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1.  Association between Anxiety Levels and Weight Change in the Multiethnic Study of Atherosclerosis 
Journal of Obesity  2014;2014:894627.
Objective. To examine the association between anxiety and weight change in a multiethnic cohort followed for approximately 10 years. Methods. The study population consisted of participants of the multiethnic study of atherosclerosis who met specified inclusion criteria (n = 5,799). Weight was measured at baseline and four subsequent follow-up exams. Anxiety was analyzed as sex-specific anxiety quartiles (QANX). The relationship between anxiety level and weight change was examined using a mixed-effect model with weight as the dependent variable, anxiety and time as the independent variables, and adjusted for covariates. Results. Average annual weight change (range) was −0.17 kg (−6.04 to 4.38 kg) for QANX 1 (lowest anxiety), −0.16 kg (−10.71 to 4.45 kg) for QANX 2, −0.15 kg (−8.69 to 6.39 kg) for QANX 3, and −0.20 kg (−7.12 to 3.95 kg) for QANX 4 (highest anxiety). No significant association was noted between QANX and weight change. However, the highest QANX was associated with a −2.48 kg (95% CI = −3.65, −1.31) lower baseline weight compared to the lowest QANX after adjustment for all covariates. Conclusions. Among adults, age 45–84, higher levels of anxiety, defined by the STPI trait anxiety scale, are associated with lower average baseline weight but not with weight change.
doi:10.1155/2014/894627
PMCID: PMC4206924  PMID: 25374677
2.  Influence of Urine Creatinine Concentrations on the Relation of Albumin-Creatinine Ratio With Cardiovascular Disease Events: The Multi-Ethnic Study of Atherosclerosis (MESA) 
Background
Higher urine albumin-creatinine ratio (ACR) is associated with cardiovascular disease (CVD) events, an association that is stronger than that between spot urine albumin on its own and CVD. Urine creatinine is correlated with muscle mass, and low muscle mass is also associated with CVD. Whether low urine creatinine in the denominator of the ACR contributes to the association of ACR with CVD is uncertain.
Study Design
Prospective cohort study.
Setting & Participants
6,770 community-living individuals without CVD.
Predictors
Spot urine albumin, the reciprocal of the urine creatinine concentration (1/UCr), and ACR.
Outcome
Incident CVD events.
Results
During a mean of 7.1 years’ follow-up, 281 CVD events occurred. Geometric means for spot urine creatinine, urine albumin and ACR were 95 ± 2 (SD) mg/dl, 0.7 ± 3.7 mg/dl and 7.0 ± 3.1 mg/g. Adjusted HRs per 2-fold higher increment in each urinary measures with CVD events were similar (1/UCr: 1.07 [95% CI, 0.94-1.22]; urine albumin: 1.08 [95% CI, 1.01-1.14]; and ACR: 1.11 [95% CI, 1.04-1.18]). Urine creatinine was lower in older, female, and low weight individuals. ACR ≥10 mg/g was more strongly associated with CVD events in individuals with low weight (HR for lowest vs. highest tertile: 4.34 vs. 1.97; p for interaction=0.006). Low weight also modified the association of urine albumin with CVD (p for interaction=0.06), but 1/urine creatinine did not (p for interaction=0.9).
Limitations
We lacked 24-hour urine data.
Conclusions
While ACR is more strongly associated with CVD events among persons with low body weight, this association is not driven by differences in spot urine creatinine. Overall, the associations of ACR with CVD events appear to be driven primarily by urine albumin and less by urine creatinine.
doi:10.1053/j.ajkd.2013.05.010
PMCID: PMC3783582  PMID: 23830183
3.  Association of Obesity and Kidney Function Decline among Non-Diabetic Adults with eGFR > 60 ml/min/1.73m2: Results from the Multi-Ethnic Study of Atherosclerosis (MESA) 
Background
Obesity is associated with higher end-stage renal disease incidence, but associations with earlier forms of kidney disease remain incompletely characterized.
Methods
We studied the association of body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) with rapid kidney function decline and incident chronic kidney disease in 4573 non-diabetic adults with eGFR ≥ 60 ml/min/1.73m2 at baseline from longitudinal Multi-Ethnic Study of Atherosclerosis cohort. Kidney function was estimated by creatinine and cystatin C. Multivariate analysis was adjusted for age, race, baseline eGFR, and hypertension.
Results
Mean age was 60 years old, BMI 28 kg/m2, baseline eGFRCr 82 and eGFRCys 95 ml/min/1.73m2. Over 5 years of follow up, 25% experienced rapid decline in renal function by eGFRCr and 22% by eGFRCys. Incident chronic kidney disease (CKD) developed in 3.3% by eGFRCys, 11% by eGFRCr, and 2.4% by both makers. Compared to persons with BMI < 25, overweight (BMI 25 – 30) persons had the lowest risk of rapid decline by eGFRCr (0.84, 0.71 – 0.99). In contrast, higher BMI categories were associated with stepwise higher odds of rapid decline by eGFRCys, but remained significant only when BMI ≥ 35 kg/m2 (1.87, 1.41 – 2.48). Associations of BMI with incident CKD were insignificant after adjustment. Large WC and WHR were associated with increased risk of rapid decline only by eGFRCys, and of incident CKD only when defined by both filtration markers.
Conclusions
Obesity may be a risk factor for kidney function decline, but associations vary by filtration marker used.
PMCID: PMC4157691  PMID: 25210651
Kidney Function Decline; MESA; Obesity; Waist Circumference; Waist-to-Hip Ratio
4.  Lifestyle-Related Factors, Obesity, and Incident Microalbuminuria: The CARDIA (Coronary Artery Risk Development in Young Adults) Study 
Background
Modifiable lifestyle-related factors are associated with risk of coronary heart disease and may also influence kidney disease risk.
Study Design
Community-based prospective cohort study.
Setting & Participants
2354 African-American and white participants ages 28–40 years, without baseline microalbuminuria or estimated glomerular filtration rate <60 ml/min/1.73 m2 recruited from four U.S. centers: Birmingham AL, Chicago IL, Minneapolis MN, and Oakland CA.
