we evaluated whether MEST-C score components are associated with the presence of microhematuria at biopsy and whether the degree of microhematuria during follow-up is associated with change in estimated glomerular filtration rate (eGFR), after adjusting for clinical and histological parameters. We identified 125 patients with biopsy-proven IgAN and MEST-C scoring who were not on immunosuppressive therapy at biopsy. Microhematuria was defined as ≥3 red blood cells (RBCs)/high-power field (hpf).

RESULTS

Of the 125 patients, 97 had microhematuria at baseline and were more likely to have M1, E1 and C ≥ 1 lesions (P < 0.05 for all) compared with patients without microhematuria. Of the 125 patients, 72 had follow-up data available. An increase in the degree of microhematuria was significantly associated with an eGFR decline of -0.81 mL/min/1.73 m2 [95% confidence interval (CI) -1.44 to -0.19, P = 0.01], after adjusting for follow-up time, proteinuria and T score. Severe microhematuria (≥21 RBCs/hpf) was associated with an even larger decline in eGFR (-3.99 mL/min/1.73 m2; 95% CI -6.9411 to -1.0552, P = 0.008), after similar adjustments.

CONCLUSION

Degree of microhematuria during follow-up is an independent predictor of eGFR decline after adjusting for clinical and histological parameters. Therefore, monitoring the degree of microhematuria as well as proteinuria is important when evaluating patients with IgAN. Additional studies using improvement in microhematuria as a primary surrogate outcome are needed.

Case series of idiopathic intracranial hypertension in three patients with immune-complex glomerulonephritis

BACKGROUND

Idiopathic intracranial hypertension (IIH) is defined by an increased cerebrospinal fluid pressure in the absence of inflammation, structural obstructions, or mass lesions. Although the underlying pathogenesis of IIH is not fully understood, associations with specific risk factors as obesity, obstruction of cerebral venous sinuses, medications, endocrine or systemic conditions and chronic kidney disease have been described. Immune-complex glomerulonephritis as IgA-nephropathy is a frequent cause of chronic kidney failure, which was reported previously in one IIH patient. To date, there is no knowledge about the variable relation of immune-complex nephritis, kidney function and the course of IIH.

CASE PRESENTATION

We report three cases (two females) of concurrent diagnosis of IIH and immune-complex glomerulonephritis. All patients presented with typical IIH symptoms of headache and visual disturbances. Two patients had been diagnosed with IgA-nephropathy only few weeks prior to IIH diagnosis. The third patient had been diagnosed earlier with terminal kidney failure due to a cryoglobulin glomerulonephritis.

CONCLUSION

We propose a possible link between renal deposition of immune-complexes and increased cerebrospinal fluid pressure. Pathophysiological hypotheses and clinical implications are discussed. We recommend clinical awareness and further systematic research to obtain more information on the association of IIH and immune-complex glomerulonephritis.

Glomerular endothelial activation, C4d deposits and microangiopathy in immunoglobulin A nephropathy

Immunoglobulin A nephropathy (IgAN) is considered as mesangiopathy since it initiates in the mesangium; however, other glomerular components are involved and the glomerular capillary wall offers the first contact to circulating macromolecular IgA1. Acute and active forms of IgAN are associated with endocapillary hypercellularity and vascular damage of various degrees, in severe cases with microangiopathy (MA) without or with thrombosis [thrombotic microangiopathy (TMA)]. Vascular damage activates complement and coagulation cascades. A defective complement regulation has recently been detected in active and progressive cases of IgAN. C4d deposits in renal biopsies have been found to be an early risk factor. These observations have raised interest in manifestation of MA and TMA in progressive cases of IgAN. MA-TMA lesions have been found in various percentages (2-53%) of patients with IgAN according to patients' selection and pathology definition of TMA. The association with hypertension (HTN) was so strong that it led to the hypothesis that MA/TMA in IgAN was a mere consequence of severe HTN. Old and new clinical and experimental data indicate that in IgAN the interaction of the glomerular capillary wall with immune reactants and complement uncontrolled activation leading to C4b deposits favours the development of MA-TMA, which plays a role in progression and renal function decline. The central role of complement activation is relevant also for the new therapeutic interventions offered by the pharma.

Machine Learning in Prediction of IgA Nephropathy Outcome: A Comparative Approach

We are overwhelmed by a deluge of data and, although its interpretation is challenging, fortunately, information technology comes to the rescue. One of the tools is artificial intelligence, allowing the identification of relationships between variables and their arbitrary classification. We focused on the assessment of both the remission of proteinuria and the deterioration of kidney function in patients with IgA nephropathy, comparing several methods of machine learning. It is of utmost importance to respond to subtle changes in kidney function, which will lead to a deceleration of the disease. This goal has been achieved by analyzing regression techniques, predicting the difference in serum creatinine concentration. We obtained the performance of the tested models which classified patients with high accuracy (Random Forest Classifier showed an accuracy of 0.8–1.0, Multi-Layer Perceptron an Area Under Curve of 0.8842–0.9035 and an accuracy of 0.7527–1.0) and regressors with a low estimation error (Decision Tree Regressor showed MAE 0.2059, RMSE 0.2645). We have demonstrated the impact of both model selection and input features on performance. Application of machine learning methods requires careful selection of models and assessed parameters. The computing power of modern computers allows searching for the models most effective in terms of accuracy.

