Risk factors for persistent proteinuria after a 2-year combination therapy for severe childhood IgA nephropathy

Immunosuppressive therapy for IgA nephropathy in children

BACKGROUND

IgA nephropathy (IgAN) is the most common cause of primary glomerulonephritis. It is a heterogeneous disease with different presentations and high morbidity. Thirty per cent of adults and 20% of children (followed into adulthood) will have a 50% decline in kidney function or develop kidney failure after 10 years.

OBJECTIVES

To determine the benefits and harms of immunosuppressive therapy for the treatment of IgAN in children.

SEARCH METHODS

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 03 October 2023 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) investigating the treatment of IgAN in children with immunosuppressive therapies compared to placebo, no treatment, supportive care, standard therapy (Japanese protocol), other immunosuppressive therapies or non-immunosuppressive therapies.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed the risk of bias. Random effects meta-analyses were used to summarise estimates of treatment effects. Treatment effects were expressed as risk ratios (RR) and 95% confidence intervals (CI) for dichotomous outcomes, and the mean difference (MD) and 95% CI for continuous outcomes. The risk of bias was assessed using the Cochrane risk of bias tool for RCTs and the ROBIN-I tool for NRSIs. The certainty of the evidence was assessed using Grading of Recommendations, Assessment, Development, and Evaluations (GRADE).

MAIN RESULTS

This review included 13 studies with 686 participants. Ten RCTs included 334 children and 191 adults, and three NRSIs included 151 participants, all children. Most participants had mild kidney disease. The risk of bias was unclear for most of the domains relating to allocation concealment, blinding of participants, personnel, and outcome assessment. In children with IgAN, it is uncertain if corticosteroid (steroid) therapy, compared to placebo reduces proteinuria (1 study, 64 children and young adults: RR 0.47, 95% CI 0.13 to 1.72; low certainty evidence) or the decline in estimated glomerular filtration rate (eGFR) (1 study, 64 children and young adults: RR 0.47, 95% CI 0.09 to 2.39; low certainty evidence). It is uncertain if steroids reduce proteinuria compared to supportive care (2 studies, 61 children: RR 0.04, 95% CI -0.83 to 0.72; low certainty evidence). Adverse events associated with steroid therapy were not assessed due to heterogeneity in steroid protocols, including dose and duration, and lack of systematic assessment for adverse events in the included studies. Azathioprine, mycophenolate mofetil, mizoribine, or cyclophosphamide alone or in combination with steroid therapy had uncertain effects on improving proteinuria or preventing eGFR decline in children with IgAN. Fish oil, vitamin E and tonsillectomy had uncertain effects on improving proteinuria or preventing eGFR decline. Effects of other immunosuppressive therapies, secondary outcomes and adverse events were not assessed due to insufficient data.

AUTHORS' CONCLUSIONS

There is a lack of high-quality evidence to guide the management of IgAN in children. There is no evidence to indicate that steroids, other immunosuppressive therapies, or tonsillectomy, when added to optimal supportive care, prevent a decline in eGFR or proteinuria in children with IgAN. Available studies were few, with small numbers, low-quality evidence, high or uncertain risk of bias, did not systematically assess harms associated with treatment, or report net benefits or harms. Severe cases and atypical presentations of IgAN were not included in the reviewed studies, and our findings cannot be generalised to these situations.

Efficacy of combination therapy for childhood complicated focal IgA nephropathy

BACKGROUND

Patients with immunoglobulin A nephropathy who present with focal mesangial proliferation (focal IgAN) can have a relatively good prognosis, and renin-angiotensin system inhibitor (RAS-i) is commonly used as the initial treatment. However, there are some complicated focal IgAN cases with resistance to RAS-i treatment or nephrotic-range proteinuria. Thus, combination therapy including corticosteroids is often used. This study aimed to evaluate the efficacy of combination therapy for complicated focal IgAN cases by comparing to diffuse mesangial proliferation (diffuse IgAN).