Factors
Current smoking, physical activity, fast food habits, obesity, and diet quality, which was based on 8 fundamental components of the Dietary Approaches to Stop Hypertension (DASH) diet, including increased intake of fruits, vegetables, low-fat dairy products, whole grains, nuts and legumes, and reduced intake of sodium, sugar sweetened beverages, and red and processed meats.
Outcomes & Measurements
Spot urine albumin-creatinine ratios (ACRs) were obtained at baseline (1995–96) and 3 5-year follow-up examinations (5, 10, and 15 years follow-up). Incident microalbuminuria was defined as presence of race and sex-adjusted ACR ≥25 mg/g at 2 or more of the successive follow-up examinations.
Results
Over the 15-year follow-up period, 77 individuals (3.3%) developed incident microalbuminuria. After multivariable adjustment, poor diet quality (OR, 2.0; 95% CI, 1.1–3.4) and obesity (OR, 1.9; 95% CI, 1.1–3.3) were significantly associated with microalbuminuria; current smoking (OR, 1.6; 95% CI, 0.9–2.8) was associated with microalbuminuria although the CI crossed 1.0. Neither low physical activity (OR, 1.0; 95% CI, 0.5–1.8) nor fast food consumption (OR, 1.2; 95% CI, 0.7–2.3) were associated with microalbuminuria. Compared to individuals with no unhealthy lifestyle-related factors (poor diet quality, current smoking and obesity), adjusted odds of incident microalbuminuria were 131%, 273%, and 634% higher for presence of 1 (OR, 2.3; 95% CI, 1.3–4.3), 2 (OR, 3.7; 95% CI, 1.8–7.7), and 3 (OR, 7.3; 95% CI, 2.1–26.1) unhealthy lifestyle-related factors.
Limitations
Self-reported dietary history and physical activity, low number of outcomes.
Conclusions
Consuming an unhealthy diet and obesity are associated with incident microalbuminuria.
doi:10.1053/j.ajkd.2013.02.363
PMCID: PMC3720776  PMID: 23601954
5.  Trajectories of Kidney Function Decline in Young Black and White Adults With Preserved GFR: Results From the Coronary Artery Risk Development in Young Adults (CARDIA) Study 
Background
Strong racial discrepancies in end-stage renal disease exist. Whether there are race differences in kidney function loss in younger, healthy persons is not well established.
Study Design
Longitudinal.
Setting & Participants
3348 Black and White adults with at least two measures of cystatin C-based estimated glomerular filtration rate (eGFRcys) at scheduled Coronary Artery Risk Development in Young Adults (CARDIA) examinations (Years 10, 15, 20).
Predictor
Race.
Outcomes & Measurements
We used linear mixed models (LMM) to examine race differences in annualized rates of eGFRcys decline, adjusting for age, sex, lifetime exposure to systolic blood pressure above 120mmHg, diabetes, and albumin-creatinine ratio. We used Poisson regression to compare racial differences in rapid decline (eGFRcys decline >3% per year) by study period (10–15 years after baseline exam defining period 1 and >15–20 years after baseline exam defining period 2).
Results
Mean age was 35 ± 3.6 (SD) years, mean eGFRcys was 110 ± 20 ml/min/1.73m2 for Blacks and 104 ± 17 ml/min/1.73m2 for Whites at baseline. For both Blacks and Whites, eGFRcys decline was minimal at younger ages (<35 years) and eGFRcys loss accelerated at older ages. However, acceleration of eGFRcys decline occurred at earlier ages for Blacks than Whites. Blacks had somewhat faster annualized rates of decline compared with whites, but differences were attenuated after adjustment in period 1 (0.13 ml/min/1.73m2 per year faster; p=0.2). In contrast, during period 2, Blacks had significantly faster annualized rates of decline, even after adjustment (0.32 ml/min/1.73m2 per year faster; p=0.003). Prevalence of rapid decline was significantly higher among Blacks vs. Whites with prevalence rate ratios of 1.31 (95% CI, 1.04–1.63) for period 1 and 1.24 (95% CI, 1.09–1.41) for period 2. Differences were attenuated after full adjustment: adjusted prevalence rate ratios were 1.20 (95% CI, 0.95–1.49) for period 1 and 1.10 (95% CI, 0.96–1.26) for period 2.
Limitations
No measured GFR.
Conclusions
eGFRcys decline differs by race at early ages, with faster annualized rates of decline among blacks. Future studies are required to explain observed differences.
doi:10.1053/j.ajkd.2013.01.012
PMCID: PMC3714331  PMID: 23473985
6.  Ethnicity and Sex Modify the Association of Serum C-Reactive Protein with Microalbuminuria 
Ethnicity & disease  2008;18(3):324-329.
Objectives
To study the association between serum C-reactive protein (CRP) and urinary albumin excretion in the Multi-Ethnic Study of Atherosclerosis and to assess whether the association is modified by ethnicity, sex, or systolic blood pressure.
Methods
This was a cross-sectional study of 6675 participants who were free from macro albuminuria and clinical cardiovascular disease (mean age 62.1 years, 53% female; 39% White, 27% African American, 22% Hispanic, and 12% Chinese). Urinary albumin excretion was measured by spot urine albumin-to-creatinine ratio (ACR). Effect modifications were tested after adjusting for age, diabetes, body mass index, smoking, use of angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker, other antihypertensive drugs, estrogens, statins, and high-density lipoprotein cholesterol and triglyceride levels.
Results
The association between CRP and ACR was modified by ethnicity (P=.01) and sex (P<.001), but not by systolic blood pressure. After multivariate adjustment, the association remained in Chinese, African American, and Hispanic men and African American women (P<.02 for African American men, and P<.04 for the other subgroups).
Conclusions
The association between CRP and ACR was modified by ethnicity and sex; it was stronger in non-White men and African American women. These interactions have not been reported before, and future studies should consider them.
PMCID: PMC4089959  PMID: 18785447
Albuminuria; C-Reactive Protein; Ethnicity; Gender
7.  Association Between Coronary Artery Calcification Progression and Microalbuminuria 
JACC. Cardiovascular imaging  2010;3(6):595-604.
OBJECTIVES
This study sought to evaluate the relationship between microalbuminuria (MA) and the development and progression of atherosclerosis, as assessed by incident and progression of coronary artery calcification (CAC).
