Renal biopsy findings among Indigenous Australians: a nationwide review

Disease profiles in the Indigenous Australian population are suggestive of a common complement control haplotype

Aboriginal and Torres Strait Islander People (respectfully referred to as Indigenous Australians herein) are disparately burdened by many infectious and chronic diseases relative to Australians with European genetic ancestry. Some of these diseases are described in other populations to be influenced by the inherited profile of complement genes. These include complement factor B, H, I and complement factor H-related (CFHR) genes that can contribute to a polygenic complotype. Here the focus is on the combined deletion of CFHR1 and 3 to form a common haplotype (CFHR3-1Δ). The prevalence of CFHR3-1Δ is high in people with Nigerian and African American genetic ancestry and correlates to a higher frequency and severity of systemic lupus erythematosus (SLE) but a lower prevalence of age-related macular degeneration (AMD) and IgA-nephropathy (IgAN). This pattern of disease is similarly observed among Indigenous Australian communities. Additionally, the CFHR3-1Δ complotype is also associated with increased susceptibility to infection with pathogens, such as Neisseria meningitidis and Streptococcus pyogenes, which also have high incidences in Indigenous Australian communities. The prevalence of these diseases, while likely influenced by social, political, environmental and biological factors, including variants in other components of the complement system, may also be suggestive of the CFHR3-1Δ haplotype in Indigenous Australians. These data highlight a need to define the Indigenous Australian complotypes, which may lead to the discovery of new risk factors for common diseases and progress towards precision medicines for treating complement-associated diseases in Indigenous and non-Indigenous populations. Herein, the disease profiles suggestive of a common complement CFHR3-1Δ control haplotype are examined.

IgA Nephropathy: Pleiotropic impact of Epstein-Barr virus infection on immunopathogenesis and racial incidence of the disease

IgA nephropathy (IgAN) is an autoimmune disease in which poorly galactosylated IgA1 is the antigen recognized by naturally occurring anti-glycan antibodies, leading to formation of nephritogenic circulating immune complexes. Incidence of IgAN displays geographical and racial disparity: common in Europe, North America, Australia, and east Asia, uncommon in African Americans, many Asian and South American countries, Australian Aborigines, and rare in central Africa. In analyses of sera and cells from White IgAN patients, healthy controls, and African Americans, IgAN patients exhibited substantial enrichment for IgA-expressing B cells infected with Epstein-Barr virus (EBV), leading to enhanced production of poorly galactosylated IgA1. Disparities in incidence of IgAN may reflect a previously disregarded difference in the maturation of the IgA system as related to the timing of EBV infection. Compared with populations with higher incidences of IgAN, African Americans, African Blacks, and Australian Aborigines are more frequently infected with EBV during the first 1-2 years of life at the time of naturally occurring IgA deficiency when IgA cells are less numerous than in late childhood or adolescence. Therefore, in very young children EBV enters "non-IgA" cells. Ensuing immune responses prevent infection of IgA B cells during later exposure to EBV at older ages. Our data implicate EBV-infected cells as the source of poorly galactosylated IgA1 in circulating immune complexes and glomerular deposits in patients with IgAN. Thus, temporal differences in EBV primo-infection as related to naturally delayed maturation of the IgA system may contribute to geographic and racial variations in incidence of IgAN.

Variations in clinical presentation and biomarkers amongst biopsy-proven Lupus Nephritis patients: a Top-End retrospective cohort study

BACKGROUND

Lupus nephritis (LN) is common feature of Systemic Lupus Erythematosus (SLE) and affects 50% of patients with SLE. Racial differences in incidence and prevalence have been well documented worldwide. In Australia, higher incidence and prevalence of SLE had been previously reported in Aboriginal and Torres Strait Australians compared to non-Indigenous Australians.

AIM

to describe the differences in clinical features and lupus biomarkers between Aboriginal and Torres Strait Islander Australian and non-Indigenous Australian LN patients.

METHODS

We retrospectively identified all consecutive biopsy-proven LN patients in our institution and compared the clinical features and lupus biomarkers between Aboriginal and Torres Strait Islander Australians and non-indigenous Australians.

RESULTS

Of the thirty-three consecutive biopsy proven LN patients, twenty-six self-identified as of Aboriginal and Torres Strait Islander descent. The estimated incidence of lupus nephritis in Aboriginal and Torres Strait Islander Australian and non-Indigenous Australians were 5.08 and 0.47 per 100,000 patient years respectively. Neurological manifestations (23.08% vs 0%), haematological manifestations (46.50 % vs 16.67) and right heart catheter proven pulmonary arterial hypertension (23.08% vs 0%) were more frequently observed amongst Indigenous Australian patients compared to non-Indigenous Australian patients. The incidence of positive Extractable Nuclear Antigen (ENA) was also higher among Indigenous Australian patients (84.62% vs 57.14%).

