Urinary findings and renal function in adult Navajo Indians and associations with type 2 diabetes

Remote Dwelling Location Is a Risk Factor for CKD Among Indigenous Canadians

Introduction

Rural and remote indigenous individuals have a high burden of chronic kidney disease (CKD) when compared to the general population. However, it has not been previously explored how these rates compare to urban-dwelling indigenous populations.

Methods

In a recent cross-sectional screening study, 1346 adults 18 to 80 years of age were screened for CKD and diabetes across 11 communities in rural and remote areas in Manitoba, Canada, as part of the First Nations Community Based Screening to Improve Kidney Health and Prevent Dialysis (FINISHED) program. An additional 284 Indigenous adults who resided in low-income areas in the city of Winnipeg, Manitoba, Canada were screened as part of the NorWest Mobile Diabetes and Kidney Disease Screening and Intervention Project.

Results

Our findings indicate that a gradient of CKD and diabetes prevalence exists for Indigenous individuals living in different geographic areas. Compared to urban-dwelling Indigenous individuals, rural-dwelling individuals had more than a 2-fold (2.1, 95% CI = 1.4-3.1) increase in diabetes whereas remote-dwelling individuals had a 4-fold (4.1, 95% CI = 2.8-6.0) increase, and more than a 3-fold (3.1, 95% CI = 2.2-4.5) increase in CKD prevalence.

Conclusion

Although these results highlight the relative importance of geography in determining the prevalence of diabetes and CKD in Indigenous Canadians, geography is but an important surrogate of other determinants, such as poverty and access to care.

Screening for chronic kidney disease in Canadian indigenous peoples is cost-effective

Canadian indigenous (First Nations) have rates of kidney failure that are 2- to 4-fold higher than the non-indigenous general Canadian population. As such, a strategy of targeted screening and treatment for CKD may be cost-effective in this population. Our objective was to assess the cost utility of screening and subsequent treatment for CKD in rural Canadian indigenous adults by both estimated glomerular filtration rate and the urine albumin-to-creatinine ratio. A decision analytic Markov model was constructed comparing the screening and treatment strategy to usual care. Primary outcomes were presented as incremental cost-effectiveness ratios (ICERs) presented as a cost per quality-adjusted life-year (QALY). Screening for CKD was associated with an ICER of $23,700/QALY in comparison to usual care. Restricting the model to screening in communities accessed only by air travel (CKD prevalence 34.4%), this ratio fell to $7,790/QALY. In road accessible communities (CKD prevalence 17.6%) the ICER was $52,480/QALY. The model was robust to changes in influential variables when tested in univariate sensitivity analyses. Probabilistic sensitivity analysis found 72% of simulations to be cost-effective at a $50,000/QALY threshold and 93% of simulations to be cost-effective at a $100,000/QALY threshold. Thus, targeted screening and treatment for CKD using point-of-care testing equipment in rural Canadian indigenous populations is cost-effective, particularly in remote air access-only communities with the highest risk of CKD and kidney failure. Evaluation of targeted screening initiatives with cluster randomized controlled trials and integration of screening into routine clinical visits in communities with the highest risk is recommended.

The Prevalence of CKD in Rural Canadian Indigenous Peoples: Results From the First Nations Community Based Screening to Improve Kidney Health and Prevent Dialysis (FINISHED) Screen, Triage, and Treat Program

BACKGROUND

Indigenous Canadians have high rates of risk factors for chronic kidney disease (CKD), in particular diabetes. Furthermore, they have increased rates of complications associated with CKD, such as kidney failure and vascular disease. Our objective was to describe the prevalence of CKD in this population.

STUDY DESIGN

Cross-sectional cohort.

SETTING & PARTICIPANTS

Indigenous (First Nations) Canadians 18 years or older screened as part of the First Nations Community Based Screening to Improve Kidney Health and Prevent Dialysis (FINISHED) project, an initiative completed in 2015 that accomplished community-wide screening in 11 rural communities in Manitoba, Canada.

PREDICTORS

Indigenous ethnicity and geographic location (communities accessible by road compared with those accessible only by air).

OUTCOME

Prevalence of CKD, presumed based on a single ascertainment of urine albumin-creatinine ratio (UACR) ≥ 30mg/g and/or estimated glomerular filtration rate (eGFR)<60mL/min/1.73m(2).

MEASUREMENTS

Kidney function measured by eGFR (CKD-EPI creatinine equation) and UACR.