BACKGROUND
MA is associated with an increased risk of cardiovascular disease, but the mechanism by which MA imparts this increased risk is not known.
METHODS
The MESA (Multi-Ethnic Study of Atherosclerosis) study is a prospective cohort study of 6,814 self-identified White, African-American, Hispanic, or Chinese participants free of clinical cardiovascular disease at entry. Of the 6,775 individuals with available urine albumin data, we excluded 97 subjects with macroalbuminuria and 1,023 with missing follow-up CAC data. The final study population consists of 5,666 subjects.
RESULTS
At baseline, individuals with MA were more likely to have CAC >0 compared with those without MA (62% vs. 48%, p < 0.0001). During a mean follow-up of 2.4 ± 0.8 years, those with MA and no CAC at baseline were more likely to develop CAC (relative risk [RR]: 2.05, 95% confidence interval [CI]: 1.41 to 3.02, p < 0.0001) as compared with those without MA in demographic-adjusted analyses. After multivariant adjustment, the relationship was attenuated but remained statistically significant (RR: 1.76, 95% CI: 1.19 to 2.61, p = 0.005). Among those with CAC at baseline, those with versus those without MA had a 15 (95% CI: 8 to 22, p < 0.0001) volume units higher median increase in CAC in demographic-adjusted analyses. After multivariant adjustment, MA remained associated with incident CAC (RR: 1.76, 95% CI: 1.19 to 2.61, p = 0.005) and with progression of CAC (median increase in CAC volume score of 9 [95% CI: 2 to 16, p = 0.009]), relative to those without MA.
CONCLUSIONS
This large multiethnic, population-based study of asymptomatic individuals demonstrates an increased risk of incident CAC as well as greater CAC progression among those with MA. Further study is needed to determine the degree to which MA precedes and predicts progression of atherosclerosis and how this information can be used to reduce cardiovascular events.
doi:10.1016/j.jcmg.2010.01.008
PMCID: PMC4083743  PMID: 20541715
coronary artery calcium; microalbuminuria; risk prediction; coronary heart disease; Multi-Ethnic Study of Atherosclerosis
8.  Cis-vaccenic acid and the Framingham Risk Score predict chronic kidney disease: the Multi-ethnic Study of Atherosclerosis (MESA) 
SUMMARY
Introduction
Data on the associations of fatty acids with chronic kidney disease (CKD) are sparse.
Materials and Methods
We performed a cross-sectional study of 2792 men and women from the MESA cohort of African-American, Caucasian, Chinese and Hispanic adults without known cardiovascular disease. Plasma phospholipid fatty acid proportions were associated with estimated glomerular filtration rate (eGFR) and the albumin/creatinine ratio.
Results
Cis-vaccenic acid (18:1n-7), adjusted for other fatty acids using multivariate logistic regression (CI: 1.0–1.4), and step-wise logistic regression (CI: 1.02–1.42), was positively associated with reduced eGFR. The Framingham Risk Score, when adjusting for fatty acid proportions and demographic factors, was positively associated with CKD as measured by the eGFR and the albumin/creatinine ratio.
Discussion and Conclusions
Plasma phospholipid proportions of the18 carbon monounsaturated cis-vaccenic acid {18:1n-7}) and the Framingham Risk Score are associated with kidney function. The potential role of 18:1n-7 in the development of CKD warrants further investigation.
doi:10.1016/j.plefa.2012.02.009
PMCID: PMC3340522  PMID: 22417701
Fatty acids; chronic kidney disease; Framingham Heart Disease Risk Score; 18:1n-7; cisvaccenic acid; monounsaturated 18 carbon fatty acid
9.  Genetic variation in APOL1 and MYH9 genes is associated with chronic kidney disease among Nigerians 
Purpose
A region of chromosome 22 which includes APOL1 and MYH9 genes was recently identified as a risk locus for non-diabetic forms of kidney disease, including idiopathic and HIV associated focal segmental glomerular sclerosis and kidney disease clinically attributed to hypertension among African Americans. The purpose of the current study was therefore to examine the frequency of these variants and to determine whether they are associated with chronic kidney disease (CKD) among native Africans.
Methods
To investigate possible evidence of association between variants in these genes and non-diabetic CKD among West Africans, we performed a case/control analysis in a sample of 166 Nigerians without history of European admixture. Our study included a total of 9 variants on APOL1 (n=4) and MYH9 (n=5) genes.
Results
We observed significantly strong associations with previously reported APOL1 variants rs73885319 and rs60910145 and their two-allele “G1” haplotype (P < 0.005). We did not observe significant evidence of association between non-diabetic CKD and any of the MYH9 variants or haplotypes after accounting for multiple testing in our sample.
Conclusions
In conclusion, APOL1 risk variants are associated with non-diabetic forms of CKD among Nigerians of Yoruba ethnicity. Further information on APOL1/MYH9 variants may lead to screening programs which could lead to earlier detection and interventions for non-diabetic kidney disease.
doi:10.1007/s11255-012-0263-4
PMCID: PMC3599169  PMID: 22956460
chronic kidney disease; APOL1; MYH9; genetic renal disease
10.  Association of Pulse Pressure, Arterial Elasticity, and Endothelial Function With Kidney Function Decline Among Adults With Estimated GFR > 60 mL/min/1.73 m2: The Multi-Ethnic Study of Atherosclerosis 
Background
The association of subclinical vascular disease and early declines in kidney function has not been well studied.
Study Design
Prospective cohort study
Setting & Participants
MESA participants with eGFR ≥60 ml/min/1.73m2 with follow-up of 5 years
Predictors
Pulse pressure (pulse pressure), small and large arterial elasticity (SAE, LAE), and flow mediated dilation.
Outcomes
kidney function decline
Measurements
SAE and LAE were measured by pulse contour analysis of the radial artery. Kidney function was measured by serum creatinine- and cystatin C-based eGFR.