CONCLUSION

Our study further supports the observation that lupus in Aboriginal and Torres Strait Islander Australians were of a 'distinct phenotype' compared to non-Indigenous Australians. Future research should be aimed at delineating the reason for this observed difference. This article is protected by copyright. All rights reserved.

Assessment of nephron number and single-nephron glomerular filtration rate in a clinical setting

Total nephron counts vary widely between individuals and may affect susceptibility to certain diseases, including hypertension and chronic kidney disease. Detailed analyses of whole kidneys collected from autopsy patients remain the only method for accurately counting nephrons in humans, with no equivalent option in living subjects. Current technological advances have enabled estimations of nephron numbers in vivo, particularly the use of total nephron number and whole-kidney glomerular filtration rate to estimate the mean single-nephron glomerular filtration rate. The use of this method would allow physicians to detect dynamic changes in filtration function at the single-nephron level rather than to simply count the number of nephrons that appear to be functioning. Currently available methods for estimating total nephron number in clinical practice have the potential to overcome limitations associated with autopsy analyses and may therefore pave the way for new therapeutic interventions and improved clinical outcomes.

Maternal Diet Influences Fetal Growth but Not Fetal Kidney Volume in an Australian Indigenous Pregnancy Cohort

Suboptimal nutrition during pregnancy is recognised as a significant modifiable determinant in the development of chronic disease in offspring in later life. The current study aimed: (i) to assess the dietary intakes of pregnant Indigenous Australian women against national recommendations and (ii) to investigate the associations between maternal nutrition during pregnancy and the growth of the offspring, including kidney development in late gestation in the Gomeroi gaaynggal cohort (n = 103). Maternal dietary intake in the third trimester was assessed using the Australian Eating Survey Food Frequency Questionnaire. Estimated fetal weight (EFW) and kidney size were obtained by ultrasound. Birth weight was retrieved from hospital birth records. Of the five key nutrients for optimal reproductive health (folate, iron, calcium, zinc and fibre), the nutrients with the highest percentage of pregnant women achieving the nutrient reference values (NRVs) were zinc (75.7%) and folate (57.3%), whereas iron was the lowest. Only four people achieved all NRVs (folate, iron, calcium, zinc and fibre) important in pregnancy. Sodium and saturated fat intake exceeded recommended levels and diet quality was low, with a median score of 28 out of 73 points. After adjusting for smoking and pre-pregnancy body mass index, only maternal intake of retinol equivalents and the proportion of energy from nutrient-dense or energy-dense, nutrient-poor (EDNP) foods were associated with fetal growth. EFW decreased by 0.13 g and birth weight decreased by 0.24 g for every µg increase in maternal dietary retinol intake. Interestingly, EFW, but not actual birth weight, was positively associated with percentage energy from nutrient dense foods and negatively associated with percentage energy from EDNP foods. Dietary supplement usage was associated with increased birthweight, most significantly iron and folate supplementation. Current dietary intakes of pregnant Australian women from this cohort do not align with national guidelines. Furthermore, current findings show that maternal retinol intake and diet composition during pregnancy can influence fetal growth, but not fetal kidney growth in late gestation. Strategies that aim to support and optimise nutrient intakes of Indigenous pregnant women are urgently needed. Future studies with long-term follow-up of the children in the current cohort to assess renal damage and blood pressure are imperative.

Evolutionary genetics and acclimatization in nephrology

Evolutionary processes, including mutation, migration and natural selection, have influenced the prevalence and distribution of various disorders in humans. However, despite a few well-known examples, such as the APOL1 variants - which have undergone positive genetic selection for their ability to confer resistance to Trypanosoma brucei infection but confer a higher risk of chronic kidney disease - little is known about the effects of evolutionary processes that have shaped genetic variation on kidney disease. An understanding of basic concepts in evolutionary genetics provides an opportunity to consider how findings from ancient and archaic genomes could inform our knowledge of evolution and provide insights into how population migration and genetic admixture have shaped the current distribution and landscape of human kidney-associated diseases. Differences in exposures to infectious agents, environmental toxins, dietary components and climate also have the potential to influence the evolutionary genetics of kidneys. Of note, selective pressure on loci associated with kidney disease is often from non-kidney diseases, and thus it is important to understand how the link between genome-wide selected loci and kidney disease occurs in relation to secondary nephropathies.

Intrauterine growth restriction, preterm birth and risk of end-stage renal disease during the first 50 years of life

Background

Low birth weight (LBW) is associated with a higher risk of end-stage renal disease (ESRD). The relative impacts of absolute birth weight, birth weight in relation to gestational age and preterm birth are, however, uncertain.

