Project description:Purpose of the reviewImmunoglobulin A (IgA) nephropathy (IgAN) is the most common primary glomerular kidney disease. Children and adults are presumed to have the same disease and are treated similarly. However, there are differences between childhood IgAN and adult IgAN that may require unique treatment considerations, even after transition to adult nephrology services. A narrative review was conducted to compare childhood and adult IgAN and to describe the distinct characteristics of childhood IgAN. Reframing childhood IgAN can inform guideline recommendations unique to childhood IgAN, the development of targeted therapies, and clinical trial design.Sources of informationMedline and Embase were searched for reports on children and adults with IgAN published between January 2013 and December 2023 (updated May 2024). The search was not restricted by age group, outcomes reported, language, or study design. Randomized controlled trials (RCTs), observational studies, review articles, and nephrology conference abstracts were included. A total of 3104 reports were retrieved. Forty-seven reports (37 primary studies and 10 reviews) were included in the review. Two RCTs and 35 observational studies included a total of 45 085 participants (9223 children and 35 862 adults).MethodData were extracted for primary IgAN and not for IgA vasculitis-associated nephritis. Findings were described with no statistical comparisons due to variations in interventions and outcome definitions.Key findingsGross hematuria was the obvious clinical difference between childhood IgAN and adult (60-88% vs 15-20%). Nephrotic syndrome was more common in children, approaching up to 44%, while <18% of adults had nephrotic syndrome. Children were biopsied sooner (6 vs 15 months) and had more inflammatory kidney lesions (mesangial hypercellularity: 41-82% vs 38-64%; endocapillary hypercellularity: 39-58% vs 17-34%). Chronic kidney lesions were more prevalent in adults (segmental sclerosis: 62-77% vs 8-51%; interstitial fibrosis/tubular atrophy: 34-37% vs 1-18%). The use of immunosuppressive therapy was higher in children (46-84% vs 35-56%). Children were started on immunosuppressive therapy sooner than adults. Adults were more likely to be optimized with renin-angiotensin system inhibitors (87-94% vs 49-75%). Children had better kidney function than adults at diagnosis (estimated glomerular filtration rate of 90-128 vs 50-88 ml/min/1.73 m2), and children also had better kidney survival, with kidney failure of 3.1% vs 13.4% at 5 years. Children had more risk alleles for IgAN and higher levels of mannose-binding lectin than adults.LimitationsMost studies were retrospective and observational, with limited data on children and disease mechanisms. Data were not pooled for analysis because of important differences in definitions and measurements of baseline characteristics and outcomes. Data from countries with established urine screening programs were different compared to countries without urine screening programs. Some observed differences may be due to practice variation and delayed diagnosis in adults (lead-time bias). Well-designed prospective studies and standardized measures for kidney function assessment and outcomes can reduce heterogeneity and improve results from reviews.ConclusionInherent differences between childhood IgAN and adult IgAN may be due to distinct disease mechanisms. Approaching childhood IgAN as a separate condition could lead to the discovery of targeted therapies and improve management during childhood and after the transition to adult care.

Project description:Background and objectivesPoly-IgA immune complex formation and glomerular deposition play a key role in IgA nephropathy. Our study sought to develop a new methodology for one-step serologic detection of poly-IgA levels.Design, setting, participants, & measurementsA novel ELISA method using recombinant CD89 as a "capturing" probe was established for detecting poly-IgA immune complex in plasma. We applied semiquantitative measurements of these poly-IgA indices in patients recruited at Peking University First Hospital who had IgA nephropathy or other kidney disease types, as compared with healthy controls. The longitudinal trend of the poly-IgA index and the association with pathologic parameters and treatment responses were evaluated. Finally, we analyzed the molecular composition of poly-IgA complexes in patients by mass spectrometry.ResultsRecombinant CD89-mounted ELISA plates specifically captured plasma poly-IgA. The levels of poly-IgA immune complex (26.7 [interquartile range (IQR) 17.1-42.6] U/ml) in IgA nephropathy were significantly higher than those in healthy controls (15.5 [IQR 10.7-20.0] U/ml; P<0.001) or in controls with non-IgA nephropathy disease (14.8 [IQR 10.5-21.9] U/ml; P<0.001). Higher levels of poly-IgA immune complex were associated with lower eGFR and worse kidney outcome. Accuracy parameters and concordant statistics showed good discrimination between IgA nephropathy and healthy controls based on poly-IgA index levels (area under the curve [AUC], 0.78; 95% confidence interval [95% CI], 0.72 to 0.83; P<0.001), significantly outperforming galactose-deficient IgA1 levels (AUC, 0.70; P=0.05). Corticosteroid and immunosuppressant treatments lowered poly-IgA indices. After a recombinant CD89-directed workflow in conjunction with mass spectrometry, we also analyzed the molecular composition of IgA immune complex in patients with IgA nephropathy.ConclusionsHigher level of recombinant CD89-bound poly-IgA immune complex was associated with the severity of the disease and with treatment response to steroids and immunosuppressants.

Project description:BackgroundImmunoglobulin 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.MethodsWe 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 (βPI), respectively.ResultsThe 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.ConclusionsThe 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.

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How I Treat IgA Nephropathy.

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How I Treat IgA Nephropathy.

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