Results
Among 4,853 adults, higher pulse pressure and lower SAE and LAE had independent and linear associations with faster rates of kidney function decline. Compared to persons with pulse pressure 40–50mmHg, eGFRSCysC decline was 0.29 (p=0.006), 0.56 (p<0.001), and 0.91 (p<0.001) ml/min/1.73m2/year faster among persons with pulse pressure 50–60, 60–70, and >70mmHg, respectively. Compared to the highest quartile of SAE (most elastic), eGFRSCysC decline was 0.26 (p=0.009), 0.35 (p=0.001), and 0.70 (p<0.001) ml/min/1.73m2/year faster for the second, third and fourth quartiles respectively. For LAE, compared to the highest quartile, eGFRSCysC decline was 0.28 (p=0.004), 0.58 (p<0.001), and 0.83 (p<0.001) ml/min/1.73m2/year faster for each decreasing quartile of LAE. Findings were similar with creatinine-based eGFR. In contrast, among 2,997 adults with flow-mediated dilation and kidney function measures, flow-mediated dilation was not significantly associated with kidney function decline. For every 1-SD greater flow-mediated dilation, eGFRSCysC and eGFRSCr changed by 0.05 ml/min/1.73m2/year (p=0.3) and 0.06 ml/min/1.73m2/year (p=0.04), respectively.
Limitations
We had no direct measure of GFR, in common with nearly all large population based studies.
Conclusions
Higher pulse pressure and lower arterial elasticity, but not flow-mediated dilation, were linearly and independently associated with faster kidney function decline among persons with eGFR ≥60 ml/min/1.73m2. Future studies investigate whether treatments to lower stiffness of large and small arteries may slow the rate of kidney function loss.
doi:10.1053/j.ajkd.2011.08.015
PMCID: PMC3242889  PMID: 22000727
kidney function; arterial elasticity; chronic kidney disease; atherosclerosis
11.  Retinal arteriolar caliber and urine albumin excretion: the Multi-Ethnic Study of Atherosclerosis 
Nephrology Dialysis Transplantation  2011;26(11):3523-3528.
Background. Changes in retinal microvascular caliber, which occur prior to onset of retinopathy, may indicate presence of kidney damage.
Methods. This study examined the association between retinal arteriolar [central retinal artery equivalent (CRAE)] and venular caliber [central retinal venule equivalent (CRVE)] and presence of albuminuria (micro- or macroalbuminuria) among participants of the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort of adults aged 45–84 years without baseline clinical cardiovascular disease. During the second MESA exam, digital fundus photography was completed in 5897 participants who provided spot urine specimens. Albuminuria was defined by spot urine albumin/creatinine ratios ≥30 mg/g. Multivariable adjusted odds of albuminuria by quintiles of CRAE and CRVE were determined using logistic regression. Analyses were repeated after stratifying by presence of type 2 diabetes.
Results. Albuminuria was noted in 11.5% (n = 675) and included 584 subjects with microalbuminuria and 91 with macroalbuminuria. A significant U-shaped pattern was seen with higher prevalence of albuminuria across quintile extremes in CRAE (15.7, 8.8 and 10.6% in CRAE Quintiles 1, 3 and 5, respectively; P <0.0001). After adjustment for covariates, both narrower CRAE [odds ratios (OR) 1.55; 95% confidence interval (CI) 1.17–2.04, Quintile 1 versus 3) and wider CRAE (OR 1.44; 95% CI 1.07–1.93, Quintile 5 versus 3) were significantly associated with albuminuria. Associations appeared substantially stronger in adults with than without type 2 diabetes but the interaction term for diabetes and CRAE on presence of albuminuria did not meet statistical significance (P = 0.3). No association was noted between CRVE quintiles and albuminuria.
Conclusions. Albuminuria is associated with narrower and wider arteriolar caliber. Future studies should determine whether variation in arteriolar caliber predicts incident albuminuria and whether associations are mediated by hypertension and diabetes. Such information could further clarify early microvascular processes in the pathogenesis of kidney disease.
doi:10.1093/ndt/gfr095
PMCID: PMC3247797  PMID: 21398363
albuminuria; diabetic retinopathy; MESA (Multi-Ethnic Study of Atherosclerosis); retinal arteriolar; retinal venular
12.  Patterns of Sodium and Potassium Excretion and Blood Pressure in the African Diaspora 
Journal of Human Hypertension  2011;26(5):315-324.
Habitual levels of dietary sodium and potassium are correlated with age-related increases in blood pressure (BP) and likely play a role in this phenomenon. Although extensive published evidence exists from randomized trials, relatively few large-scale community surveys with multiple 24-hour urine collections have been reported. We obtained three 24-hour samples on 2,704 individuals from Nigeria, Jamaica and the US to evaluate patterns of intake and within-person relationships to blood pressure. The average (±s.d.) age and weight of participants across all three sites were 39.9±8.6 years and 76.1±21.2 kg, respectively, and 55% of the total participants were females. Sodium excretion increased across the East-West gradient (e.g., 123.9±54.6, 134.1±48.8, 176.6±71.0 (±s.d.) mmol, Nigeria, Jamaica and US, respectively), while potassium was essentially unchanged (e.g., 46.3±22.9, 40.7±16.1, 44.7±16.4 (±s.d.) mmol, respectively). In multivariate analyses both sodium (positively) and potassium (negatively) were strongly correlated with blood pressure (p < 0.001); quantitatively the association was stronger, and more consistent in each site individually, for potassium. Within-population day-to-day variation was also greater for sodium than for potassium. Among each population group a significant correlation was observed between sodium and urine volume, supporting the prior finding of sodium as a determinant of fluid intake in free-living individuals. These data confirm the consistency with the possible role of dietary electrolytes as hypertension risk factors, reinforcing the relevance of potassium in these populations.
doi:10.1038/jhh.2011.39
PMCID: PMC3158967  PMID: 21593783
blood pressure; sodium excretion; potassium excretion; African Diaspora
13.  Mortality Rates Across 25-Hydroxyvitamin D (25[OH]D) Levels among Adults with and without Estimated Glomerular Filtration Rate <60 ml/min/1.73 m2: The Third National Health and Nutrition Examination Survey 
PLoS ONE  2012;7(10):e47458.
Background
Previous studies exploring the association between 25[OH]D levels and mortality in adults with and without kidney disease utilized 25[OH]D thresholds that have recently been scrutinized by the Institute of Medicine Committee to Review Dietary References Intakes for Vitamin D and Calcium.
Objective
We explored all-cause mortality rates across the spectrum of 25[OH]D levels over an eighteen-year follow-up among adults with and without an estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2.
