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.

APOL1 Genotype, Kidney and Cardiovascular Disease, and Death in Older Adults.

OBJECTIVE: We sought to evaluate the cardiovascular impact of coding variants in the apolipoprotein L1 gene APOL1 that protect against trypanosome infection but have been associated with kidney disease among African Americans. APPROACH AND RESULTS: As part of the Cardiovascular Health Study, a population-based cohort of Americans aged ≥65 years, we genotyped APOL1 polymorphisms rs73885319 and rs71785153 and examined kidney function, subclinical atherosclerosis, and incident cardiovascular disease and death over 13 years of follow-up among 91 African Americans with 2 risk alleles, 707 other African Americans, and 4964 white participants. The high-risk genotype with 2 risk alleles was associated with 2-fold higher levels of albuminuria and lower ankle-brachial indices but similar carotid intima-media thickness among African Americans. Median survival among high-risk African Americans was 9.9 years (95% confidence interval [CI], 8.7-11.9), compared with 13.6 years (95% CI, 12.5-14.3) among other African Americans and 13.3 years (95% CI, 13.0-13.6) among whites (P=0.03). The high-risk genotype was also associated with increased risk for incident myocardial infarction (adjusted hazard ratio 1.8; 95% CI, 1.1-3.0) and mortality (adjusted hazard ratio 1.3; 95% CI 1.0-1.7). Albuminuria and risk for myocardial infarction and mortality were nearly identical between African Americans with 0 to 1 risk alleles and whites. CONCLUSIONS: APOL1 genotype is associated with albuminuria, subclinical atherosclerosis, incident myocardial infarction, and mortality in older African Americans. African Americans without 2 risk alleles do not differ significantly in risk of myocardial infarction or mortality from whites. APOL1 trypanolytic variants may account for a substantial proportion of the excess risk of chronic disease in African Americans.

Validation of an Albuminuria Self-assessment Tool in the Multi-Ethnic Study of Atherosclerosis.

OBJECTIVE: We previously developed an 8-item self-assessment tool to identify individuals with a high probability of having albuminuria. This tool was developed and externally validated among non-Hispanic Whites and non-Hispanic Blacks. We sought to validate it in a multi-ethnic cohort that also included Hispanics and Chinese Americans. DESIGN: This is a cross-sectional study. SETTING: Data were collected using standardized questionnaires and spot urine samples at a baseline examination in 2000-2002. The 8 items in the self-assessment tool include age, race, gender, current cigarette smoking, history of diabetes, hypertension, or stroke, and self-rated health. PARTICIPANTS: Of 6,814 community-dwelling adults aged 45-84 years participating in the Multi-Ethnic Study of Atherosclerosis (MESA), 6,542 were included in the primary analysis. MAIN OUTCOME MEASURES: Albuminuria was defined as urine albumin-to-creatinine ratio ≥ 30 mg/g at baseline. RESULTS: Among non-Hispanic Whites, non-Hispanic Blacks, Hispanics, and Chinese Americans, the prevalence of albuminuria was 6.0%, 11.3%, 11.6%, and 10.8%, respectively. The c-statistic for discriminating participants with and without albuminuria was .731 (95% CI: .692, .771), .728 (95% CI: .687, .761), .747 (95% CI: .709, .784), and .761 (95% CI: .699, .814) for non-Hispanic Whites, non-Hispanic Blacks, Hispanics, and Chinese Americans, respectively. The self-assessment tool over-estimated the probability of albuminuria for non-Hispanic Whites and Blacks, but was well-calibrated for Hispanics and Chinese Americans. CONCLUSIONS: The albuminuria self-assessment tool maintained good test characteristics in this large multi-ethnic cohort, suggesting it may be helpful for increasing awareness of albuminuria in an ethnically diverse population.

Ethnic disparity in prevalence of diabetic kidney disease in an Asian primary healthcare cluster.