RESULTS

1,346 adults were screened; 25.5% had CKD, defined as UACR≥30mg/g or eGFR<60mL/min/1.73m(2). Communities accessible by road had a lower prevalence of CKD (17.6%) than more remote communities accessible only by air (34.4%). Of those screened, 3.3% had reduced kidney function (defined as eGFR<60mL/min/1.73m(2)). Severely increased albuminuria was present in 5.0% of those screened.

LIMITATIONS

Presumption of chronicity based on a single ascertainment. There is a possibility of sampling bias, the net direction of which is uncertain.

CONCLUSIONS

We found a 2-fold higher prevalence of CKD in indigenous Canadians in comparison to the general population and a prevalence of severely increased albuminuria that was 5-fold higher. This is comparable to patients with diabetes and/or hypertension. Public health strategies to screen, triage, and treat all Canadian indigenous peoples with CKD should be considered.

Linkage analysis of glomerular filtration rate in American Indians

American Indians have a disproportionately high rate of kidney disease likely due to a combination of environmental and genetic factors. We performed a genome wide scan of estimated glomerular filtration rate in 3665 participants of the Strong Heart Family Study to localize genes influencing kidney disease risk factors. The participants were men and women from 13 American Indian tribes recruited from 3 centers located in Arizona, the Dakotas and Oklahoma. Multipoint variance component linkage analysis was performed for each center and on the entire cohort after controlling for center effects. Modeling strategies that incorporated age, gender and interaction terms (model 1) and another that also controlled for diabetes mellitus, systolic and diastolic blood pressure, body mass index, low density and high density lipoproteins, triglycerides and smoking status (model 2) were used. Significant evidence for linkage in the Arizona group was found on chromosome 12p12.2 at 39cM (nearest marker D12S310) using model 1. Additional loci with very suggestive evidence for linkage were detected at 1p36.31 for all groups using both models and at 2q33.3 and 9q34.2 for the Dakotas group each using model 1. No significant evidence for additive interaction with diabetes, hypertension or obesity was noted. This evidence for linkage of a quantitative trait locus influencing estimated glomerular filtration rate to a region of chromosome 12p in a large cohort of American Indians will be worth studying in more detail in the future.

Indigenous health: update on the impact of diabetes and chronic kidney disease

PURPOSE OF REVIEW

With respect to chronic diseases such as diabetes and its complications, indigenous populations are known to suffer from poor health outcomes in comparison with whites. The purpose of this review is to highlight recent epidemiologic and intervention studies that have occurred in the areas of diabetes and renal disease among indigenous populations.

RECENT FINDINGS

The burden of diabetes is increasing among younger indigenous groups with epidemic levels of end-stage kidney disease. As dialysis therapy has contributed to prolong life among indigenous patients, cardiovascular disease has now become the leading cause of mortality in these populations. Clear preventive intervention strategies to improve rates of progression to end-stage kidney disease are not prevalent nor are they emerging over time. Access to kidney transplantation is also reduced among indigenous populations in Australia, New Zealand, the USA and Canada. Reasons for this disparity are unclear but likely multifactorial.

SUMMARY

Diabetes and its complications have produced a health crisis among indigenous populations. The impact on healthcare systems in countries where these indigenous populations reside will be substantial unless significant efforts are made to improve diabetic renal disease outcomes in the near future.

Kidney disease among the Zuni Indians: The Zuni Kidney Project

BACKGROUND

There is an epidemic of kidney disease among the Zuni Indians. In collaboration with health care providers and research institutions, the Zuni Pueblo established the Zuni Kidney Project to reduce the burden of kidney disease.

METHODS

The Zuni Kidney Project conducted a population-based, cross-sectional survey to estimate the prevalence of albuminuria, hematuria, and related risk factors. Neighborhood household clusters served as the sampling frame. Participants completed a questionnaire, donated blood and urine samples, and had blood pressure, height, and weight measured. This survey provided the foundation for ongoing studies to identify genetic and environmental risk factors for disease susceptibility and progression.