Methods

The Medical Birth Registry of Norway has since 1967 recorded data on all births. All patients with ESRD since 1980 have been registered in the Norwegian Renal Registry. Data from these registries were linked. All individuals registered in the Medical Birth Registry were included and the development of ESRD was used as endpoint in Cox regression statistics. LBW and LBW for gestational age [small for gestational age (SGA)] according to the 10th percentiles were used as the main predictor variables.

Results

Of the 2 679 967 included subjects, 1181 developed ESRD. Compared with subjects without LBW, subjects with LBW had an adjusted hazard ratio (aHR) for ESRD of 1.61 (1.38–1.98). SGA had an aHR of 1.44 (1.22– 1.70). Further analyses showed that as compared with subjects who had none of the risk factors LBW, SGA and preterm birth, subjects with one risk factor had an aHR of 1.05 (0.84–1.31), subjects with two risk factors had an aHR of 1.67 (1.40–1.98) and subjects with three risk factors had an aHR of 2.96 (1.84–4.76).

Conclusions

We conclude that LBW was associated with increased risk for ESRD during the first 50 years. Our analyses add to previous knowledge showing that only subjects with at least two of the risk factors LBW, SGA or preterm birth have increased risk.

Birth Weight and Susceptibility to Chronic Kidney Disease

The worldwide prevalence of noncommunicable diseases (NCDs) is projected to increase substantially over the next few decades. Chronic kidney disease (CKD) is a key determinant of poor health outcomes for major NCD. Genetic predisposition and environmental exposures are contributory factors, but increasingly, it is being recognized that fetal development is also an important modulator of the NCD risk. Low birth weight (LBW) and CKD affect more disadvantaged populations and ethnic minorities and, therefore, causes a disproportionate burden on the poor. Human nephron number is highly variable and may range from under half a million to almost over two million. Significant variability is already present at birth, highlighting the importance of early nephrogenesis. Nearly 60% of nephrons are developed in the third-trimester of pregnancy. Nephron numbers increase in proportion to birth weight and gestational age. This wide-variability probably contributes to individual susceptibility to develop CKD where individuals with nephron numbers on the lower side of the spectrum are those at higher risk of developing kidney dysfunction at higher rate and progress more toward end-stage CKD. This article aims at discussing LBW and the susceptibility to CKD. Furthermore, in postnatal environment, the weight gain or change at adult life increases the metabolic demand and determines the phenotypic expression of disease along with the spectrum of nephron number. Hence, a cycle of hyperfiltration mechanism of these nephrons leads to proteinuria, glomerulo- sclerosis, and progressive development of larger glomeruli, a greater risk of proteinuria and progressive CKD. Therefore, LBW offspring are at risk of developing CKD (defined as albuminuria, a reduced glomerular filtration rate, or renal failure) in later life. Furthermore, the impact of prenatal programming is expected to be compounded with age, and the association of LBW with the risk of CKD seen in younger adults may become greater with age. It would be prudent, to adopt policies of intensified life-long surveillance of LBW people, anticipating this risk.

Progressive Nephron Loss in Aging Kidneys: Clinical–Structural Associations Investigated by Two Anatomical Methods

Two major studies of structural changes associated with aging in human kidneys are reviewed and new information presented. The studies are the Monash University stereologically analyzed series of 319 autopsy kidneys from the United States in which 44% were white and the Mayo Clinic CT angiogram/biopsy analysis of 1,388 US kidney donors in which 97% were white. Hypertension rates in the Monash series were 48% and included moderate and severe hypertension. In the Mayo Clinic study, 12% had mild hypertension. The studies showed no relationship between glomerular number and hypertension except for a weak relationship with older white women in the Monash series. An inverse relationship was present between glomerular number and glomerular volume, a reciprocity that tended to enhance glomerular mass and by inference filtration capacity with lower nephron numbers. This relationship seemed to be present whether low nephron numbers were intrinsic or acquired. In the Mayo Clinic studies, pretransplant iothalamate clearances demonstrated that single nephron (SN) glomerular filtration rates (GFR) were similar throughout the range of glomerular number in subjects younger than 70 years, but that increased SNGFR correlated with nephron hypertrophy and increased nephrosclerosis particularly at 70 years of age and over. Hypertension at least through middle age cannot be related to a deficiency of glomeruli, but glomeruli are lost with later aging in association with adaptive nephron hypertrophy that can maintain GFR near normal. These studies help define an age‐related nephropathy that overlaps with hypertension as a potential cause of end‐stage renal disease when glomerulosclerosis is advanced.