AIMS: Diabetic kidney disease (DKD) incidence is rising in Singapore. While measures to prevent onset and early detection of diabetes as well as optimal diabetes and blood pressure control are important, early detection and treatment of DKD at primary care are crucial to ameliorate its course. This study aimed to evaluate the prevalence of DKD in a primary care cluster in Singapore and identify its risk factors in a multi-ethnic Asian population. METHODS: A total of 57,594 patients with type 2 diabetes mellitus (T2DM) followed-up at the National Healthcare Group Polyclinics with estimated glomerular filtration rate and at least two urine albumin/creatinine ratio (UACR) were stratified into DKD stages: normoalbuminuria (UACR <30 mg/g), microalbuminuria (MI, UACR 30-299 mg/g), macroalbuminuria (MA, ≥300 mg/g) and renal impairment (RI, estimated glomerular filtration rate eGFR <60 mL/min per 1.73 m(2)). Factors associated with DKD stages were evaluated. RESULTS: Overall DKD prevalence (T2DM with MI, MA or RI) was high at 52.5%; 32.1% had MI, 5.3% had MA and 15.1% had RI. DKD prevalence within ethnic subpopulations was different: 52.2% of Chinese, 60.4% of Malays and 45.3% of Indians had DKD, respectively. Malays had a 1.42-fold higher DKD prevalence, while Indians had a 0.86-fold lower. Other independent risk factors were age, female gender, duration of diabetes and hypertension, HbA1c and body mass index. CONCLUSION: The high prevalence of DKD and its interethnic differences suggest need for additional measures to optimize the care of T2DM at primary care to mitigate its progression.

Role of vitamin D receptor activation in racial disparities in kidney disease outcomes.

African Americans have lower 25-hydroxyvitamin D (25(OH)D) levels compared with whites. African Americans also have a higher risk of developing albuminuria and end-stage renal disease but a lower risk of death once they commence hemodialysis compared with whites. Vitamin D levels have been associated with multiple outcomes including albuminuria, progression to end-stage renal disease, and all-cause and cardiovascular mortality. In this review, we examine the evidence linking 25(OH)D to outcomes and the possibility that differential 25(OH)D may explain certain racial differences in outcomes.

Limited value of routine microalbuminuria assessment in multi-ethnic obese children.

BACKGROUND: To determine the prevalence of microalbuminuria and its association with cardiometabolic risk factors in a multi-ethnic cohort of overweight and obese children. CASE-DIAGNOSIS/TREATMENT: A retrospective analysis of prospectively collected data was performed using data from 408 overweight and obese children (age 3-19 years). In addition to administering an oral glucose tolerance test, we measured anthropometric variables, plasma lipid levels, alanine aminotransferase and the urinary albumin/creatinine ratio (ACR). Microalbuminuria was defined as an ACR of between 2.5 and 25 mg/mmol in boys and 3.5 and 25 mg/mmol in girls. In total, only 11 (2.7 %) of the children analyzed presented with microalbuminuria, with no differences between ethnic groups, sex or in the prevalence of hypertension compared to the children with normoalbuminuria. After adjustment for confounders, the body mass index Z-score tended to be different between the group with microalbuminuria versus that without (3.6 vs. 3.2, respectively; P = 0.054). ACR was not associated with hypertension, impaired glucose tolerance, high triglycerides or low high-density lipoprotein-cholesterol. CONCLUSIONS: In a large multi-ethnic cohort of overweight and obese children, we found a low prevalence of microalbuminuria (11 children, 2.7 %), and in this small number of individuals, we found no association with any of the cardiometabolic risk factors assessed. Therefore, our data do not support the routine measurement of microalbuminuria in asymptomatic overweight and obese children and adolescents.

Cost-effectiveness of screening for microalbuminuria among African Americans.

Compared with other racial groups, African Americans have a similar prevalence of CKD but are much more likely to progress to ESRD, suggesting that the cost-effectiveness of screening strategies requires dedicated study in this population. Here, we calibrated the CKD Health Policy Model so that it accurately forecasts the higher rates for ESRD observed for African Americans. We then used the calibrated model to estimate the cost-effectiveness of screening for microalbuminuria followed by treatment with angiotensin-converting enzyme inhibitors or angiotensin II-receptor blockers. Incorporating racial differences in risk factors did not fully explain the much higher lifetime incidence of ESRD among African Americans. Thus, to calibrate the model, we applied a 20% increase in the rate of GFR decline at stage 3 and a 60% increase in the rate of GFR decline at stage 4, which resulted in a model that closely reflects lifetime ESRD incidence among African Americans. Compared with usual care, screening African Americans for microalbuminuria at 10-, 5-, 2-, and 1-year intervals had incremental cost-effectiveness ratios of $9000, $11,000, $19,000, and $35,000 per quality-adjusted life year, respectively. Incremental cost-effectiveness ratios for the same screening intervals were higher for non-African Americans: $17,000, $23,000, $44,000, and $81,000 per quality-adjusted life year, respectively. In summary, these models suggest that screening African Americans for microalbuminuria at either 5- or 10-year intervals is highly cost-effective.