Design
The study included 1,097 U.S. adults with eGFR <60 ml/min/1.73 m2 and 14, 002 adults with eGFR ≥60 ml/min/1.73 m2. Mortality rates and rate ratios (RR) across 25[OH]D groups were calculated with Poisson regression and restricted cubic splines while adjusting for covariates.
Results
Prevalence of 25[OH]D levels <30 and <20 ng/ml among adults with eGFR <60 ml/min/1.73 m2 was 76.5% (population estimate 6.2 million) and 35.4% (population estimate 2.9 million), respectively. Among adults with eGFR ≥60 ml/min/1.73 m2, 70.5% had 25[OH]D levels <30 ng/ml (population estimate 132.2 million) while 30.3% had 25[OH]D levels <20 ng/ml (population estimate 56.8 million). Significantly higher mortality rates were noted among individuals with 25[OH]D levels <12 ng/ml compared to referent group (24 to <30 ng/ml): RR1.41 (95% CI 1.17, 1.71) among individuals with eGFR <60 ml/min/1.73 m2 and RR 1.32 (95% CI 1.13, 1.56) among individuals with eGFR ≥60 ml/min/1.73 m2 after adjustment for covariates including co-morbid conditions. Mortality rates were fairly similar across all 25[OH]D groups with levels >20 ng/ml after adjustment for all covariates.
Conclusions
Regardless of presence of eGFR <60 ml/min/1.73 m2, mortality rates across groups with 25[OH]D levels 20–40 ng/ml are similar.
doi:10.1371/journal.pone.0047458
PMCID: PMC3480387  PMID: 23112816
14.  The Effect of Including Cystatin C or Creatinine in a Cardiovascular Risk Model for Asymptomatic Individuals 
American Journal of Epidemiology  2011;174(8):949-957.
The authors studied the incremental value of adding serum cystatin C or creatinine to the Framingham risk score variables (FRSVs) for the prediction of incident cardiovascular disease (CVD) among 6,653 adults without clinical CVD utilizing the Multi-Ethnic Study of Atherosclerosis (2000–2008). CVD events included coronary heart disease, heart failure, stroke, and peripheral arterial disease. Variables were transformed to yield optimal prediction of 6-year CVD events in sex-stratified models with FRSVs alone, FRSVs + cystatin C, and FRSVs + creatinine. Risk prediction in the 3 models was assessed by using the C statistic, and net reclassification improvement was calculated. The mean ages were 61.9 and 64.6 years for individuals with and without diabetes, respectively. After 6 years of follow-up, 447 (7.2%) CVD events occurred. In the total cohort, no significant change in the C statistic was noted with FRSVs + cystatin C and FRSVs + creatinine compared with FRSVs alone, and net reclassification improvement for CVD risk was extremely small and not significant with the addition of cystatin C or creatinine to FRSVs. Similar findings were noted after stratifying by baseline presence of diabetes. In conclusion, the addition of cystatin C or serum creatinine to FRSVs does not improve CVD risk prediction among adults without clinical CVD.
doi:10.1093/aje/kwr185
PMCID: PMC3218629  PMID: 21880578
cardiovascular diseases; creatinine; cystatin C; risk model
15.  Genetic variation in APOL1 and MYH9 genes is associated with chronic kidney disease among Nigerians 
Purpose
A region of chromosome 22 which includes APOL1 and MYH9 genes was recently identified as a risk locus for non-diabetic forms of kidney disease, including idiopathic and HIV-associated focal segmental glomerular sclerosis and kidney disease clinically attributed to hypertension among African Americans. The purposes of the current study were, therefore, to examine the frequency of these variants and to determine whether they are associated with chronic kidney disease (CKD) among native Africans.
Methods
To investigate the possible evidence of association between variants in these genes and non-diabetic CKD among West Africans, we performed a case/control analysis in a sample of 166 Nigerians without history of European admixture. Our study included a total of 9 variants on APOL1 (n = 4) and MYH9 (n = 5) genes.
Results
We observed significantly strong associations with previously reported APOL1 variants rs73885319 and rs60910145, and their two-allele “G1” haplotype (P < 0.005). We did not observe significant evidence of association between non-diabetic CKD and any of the MYH9 variants or haplotypes after accounting for multiple testing in our sample.
Conclusions
In conclusion, APOL1 risk variants are associated with non-diabetic forms of CKD among Nigerians of Yoruba ethnicity. Further information on APOL1/MYH9 variants may lead to screening programs, which could lead to earlier detection and interventions for non-diabetic kidney disease.
doi:10.1007/s11255-012-0263-4
PMCID: PMC3599169  PMID: 22956460
Chronic kidney disease; APOL1; MYH9; Genetic renal disease
16.  Association of Waist Circumference and Body Mass Index With All-Cause Mortality in CKD: The REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study 
Background
Obesity management requires understanding of the mortality risks associated with different adiposity measures.
Study Design
Prospective cohort
Setting and Participants
5,805 adults with BMI ≥ 18.5 and stage 1–4 CKD defined by a spot urine albumin-creatinine ratio ≥ 30 mg/g and/or an estimated glomerular filtration rate < 60 ml/min/1.73 m2 enrolled in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study
Predictor
Body mass index (BMI) in kg/m2 categorized as 18.5–24.9, 25.0–29.9, 30.0–34.9, 35.0–39.9 and ≥ 40 kg/m2 and waist circumference categorized as < 80, 80–87.9, 88–97.9, 98–107.9, and ≥ 108 cm in women and < 94, 94–101.9, 102–111.9, 112–121.9, and ≥122 cm in men.
Outcomes
All cause mortality
Measurements
BMI and WC were measured using a standardized protocol during the home visit.