The relationship between maternal adiposity during pregnancy and fetal kidney development and kidney function in infants: the Gomeroi gaaynggal study

Maternal obesity during pregnancy has a detrimental impact on offspring renal development and function. This is pertinent to Indigenous Australians as they are twice as likely as non-Indigenous Australians to develop chronic kidney disease (CKD). The aim of this study was to examine whether there was an association between maternal adiposity and fetal kidney growth in late gestation (>28 weeks) and kidney function in infants, <2.5 years of age, from the Gomeroi gaaynggal cohort. Pre-pregnancy body mass index (BMI) was recorded at the first prenatal visit and maternal adiposity indicators (percent body fat and visceral fat area) measured at >28 weeks gestation by bioelectrical impedance analysis. Fetal kidney structure was assessed by ultrasound. Renal function indicators (urinary albumin:creatinine and protein:creatinine) were measured in infants from a spot urine collection from nappies. Multiple linear regression and multi-level mixed effects linear regression models with clustering were used to account for repeated measures of urine. 147 mother-child pairs were examined. Estimated fetal weight (EFW), but not fetal kidney size, was positively associated with maternal adiposity and pre-pregnancy BMI. When adjusted for smoking, combined kidney volume relative to EFW was negatively associated with maternal percentage body fat. Infant kidney function was not influenced by maternal adiposity and pre-pregnancy BMI (n = 84 observations). Current findings show that Indigenous babies born to obese mothers have reduced kidney size relative to EFW. We suggest that these babies are experiencing a degree of glomerular hyperfiltration in utero, and therefore are at risk of developing CKD in later life, especially if their propensity for obesity is maintained. Although no impact on renal function was observed at <2.5 years of age, long-term follow-up of offspring is required to evaluate potential later life impacts.

Epidemiology of IgA Nephropathy: A Global Perspective

IgA nephropathy (IgAN), or Berger's disease, is the most common primary glomerular disease worldwide, but varies largely in its geographic distribution. A systematic review of 1,619 publications from the five continental regions of the world was performed to assess the prevalence of IgAN in different worldwide regions and analyze factors responsible for geographic differences. All observational studies that described the prevalence and incidence data on glomerulonephritis were considered. IgAN is more frequent in Asian populations (45 cases per million population/y in Japan) than in Caucasians (31 cases per million population/y in France). These differences are owing to some relevant aspects: (1) systematic mass screening of urine in populations, as occurring in some Asian countries (Hong Kong, Japan, Korea, and Singapore), is not common in Western countries; (2) general practitioners and health care professionals in Western countries underestimate persistent microscopic hematuria and/or mild proteinuria in apparently healthy individuals causing late referral to a nephrologist; and (3) nephrologists adopt different indications for kidney biopsy in individuals with persistent urinary abnormalities. In addition, differences also are owing to the source of data, because the frequency of IgAN observed in a nephrology center with a high incidence of kidney biopsies is higher than in a regional renal biopsy registry that receives data from many centers. In conclusion, greater efforts should be made to diagnose IgAN earlier in individuals who manifest persistent microhematuria and/or mild proteinuria and to introduce less stringent indications for kidney biopsies. This preventive approach, followed by early therapy, may reduce the global burden of end-stage kidney disease caused by IgAN.

Contribution of cardiometabolic risk factors to estimated glomerular filtration rate decline in Indigenous Australians with and without albuminuria - the eGFR Follow-up Study

AIM

We assessed associations between cardiometabolic risk factors and estimated glomerular filtration rate (eGFR) decline according to baseline albuminuria to identify potential treatment targets in Indigenous Australians.

METHODS

The eGFR Follow-up Study is a longitudinal cohort of 520 Indigenous Australians. Linear regression was used to estimate associations between baseline cardiometabolic risk factors and annual Chronic Kidney Disease Epidemiology Collaboration eGFR change (mL/min per 1.73m² /year), among those classified with baseline normoalbuminuria (urine albumin-to-creatinine ratio (uACR) <3 mg/mmol; n = 297), microalbuminuria (uACR 3-30 mg/mmol; n = 114) and macroalbuminuria (uACR ≥30 mg/mmol; n = 109).

RESULTS

After a median of 3 years follow-up, progressive declines of the age- and sex-adjusted mean eGFR were observed across albuminuria categories (-2.0 [-2.6 to -1.4], -2.5 [-3.7 to -1.3] and -6.3 [-7.8 to -4.9] mL/min per 1.72m² /year). Although a borderline association was observed between greater baseline haemoglobin A_1c and eGFR decline in those with macroalbuminuria (P = 0.059), relationships were not significant in those with microalbuminuria (P = 0.187) or normoalbuminuria (P = 0.23). Greater baseline blood pressure, C-reactive protein, waist-to-hip ratio and lower high-density lipoprotein cholesterol showed non-significant trends with greater eGFR decline in the presence of albuminuria.

CONCLUSION

Over a 3 year period, marked eGFR decline was observed with greater baseline albuminuria. Cardiometabolic risk factors were not strong predictors for eGFR decline in Indigenous Australians without albuminuria. Longer follow-up may elucidate the role of these predictors and other mechanisms in chronic kidney disease progression in this population.

Female preterm indigenous Australian infants have lower renal volumes than males: A predisposing factor for end-stage renal disease?