Ethnic differences in the development of albuminuria: the DISTANCE study.

OBJECTIVES: To determine whether ethnic differences in the incidence of albuminuria are present in patients with diabetes, and to identify social, behavioral, and provider factors that explain ethnic differences. STUDY DESIGN: Survey follow-up design with a race-stratified baseline survey (2005-2006) in diabetic patients from a nonprofit, fully integrated healthcare system in Northern California. We followed the 10,596 respondents (30% whites, 20% blacks, 23% Hispanics, 14% Asians, and 13% Filipinos) without evidence of prevalent albuminuria at baseline. METHODS: Incident albuminuria was defined by positive dipstick urinalysis (>1) or urine albumin to creatinine level (>30 mg/g), and confirmed with repeat testing at least 3 months later. RESULTS: The 27,292 person-years of observation yielded 981 incident albuminuria events. Agestandardized rates of albuminuria (per 1000 person-years) ranged from 13.6 (95% confidence interval [CI] 10.5-17.0) in whites to 27.8 (CI 18.2- 38.3) in blacks. In fully adjusted Cox models, the hazard ratio for blacks (1.22, 95% CI 1.09-1.38), Asians (1.35, 95% CI 1.13-1.61), and Filipinos (1.93, 95% CI 1.61-2.32), but not Hispanics, was significantly greater than it was for whites. In some cases, point estimates changed markedly from the base model when fully adjusted for potential confounders. Moreover, adjustment for an array of potentially mediating factors explained only a small proportion of the observed ethnic disparities. CONCLUSIONS: Despite uniform medical care coverage, Filipinos, blacks, and Asians with diabetes developed albuminuria at higher rates than white and Hispanic adults.

Racial and ethnic differences in albuminuria in individuals with estimated GFR greater than 60 mL/min/1.73 m(2): results from the Kidney Early Evaluation Program (KEEP).

BACKGROUND: Albuminuria is an important marker for chronic kidney disease and progression to end-stage renal disease in the general population; understanding racial and ethnic differences can help inform efforts to reduce health disparities. We sought to estimate independent associations of race/ethnicity with albuminuria to determine whether observed differences were attributable to known kidney disease risk factors. METHODS: This cross-sectional study included 64,161 Kidney Early Evaluation Program (KEEP) participants, 2000-2008, with estimated glomerular filtration rate > or = 60 mL/min/1.73 m(2), not on regular dialysis therapy, and without a previous kidney transplant. Albuminuria (urine albumin-creatinine ratio > or = 30 mg/g) was examined by self-reported race and ethnicity. Covariates were age, sex, educational level, body mass index, diabetes status or glucose level, hypertension status or blood pressure measurement, smoking status, health insurance status, and geographic region. RESULTS: Albuminuria prevalences were 8% (n = 2,303) in whites, 11% (n = 2,310) in African Americans, 9% (n = 730) in Hispanics, 10% (n = 381) in Asians, and 15% (n = 344) in American Indians/Alaska Natives. Compared with whites, odds of albuminuria were higher for all groups after multivariate adjustment. Odds were highest for American Indians/Alaska Natives (adjusted OR, 1.93; 95% CI, 1.70-2.20), then Asians (adjusted OR, 1.42; 95% CI, 1.26-1.61), African Americans (adjusted OR, 1.38; 95% CI, 1.29-1.47), and Hispanics (adjusted OR, 1.19; 95% CI, 1.08-1.31). CONCLUSIONS: In the KEEP study population, albuminuria prevalence was higher in African Americans, Hispanics, Asians, and American Indians/Alaska Natives than in non-Hispanic whites, suggesting a need for screening for early detection of kidney damage, especially in people at increased risk, in the community primary care setting.

An association between ethnicity and cardiovascular outcomes for people with Type 2 diabetes in New Zealand.