Long term outcome of immunoglobulin A (IgA) nephropathy: A single center experience

INTRODUCTION

IgA nephropathy (IgAN) has a heterogeneous presentation and the progression to end stage renal disease (ESRD) is often influenced by demographics, ethnicity, as well as choice of treatment regimen. In this study, we investigated the long term survival of IgAN patients in our center and the factors affecting it.

METHODS

This study included all biopsy-proven IgAN patients with ≥ 1year follow-up. Patients with diabetes mellitus at diagnosis and secondary IgAN were excluded. Medical records were reviewed for demographics, clinical presentation, blood pressure, 24-hour urine protein, serum creatinine, renal biopsy and treatment received. The primary outcome was defined as combined event of 50% estimated glomerular filtration rate (eGFR) reduction or ESRD.

RESULTS

We included 130 (74 females; 56 males) patients of mean age 38.0 ± 14.0 years and median eGFR of 75.2 (interquartile range (IQR) 49.3-101.4) ml/min/1.73m2. Eighty-four (64.6%) were hypertensive at presentation, 35 (26.9%) had nephrotic syndrome and 57 (43.8%) had nephrotic range proteinuria (NRP). Median follow-up duration was 7.5 (IQR 4.0-13.0) years. It was noted that 18 (13.8%) developed ESRD and 34 (26.2%) reached the primary outcome. Annual eGFR decline was -2.1 (IQR -5.3 to -0.1) ml/min/1.73m2/year, with median survival of 20 years. Survival rates from the combined event (50% decrease in eGFR or ESRD) at 10, 20 and 30 years were 80%, 53% and 25%, while survival from ESRD were 87%, 73% and 65%, respectively. In the univariate analysis, time-average proteinuria (hazard ratio (HR) = 2.41, 95% CI 1.77-3.30), eGFR <45ml/min/1.73m2 at biopsy (HR = 2.35, 95% CI 1.03-5.32), hypertension (HR = 2.81, 95% CI 1.16-6.80), mean arterial pressure (HR = 1.02, 95% CI 1.01-1.04), tubular atrophy/interstitial fibrosis score (HR = 3.77, 95% CI 1.84-7.73), and cellular/fibrocellular crescent score (HR = 2.44, 95% CI 1.19-5.00) were found to be significant. Whereas only time-average proteinuria (TA-proteinuria) remained as a significant predictor in the multivariate analysis (HR = 2.23, 95% CI 1.57-3.16).

CONCLUSION

In our cohort, TA-proteinuria was the most important predictor in the progression of IgAN, irrespective of degree of proteinuria at presentation.

Total Nephron Number and Single-Nephron Parameters in Patients with IgA Nephropathy

Background

Single-nephron dynamics in progressive IgA nephropathy (IgAN) have not been studied. We applied novel methodology to explore single-nephron parameters in IgAN.

Methods

Nonglobally sclerotic glomeruli (NSG) and globally sclerotic glomeruli (GSG) per kidney were estimated using cortical volume assessment via unenhanced computed tomography and biopsy-based stereology. Estimated single-nephron GFR (eSNGFR) and single-nephron urine protein excretion (SNUPE) were calculated by dividing eGFR and UPE by the number of NSG. Associations with CKD stage and clinicopathologic findings were cross-sectionally investigated.

Results

This study included 245 patients with IgAN (mean age 43 years, 62% male, 45% on renin-angiotensin aldosterone system [RAAS] inhibitors prebiopsy) evaluated at kidney biopsy. CKD stages were 10% CKD1, 43% CKD2, 19% CKD3a, 14% CKD3b, and 14% CKD4-5. With advancing CKD stage, NSG decreased from mean 992,000 to 300,000 per kidney, whereas GSG increased from median 64,000 to 202,000 per kidney. In multivariable models, advancing CKD stage associated with lower numbers of NSG, higher numbers of GSG, and lower numbers of GSG + NSG, indicating potential resorption of sclerosed glomeruli. In contrast to the higher mean glomerular volume and markedly elevated SNUPE in advanced CKD, the eSNGFR was largely unaffected by CKD stage. Lower SNGFR associated with Oxford scores for endocapillary hypercellularity and crescents, whereas higher SNUPE associated with segmental glomerulosclerosis and tubulointerstitial scarring.

Conclusions

SNUPE emerged as a sensitive biomarker of advancing IgAN. The failure of eSNGFR to increase in response to reduced number of functioning nephrons suggests limited capacity for compensatory hyperfiltration by diseased glomeruli with intrinsic lesions.

Validation of an international prediction model including the Oxford classification in Korean patients with IgA nephropathy

BACKGROUND

Recently, a new international risk prediction model including the Oxford classification was published which was validated in a large multi-ethnic cohort. Therefore, we aimed to validate this risk prediction model in Korean patients with IgA nephropathy.

METHODS

This retrospective cohort study was conducted with 545 patients who diagnosed IgA nephropathy with renal biopsy in three medical centers. The primary outcome was defined as a reduction in estimated glomerular filtration rate (eGFR) of >50% or incident end-stage renal disease (ESRD). Continuous net reclassification improvement (cNRI) and integrated discrimination improvement (IDI) were used to validate models.

RESULTS

During the median 3.6 years of follow-up period, 53 (9.7%) renal events occurred. In multivariable Cox regression model, M1 (hazard ratio [HR], 2.22; 95% confidence interval [CI], 1.02-4.82; p = .043), T1 (HR, 2.98; 95% CI, 1.39-6.39; p = .005) and T2 (HR, 4.80; 95% CI, 2.06-11.18; p < .001) lesions were associated with increased risk of renal outcome. When applied the international prediction model, the area under curve (AUC) for 5-year risk of renal outcome was 0.69, which was lower than previous validation and internally derived models. Moreover, cNRI and IDI analyses showed that discrimination and reclassification performance of the international model was inferior to the internally derived models.