Aim

Indigenous Australians have an increased risk of developing chronic kidney disease (CKD). Indigenous women have a higher rate of CKD than men. In a cohort of Indigenous and non‐Indigenous preterm neonates, we assessed total renal volume (TRV) (a proxy indicator for nephron number). We hypothesized that there would be no difference in renal volume between these two groups at term corrected (37 weeks gestation).

Methods

Normally grown preterm neonates less than 32 weeks of gestation were recruited and at term corrected dates, the neonates underwent renal ultrasonography (TRV measurements), urine microalbumin‐creatinine ratio and serum analysis for Cystatin C measurement for estimated glomerular filtration rate (eGFR) calculation.

Results

One hundred and five neonates (38 Indigenous; 67 non‐Indigenous) were recruited. Indigenous neonates were significantly more premature and of lower birth weight. At term corrected age, Indigenous neonates had a significantly smaller TRV (18.5 (4.2) vs 21.4 (5.1) cm³; P = 0.027) despite no significant difference in body weight. Despite having a smaller TRV, there was no significant difference in eGFR between Indigenous and Non‐indigenous neonates (47.8 [43.2–50.4] vs 46.2 [42.6–53.3] ml/min per 1.73 m²; P = 0.986). These infants achieve similar eGFR through hyperfiltration, which likely increases their future risk of CKD. There was no difference in microalbumin‐creatinine ratio. Female Indigenous neonates, however, had significantly smaller TRV compared with Indigenous male neonates (15.9 (3.6) vs 20.6 (3.6) cm³; P = 0.006), despite no difference in eGFR, birth weight, gestational age, and weight at term corrected.

Conclusion

The difference in TRV is likely to be an important risk factor for the difference in morbidity and mortality from renal disease reported between male and female Indigenous adults.

Indigenous Australians are known to have an increased risk of developing CKD. The authors examined total renal volume (TRV) in a cohort of Indigenous and non‐Indigenous preterm neonates, and found that female Indigenous neonates had significantly smaller TRV compared with Indigenous male neonates.

Clinical presentation, treatment and outcome of focal segmental glomerulosclerosis in Far North Queensland Australian adults

AIM

The aim is to describe the clinical features, treatment and outcomes in Australian adults with focal segmental glomerulosclerosis and identify predictors of disease progression and all-cause mortality.

METHODS

The study included all patients with biopsy confirmed focal segmental glomerulosclerosis between January 1997 and June 2014 at participating hospitals. Clinical factors, histopathological findings, biochemical markers and treatments were analysed and potential predictors of doubling serum creatinine, end stage kidney disease or death identified.

RESULTS

A total of 98 patients were included with a median follow up of 4.3 years. Thirty-four (35%) patients were Aboriginal or Torres Strait Islander. Focal segmental glomerulosclerosis not-otherwise-specified was the most common variant. Seventeen (59%) patients initially treated with immunosuppression experienced an improvement in renal function. At the end of follow up, 43 (44%) patients had progressed to the composite outcome. Baseline tubulointerstitial scarring and lower haemoglobin predicted shorter time to doubling serum creatinine. Dual diagnosis, higher serum creatinine, lower estimated glomerular filtration rate and doubling creatinine were associated with shorter time to end stage kidney disease with remission the only protective factor. Age was the only variable associated with all-cause mortality.

CONCLUSION

Focal segmental glomerulosclerosis holds serious implications for patients. Concomitant diabetic nephropathy, higher serum creatinine and lower estimated glomerular filtration rate at renal biopsy were associated with poorer renal prognosis. Indigenous people had a female predominance and are over-represented in relation to their population size, however, were not associated with poorer prognosis. Remission was the only modifiable variable and thus should be at the forefront of patient management goals and future studies.

Analysis of clinical presentation, pathological spectra, treatment and outcomes of biopsy-proven acute postinfectious glomerulonephritis in adult indigenous people of the Northern Territory of Australia

AIM

Acute postinfectious glomerulonephritis is common in indigenous communities in the Northern Territory, Australia. It is a major risk factor for the high prevalence of chronic kidney disease. We aimed to analyse the clinical presentation, pathological spectra, treatment and outcomes of biopsy-proven acute postinfectious glomerulonephritis in the Northern Territory.

METHODS

We performed a retrospective cohort analysis of all adult patients (≥18 years) who were diagnosed with acute postinfectious glomerulonephritis on native renal biopsies from 01/01/2004 to 31/05/2014. The outcome measure was end-stage renal disease requiring long-term dialysis.