Results
A total of 686 deaths (11.8%) occurred during a median follow-up of 4 years. Compared to the referent BMI category 25–29.9 kg/m2, hazard ratios for mortality were 1.27 (95% CI, 0.96–1.69) for BMI < 25 kg/m2, and 0.84 (95% CI, 0.62–1.13), 0.81 (0.52–1.26) and 0.95 (95% CI, 0.54–1.65) for BMI categories 30–34.9, 35–39.9 and ≥ 40 kg/m2, respectively, after adjustment for covariates including waist circumference. In contrast, after adjustment for covariates including BMI, higher mortality rates were noted for all waist circumference categories compared to the referent (< 80 cm in women and < 94 cm in men) with hazard ratios 1.04 (95% CI, 0.77–1.41) for waist circumference 80–87.9 in women and 94–101.9 in men, 1.29 (95% CI, 0.92–1.81) for waist circumference 88–97.9 in women and 102–111.9 in men, 1.72 (95% CI, 1.12–2.62) for waist circumference 98–107.9 in women and 112–121.9 in men, and 2.09 (95% CI, 1.26–3.46) for waist circumference ≥ 108 in women and ≥ 122 in men.
Limitations
BMI and waist circumference measured at baseline only.
Conclusions
waist circumference should be considered in conjunction with BMI when assessing mortality risk associated with obesity in adults with CKD.
doi:10.1053/j.ajkd.2011.02.390
PMCID: PMC3144322  PMID: 21601327
Obesity; waist circumference; mortality; chronic kidney disease
17.  Retinal Arteriolar Narrowing and Subsequent Development of CKD Stage 3: The Multi-Ethnic Study of Atherosclerosis (MESA) 
Background
Microvascular disease is a major pathogenic factor for chronic kidney disease (CKD) in persons with diabetes, but the role of microvascular disease in the development of CKD in the general population is unclear. The aim of this study is to examine whether microvascular disease precedes the development of CKD stage 3 in participants of the Multi-Ethnic Study of Atherosclerosis (MESA).
Study Design
Population-based cohort study.
Setting & Participants
MESA is a prospective cohort study of adults aged 45-84 years living in 6 US communities; 4,594 adults with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 when they underwent retinal photography (visit 2: in 2002-2004) were examined.
Predictor
Retinal microvascular caliber measured from fundus photographs.
Outcomes
Incident CKD stage 3 (ie, eGFR <60 mL/min/1.73 m2) at 2 subsequent follow-up examinations (visit 3 in 2004-2005, and visit 4 in 2005-2007) and an annual eGFR decrease >1 mL/min/1.73 m2 computed using the CKD Epidemiology Collaboration (CKD-EPI) equation.
Results
After a median follow-up of 4.8 years, there were 232 incident CKD stage 3 cases. Overall, retinal microvascular caliber was not associated with incident CKD stage 3. However, in race-stratified analysis, narrower arterioles in whites was associated with a higher risk of developing CKD stage 3 after adjusting for age, sex, blood pressure, diabetes, and other factors (HR, 1.78; 95% CI, 1.01-3.15; P = 0.04, lowest vs highest arteriolar caliber tertile). This association was seen even in whites without hypertension and diabetes (HR, 2.95; 95% CI, 1.10-7.98; P = 0.03). Retinal arteriolar caliber was not associated with incident CKD stage 3 in African Americans, Chinese, or Hispanics.
Limitations
Analyses were based on a single eGFR measurement, and retinal microvascular caliber and eGFR measurements were not ascertained concurrently.
Conclusion
Microvascular changes as manifest in the eye may contribute to the development of CKD stage 3 in whites.
doi:10.1053/j.ajkd.2011.02.382
PMCID: PMC3197818  PMID: 21549464
Microvascular changes; retinal microvascular caliber; chronic kidney disease
18.  Cystatin C and Albuminuria as Risk Factors for Development of CKD Stage 3: The Multi-Ethnic Study of Atherosclerosis (MESA) 
Background
The growing burden and morbidity of chronic kidney disease (CKD) warrant effective strategies for identifying those at increased risk. We examined the association of cystatin C and albuminuria with development of CKD stage 3.
Study Design
Prospective observational study.
Setting and Participants
5,422 participants from the Multi-Ethnic Study of Atherosclerosis with estimated glomerular filtration rate (eGFR) ≥ 60 ml/min/1.73m2.
Predictor
Participants were categorized into four mutually exclusive groups: presence or absence of microalbuminuria (albumin-creatinine ratio >17 and > 25 µg/mg in men and women, respectively) in those with or without cystatin C ≥ 1.0 mg/L.
Outcomes and Measurements
Incident CKD stage 3 was defined as eGFR < 60 ml/min/1.73m2 at the 3rd or 4th visit and an annual decline of > 1 ml/min/1.73 m2. Poisson regression was used to evaluate incident rate ratios in unadjusted and adjusted analyses that include baseline eGFR.
Results
Mean age was 61 years, 49% were men, 38% white, 11% had diabetes, 13.7% had cystatin C ≥ 1mg/L, 8.4% had microalbuminuria, and 2.7 % had cystatin C ≥ 1 mg/L with microalbuminuria. 554 (10%) participants developed CKD stage 3 over a median follow-up of 4.7 years and the adjusted incidence rate ratios (95% CI) were 1.57 (1.19–2.07), 1.37 (1.13–1.66), and 2.12 (1.61–2.80) in those with microalbuminuria, cystatin C ≥ 1 mg/L, and both, respectively, compared to those with neither.
Limitations
Relatively short follow up and absence of measured GFR.
Conclusions
Cystatin C and microalbuminuria are independent risk factors for incident CKD stage 3 and could be useful as screening tools to identify those at increased risk.
doi:10.1053/j.ajkd.2010.11.021
PMCID: PMC3090544  PMID: 21296473
19.  Genetic Association for Renal Traits among Participants of African Ancestry Reveals New Loci for Renal Function 
PLoS Genetics  2011;7(9):e1002264.
