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1.  High Prevalence and Diversity of Kidney Dysfunction in Patients with Type 2 Diabetes Mellitus and Coronary Artery Disease: The BARI 2D Baseline Data 
Background
We describe baseline renal function and albumin excretion rate in patients enrolled in BARI 2D, a randomized clinical trial comparing revascularization and medical therapy with medical therapy alone and deferred or no revascularization, and the impact of glycemic control with either insulin providing or insulin sensitizing drugs, on 5 year mortality.
Methods
Study participants had T2DM, documented CAD, and creatinine < 2 mg/dl. Albuminuria status (albumin/creatinine ratio [ACR]) and estimated glomerular filtration rate (eGFR), utilizing the abbreviated MDRD equation, were determined at baseline. Univariate and multivariate relationships between baseline clinical characteristics and the presence of albuminuria and reduced eGFR rate were estimated.
Results
2146 subjects were included in the analysis. 43% of the cohort had evidence of kidney dysfunction at baseline: 23% had an eGFR ≥ 60 ml/min/1.73 m2 with either micro (>30 ACR; 17%) or macro (> 300 ACR; 6%) albuminuria. 21 % had a reduced eGFR < 60 ml/min/1.73 m2; 52 % with reduced eGFR had no albuminuria; 28 % had microalbuminuria and 20 % had macroalbuminuria. Race, smoking status, duration of diabetes, hypertension, HbA1c, triglycerides, vascular disease, abnormal ejection fraction, and reduced eGFR were associated with greater albuminuria. Age, sex, duration of diabetes, ACR, HbA1c, HDL, and number of hypertensive medications were associated with reduced eGFR.
Conclusion
Kidney dysfunction is common in older patients with T2DM and CAD; Albuminuria was present in 33%. Reduced eGFR was present in 21%, and half the patients with reduced eGFR had no evidence of albuminuria.
doi:10.1097/MAJ.0b013e3181d430ad
PMCID: PMC4312489  PMID: 20375690
2.  Does albuminuria predict renal risk and/or cardiovascular risk in obese type 2 diabetic patients? 
Increased urinary albumin excretion (UAE) is a marker of renal and cardiovascular risk in patients with type 2 diabetes (DT2). What about the obese patient with DT2? Does albuminuria predict the progression of renal disease and/or cardiovascular disease? The objective of this study is to determine the link between albuminuria, renal risk and cardiovascular risk in a cohort of obese DT2 patients. This is a prospective study begun in September 2006. It included DT2 patients presenting obesity defined by a body mass index (BMI)>30 Kg/m2. Three groups of patients were defined: normo-albuminuria (Urinary Albumin Excretion UAE<30 mg/day or Albumin Creatinine Ratio ACR<30 mg/g), micro-albuminuria (UAE=30-300 mg/day or ACR=30-300 mg/g) and macro-albuminuria (UAE>300 mg/day or ACR>300 mg/g). Data on 144 obese DT2 patients were compiled: The mean age of our patients was 59 ± 9 years and the sex ratio 0.26. The incidence of ESRD was higher in the macro-albuminuria group than in the two other groups (26.5% vs. 1.2%, p<0.001). The incidence of cardiovascular events was 15.4%, 14.3% and 23.5% in the normo, micro and macro-albuminuria groups (p=0.48). A history of cardiovascular comorbidities was the main cardiovascular risk in multivariate analysis (0R=15.07; 95% CI=5.30-42.82; p<0.001) and the low admission GFR (0R=5.67; 95% CI=1.23-9.77; p=0.008) was the main factor for progression of kidney disease in multivariate analysis. Albuminuria may be a better marker of kidney disease progression than of cardiovascular risk in the obese DT2 patient, according to our results. However, to accurately demonstrate the link albuminuria - renal risk and albuminuria - cardiovascular risk in the obese DT2 patient, additional studies using very strict criteria of selection and judgment are needed.
PMCID: PMC3925884  PMID: 24551483
Diabete type 2; obesity; albuminuria; renal risk; cardiovascular risk
3.  Prevalence of chronic kidney disease across levels of glycemia among adults in Pudong New Area, Shanghai, China 
BMC Nephrology  2013;14:253.
Background
Few population-based studies have examined the relationship between glycemic status and chronic kidney disease (CKD) in China. We examined the prevalence of CKD across categories of glycemia [diagnosed diabetes, undiagnosed diabetes (fasting plasma glucose [FPG] ≥ 126 mg/dL), prediabetes (FPG 100–126 mg/dL) and normal glycemia (FPG <100 mg/dL)] among Chinese adults and assessed the relative contribution of dysglycemia (prediabetes and/or diabetes) to the burden of CKD.
Methods
5,584 Chinese adults aged 20–79 years were selected from the Pudong New Area of Shanghai through a multistage random sampling. Demographic and lifestyle characteristics, anthropometry and blood pressure were measured. Biochemical assays included FPG, serum creatinine and lipids, urinary creatinine and albumin. Prevalence of albuminuria [urine albumin-to-creatinine ratio (ACR) ≥ 30 mg/g], decreased kidney function and CKD (either decreased kidney function or albuminuria) across levels of glycemia were estimated.