RESULTS

Forty-three of 340 patients who had renal biopsies had acute postinfectious glomerulonephritis. Most were Aboriginals (88.4%). They had co-morbidities; diabetes mellitus (60.5%), hypertension (60.5%) and smoking (56.4%). Forty-nine per cent had multiple pathologies on biopsy. Predominant histological pattern was diffuse proliferative glomerulonephritis (72%). Main sites of infections were skin (47.6%) and upper respiratory tract infection (26.2%) with streptococcus and staphylococcus as predominant organisms. Fifty per cent of patients developed end-stage renal disease. On multivariable logistic regression analysis, those on dialysis had higher baseline creatinine (P = 0.003), higher albumin/creatinine ratio at presentation (P = 0.023), higher serum creatinine at presentation (P = 0.02) and lower estimated glomerular filtration rate at presentation (P = 0.012).

CONCLUSION

Overall, most patients had pre-existing pathology with superimposed acute postinfectious glomerulonephritis that led to poor outcomes in our cohort.

An expanded nationwide view of chronic kidney disease in Aboriginal Australians

We summarize new knowledge that has accrued in recent years on chronic kidney disease (CKD) in Indigenous Australians. CKD refers to all stages of preterminal kidney disease, including end‐stage kidney failure (ESKF), whether or not a person receives renal replacement therapy (RRT). Recently recorded rates of ESKF, RRT, non‐dialysis CKD hospitalizations and CKD attributed deaths were, respectively, more than sixfold, eightfold, eightfold and threefold those of non‐Indigenous Australians, with age adjustment, although all except the RRT rates are still under‐enumerated. However, the nationwide average Indigenous incidence rate of RRT appears to have stabilized. The median age of Indigenous people with ESKF was about 30 years less than for non‐Indigenous people, and 84% of them received RTT, while only half of non‐Indigenous people with ESKF did so. The first‐ever (2012) nationwide health survey data showed elevated levels of CKD markers in Indigenous people at the community level. For all CKD parameters, rates among Indigenous people themselves were strikingly correlated with increasing remoteness of residence and socio‐economic disadvantage, and there was a female predominance in remote areas. The burden of renal disease in Australian Indigenous people is seriously understated by Global Burden of Disease Mortality methodology, because it employs underlying cause of death only, and because deaths of people on RRT are frequently attributed to non‐renal causes.

These data give a much expanded view of CKD in Aboriginal people. Methodologic approaches must be remedied for a full appreciation of the burden, costs and outcomes of the disease, to direct appropriate policy development.

Excellent review on the kidney health in the Aboriginal communities in Australia, describing the challenges and important priorities.

Low Birth Weight and Risk of Progression to End Stage Renal Disease in IgA Nephropathy--A Retrospective Registry-Based Cohort Study

Background

Low Birth Weight (LBW) is a surrogate for fetal undernutrition and is associated with impaired nephron development in utero. In this study, we investigate whether having been born LBW and/or small for gestational age (SGA) predict progression to ESRD in IgA nephropathy (IgAN) patients.

Study Design

Retrospective registry-based cohort study.

Settings & Participants

The Medical Birth Registry has recorded all births since 1967 and the Norwegian Renal Registry has recorded all patients with ESRD since 1980. Based on data from the Norwegian Kidney Biopsy Registry we included all patients diagnosed with IgAN in Norway from 1988–2013. These registries were linked and we analysed risk of progression to ESRD associated with LBW (defined as birth weight less than the 10^th percentile) and/or SGA (defined as birth weight less than the 10^th percentile for gestational week) by Cox regression statistics.

Results

We included 471 patients, of whom 74 developed ESRD. As compared to patients without LBW, patients with LBW had a hazard ratio (HR) of 2.0 (95% confidence interval 1.1–3.7) for the total cohort, 2.2 (1.1–4.4) for males and 1.3 (0.30–5.8) for females. Corresponding HRs for SGA were 2.2 (1.1–4.2), 2.7 (1.4–5.5) and 0.8 (0.10–5.9). Further analyses showed that as compared to patients with neither LBW nor SGA, patients with either SGA or LBW did not have significantly increased risks (HRs of 1.3–1.4) but patients who were both LBW and SGA had an increased risk (HR 3.2 (1.5–6.8).

Limitation

Mean duration of follow-up only 10 years and maximum age only 46 years.

Conclusion

Among IgAN patients, LBW and/or SGA was associated with increased risk for progression to ESRD, the association was stronger in males.

Persistent Albuminuria in Children with Type 2 Diabetes: A Canadian Paediatric Surveillance Program Study

OBJECTIVE

To determine the prevalence and the clinical features associated with persistent albuminuria in Canadian children aged <18 years with type 2 diabetes.

STUDY DESIGN

This national prospective surveillance study involved a network of pediatricians and pediatric endocrinologists. Cases of persistent albuminuria in children with type 2 diabetes were reported during a 24-month period from 2010 to 2012. Persistent albuminuria was defined as an elevated albumin-to-creatinine ratio in a minimum of 2 out of 3 urine samples obtained at least 1 month apart over 3-6 months and confirmed with a first morning sample. Descriptive statistics were used to illustrate demographic and clinical features of the population. The prevalence of persistent albumuria was estimated using data from a previous national surveillence study of type 2 diabetes in children.