Chronic kidney disease (CKD) is an increasing global public health concern, particularly among populations of African ancestry. We performed an interrogation of known renal loci, genome-wide association (GWA), and IBC candidate-gene SNP association analyses in African Americans from the CARe Renal Consortium. In up to 8,110 participants, we performed meta-analyses of GWA and IBC array data for estimated glomerular filtration rate (eGFR), CKD (eGFR <60 mL/min/1.73 m2), urinary albumin-to-creatinine ratio (UACR), and microalbuminuria (UACR >30 mg/g) and interrogated the 250 kb flanking region around 24 SNPs previously identified in European Ancestry renal GWAS analyses. Findings were replicated in up to 4,358 African Americans. To assess function, individually identified genes were knocked down in zebrafish embryos by morpholino antisense oligonucleotides. Expression of kidney-specific genes was assessed by in situ hybridization, and glomerular filtration was evaluated by dextran clearance. Overall, 23 of 24 previously identified SNPs had direction-consistent associations with eGFR in African Americans, 2 of which achieved nominal significance (UMOD, PIP5K1B). Interrogation of the flanking regions uncovered 24 new index SNPs in African Americans, 12 of which were replicated (UMOD, ANXA9, GCKR, TFDP2, DAB2, VEGFA, ATXN2, GATM, SLC22A2, TMEM60, SLC6A13, and BCAS3). In addition, we identified 3 suggestive loci at DOK6 (p-value = 5.3×10−7) and FNDC1 (p-value = 3.0×10−7) for UACR, and KCNQ1 with eGFR (p = 3.6×10−6). Morpholino knockdown of kcnq1 in the zebrafish resulted in abnormal kidney development and filtration capacity. We identified several SNPs in association with eGFR in African Ancestry individuals, as well as 3 suggestive loci for UACR and eGFR. Functional genetic studies support a role for kcnq1 in glomerular development in zebrafish.
Author Summary
Chronic kidney disease (CKD) is an increasing global public health problem and disproportionately affects populations of African ancestry. Many studies have shown that genetic variants are associated with the development of CKD; however, similar studies are lacking in African ancestry populations. The CARe consortium consists of more than 8,000 individuals of African ancestry; genome-wide association analysis for renal-related phenotypes was conducted. In cross-ethnicity analyses, we found that 23 of 24 previously identified SNPs in European ancestry populations have the same effect direction in our samples of African ancestry. We also identified 3 suggestive genetic variants associated with measurement of kidney function. We then tested these genes in zebrafish knockdown models and demonstrated that kcnq1 is involved in kidney development in zebrafish. These results highlight the similarity of genetic variants across ethnicities and show that cross-species modeling in zebrafish is feasible for genes associated with chronic human disease.
doi:10.1371/journal.pgen.1002264
PMCID: PMC3169523  PMID: 21931561
20.  Associations between Genetic Variants in the ACE, AGT, AGTR1 and AGTR2 Genes and Renal Function in the Multi-Ethnic Study of Atherosclerosis 
American Journal of Nephrology  2010;32(2):156-162.
Background/Aims
Some studies suggest that polymorphisms in angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II type I receptor (AGTR1) and angiotensin II type II receptor (AGTR2) genes may contribute to renal function variation.
Methods
Genotyping for single nucleotide polymorphisms (SNPs) in these candidate genes was performed in 2,847 participants from four racial/ethnic groups (African American, Chinese, White and Hispanic) without known cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis. SNP and haplotype analyses were performed to determine associations between genotypes and cross-sectional renal function measurements, including urine albumin excretion (UAE) and estimated glomerular filtration rate (eGFR) using serum creatinine and cystatin C.
Results
Twenty-four ACE SNPs, 10 AGT SNPs, 15 AGTR1 SNPs and 6 AGTR2 SNPs were typed successfully. After adjusting for ancestry, age and gender, 3 SNPs (AGT M235T, AGT rs2148582 and AGTR1 rs2131127) showed associations with an empiric p value <0.05 with the same phenotype in multiple racial/ethnic groups, suggesting replication. The AGT M235T SNP has been shown previously to be associated with diabetic and hypertensive nephropathy. Conclusions: These data suggest that genetic polymorphisms in the renin-angiotensin system are associated with renal phenotypes in the general population, but that many associations differ across racial/ethnic groups.
doi:10.1159/000315866
PMCID: PMC2941827  PMID: 20606419
Renin-angiotensin; ACE; AGT; AGTR1; AGTR2; Albuminuria; Creatinine clearance epidemiology; Genetics
21.  The Association of Chronic Kidney Disease and Metabolic Syndrome with Incident Cardiovascular Events: Multiethnic Study of Atherosclerosis 
Background. There is an association between chronic kidney disease (CKD) and metabolic syndrome (MetS). We examined the joint association of CKD and MetS with incident cardiovascular (CVD) events in the Multiethnic Study of Atherosclerosis (MESA) cohort. Methods. We analyzed 2,283 Caucasians, 363 Chinese, 1,449 African-Americans, and 1,068 Hispanics in the MESA cohort. CKD was defined by cystatin C estimated glomerular filtration rate ≤ 60 mL/min/1.73 m2 and MetS was defined by NCEP criteria. Cox proportional regression adjusting for age, ethnicity, gender, study site, education, income, smoking, alcohol use, physical activity, and total and LDL cholesterol was performed to assess the joint association of CKD and MetS with incident CVD events. Participants were divided into four groups by presence of CKD and/or MetS and compared to the group without CKD and MetS (CKD−/MetS−). Tests for additive and multiplicative interactions between CKD and MetS and prediction of incident CVD were performed. Results. During follow-up period of 5.5 years, 283 participants developed CVD. Multivariate Cox regression analysis demonstrated that CKD and MetS were independent predictors of CVD (hazard ratio, 2.02 for CKD, and 2.55 for MetS). When participants were compared to the CKD−/MetS− group, adjusted HR for the CKD+/MetS+ group was 5.56 (95% CI 3.72–8.12). There was no multiplicative interaction between CKD and MetS (P = 0.2); however, there was presence of additive interaction. The relative excess risk for additive interaction (RERI) was 2.73, P = 0.2, and the attributable portion (AP) was 0.49 (0.24–0.74). Conclusion. Our findings illustrate that the combination of CKD and MetS is a strong predictor of incident clinical cardiovascular events due to presence of additive interaction between CKD and MetS.
doi:10.1155/2012/806102
PMCID: PMC3154776  PMID: 21860804
22.  Baseline depressive symptoms are not associated with clinically important levels of incident hypertension during two years of follow-up: the Multi-Ethnic Study of Atherosclerosis 
Hypertension  2010;55(2):408.