CONCLUSION

The international risk prediction model for IgA nephropathy showed not as good performance in Korean patients as previous validation in other ethnic group. Further validation of risk prediction model is needed for Korean patients with IgA nephropathy.

Mesangial C3 deposition and serum C3 levels predict renal outcome in IgA nephropathy

BACKGROUND

Complement activation plays an important role in the pathogenesis of IgA nephropathy (IgAN). We aimed to evaluate the relationship between mesangial C3 deposition and histologic lesions and to investigate the role of mesangial C3 deposition and serum C3 reduction in predicting renal outcome in IgAN children.

METHODS

We performed a retrospective cohort study in children with biopsy-proven IgAN. Mesangial C3 deposition (< 2+ vs. ≥ 2+) was detected by the immunofluorescence. Histopathologic kidney grades were determined by the Oxford classification. A decreased serum C3 concentration (hypoC3) was defined when C3 < 90 mg/dl. The endpoint was composite kidney outcome with either a 30% decline in glomerular filtration rates from baseline or kidney failure during the follow-up period.

RESULTS

A total of 98 children were analyzed. Mesangial hypercellularity (M) was an independent factor associated with mesangial C3 deposition (HR 3.267; 95% CI 1.028-10.389; P = 0.045). After a median follow-up period of 25 months (interquartile range 18-36 months), 6 (6.1%) children reached the endpoint. Compared with other children, a significantly higher proportion of children with composite kidney outcomes had mesangial C3 deposition ≥ 2+ and hypoC3 (3.4% versus 27.3%, P = 0.002). After adjustment for clinicopathologic risk factors, mesangial C3 deposition ≥ 2+ and hypoC3 were associated with renal outcome (HR 9.772; 95% CI 1.264-75.518; P = 0.029).

CONCLUSION

Mesangial C3 deposition was associated with M in IgAN. Mesangial C3 deposition and hypoC3 were risk factors for renal outcome in children with IgAN.

Grading system utilising the total score of Oxford classification for predicting renal prognosis in IgA nephropathy

The Oxford classification of IgA nephropathy (IgAN) can evaluate each MEST-C score individually. We analysed a new grading system that utilised the total MEST-C score in predicting renal prognosis. Altogether, 871 IgAN patients were classified into three groups using the new Oxford classification system (O-grade) that utilised the total MEST-C score (O-grade I: 0–1, II: 2–4, and III: 5–7 points), and the 10-year renal prognosis was analysed. The clinical findings became significantly severer with increasing O-grades, and the renal survival rate by the Kaplan–Meier method was 94.1%, 86.9%, and 74.1% for O-grades I, II, and III, respectively. The hazard ratios (HRs) for O-grades II and III with reference to O-grade I were 2.8 (95% confidence interval [CI] 1.3–6.0) and 6.3 (95% CI 2.7–14.5), respectively. In the multivariate analysis, mean arterial pressure and eGFR, proteinuria at the time of biopsy, treatment of corticosteroids/immunosuppressors, and O-grade (HR 1.63; 95% CI 1.11–2.38) were the independent factors predicting renal prognosis. Among the nine groups classified using the O-grade and Japanese clinical-grade, the renal prognosis had an HR of 15.2 (95% CI 3.5–67) in the severest group. The O-grade classified by the total score of the Oxford classification was associated with renal prognosis.

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

INTRODUCTION

Glomerular Research And Clinical Experiments-IgA Nephropathy in Indians (GRACE-IgANI) is the first prospective South Asian IgAN cohort with protocolized follow-up and extensive biosample collection. Here we report the baseline clinical, biochemical, and histopathologic characteristics of GRACE IgANI and calculate baseline risk of progression for the cohort.

METHODS

201 incident adults with kidney biopsy-proven primary IgAN were recruited into GRACE-IgANI between March 2015 and September 2017. As of April 30, 2020, the cohort had completed a median follow-up of 30 months (interquartile range [IQR] 16-39).

RESULTS

The commonest clinical presentation in GRACE IgANI was hypertension, with or without proteinuria, and nephrotic-range proteinuria was present in 34%, despite <10 months of lead time to kidney biopsy. The GRACE-IgANI kidney biopsy data demonstrated a disproportionate absence of active glomerular lesions and overrepresentation of segmental sclerosing lesions and tubulointerstitial fibrosis at presentation, often coexistent with relatively well-preserved estimated glomerular filtration rate (eGFR) and low levels of proteinuria, especially in males. Baseline risk of progression was calculated for each evaluable patient using 2 different risk prediction tools. The median 5-year absolute risk of end-stage kidney disease (ESKD) was 19.8% (IQR 2.7-57.4) and median 5-year risk of progression to the combined endpoint of 50% decline in eGFR or ESKD was 35.5% using the 2 tools.

CONCLUSIONS

The predicted risk of progression in this cohort was considerable. Over the next 5 years, we will dissect the pathogenic pathways that underlie this severe South Asian IgAN phenotype.