RESULTS

Age and gender distributions among survey participants were similar to those in the eligible Zuni population. Prevalence of incipient albuminuria (IA) (0.03< or = urine albumin:creatinine ratio, UACR <0.3) and overt albuminuria (OA) (UACR < 0.3) were higher among diabetics [IA 34.3% (28.3, 40.4%); OA 18.6% (13.7, 23.6%)] than nondiabetics [IA 11.1% (9.3, 12.8%); OA 1.7% (1.0, 2.5%)]. Nondiabetics comprised 58.6% (52.2, 65.0%) and 30.9% (19.9, 41.9%) of participants with IA and OA, respectively. The prevalence of hematuria was higher among diabetics [> or = trace 47.0% (40.7, 53.4); > or =50 red blood cell/microL 25.8% (20.3, 31.4%)] than nondiabetics [> or = trace 31.1% (28.5, 33.7%); > or =50 red blood cell/microL 16.6% (14.5, 18.7%)]. Hypertension was associated with albuminuria among diabetic and nondiabetic participants. Hypercholesterolemia was associated with albuminuria among nondiabetic participants. Diabetes and alcohol use were associated with hematuria.

CONCLUSION

The high prevalences of albuminuria among nondiabetics and of hematuria among diabetics and nondiabetics are consistent with high rates of nondiabetic kidney disease among Zuni Indians with and without diabetes.

Microalbuminuria and Lower Glomerular Filtration Rate at Young Adult Age in Subjects Born Very Premature and after Intrauterine Growth Retardation

This prospective follow-up study of 422 19-yr-old subjects born very preterm in The Netherlands was performed to determine whether intrauterine growth retardation (IUGR) predisposes to abnormal GFR and microalbuminuria in adolescents. GFR (ml/min per 1.73 m2) was estimated using the Cockcroft-Gault equation, and albumin-creatinine ratio (mg/mmol) was calculated in a cohort of 19-yr-old subjects born very preterm (gestational age <32 wk) in 1983. Birth weights were adjusted for gestational age and expressed as standard deviation scores (sds) as a measure of IUGR. All subjects had normal renal function. Birth weight (sds) was associated negatively with serum creatinine concentration (micromol/L) (beta = -1.0 micromol/L, 95% confidence interval [CI]: -1.9 to -0.2), positively with GFR (beta = 3.0, 95% CI: 1.7 to 4.2), and negatively with the logarithm of albumin-creatinine ratio (beta = -0.05, 95% CI: -0.09 to -0.01) in young adults born very preterm. IUGR is associated with unfavorable renal functions at young adult age in subjects born very premature. These data suggest that intrauterine growth-retarded subjects born very premature have an increased risk to develop progressive renal failure in later life.

Acanthocytes in the urine: useful tool to differentiate diabetic nephropathy from glomerulonephritis?

OBJECTIVE

The presence of hematuria has been suggested to indicate nondiabetic nephropathy in diabetic patients with proteinuria. However, hematuria is frequently found in patients with biopsy-proven diabetic glomerulosclerosis without nondiabetic nephropathy. Urine microscopy allows discrimination of glomerular hematuria, which is defined as acanthocyturia (urinary excretion of acanthocytes, which are dysmorphic erythrocytes with vesicle-like protrusions), from nonglomerular hematuria. We hypothesized that acanthocyturia is an uncommon finding in diabetic nephropathy, which suggests the presence of a nondiabetic nephropathy in diabetic patients with proteinuria.

RESEARCH DESIGN AND METHODS

Urine samples of patients with the clinical diagnosis of diabetic nephropathy (n = 68), of patients with biopsy-proven glomerulonephritis (n = 43), and of age-matched healthy control subjects (n = 20) were examined by phase-contrast microscopy for the presence of hematuria (>/=8 erythrocytes/ micro l) and acanthocyturia. Acanthocyturia of >/=5% (5 acanthocytes among 100 excreted erythrocytes) was classified as glomerular hematuria; acanthocyturia of 2-4% was classified as suspected glomerular hematuria.

RESULTS

Hematuria was found in 62% of patients with the clinical diagnosis of diabetic nephropathy, in 84% of patients with glomerulonephritis, and in 20% of the healthy control subjects upon a single urine examination. In contrast, glomerular hematuria occurred in 4% of patients with diabetic nephropathy and in 40% of patients with glomerulonephritis (P < 0.001).

CONCLUSIONS

In contrast to hematuria, acanthocyturia is uncommon in patients with the clinical diagnosis of diabetic nephropathy. In diabetic patients with proteinuria, the finding of acanthocyturia points to nondiabetic glomerulopathies, and renal biopsy should be considered.

