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Rationale & Objective: Research on pediatric kidney replacement therapy (KRT) has primarily focused on Europe and North America. In this study, we describe the mortality risk of children treated with maintenance peritoneal dialysis (MPD) in different parts of the world and characterize the associated demographic and macroeconomic factors., Study Design: Prospective cohort study., Setting & Participants: Patients younger than 19 years at inclusion into the International Pediatric Peritoneal Dialysis Network registry, who initiated MPD between 1996 and 2017., Exposure: Region as primary exposure (Asia, Western Europe, Eastern Europe, Latin America, North America, and Oceania). Other demographic, clinical, and macroeconomic (4 income groups based on gross national income) factors also were studied., Outcome: All-cause MPD mortality., Analytical Approach: Patients were observed for 3 years, and the mortality rates in different regions and income groups were calculated. Cause-specific hazards models with random effects were fit to calculate the proportional change in variance for factors that could explain variation in mortality rates., Results: A total of 2,956 patients with a median age of 7.8 years at the start of KRT were included. After 3 years, the overall probability of death was 5%, ranging from 2% in North America to 9% in Eastern Europe. Mortality rates were higher in low-income countries than in high-income countries. Income category explained 50.1% of the variance in mortality risk between regions. Other explanatory factors included peritoneal dialysis modality at start (22.5%) and body mass index (11.1%)., Limitations: The interpretation of interregional survival differences as found in this study may be hampered by selection bias., Conclusions: This study shows that the overall 3-year patient survival on pediatric MPD is high, and that country income is associated with patient survival., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

IgA nephropathy (IgAN), major cause of kidney failure worldwide, is common in Asians, moderately prevalent in Europeans, and rare in Africans. It is not known if these differences represent variation in genes, environment, or ascertainment. In a recent GWAS, we localized five IgAN susceptibility loci on Chr.6p21 (HLA-DQB1/DRB1, PSMB9/TAP1, and DPA1/DPB2 loci), Chr.1q32 (CFHR3/R1 locus), and Chr.22q12 (HORMAD2 locus). These IgAN loci are associated with risk of other immune-mediated disorders such as type I diabetes, multiple sclerosis, or inflammatory bowel disease. We tested association of these loci in eight new independent cohorts of Asian, European, and African-American ancestry (N = 4,789), followed by meta-analysis with risk-score modeling in 12 cohorts (N = 10,755) and geospatial analysis in 85 world populations. Four susceptibility loci robustly replicated and all five loci were genome-wide significant in the combined cohort (P = 5×10⁻³²-3×10⁻¹⁰), with heterogeneity detected only at the PSMB9/TAP1 locus (I² = 0.60). Conditional analyses identified two new independent risk alleles within the HLA-DQB1/DRB1 locus, defining multiple risk and protective haplotypes within this interval. We also detected a significant genetic interaction, whereby the odds ratio for the HORMAD2 protective allele was reversed in homozygotes for a CFHR3/R1 deletion (P = 2.5×10⁻⁴). A seven-SNP genetic risk score, which explained 4.7% of overall IgAN risk, increased sharply with Eastward and Northward distance from Africa (r = 0.30, P = 3×10⁻¹²⁸). This model paralleled the known East-West gradient in disease risk. Moreover, the prediction of a South-North axis was confirmed by registry data showing that the prevalence of IgAN-attributable kidney failure is increased in Northern Europe, similar to multiple sclerosis and type I diabetes. Variation at IgAN susceptibility loci correlates with differences in disease prevalence among world populations. These findings inform genetic, biological, and epidemiological investigations of IgAN and permit cross-comparison with other complex traits that share genetic risk loci and geographic patterns with IgAN., Competing Interests: The authors have declared that no competing interests exist.

Aims: To determine if rates of diabetic and non-diabetic end-stage renal disease (ESRD), which had been rising in young and middle-aged adults in all populations up to the mid-1990s, had started to decline, and if so, whether improvement had occurred in respect of each of the principal primary renal diseases causing ESRD., Methods: Poisson regression of age- and sex-standardized incidence of ESRD for persons aged 20-64 years in 18 populations from Europe, Canada and the Asia-Pacific region, for 1998-2002., Results: In persons from 12 European descent (Europid) populations combined, there was a small downward trend in all-cause ESRD (-1.7% per year, P = 0.001), with type 1 diabetic ESRD falling by 7.8% per year (P < 0.001), glomerulonephritic ESRD by 3.1% per year (P = 0.001), and 'all other non-diabetic' ESRD by 2.5% per year (P = 0.02). The reductions in ESRD attributed to hypertensive (-2.2% per year) and polycystic renal disease (-1.5% per year) and unknown diagnosis (-0.2% per year) were not statistically significant. On the other hand, the incidence of type 2 diabetic ESRD rose by 9.9% per year (P < 0.001) in the combined Europid population, although that of (principally type 2) diabetic ESRD remained unchanged in the pooled data from the four non-Europid populations., Conclusion: Recent preventive strategies, probably chiefly modern renoprotective treatment, appear to have been effective for tertiary prevention of ESRD caused by the proteinuric nephropathies other than type 2 diabetic nephropathy, for which the continuing increase in Europid populations represents a failure of prevention and/or a change in the nephropathic potential of type 2 diabetes.