IgA Nephropathy: An Interesting Autoimmune Kidney Disease

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. It is a leading cause of chronic kidney disease and progresses to end-stage kidney disease in up to 40% of patients about 20 years after diagnosis. Additionally, IgAN is associated with significant mortality. The diagnosis currently necessitates a kidney biopsy, as no biomarker sufficiently specific and sensitive is available to supplant the procedure. Patients display significant heterogeneity in the epidemiology, clinical manifestations, renal progression, and long-term outcomes across diverse racial and ethnic populations. Recent advances in understanding the underlying pathophysiology of the disease have led to the proposal of a four-hit hypothesis supporting an autoimmune process. To date, there is no disease-specific treatment but, with a better understanding of the disease pathogenesis, new therapeutic approaches are currently being tested in clinical trials. In this review, we examine the multiple facets and most recent advances of this interesting disease.

The Utility of Assessing CD68+ Glomerular Macrophages in Assessing Endocapillary Hypercellularity in IgA Nephropathy

Introduction:

IgA nephropathy (IgAN) is the most common form of glomerulonephritis across the world. Oxford classification defines criteria and effects of endocapillary hypercellularity on E score but the reproducibility of the same is debatable. Hence, there is a need for an objective marker that could establish a gold standard in assessing endocapillary hypercellularity.

Methods:

Forty biopsies of proven IgAN were taken and grouped into two groups based on the presence or absence of endocapillary hypercellularity (n = 20 each). These biopsies were then stained by CD68 immune stain and the glomerular macrophages were quantified. Mean serum creatinine, presence of hypertension, degree of proteinuria and haematuria at the time of biopsy were also recorded and the correlation between these parameters and endocapillary hypercellularity was also studied.

Results:

Mean glomerular CD 68+ cell count was significantly higher in glomeruli showing endocapillary hypercellularity. Utilising the objective cutoff values of 0.6 CD68+ per glomerulus, more than 8 glomerular CD68+ cells in the entire biopsy and/or around 4 CD68+ cells in the most inflamed glomerulus, endocapillary hypercellularity can be predicted with a sensitivity of 70–80% and specificity of 70%. After regrouping the biopsies based on the cutoff values obtained from the receiver operating curve analysis the mean urine RBC count per high power field showed a significant correlation with endocapillary hypercellularity.

Conclusion:

Glomerular CD68+ macrophage count seems to be a promising approach in assessing endocapillary hypercellularity. Further studies with emphasis on correlation with the clinical outcome are needed to validate its utility as an objective tool.

Tubular decoy receptor 2 as a predictor of prognosis in patients with immunoglobulin A nephropathy

Background

Accelerated senescence of renal tubular epithelial cells (RTECs) might contribute to immunoglobulin A nephropathy (IgAN) progression. This study aimed to determine whether the RTEC senescence marker, decoy receptor 2 (DcR2), could predict prognosis in IgAN.

Methods

We included a retrospective cohort of 105 patients with biopsy-proven IgAN. Tubular DcR2 expression was assessed at renal biopsy and the Oxford histological MEST-C score [mesangial hypercellularity (M), endocapillary proliferation (E), segmental sclerosis (S), interstitial fibrosis/tubular atrophy (T) and crescents (C)] defined disease severity. IgAN progression was defined as a composite of end-stage renal disease or a 30% decline in the estimated glomerular filtration rate (eGFR), analyzed using Kaplan–Meier and Cox regression analyses.

Results

Tubular DcR2 was overexpressed in IgAN. Numbers of DcR2 and p16 double-positive RTECs increased with increasing severity of tubular atrophy/interstitial fibrosis (T lesion). Patients with ≥25% tubular DcR2 expression experienced worse proteinuria, T lesions and a lower eGFR. Cumulative renal survival was significantly lower in patients with ≥25% DcR2 positivity. Multivariate regression analyses showed that ≥25% tubular DcR2 expression was significantly associated with worse eGFR slopes (the rate of renal function decline; P = 0.003) and the incidence of the composite outcome (P = 0.001) in IgAN. The addition of tubular DcR2 to a model with clinical data at biopsy (mean arterial pressure, proteinuria and eGFR) or MEST-C score significantly improved the 5-year risk prediction of IgAN progression, as confirmed by receiver operating characteristic curve analyses.

Conclusions

Tubular DcR2 expression detected at biopsy was a strong independent predictor for IgAN progression and might have prognostic value in addition to established risk markers.

Combining clinical features and MEST-C score in IgA nephropathy may be a better determinant of kidney survival

Introduction. IgA nephropathy (IgAN) is a heterogeneous disease with highly variable clinical and histopathological features. We investigated the effects of Oxford classification and clinical features on renal survival in patients with IgAN.Methods. This retrospective observational study conducted from 2013 to 2017. Ninety-seven patients who were followed up more than six months were examined.Results. A total of 97 patients (68% male and median age 40 years) were enrolled in this study. 13% of patients developed end stage renal disease (ESRD) within the median of 37 months of follow-up. Need for renal replacement therapy at the time of diagnosis, serum creatinine level of higher than 1.97 mg/dl, serum albumin level less than 3.5 gr/dl, 24-hour urine protein level of higher than > 3.5 g/day, the percentage of glomerulosclerosis higher than 53%, T2 score and total MEST-C score higher than two were found to be significant predictors of development of ESRD. None of the clinical or histopathological features were found to be significant predictor of steroid treatment sensitivity except T1-2 scores.Conclusion. We think that IgA nephropathy is a heterogeneous disease that requires clinical and histopathological features to be evaluated together, but not individually, to determine renal survival.What is new. Iga nephropathy is a heterogeneous disease and modern pathologic classification systems is not enough to predict to prognosis. Histopathological features to be evaluated with clinical features, but not individually, to determine renal survival. Also glucocorticoid treatment response seems to be independent from clinical and histopathological features except T1-2 score.