The role of active family nutritional support in Navajos' type 2 diabetes metabolic control

OBJECTIVE

We examined if active family nutritional support is associated with improved metabolic outcomes for Diné (Navajo) individuals living with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The presence of family support, using variables identified in earlier ethnographic research, was assessed via surveys in a convenience sample of 163 diabetic individuals. Diabetes outcome measures (HbA(1c), serum glucose, triglycerides, total cholesterol, creatinine, and systolic and diastolic blood pressure measures) were extracted from participants' medical records. Bivariate analyses and multiple logistic regressions were conducted.

RESULTS

All measures of family support showed a relation with one or more indicators of metabolic control in bivariate analyses. In multivariate analyses, respondents were more likely to be in the best tertile for triglyceride (P < 0.05), cholesterol (P < 0.05), and HbA(1c) (P < 0.05) if another person cooked most of the meals. Respondents in families who bought/cooked "light" foods were more likely to be in the best tertile for triglyceride (P < 0.005) and cholesterol levels (P < 0.005), and those in families whose members ate "light" foods with them were more likely to be in the best tertile for triglycerides (P < 0.005). When all three support variables were entered into a multivariate model, only the variable "other family members cook the majority of the meals" was significantly associated with being in the lowest triglyceride (P = 0.05), HbA(1c) (P < 0.05), or cholesterol tertiles (P < 0.05). These relationships were most evident for women with diabetes.

CONCLUSIONS

Active family nutritional support, as measured by culturally relevant categories, is significantly associated with control of triglyceride, cholesterol, and HbA(1c) levels. The findings suggest that the family is a more useful unit of intervention for Diné individuals than for the individual alone when designing diabetes care strategies.

Prevalence of hematuria among Zuni Indians with and without diabetes: The Zuni kidney Project

BACKGROUND

There is an epidemic of kidney disease among the Zuni Indians. In contrast to other American Indian tribes, the epidemic among the Zuni Indians is attributable to diabetic and nondiabetic renal disease.

METHODS

The Zuni Kidney Project, established to reduce the burden of renal disease, conducted a population-based cross-sectional survey of Zuni Indians aged 5 years or older to precisely estimate the prevalence of hematuria. The survey used neighborhood household clusters as the sampling frame to maximize ascertainment and minimize bias. During the survey, we administered a questionnaire; collected blood and urine samples; and measured blood pressure, height, and weight.

RESULTS

Age and sex distributions in our sample (n = 1,469) were similar to those of the eligible Zuni population (n = 9,228). Prevalences of hematuria, defined as dipstick of trace or greater and 50 red blood cells/microL or greater, age- and sex-adjusted to the Zuni population aged 5 years or older, were 33.2% (95% confidence interval [CI], 30.7 to 35.6) and 17.8% (95% CI, 15.8 to 19.8), respectively. Hematuria of trace or greater was more common among females (40.6%; 95% CI, 37.0 to 44.1) than males (25.1%; 95% CI, 21.8 to 28.4). Hematuria of trace or greater was common among Zuni Indians without diabetes (females, 39.7%; 95% CI, 35.7 to 43.8; males, 22.7%; 95% CI, 19.4 to 26.1) and with diabetes (females, 47.5%; 95% CI, 39.8 to 55.2; males, 45.8%; 95% CI, 34.3 to 57.3). Diabetes and alcohol use for greater than 10 years were associated with hematuria among males, but not females.

CONCLUSION

The prevalence of hematuria is high among Zuni Indians with and without diabetes. These findings are consistent with the hypothesis that nondiabetic kidney disease is common among Zuni Indians with and without diabetes.

Association of albuminuria and the metabolic syndrome

Microalbuminuria clusters with the metabolic syndrome, and both conditions predict cardiovascular disease mortality. The reported relationships of microalbuminuria with the individual components of the metabolic syndrome (i.e., hyperglycemia, insulin resistance, hypertension, dyslipidemia, abdominal obesity) are variable. Each of these components, as well as intrauterine effects and diet and other lifestyle factors, may contribute to elevated risk of microalbuminuria in certain population groups. Recent evidence indicates a role for oxidation and inflammation in cardiovascular disease, and endothelial dysfunction (exacerbated by factors such as dyslipidemia) may be the mediator of this relationship. Because endothelial dysfunction can also be manifested as microalbuminuria, this provides a potential explanation of the observed association of the metabolic syndrome, chronic inflammation, and microalbuminuria.