RESULTS

Fifty cases were reported over the 24-month study period. The estimated prevalence of persistent albuminuria in children with type 2 diabetes in Canada was 5.1%. The median duration of diabetes at the time of diagnosis of albuminuria was 21 days (IQR, 0-241 days). Almost two-thirds (64%) were female, 80% were of Canadian First Nations heritage, and 76% were from Manitoba. Exposure to gestational or pregestational diabetes in utero occurred in 65%, and 48% had a family history of diabetes-related renal disease. Structural anomalies of the kidney were found in 37%.

CONCLUSION

Persistent albuminuria occurs in youths with type 2 diabetes in the first year after diagnosis, demonstrates regional variation, and is associated with First Nations heritage and exposure to maternal diabetes during pregnancy.

Hyperfiltration in Indigenous Australians with and without diabetes

BACKGROUND

Hyperfiltration (HF) has been linked to the development of diabetic kidney disease (DKD), but the causative or predictive role of HF in the pathogenesis of DKD still remains unclear. To date, there have been no studies of HF in Indigenous Australians, a population with high rates of both diabetes and end-stage kidney disease. We aimed to compare the characteristics and frequency of HF in Indigenous Australians with and without type 2 diabetes.

METHODS

Indigenous Australian participants, recruited across five pre-defined strata of health, diabetes status and kidney function, had a reference glomerular filtration rate (GFR) measured using plasma disappearance of iohexol [measured GFR(mGFR)] over 4 h. HF was defined in various ways: (i) mGFR > 144 mL/min/1.73 m(2), which is mGFR > 1.96 × SD above the mean of the mGFR in non-diabetic participants with normal albuminuria and normal renal function (mGFR > 90 mL/min/1.73 m(2)); (ii) age-corrected mGFR (>144 mL/min/1.73 m(2)) to account for the effect of ageing on GFR in subjects over 40 years of age with cut-off 1 mL/min/1.73 m(2) lower for every year; (iii) mGFR > 144 mL/min, without correction for body surface area or age, as well as (iv) mGFR > 125 mL/min/1.73 m(2), without adjustment for age.

RESULTS

A total of 383 Indigenous participants, 125 with and 258 without diabetes, with mGFR > 90 mL/min/1.73 m(2) were studied. The proportion of participants with HF was 7% using mGFR > 144 mL/min/1.73 m(2), 11% using the age-adjusted definition, 19% using mGFR > 144 mL/min and 27% using mGFR > 125 mL/min/1.73 m(2). Diabetes was more common in participants with HF (40-74%) compared with normofiltering participants (28-31%), regardless of the definition of HF.

CONCLUSIONS

HF exists in Indigenous Australians with and without diabetes. A greater proportion of participants had diabetes in HF group compared with normofiltration group. Long-term follow-up of this cohort is necessary to determine if HF plays a role in the development of DKD and non-DKD.

Chronic kidney disease in disadvantaged populations

The increased burden of chronic kidney disease (CKD) in disadvantaged populations is due to both global factors and population-specific issues. Low socioeconomic status and poor access to care contribute to health care disparities and exacerbate the negative effects of genetic or biological predisposition. Provision of appropriate renal care to these populations requires a two-pronged approach: expanding the reach of dialysis through development of low-cost alternatives that can be practiced in remote locations, and implementation and evaluation of cost-effective prevention strategies. Kidney transplantation should be promoted by expansion of deceased donor transplant programs and use of inexpensive, generic immunosuppressive drugs. The message of World Kidney Day 2015 is that a concerted attack against the diseases that lead to end-stage renal disease, by increasing community outreach, better education, improved economic opportunity, and access to preventive medicine for those at highest risk, could end the unacceptable relationship between CKD and disadvantage in these communities.

Chronic kidney disease in disadvantaged populations

The increased burden of CKD in disadvantaged populations is due to both global factors and population-specific issues. Low socioeconomic status and poor access to care contribute to healthcare disparities and exacerbate the negative effects of genetic or biologic predisposition. Provision of appropriate renal care to these populations requires a two-pronged approach: expanding the reach of dialysis through development of low-cost alternatives that can be practiced in remote locations, and implementation and evaluation of cost-effective prevention strategies. Kidney transplantation should be promoted by expanding both deceased donor transplant programs and the use of inexpensive, generic immunosuppressive drugs. The message of WKD 2015 is that a concerted attack against the diseases that lead to ESRD, by increasing community outreach, better education, improved economic opportunity, and access to preventive medicine for those at highest risk, could end the unacceptable relationship between CKD and disadvantage in these communities.