Repeat renal biopsy improves the Oxford classification-based prediction of immunoglobulin A nephropathy outcome

BACKGROUND

The prognosis of IgA nephropathy (IgAN) is very heterogeneous. Predicting the nature and the rate of the disease progression is crucial for refining patient treatment. The aim of this study was to evaluate the prognostic impact of an Oxford classification-based repeat kidney tissue evaluation to predict end-stage renal disease (ESRD).

METHODS

Patients with biopsy-proven primary IgAN who underwent two renal biopsies at our centre were analyzed retrospectively. Renal biopsies were scored by two pathologists blinded to the clinical data and according to the updated Oxford classification. Cox models were generated to evaluate the prognostic impact considering the Oxford classification elementary lesions from the first (Model 1) or the second (Model 2) biopsy, adjusted on clinical data at time of reevaluation. The prognostic impacts of the dynamic evolution of each elementary lesion between biopsies were also assessed through univariate and multivariate evaluation.

RESULTS

A total of 168 adult patients were included, with a median follow-up duration of 18 (range 11-24) years. The second biopsy was performed either systematically (n = 112) of for-cause (n = 56), after a median time of 5.4 years. The prognostic performances of Model 2 (second biopsy) were significantly better than Model 1 (first biopsy, analysis of deviance P < 0.0001). The dynamic changes of C and T lesions were significantly associated with the progression toward ESRD after adjustment on variables from Model 2.

CONCLUSION

Both static and dynamic Oxford-based histological evaluation offered by a repeat biopsy improves the prediction of ESRD in patients with IgAN.

Monitoring Immune Responses in IgA Nephropathy: Biomarkers to Guide Management

IgA nephropathy (IgAN) is the commonest biopsy-reported primary glomerulonephritis worldwide. It has an incidence which peaks among young adults, and 30 to 40% of patients' progress to end stage kidney disease within twenty years of diagnosis. Ten-year kidney survival rates have been reported to be as low as 35% in some parts of the world. The successful management of IgAN is limited by an incomplete understanding of the pathophysiology of IgAN and a poor understanding of how pathophysiology may vary both from patient to patient and between patient groups, particularly across races. This is compounded by a lack of rigorously designed and delivered clinical trials in IgAN. This is slowly changing, with a number of Phase 2 and 3 clinical trials of novel therapies targeting a number of different putative pathogenic pathways in IgAN due to report in the next 5 years. From our current, albeit limited, understanding of the pathophysiology of IgAN it is unlikely a single therapy will be effective in all patients with IgAN. The successful management of IgAN in the future is, therefore, likely to be reliant on targeted therapies, carefully selected based on an individualized understanding of a patient's risk of progression and underlying pathophysiology. The potential role of biomarkers to facilitate personalization of prognostication and treatment of IgAN is immense. Here we review the progress made over the past decade in identifying and validating new biomarkers, with a particular focus on those that reflect immunological responses in IgAN.

External Validation of International Risk-Prediction Models of IgA Nephropathy in an Asian-Caucasian Cohort

Introduction

Two prediction models for IgA nephropathy (IgAN) using clinical variables and the Oxford MEST scores were developed and validated in 2 multiethnic cohorts. Additional external validation is required.

Methods

Biopsy-proven Chinese and Argentinian patients with IgAN were included. The primary outcome was defined as a 50% decline in estimated glomerular filtration rate (eGFR) or end-stage renal disease. C-statistics and stratified analyses were used for model discrimination, coefficient of determination (R²_D) for model fit, and calibration plots for model calibration. Baseline survival function was also evaluated.

Results

A total of 1275 patients were enrolled, with a mean age of 34 (interquartile range: 27–42) years, 50% of whom (638 of 1275) were men. Use of renin-angiotensin system blockers was higher than in previously reported cohorts, whereas other variables were comparable. The C-statistic of the models was 0.81, and R²_D was higher than reported. Survival curves in the subgroups (<16th, ∼16th to <50th, ∼50th to <84th, and ≥84th percentiles of linear predictor) were well separated. Most of the predictor variables, including hazard ratio, predicted 5-year risk, and eGFR decline slope, were worse with risk increasing. The baseline survival function was comparable in our cohort and the reported cohorts. The calibration was acceptable for the full model without race. However, the risk probability over 3 years was overestimated in the full model with race included.

Conclusion

The prediction models showed good performance on personalized risk assessment, which may be used as drug-specific, precision-medicine approaches to treatment decisionmaking.

Increased Lifetime Risk of ESRD in Familial IgA Nephropathy

Introduction

Familial IgA nephropathy (IgAN) has been widely reported. However, its clinicohistologic characteristics and long-term prognosis are not clear.

Methods

A total of 348 familial IgAN cases from 167 independent families were recruited and their clinicohistologic characteristics as well as lifetime risk of end-stage renal disease (ESRD) were compared to 1116 sporadic IgAN patients from the same geographic region.