Previous longitudinal cohort studies have suggested an association between baseline depressive symptoms and incident hypertension. We assessed this possible association using data from the Multi-ethnic Study of Atherosclerosis, a population-based prospective cohort study of 6,814 US adults from 4 different racial/ethnic groups. Baseline users of antihypertensive medications and participants lost to follow-up were excluded leaving 3914 participants. Patients with baseline depressive symptoms (n=622) were defined using a high score on the Center for Epidemiologic Studies Depression Scale (≥ 16) or the use of an antidepressant medication. Hypertension was defined as systolic blood pressure ≥ 140, diastolic blood pressure ≥90 or new use of antihypertensive medications plus physician diagnosis. Estimates were adjusted for known risk factors including: age, sex, baseline blood pressure, diabetes, and body mass index. Untreated blood pressure was estimated using an imputation approach. A total of 477 participants developed hypertension. Using relative risk regression, patients with baseline depressive symptoms did not have an increased risk of incident hypertension (Relative Risk = 1.02; 95% Confidence Interval (CI):0.99 to 1.05) although an association between tricyclic antidepressants and hypertension (Relative Risk 1.20; 95% CI:1.05 to 1.37) was observed in sub-group analysis. Depression, even after adjustment for covariates, was associated with small changes in systolic (+2.4 mmHG; 95% CI: 0.2 to 4.7) and diastolic (+0.8 mmHG; 95% CI: −0.6 to 2.3) blood pressure. Depressive symptoms may be associated with slight increases in blood pressure in this multi-ethnic cohort but it is premature to conclude much without longer studies in other populations.
doi:10.1161/HYPERTENSIONAHA.109.139824
PMCID: PMC2821214  PMID: 20065156
Multi-Ethnic Study of Atherosclerosis; depression; hypertension; blood pressure; imputation; censored normal regression
23.  Obesity and Albuminuria Among Adults With Type 2 Diabetes 
Diabetes Care  2009;32(5):851-853.
OBJECTIVE
To determine the association between obesity measures and albuminuria in adults with type 2 diabetes.
RESEARCH DESIGN AND METHODS
In the Look AHEAD (Action for Health in Diabetes) Study, BMI and waist circumference were measured among 4,985 participants while total percent body fat was measured by whole-body DEXA scans among 1,351 participants. Odds of albuminuria by quartiles of BMI, waist circumference, and percent total body fat were calculated using logistic regression analysis while adjusting for covariates.
RESULTS
The highest quartile of BMI (odds ratio [OR] 1.72 [95% CI 1.40–2.11]) and waist circumference (OR 1.75 [95% CI 1.42–2.15]) was significantly associated with albuminuria compared with the lowest quartile after adjustment for covariates. No associations were noted between quartiles of percent total body fat and albuminuria in any model.
CONCLUSIONS
Increased BMI and abdominal obesity are associated with albuminuria in overweight and obese adults with type 2 diabetes.
doi:10.2337/dc08-2059
PMCID: PMC2671132  PMID: 19196893
24.  The Association of Cell Cycle Checkpoint 2 Variants and Kidney Function: Findings of the Family Blood Pressure Program and the Atherosclerosis Risk in Communities Study 
American journal of hypertension  2009;22(5):552-558.
BACKGROUND
Recent experimental evidence suggests that DNA damage and cell cycle regulatory proteins are involved in kidney injury and apoptosis. The checkpoint 2 gene (CHEK2) is an important transducer in DNA damage signaling pathways in response to injury, and therefore, CHEK2 variants may affect susceptibility to kidney disease.
METHODS
We used tag-single-nucleotide polymorphisms (tag-SNPs) to evaluate the association of the CHEK2 with kidney function (estimated glomerular filtration rate, eGFR) in 1,549 African-American and 1,423 white Hypertension Genetic Epidemiology Network (HyperGEN) participants. We performed replication analyses in the Genetic Epidemiology Network of Arteriopathy (GENOA) participants (1,746 African Americans and 1,418 whites), GenNet participants (706 whites), and Atherosclerosis Risk in Communities (ARIC) study participants (3,783 African Americans and 10,936 whites). All analyses were race-stratified and used additive genetic models with adjustments for covariates and for family structure, if needed.
RESULTS
One tag-SNP, rs5762764, was associated with eGFR in HyperGEN P = (0.003) and GENOA white participants (P = 0.009), and it was significantly associated with eGFR in meta-analyses (P = 0.002). The associations were independent of type 2 diabetes.
CONCLUSIONS
These results suggest that CHEK2 variants may influence eGFR in the context of hypertension.
doi:10.1038/ajh.2009.41
PMCID: PMC2727134  PMID: 19265784
25.  The Differential Association of Kidney Dysfunction With Small and Large Arterial Elasticity 
American Journal of Epidemiology  2009;169(6):740-748.
Vascular remodeling may be a mechanism linking chronic kidney disease to cardiovascular disease. Whether early kidney dysfunction is associated with small and large arterial remodeling is not well understood. Using multivariable linear regression, back-transforming beta-coefficients to relative difference, the authors studied the association of cystatin C, creatinine-based estimated glomerular filtration rate (GFR), and albuminuria with small (SAE) and large (LAE) arterial elasticity and aortic distensibility among 6,282 participants in the Multiethnic Study of Atherosclerosis at baseline (2000–2002). Compared with the lowest quintile, higher quintiles of cystatin C were incrementally associated with lower SAE: third quintile relative difference = −5% (95% confidence interval (CI): −8, −2); fourth quintile relative difference = −10% (95% CI: −13, −8); and highest quintile relative difference = −16% (95% CI: −20, −12). By use of creatinine, the association was observed only among those with chronic kidney disease (estimated GFR, <60 mL/minute/1.73 m2): relative difference = −9% (95% CI: −13, −4). Albuminuria was significantly associated with lower SAE: relative difference = −6% (95% CI: −10, −1). Cystatin C was associated with lower LAE only at the highest quintile (relative difference = −3%, 95% CI: −6, 0) compared with the lowest quintile. By use of creatinine, chronic kidney disease was not independently associated with LAE (P = 0.912). Cystatin C, estimated GFR, and albuminuria were not associated with aortic distensibility (P = 0.26, 0.48, 0.45). Early kidney dysfunction is significantly associated with decreased arterial elasticity in smaller arteries and, to a lesser degree, in larger arteries.
doi:10.1093/aje/kwn392
PMCID: PMC2727212  PMID: 19131564
albuminuria; cystatin C; elasticity; kidney; kidney diseases

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