Results
The prevalence of albuminuria, decreased kidney function and CKD each increased with higher glycemic levels (P < 0.001). Based on the MDRD Study equation, the unadjusted CKD prevalence was 30.9%, 28.5%, 14.1% and 9.2% in those with diagnosed diabetes, undiagnosed diabetes, prediabetes and normoglycemia, respectively. The corresponding age-, gender- and hypertension-adjusted CKD prevalence were 25.8%, 25.0%, 12.3% and 9.1%, respectively. In a multivariable analysis, the factors associated with CKD were hypertension (Odds ratio [OR] 1.70, 95% confidence interval [CI]: 1.42-2.03), dysglycemia (OR 1.65, 95% CI: 1.39-1.95), female gender (OR 1.48, 95% CI: 1.25-1.75), higher triglycerides (OR 1.14, 95% CI: 1.08-1.20 per mmol/L), higher body mass index (OR 1.08, 95% CI: 1.05-1.10 per kg/m2), and older age (OR 1.02, 95% CI: 1.01 -1.03 per year). The population attributable risks (PARs) associated with diabetes, prediabetes, dysglycemia (diabetes and prediabetes) and hypertension were 18.4%, 19.7%, 30.3% and 44.5% for CKD as defined by the MDRD study equation, and 15.8%, 24.4%, 29.2% and 10.0% with the CKD-EPI equation. Estimates of prevalence and ORs of the relative contribution of various risk factors to CKD obtained with the CKD-EPI equation were similar.
Conclusions
As much as 30% of the CKD burden may be associated with dysglycemia among Chinese adults, independent of age, gender and hypertension status. Prevention and control of diabetes and prediabetes should be a high priority in reducing the CKD burden in China.
doi:10.1186/1471-2369-14-253
PMCID: PMC4225706  PMID: 24238578
Chronic kidney disease; Glycemia; Epidemiology
4.  Inflammation and Albuminuria in HIV-infected Patients Receiving Combination Antiretroviral Therapy 
Background:
The observed higher prevalence of albuminuria among HIV-infected patients has been strongly associated with cardiovascular disease and higher mortality. In HIV-seronegative patients with metabolic syndrome, malignancies and infections, pro-inflammatory cytokines, and acute phase reactants have been associated with albuminuria. However, the pathophysiology of albuminuria in HIV-seropositive individuals is poorly understood. We investigated the association of albuminuria with inflammatory biomarkers among HIV-infected patients on combination antiretroviral therapy.
Methods:
This is a cross-sectional analysis of the entry data of the participants enrolled in the Hawai‘i Aging with HIV-Cardiovascular Cohort. Participants were ≥ 40 years old, lived in Hawai‘i, documented HIV-positive, and had been on antiretroviral therapy for at least 6 months prior to recruitment. Albuminuria was defined as urine albumin-to-creatinine ratio (ACR) of 30 mg/g or higher, as assessed from single random urine collection. Microalbuminuria was defined as urine ACR between 30 and 300 mg/g and macroalbuminuria as urine ACR more than 300 mg/g. Plasma inflammatory biomarkers were assessed by multiplexing using Milliplex Human Cardiovascular Disease panels. Differences in clinical and laboratory characteristics between subjects with and without albuminuria were compared using a non-parametric Wilcoxon rank test for continuous variables and a chi-squared test for categorical variables. Univariate and multivariate logistic regression analyses were utilized to assess the association between presence of albuminuria as the dependent variable and plasma biomarkers as independent variables. Log-transformed plasma inflammatory biomarkers with P-value less than .1 in univariate logistic regression analysis were selected for examination in separate multivariate logistic regression models, adjusting for previously reported risk factors for albuminuria (age, gender, race, diabetes, hypertension, CD4 percent, current ritonavir, and tenofovir use).
Results:
Among a cohort of 111 HIV-infected patients (median age of 52 (Q1: 46, Q3: 57); male 86%; diabetes 6%; hypertension 33%; median CD4 count of 489 cells/mm3(Q1:341, Q3: 638); HIV RNA PCR < 48 copies/ml 85%), eighteen subjects (16.2%) had microalbuminuria, and two subjects (1.8%) had macroalbuminuria. There was no significant difference in CD4 count and HIV viral loads between patients with and without albuminuria. In univariate logistic regression analysis, higher levels of log-transformed soluble E-selectin (sE-selectin), soluble vascular cell adhesion molecule 1 (sVCAM-1), tissue plasminogen activator inhibitor-1 (tPAI-1), C-reactive protein (CRP), serum amyloid A (SAA), serum amyloid P (SAP), interleukin-1β, interleukin-8, and tumor necrosis factor-α (TNF-α) were associated with albuminuria (P < .10). In multivariate logistic regression models, sE-selectin, sVCAM-1, tPAI-1, CRP, and SAP remained significant (P < .05) even after adjustment for previously reported risk factors for albuminuria.