Results

Of all familial IgAN patients, 60 (17%) came from 32 single-generation (SG; all affected individuals are siblings) families, whereas 286 (82%) came from 134 multiple-generation (MG; affected individuals were present in at least 2 consecutive generations) families. The lifetime ESRD risk was significantly higher in familial patients than sporadic ones after adjusting by gender (hazard ratio [HR]=1.40, 95% confidence interval [CI]: 1.12–1.74, P = 0.004), with 5 years younger in median ESRD age (60 years vs. 65 years in familial and sporadic cases separately). Interestingly, among familial patients, we found cases from SG families (vs. MG families: HR = 2.62, 95% CI: 1.59–4.31, P < 0.001) or with early onset (onset age <30 years) (vs. late onset: HR = 4.79, 95% CI: 3.16–7.26, P < 0.001) had higher lifetime ESRD risk. Furthermore, among sporadic patients, men had lower estimated glomerular filtration rate (eGFR), higher urine protein, higher Oxford T score, and higher risk for life span ESRD compared with women (male vs. female, 25% vs. 17%, P = 0.003) whereas these gender differences were not seen in familial patients.

Conclusion

Familial IgAN cases had poorer renal outcomes and less gender differences compared with sporadic cases. These findings provide evidence that familial disease represent a distinct subtype of more progressive IgAN. Early diagnosis could improve the prognosis of cases with familial IgAN.

Modifications of gut microbiota are associated with the severity of IgA nephropathy in the Chinese population

Immunoglobulin A nephropathy (IgAN) is a common glomerular disease. The pathogenesis of IgAN is associated with dysregulated intestinal mucosal immunity. However, whether gut microbial modifications play a role in IgAN remains unclear. Blood and faecal samples were collected from 52 patients with IgAN and 25 healthy controls (HCs). The gut microbiome was analysed using the 16S ribosomal RNA gene. The levels of galactose-deficient IgA1 (Gd-IgA1), soluble cluster of differentiation 14 (sCD14), lipopolysaccharide binding protein (LBP), intercellular adhesion molecule-1 (ICAM-1), tumour necrosis factor α (TNF-α), interleukin-1, and C-reactive protein were quantified. Substantial differences in the gut microbiota were identified between patients with IgAN and HCs (P < 0.05). Bacteroides and Escherichia-Shigella levels were significantly higher in patients with IgAN than in HCs, while Bifidobacterium and Blautia spp. Levels were lower. Higher proportions of Escherichia-Shigella and lower proportions of Bifidobacterium spp. were observed in patients with IgAN with high urine RBC count (≥10/HP) and proteinuria (≥1 g/24 h) levels. Correlation analysis was used to assess the association between gut microbiota and biomarkers in patients with IgAN. The results showed that Prevotella 7 levels were negatively correlated with Gd-IgA1, LBP, sCD14, ICAM-1, and TNF-α levels, while Bifidobacterium spp. Levels presented a significant inverse relationship with LBP and Gd-IgA1. Additionally, Escherichia-Shigella levels were negatively correlated with Prevotella 7. In patients with IgAN, gut modifications were characterised by an increase in the number of pathogenic bacteria and a reduction in the levels of beneficial bacteria, suggesting that the disturbance of intestinal microflora might be important in the severity of IgAN.

Clinical and prognostic significance of C1q deposition in IgAN patients-a retrospective study

BACKGROUND/AIM

IgA nephropathy (IgAN) is the most prevalent primary glomerular disease worldwide and is responsible for 45-50% of primary glomerular diseases in China. We are essentially dependent on the degree of proteinuria to determine prognosis and it has been reported that histopathologic lesions are risk factors for the progression of IgAN. The aim of this study was to investigate the clinicopathologic features and prognosis of IgAN with C1q deposition in adult Chinese patients.

METHODS

The patients of primary IgAN diagnosed by renal biopsy from January 2002 to December 2018 at the Second Hospital of Shanxi Medical University were retrospectively analyzed and divided into C1q deposit group and C1q negative group according to glomerular immunofluorescence examination. We evaluated their serologic and histopathologic findings. We collected data of patients during January 1, 2015 to December 31, 2018 and performed the clinical follow-up until the patient's estimated glomerular filtration rate (eGFR) decreased by more than 30%, entering end-stage renal disease (ESRD). Kaplan-Meier survival analysis was used to evaluate the cumulative incidence of renal progression in two groups. Univariate and multivariate Cox proportional hazard regression models were used to analyze the effect of C1q deposition on the prognosis of patients with IgA nephropathy.

RESULTS

The baseline data of total 491 cases were available and 172 cases had the follow-up data. The baseline eGFR and plasma albumin (ALB) levels in C1q deposit group were lower than those in the C1q negative group, while the levels of serum creatinine (Scr), total cholesterol (TC), 24 h urine protein, low-density lipoprotein (LDL), β2 microglobulin, etc. were higher than those in C1q negative group (all P < 0.05). Pathological indexes: glomerular segment sclerosis and adhesion (S), renal tubular atrophy/interstitial fibrosis (T), and cell/fibroblastic crescent (C) scores in C1q deposit group were higher than those in C1q negative group (all P < 0.05). With a median follow-up time of 32.5 (24,42) months, a total of 18 patients (C1q deposit: 11; C1q negative: 7) developed to endpoints. Kaplan-Meier survival curve analysis showed that there was significant decrease in cumulative incidence of renal progression between the two groups (Log-rank test χ2 = 4.78, P = 0.029). Cox regression analysis showed that the risk of renal end-point events in IgAN patients with C1q deposit group was 6.35 times higher than that in C1q negative group (HR = 6.35, 95% CI: 1.21-33.30, P = 0.029).

CONCLUSION

The clinical and renal pathological changes of IgAN patients with C1q deposition are more severe than those of C1q negative patients, and has a worse outcome. C1q deposition is an independent risk factor for the progression of renal function and contributes to a poor renal prognosis in adult IgAN patients.