METHODS

We conducted a multicenter retrospective study on 88 children who received 2-year combination therapy. The participants were classified based on pathological severity: focal IgAN (n = 26) and diffuse IgAN (n = 62).

RESULTS

In total, 26 patients with focal IgAN and 52 with diffuse IgAN achieved proteinuria disappearance within 2 years (100 vs. 83.9%, P = 0.03). Moreover, the time to proteinuria disappearance was significantly shorter in the focal IgAN group than in the diffuse IgAN group (2.9 vs. 4.2 months, P < 0.01) and all patients with focal IgAN achieved proteinuria disappearance within 8 months. At the last observation (8.6 vs. 10.4 years, P = 0.13), only patients with diffuse IgAN (n = 12) had greater than stage 2 chronic kidney disease. In terms of irreversible adverse events, one patient exhibited cataracts.

CONCLUSION

Combination therapy was significantly effective in patients with complicated focal IgAN. Moreover, the long-term prognosis was good, and the duration of combination therapy for complicated focal IgAN can be decreased to reduce adverse events.

Coagulation potential in pediatric patients with immunoglobulin A nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most prevalent primary chronic glomerular disease in children. Understanding the changes in coagulability caused by IgAN is important for clarifying pathophysiology and choice of treatment. The coagulation potential in patients with IgAN remains to be investigated, however. We aimed to assess comprehensive coagulation potential in pediatric patients with IgAN and explore its relationship with pathological disease severity.

METHODS

Fourteen children with IgAN diagnosed by renal biopsy, who were admitted at Nara Medical University Hospital between 2015 and 2020, were analyzed. Rotational thromboelastometry was used to evaluate coagulation potential. Values of rotational thromboelastometry parameters in patients with IgAN were compared with those in control children.

RESULTS

In patients with IgAN (aged median 9.5 year), clotting time plus clot formation time (CT + CFT) was shortened (P = 0.003) and α angle was greater (P < 0.001) than those in controls, indicating a hypercoagulable state. The rate of mesangial hypercellularity of glomeruli correlated with CT + CFT, α, and maximum clot firmness (MCF) (r_s = -0.79, 0.56, and 0.37). The rate of cellular/fibrocellular crescent of glomeruli correlated with CT + CFT, α, and MCF (r_s = -0.41, 0.60, and 0.50). Patients with mesangial hypercellularity ≥80% of glomeruli showed reduced CT + CFT and increased α angle (P = 0.007 and 0.03). Patients with cellular/fibrocellular crescent ≥10% of glomeruli showed decreased CT + CFT and increased α angle (both P = 0.02).

CONCLUSIONS

The hypercoagulable state in pediatric patients with IgAN may be associated with the pathological severity of their disease.

Association of Treatment Effects on Early Change in Urine Protein and Treatment Effects on GFR Slope in IgA Nephropathy: An Individual Participant Meta-analysis

RATIONALE & OBJECTIVE

An early change in proteinuria is considered a reasonably likely surrogate end point in immunoglobulin A nephropathy (IgAN) and can be used as a basis for accelerated approval of therapies, with verification in a postmarketing confirmatory trial. Glomerular filtration rate (GFR) slope is a recently validated surrogate end point for chronic kidney disease progression and may be considered as the end point used for verification. We undertook a meta-analysis of clinical trials in IgAN to compare treatment effects on change in proteinuria versus change in estimated GFR (eGFR) slope.

STUDY DESIGN

Individual patient-level meta-analysis.

SETTING & STUDY POPULATIONS

Individual data of 1,037 patients from 12 randomized trials.

SELECTION CRITERIA FOR STUDIES

Randomized trials of IgAN with proteinuria measurements at baseline and 6 (range, 2.5-14) months and at least a further 1 year of follow-up for the clinical outcome.