Nutrition project in a remote Australian aboriginal community

Much of the ill health of Australian indigenous populations can be attributed to diet-related diseases. This community nutrition project is part of a wider renal screening and prevention program based in the Umoona aboriginal community in Coober Pedy in South Australia's far north. The nutrition project facilitates the capacity of the Umoona aboriginal community to identify and redress nutrition-related issues considered important in improving their overall health status. Project nutritionists developed and implemented a specialized nutrition training program with the Umoona aboriginal health workers. The nutritionists were responsive to requests from community groups to provide nutrition expertise and support in program development. Individual nutrition counseling for adults and children taking part in renal health screening was also provided. The aboriginal health workers reported increased nutritional knowledge and confidence in addressing nutrition-related issues within the community after nutrition training. Individual consultations and partnerships formed with community groups have increased awareness and prompted action to address the importance of nutrition in renal disease and overall health in the Umoona community.

Genetic susceptibility to end-stage renal disease

New methods have been developed to uncover the genotypes that result in complex diseases. End-stage renal disease is a complex disease, without a simple correspondence between genotype and phenotype. Both population-based and family-based epidemiological studies and analysis of model organisms suggest that the pathogenesis of end-stage renal disease may have a genetic component. A number of studies have analyzed candidate nephropathy genes with little success, but recently several well-designed studies of multiplex families with diabetic nephropathy have identified candidate nephropathy susceptibility loci. To date, kidney disease-oriented research has focused on effector mechanisms responsible for the initiation and progression of chronic renal disease. However, because end-stage renal disease is a complex disease, interruption of a single effector pathway is unlikely to result in significant therapeutic benefit. Further understanding of the pathogenesis of kidney disease and the development of new kidney disease therapies will require continued application of genetic and genomic tools to kidney disease research.

Acanthosis Nigricans as an early clinical proxy marker of increased risk of type II diabetes

Diabetes affects 6% of the national population, yet approximately 50% of persons with diabetes remain undiagnosed and receive no treatment. In specific populations, Acanthosis Nigricans (AN) may serve as an early clinical proxy marker of increased risk of type II diabetes. The results of this pilot project to screen selected school age students in New Mexico for AN indicate that a large number of these students may be at increased risk for developing type II diabetes as young adults. The future burden of diabetes on individuals, families, communities, and health care systems may be greater than previously recognized.

The multidimensional nature of renal disease: rates and associations of albuminuria in an Australian Aboriginal community

BACKGROUND

An epidemic of end-stage renal disease (ESRD) is accompanying the rising rates of hypertension, type 2 diabetes and cardiovascular disease among Aborigines in the Northern Territory of Australia. Incidence rates are now 21 times those of nonAboriginal Australians and are doubling every four years. We describe the rates and associations of renal disease in one remote community, which has a current ESRD incidence of 2700 per million, and cardiovascular mortality among the highest in Australia.

METHODS

Between 1992 and 1995 a community-wide screening program was conducted, in which the urinary albumin/creatinine ratio (ACR) was used as the chief renal disease marker. More than 90% of the population ages five and older participated.

RESULTS

Albuminuria was evident in early childhood and increased dramatically with age; 26% of adults had microalbuminuria and 24% had overt albuminuria. All renal failure developed out of a background of overt albuminuria. ACR was significantly correlated with the presence of scabies at screening, with a history of poststreptococcal glomerulonephritis, which is epidemic and endemic in the community, with increasing body wt, blood pressure, glucose, insulin and lipid levels, and with evidence of heavy drinking. ACR was also significantly and inversely correlated with birth weight. As a result of its association with deteriorating hemodynamic and metabolic profiles, increasing ACR was also correlated with increasing cardiovascular risk score. Direct observations showed, and multivariate models predicted, progressive amplification of ACR when multiple risk factors were present simultaneously. Albuminuria also clustered in families.

CONCLUSION

Renal disease in this population is multifactorial, with risk factors related to whole-of-life nutrition, metabolic and hemodynamic profiles, infections, health behaviors, and possibly a family predisposition. Its relationship to low birth weight, and its associations with deteriorating metabolic and hemodynamic profiles, suggest that renal disease is, in part, a component of Syndrome X, which explains the simultaneous increase in metabolic, cardiovascular and renal disease in Aboriginal people. The family clustering might have both environmental and genetic causes, and is under further investigation. Most of the identified risk factors arise out of poverty, disadvantage and accelerated lifestyle change, and the current epidemic can be explained by the confluence of many risk factors in the last few decades. The introduction of effective and sustained programs to address social, economic and educational inequities in all Aboriginal communities, and of screening and renal- and cardiovascular-protective treatment programs for those already afflicted are matters of great urgency.