How to optimize the design and implementation of risk prediction tools: focus group with patients with IgA nephropathy

Background

IgA nephropathy (IgAN) is a common type of chronic immune-mediated kidney disease with variable risk of progression to end-stage kidney disease. Risk stratification helps clinicians weight the potential risks and benefits of immunosuppressive therapy for individual patients, and can inform patient-centred communication. No prior research examined barriers of risk predication tools (RPT) specific to IgAN. The purpose of this study was to explore determinants (facilitators, barriers) of RPT use from the patient perspective.

Methods

We conducted a single focus group with English-speaking adults aged 18 or older with biopsy-proven IgAN. We asked about how they would use an IgAN RPT, and how to improve its design and implementation. We analyzed the transcript using constant comparison to inductively derive themes, and complied with qualitative research reporting criteria.

Results

The 5 participants were Caucasian men who varied in age from 35 to 55. The glomerular filtration rate ranged from 29 to 71 mL/min/1.73m², and proteinuria ranged from 0.36 to 1.41 g/d. Participants identified both benefits and harms of the risk score. They said physicians should first ask patients for permission to use it. To make it more useful, participants offered suggestions to enhance RTP design: visual display, information on how to interpret the risk score, risk categories, health implications, modifiable risk factors, multiple scenarios, and comparison with similar patients. They offered additional suggestions to enhance RPT implementation: it should not replace patient-provider discussion, it should be accompanied by self-management education so that patients can take an active role in their health. Participants appreciated information from members of the multidisciplinary team in addition to physicians. Participants also said that physicians should monitor patient emotions or concerns on an ongoing basis.

Conclusions

Patients with IgAN identified numerous ways to enhance the design and use of an RPT. Others could use this information to design and implement RPTs for patients with other conditions, but should employ user-centred design to develop RPTs that address patient preferences.

Urinary cMet as a prognostic marker in immunoglobulin A nephropathy

The prediction of prognosis in patients with immunoglobulin A nephropathy (IgAN) is challenging. We investigated the correlation between urinary cMet (ucMet) levels and clinical parameters and examined the effects of cMet agonistic antibody (cMet Ab) in an in vitro IgAN model. Patients diagnosed with IgAN (n = 194) were divided into three groups representing undetectable (Group 1), below‐median (Group 2) and above‐median (Group 3) levels of ucMet/creatinine (ucMet/Cr). Stained kidney biopsy samples were graded according to cMet intensity. Primary‐cultured human mesangial cells were stimulated with recombinant tumour necrosis factor (TNF)‐α and treated with cMet Ab. Our results showed that ucMet/Cr levels positively correlated with proteinuria (P < .001). During the follow‐up, patients in Group 3 showed a significantly lower probability of complete remission (CR; uPCr < 300 mg/g) than those in groups 1 and 2, after adjusting for blood pressure, estimated glomerular filtration rate, and proteinuria, which influence clinical prognosis (HR 0.60, P = .038); moreover, ucMet/Cr levels were also associated with glomerular cMet expression. After TNF‐α treatment, the proliferation of mesangial cells and increased interleukin‐8 and intercellular adhesion molecule‐1 expression were markedly reduced by cMet Ab in vitro. In conclusion, ucMet/Cr levels significantly correlated with proteinuria, glomerular cMet expression, and the probability of CR. Further, cMet Ab treatment alleviated the inflammation and proliferation of mesangial cells. Hence, ucMet could serve as a clinically significant marker for treating IgAN.

Retrospective Analysis of Clinical Outcomes in Patients with Immunoglobulin A Nephropathy and Persistent Hematuria Following Renin-Angiotensin System Blockade

Background

Recent guidelines recommend that patients with immunoglobulin A nephropathy (IgAN) and proteinuria 0.5–1 g/d and >1 g/d be treated with long-term renin–angiotensin system blockade (RASB). This study investigated whether patients with IgAN and persistent hematuria, but without proteinuria, can benefit from RASB.

Material/Methods

IgAN patients with persistent hematuria at four centers were recruited from January 2013 to December 2018. Patients were divided into those who did and did not receive long-term RASB. The primary outcome was the appearance of proteinuria, and the secondary outcomes were the decreased percentage of hematuria, rate of decline in estimated glomerular filtration rate (eGFR) and final blood pressure. The effects of RASB on these outcomes were assessed by multivariate Cox regression models and propensity score matching.

Results

Of the 110 eligible patients, 44 (40.0%) received RASB and 66 (60.0%) did not. Treated patients had higher diastolic pressure. The unadjusted primary outcome, the appearance of proteinuria, was significantly less frequent in individuals who were than who were not treated with RASB. Multivariate Cox regression showed that RASB reduced the risk of the primary outcome and the levels of hematuria. The rate of eGFR decline and final blood pressure did not differ in the two groups.

Conclusions

RASB reduced the risk of proteinuria development and increased the remission of hematuria in patients with IgAN who presented with persistent hematuria alone. RASB, however, did not affect blood pressure in patients without hypertension and did not affect the rate of eGFR decline.

External Validation of the International IgA Nephropathy Prediction Tool

BACKGROUND AND OBJECTIVES

The International IgA Nephropathy Network recently developed and externally validated two models to predict the risk of progression of IgA nephropathy: full models without and with race. This study sought to externally validate the International IgA Nephropathy Prediction Tool in a large, independent, and contemporary cohort in China.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We included 1373 patients with biopsy-confirmed primary IgA nephropathy from The First Affiliated Hospital of Zhengzhou University from January 2012 to May 2018 and calculated predicted risks for each patient. The outcomes of interest were a 50% decline in eGFR or kidney failure. We assessed the performance of both models using discrimination (concordance statistics and Kaplan-Meier curves between subgroups), calibration (calibration plots), reclassification (net reclassification improvement and integrated discrimination improvement), and clinical utility (decision curve analysis).

