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.