Chronic kidney disease (CKD) in disadvantaged populations

Twelve March 2015 will mark the 10th anniversary of World Kidney Day (WKD), an initiative of the International Society of Nephrology and the International Federation of Kidney Foundations. Since its inception in 2006, WKD has become the most successful effort ever mounted to raise awareness among decision-makers and the general public about the importance of kidney disease. Each year WKD reminds us that kidney disease is common, harmful and treatable. The focus of WKD 2015 is on chronic kidney disease (CKD) in disadvantaged populations. This article reviews the key links between poverty and CKD and the consequent implications for the prevention of kidney disease and the care of kidney patients in these populations.

Early-life course socioeconomic factors and chronic kidney disease

Kidney failure or ESRD affects approximately 650,000 Americans, whereas the number with earlier stages of CKD is much higher. Although CKD and ESRD are usually associated with adulthood, it is likely that the initial stages of CKD begin early in life. Many of these pathways are associated with low birth weight and disadvantaged socioeconomic status (SES) in childhood, translating childhood risk into later-life CKD and kidney failure. Social factors are thought to be fundamental causes of disease. Although the relationship between adult SES and CKD has been well established, the role of early childhood SES for CKD risk remains obscure. This review provides a rationale for examining the association between early-life SES and CKD. By collecting data on early-life SES and CKD, the interaction with other periods in the life course could also be studied, allowing for examination of whether SES trajectories (eg, poverty followed by affluence) or cumulative burden (eg, poverty at multiple time points) are more relevant to lifetime CKD risk.

Kidney disease in Aboriginal Australians: a perspective from the Northern Territory

This article outlines the increasing awareness, service development and research in renal disease in Aboriginal people in Australia's Northern Territory, among whom the rates of renal replacement therapy (RRT) are among the highest in the world. Kidney failure and RRT dominate the intellectual landscape and consume the most professional energy, but the underlying kidney disease has recently swung into view, with increasing awareness of its connection to other chronic diseases and to health profiles and trajectories more broadly. Albuminuria is the marker of the underlying kidney disease and the best treatment target, and glomerulomegaly and focal glomerulosclerosis are the defining histologic features. Risk factors in its multideterminant genesis reflect nutritional and developmental disadvantage and inflammatory/infectious milieu, while the major putative genetic determinants still elude detection. A culture shift of "chronic disease prevention" has been catalyzed in part by the human pain, logistic problems and great costs associated with RRT. Nowadays chronic disease management is the central focus of indigenous primary care, with defined protocols for integrated testing and management of chronic diseases and with government reimbursed service items and free medicines for people in remote areas. Blood pressure, cardiovascular risk and chronic kidney disease (CKD) are all mitigated by good treatment, which centres on renin-angiotensin system blockade and good metabolic control. RRT incidence rates appear to be stabilizing in remote Aboriginal people, and chronic disease deaths rates are falling. However, the profound levels of disadvantage in many remote settings remain appalling, and there is still much to be done, mostly beyond the direct reach of health services.

Nephron hypertrophy and glomerulosclerosis and their association with kidney function and risk factors among living kidney donors

BACKGROUND AND OBJECTIVES

The relationship of kidney function and CKD risk factors to structural changes in the renal parenchyma of normal adults is unclear. This study assessed whether nephron hypertrophy and nephrosclerosis had similar or different associations with kidney function and risk factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

From 1999 to 2009, 1395 living kidney donors had a core needle biopsy of their donated kidney during transplant surgery. The mean nonsclerotic glomerular volume and glomerular density (globally sclerotic and nonsclerotic) were estimated using the Weibel and Gomez stereologic methods. All tubules were counted in 1 cm(2) of cortex to determine a mean profile tubular area. Nephron hypertrophy was identified by larger glomerular volume, larger profile tubular area, and lower nonsclerotic glomerular density. Nephrosclerosis was identified by higher globally sclerotic glomerular density.

RESULTS

The mean (± SD) age was 44 ± 12 years, 24-hour urine albumin excretion was 5 ± 7 mg, measured GFR was 103 ± 17 ml/min per 1.73 m(2), uric acid was 5.2 ± 1.4 mg/dl, and body mass index was 28 ± 5 kg/m(2). Of the study participants, 43% were men, 11% had hypertension, and 52% had a family history of ESRD. Larger glomerular volume, larger profile tubular area, and lower nonsclerotic glomerular density were correlated. Male sex, higher 24-hour urine albumin excretion, family history of ESRD, and higher body mass index were independently associated with each of these measures of nephron hypertrophy. Higher uric acid, higher GFR, and older age were also independently associated with some of these measures of nephron hypertrophy. Hypertension was not independently associated with measures of nephron hypertrophy. However, hypertension and older age were independently associated with higher globally sclerotic glomerular density.

CONCLUSIONS

Nephron hypertrophy and nephrosclerosis are structural characteristics in normal adults that relate differently to clinical characteristics and may reflect kidney function and risk factors via separate but inter-related pathways.