RESULTS

The median follow-up was 29 months (interquartile range, 21-43 months; range, 1-95 months), and 186 (14%) patients reached the kidney outcomes of interest. Both models showed excellent discrimination (concordance statistics >0.85 and well separated survival curves). Overall, the full model without race generally underestimated the risk of primary outcome, whereas the full model with race was well calibrated for predicting 5-year risk. Compared with the full model without race, the full model with race had significant improvement in reclassification, as assessed by the net reclassification improvement (0.49; 95% confidence interval, 0.41 to 0.59) and integrated discrimination improvement (0.06; 95% confidence interval, 0.04 to 0.08). Decision curve analysis showed that both full models had a higher net benefit than default strategies, and the model with race performed better.

CONCLUSIONS

In this study, both full models demonstrated remarkable discrimination, acceptable calibration, and satisfactory clinical utility. The relatively short follow-up time may have limited the validation of these models.

Outcomes of normotensive IgA nephropathy patients with mild proteinuria who have impaired renal function

Purpose: Typically, IgA nephropathy is a slowly progressive type of glomerulonephritis. High-grade proteinuria and hypertension are predictors of reduced kidney function. However, we found some normotensive patients with mild proteinuria could exhibit impaired renal function at the time of IgAN diagnosis. We therefore conduct a study to highlight the occurrence of these cases and to define their clinical characteristics and outcomes.

Methods: The clinical, laboratory, pathological manifestations and outcomes of these IgAN patients were collected and were compared with normotensive IgA nephropathy patients with mild proteinuria and normal renal function. Patients were analyzed according to different pathological characteristics. Survival curves were constructed according to the Kaplan–Meier method.

Results: Of all normotensive IgA nephropathy patients with mild proteinuria, 108 (10.1%) patients had impaired renal function. Ischemic sclerosis (79 patients) and fibrous crescent (25 patients) were the main pathological characteristics. Macroscopic hematuria (1.3%), prodromal infection (13.9%) and high serum IgA (11.4%) were significantly lower prevalences, but only proteinuria (26.6%) was more common in ischemic sclerosis group patients. Only hematuria were not found in ischemic sclerosis group and crescent group patients. The median follow-up were about 5 years. Patients in crescent group had a poor outcome compared with patients in ischemic sclerosis group.

Conclusions: Some normotensive IgA nephropathy patients with mild proteinuria had impaired renal function at diagnosis. Ischemic sclerosis and fibrous crescent were the main pathological features in these patients. Patients in the crescent group had a worse outcome than patients in the ischemic sclerosis group.

Predictive value of mesangial C3 and C4d deposition in IgA nephropathy

We aimed to determine the relative contribution of each complement (C3 and C4d) deposition to the progression of IgA nephropathy (IgAN). We enrolled a total of 380 patients with biopsy-confirmed IgAN. Mesangial deposition of C3(<2+ vs. ≥2+) and C4d(positive vs. negative) was evaluated by immunofluorescence staining and immunohistochemistry, respectively. Study endpoint was the composite of a 30% decline in eGFR or ESRD. The risk of reaching the primary outcome was significantly higher in patients having C3 ≥ 2+ and C4d(+) than in corresponding counterparts. Adding C3 deposition to clinical data acquired at kidney biopsy modestly increased the area under the receiver-operating characteristic curve, net reclassification improvement, and integrated discrimination improvement (IDI); adding C4d increased IDI only. In conclusion, mesangial C3 and C4d deposition was an independent risk factor for progression of IgAN. C3 showed better predictability than C4d, suggesting that lectin pathway alone has limited clinical prognostic value.

The impact of tonsillectomy combined with steroid pulse therapy in patients with advanced IgA nephropathy and impaired renal function

BACKGROUND

Preventing progression to end-stage renal disease (ESRD) in advanced IgA nephropathy (IgAN) patients with impaired renal function remains challenging. We analyzed the efficacy of tonsillectomy combined with steroid pulse therapy (TSP).

METHODS

In this retrospective analysis, IgAN patients with proteinuria > 0.5 g/day and estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² were divided into three groups: patients treated with TSP (TSP group; n = 23), oral prednisolone (oPSL group; n = 41), and conservative therapy (CONS group, n = 51). We analyzed the clinical and histological backgrounds, remission of urinary findings, and renal survival rate to a 25% decline in eGFR from baseline, and incidence of ESRD.

RESULTS

There were significant differences in the patients' backgrounds among the groups. Therefore, we adjusted the background using propensity score marching between TSP group and oPSL or CONS group. The 5-year remission rate of hematuria was significantly higher in the TSP group than in the oPSL group, and that of both hematuria and proteinuria was significantly higher in the TSP group than in the CONS group. The 10-year renal survival rate was significantly higher in the TSP group than in the oPSL and CONS groups. In a multivariate Cox regression analysis, TSP was found to be an independent factor for the 25% decline in eGFR in entire cohort. The adverse effect frequency in the TSP group was similar to the CONS group.

CONCLUSIONS

TSP can effectively induce remission of urinary abnormality and improve the prognosis without frequent adverse effects in IgAN patients with impaired renal function.