ANALYTICAL APPROACH

For each trial, we estimated the treatment effects on proteinuria and on the eGFR slope, computed as the total slope starting at baseline or the chronic slope starting 3 months after randomization. We used a Bayesian mixed-effects analysis to relate the treatment effects on proteinuria to effects on GFR slope across these studies and developed a prediction model for the treatment effect on the GFR slope based on the effect on proteinuria.

RESULTS

Across all studies, treatment effects on proteinuria accurately predicted treatment effects on the total slope at 3 years (median R2 = 0.88; 95% Bayesian credible interval [BCI], 0.06-1) and on the chronic slope (R2 = 0.98; 95% BCI, 0.29-1). For future trials, an observed treatment effect of approximately 30% reduction in proteinuria would confer probabilities of at least 90% for nonzero treatment benefits on the total and chronic slopes of eGFR. We obtained similar results for proteinuria at 9 and 12 months and total slope at 2 years.

LIMITATIONS

Study population restricted to 12 trials of small sample size, leading to wide BCIs. There was heterogeneity among trials with respect to study design and interventions.

CONCLUSIONS

These results provide new evidence supporting that early reduction in proteinuria can be used as a surrogate end point for studies of chronic kidney disease progression in IgAN.

Early Change in Urine Protein as a Surrogate End Point in Studies of IgA Nephropathy: An Individual-Patient Meta-analysis

BACKGROUND

The role of change in proteinuria as a surrogate end point for randomized trials in immunoglobulin A nephropathy (IgAN) has previously not been thoroughly evaluated.

STUDY DESIGN

Individual patient-level meta-analysis.

SETTING & POPULATION

Individual-patient data for 830 patients from 11 randomized trials evaluating 4 intervention types (renin-angiotensin system [RAS] blockade, fish oil, immunosuppression, and steroids) examining associations between changes in urine protein and clinical end points at the individual and trial levels.

SELECTION CRITERIA FOR STUDIES

Randomized controlled trials of IgAN with measurements of proteinuria at baseline and a median of 9 (range, 5-12) months follow-up, with at least 1 further year of follow-up for the clinical outcome.

PREDICTOR

9-month change in proteinuria.

OUTCOME

Doubling of serum creatinine level, end-stage renal disease, or death.

RESULTS

Early decline in proteinuria at 9 months was associated with lower risk for the clinical outcome (HR per 50% reduction in proteinuria, 0.40; 95% CI, 0.32-0.48) and was consistent across studies. Proportions of treatment effect on the clinical outcome explained by early decline in proteinuria were estimated at 11% (95% CI, -19% to 41%) for RAS blockade and 29% (95% CI, 6% to 53%) for steroid therapy. The direction of the pooled treatment effect on early change in proteinuria was in accord with the direction of the treatment effect on the clinical outcome for steroids and RAS blockade. Trial-level analyses estimated that the slope for the regression line for the association of treatment effects on the clinical end points and for the treatment effect on proteinuria was 2.15 (95% Bayesian credible interval, 0.10-4.32).

LIMITATIONS

Study population restricted to 11 trials, all having fewer than 200 patients each with a limited number of clinical events.

CONCLUSIONS

Results of this analysis offer novel evidence supporting the use of an early reduction in proteinuria as a surrogate end point for clinical end points in IgAN in selected settings.

Proteinuria rebound in IgA nephropathy associated with obesity-related glomerulopathy

IgA nephropathy (IgAN), the most prevalent primary chronic glomerulonephritis worldwide, has three major risk factors: hypertension, proteinuria >1 g/day, and severe renal lesions. Obesity also portends a poor prognosis. A Japanese boy with IgAN showed nephrotic syndrome at presentation. Pathological features resembled those of membranoproliferative glomerulonephritis (MPGN), although IgA deposition differed from MPGN and IgAN. Combination therapy improved renal lesions, but rebound deterioration of proteinuria occurred in this patient, who had marked obesity and hypertension. Serial kidney biopsy specimens were compatible with obesity-related glomerulopathy (ORG). Rebound proteinuria was apparently attributable to ORG rather than relapse and flaring up of IgAN.