AIMS: To investigate the association between ethnicity and risk of first cardiovascular (CV) event for people with Type 2 diabetes in New Zealand. METHODS: A prospective cohort study using routinely collected data from a national primary health care diabetes annual review programme linked to national hospital admission and mortality data. Ethnicity was recorded as European, Maori, Pacific, Indo-Asian, East-Asian or Other. A Cox proportional hazards model was used to investigate factors associated with first CV event. Data was collected from 48,444 patients with Type 2 diabetes, with first data collected between 1 January 2000 and 20 December 2005, no previous cardiovascular event at entry and with complete measurements. Risk factors included ethnicity, gender, socio-economic status, body mass index, smoking, age at diagnosis, duration of diabetes, systolic blood pressure, serum lipids, glycated haemoglobin and urine albumin : creatinine ratio. The main outcome measures were time to first fatal or non-fatal CV event. RESULTS: Median follow-up was 2.4 years. Using combined European and Other ethnicities as a reference, hazard ratios for first CV event were 1.30 for Maori (95% confidence interval 1.19-1.41), 1.04 for Pacific (0.95-1.13), 1.06 for Indo-Asian (0.91-1.24) and 0.73 for East-Asian (0.62-0.85) after controlling for all other risk factors. CONCLUSIONS: Ethnicity was independently associated with time to first CV event in people with Type 2 diabetes. Maori were at 30% higher risk of first CV event and East-Asian 27% lower risk compared with European/Other, with no significant difference in risk for Pacific and Indo-Asian peoples.

Associations of acculturation and socioeconomic status with subclinical cardiovascular disease in the multi-ethnic study of atherosclerosis.

OBJECTIVES: We assessed whether markers of acculturation (birthplace and number of US generations) and socioeconomic status (SES) are associated with markers of subclinical cardiovascular disease-carotid artery plaque, internal carotid intima-media thickness, and albuminuria-in 4 racial/ethnic groups. METHODS: With data from the Multi-Ethnic Study of Atherosclerosis (n = 6716 participants aged 45-84 years) and race-specific binomial regression models, we computed prevalence ratios adjusted for demographics and traditional cardiovascular risk factors. RESULTS: The adjusted US- to foreign-born prevalence ratio for carotid plaque was 1.20 (99% confidence interval [CI] = 0.97, 1.39) among Whites, 1.91 (99% CI = 0.94, 2.94) among Chinese, 1.62 (99% CI = 1.28, 2.06) among Blacks, and 1.23 (99% CI = 1.15, 1.31) among Hispanics. Greater carotid plaque prevalence was found among Whites, Blacks, and Hispanics with a greater number of generations with US residence (P < .001) and among Whites with less education and among Blacks with lower incomes. Similar associations were observed with intima-media thickness. There was also evidence of an inverse association between albuminuria and SES among Whites and Hispanics. CONCLUSIONS: Greater US acculturation and lower SES were associated with a higher prevalence of carotid plaque and greater intima-media thickness but not with albuminuria. Maintenance of healthful habits among recent immigrants should be encouraged.

Racial and ethnic differences in microalbuminuria prevalence in a diabetes population: the pathways study.

The objective of this study was to determine whether racial or ethnic differences in prevalence of diabetic microalbuminuria were observed in a large primary care population in which comparable access to health care exists. A cross-sectional analysis of survey and automated laboratory data 2969 primary care diabetic patients of a large regional health maintenance organization was conducted. Study data were analyzed for racial/ethnic differences in microalbuminuria (30 to 300 mg albumin/g creatinine) and macroalbuminuria (>300 mg albumin/g creatinine) prevalence among diabetes registry-identified patients who completed a survey that assessed demographics, diabetes care, and depression. Computerized pharmacy, hospital, and laboratory data were linked to survey data for analysis. Racial/ethnic differences in the odds of microalbuminuria and macroalbuminuria were assessed by unconditional logistic regression, stratified by the presence of hypertension. Among those tested, the unadjusted prevalence of micro- or macroalbuminuria was 30.9%, which was similar among the various racial/ethnic groups. Among those without hypertension, microalbuminuria was twofold greater (odds ratio [OR] 2.01; 95% confidence interval [CI] 1.14 to 3.53) and macroalbuminuria was threefold greater (OR 3.17; 95% CI 1.09 to 9.26) for Asians as compared with whites. Among those with hypertension, adjusted odds of microalbuminuria were greater for Hispanics (OR 3.82; 95% CI 1.16 to 12.57) than whites, whereas adjusted odds of macroalbuminuria were threefold greater for blacks (OR 3.32; 95% CI 1.26 to 8.76) than for whites. For most racial/ethnic minorities, hypertriglyceridemia was significantly associated with greater odds of micro- and macroalbuminuria. Among a large primary care population, racial/ethnic differences exist in the adjusted prevalence of microalbuminuria and macroalbuminuria depending on hypertension status. In this setting, racial/ethnic differences in early diabetic nephropathy were observed despite comparable access to diabetes care.