Conclusions:
This study has shown an association between inflammation and albuminuria independent of previously reported risk factors for albuminuria in HIV-infected subjects on stable combination antiretroviral therapy. Chronic low-grade inflammation despite potent antiretroviral treatment may be one of the factors causing higher rates of albuminuria among HIV-infected patients. Future studies are needed to further elucidate the pathophysiologic mechanisms of chronic inflammation in HIV and its impact on kidney disease.
PMCID: PMC4175929
5.  Vitamin D and Racial Disparity in Albuminuria: NHANES 2001–2006 
American Journal of Hypertension  2011;24(10):1114-1120.
Background
National data show unexplained racial disparity in albuminuria. We assessed whether low serum vitamin D status contributes to racial disparity in albuminuria.
Methods
We examined the association between race and albuminuria (spot urinary albumin/creatinine ratio (ACR) ≥30) among non-Hispanic black and white nonpregnant adults who were free of renal impairment in the National Health and Nutrition Examination Survey (NHANES) from 2001–2006. We conducted analyses without and with serum 25(OH)D. We adjusted for age, sex, education level, smoking, body mass index (BMI), diabetes, diagnosis of hypertension, and use of antihypertensive medication.
Results
Albuminuria was present in 10.0% of non-Hispanic blacks and 6.6% in non-Hispanic whites. Being black (odds ratio (OR) 1.46; 95% confidence interval (CI) 1.23–1.73) was independently associated with albuminuria. There was a graded, inverse association between 25(OH)D level and albuminuria. Notably, the association between race and albuminuria was no longer significant (OR 1.19; 95% CI 0.97–1.47) after accounting for participants' serum 25(OH)D. Similar results were observed when participants with macroalbuminuria (ACR ≥300 mg/g) or elevated parathyroid hormone (>74 pg/ml) were excluded or when a continuous measure of 25(OH)D was substituted for the categorical measure. There were no interactions between race and vitamin D status though racial disparity in albuminuria was observed among participants with the highest 25(OH)D levels.
Conclusion
Suboptimal vitamin D status may contribute to racial disparity in albuminuria. Randomized controlled trials are needed to determine whether supplementation with vitamin analogues reduces risk for albuminuria or reduce racial disparity in this outcome.
doi:10.1038/ajh.2011.108
PMCID: PMC3176582  PMID: 21716328
albuminuria; blood pressure; health status disparities; hypertension; vitamin D
6.  Assessment of Proteinuria in Patients with Chronic Kidney Disease Stage 3: Albuminuria and Non-Albumin Proteinuria 
PLoS ONE  2014;9(5):e98261.
Background and Objective
Proteinuria assessment is key in investigating chronic kidney disease (CKD) but uncertainty exists regarding optimal methods. Albuminuria, reflecting glomerular damage, is usually measured, but non-albumin proteinuria (NAP), reflecting tubular damage, may be important. This study investigated the prevalence and associations of albuminuria and NAP, and the optimum number of urine specimens required.
Methods
1,741 patients with CKD stage 3, recruited from primary care, underwent medical history, clinical assessment, blood sampling, and submitted three early morning urine samples for albumin to creatinine ratio (uACR) and protein to creatinine ratios (uPCR). Albuminuria was defined as uACR ≥3 mg/mmol in at least two of three samples. Isolated NAP was defined as uPCR ≥17 mg/mmol in two of three samples and uACR <3 mg/mmol in all three. Prevalence and associations of albuminuria and NAP, degree of agreement between single uACR and average of three uACRs, and urine albumin to protein ratio (uAPR = uACR/uPCR) were identified.
Results
Albuminuria prevalence was 16% and NAP 6%. Using a <1 mg/mmol threshold for uACR reduced NAP prevalence to 3.6%. Independent associations of albuminuria were: males (OR 3.06 (95% CI, 2.23–4.19)), diabetes (OR 2.14 (1.53–3.00)), lower estimated glomerular filtration rate ((OR 2.06 (1.48–2.85) 30–44 vs 45–59), and high sensitivity CRP ((OR 1.70 (1.25–2.32)). NAP was independently associated with females (OR 6.79 (3.48–13.26)), age (OR 1.62 (1.02–2.56) 80 s vs 70–79) and high sensitivity CRP ((OR 1.74 (1.14–2.66)). Of those with uPCR≥17 mg/mmol, 62% had uAPR<0.4. Sensitivity of single uACR was 95%, specificity 98%, PPV 90%. Bland Altman plot one vs average of three uACRs showed: mean difference 0.0064 mg/mmol (SD 4.69, limits of agreement −9.19 to +9.20, absolute mean difference 0.837).
Conclusions
In CKD stage 3, albuminuria has associations distinct from those of isolated NAP (except for inflammatory markers). Single uACR categorised albuminuria but average of three performed better for quantification.
doi:10.1371/journal.pone.0098261
PMCID: PMC4035283  PMID: 24867154
7.  Serum Gamma - Glutamyltransferase Is Associated with Albuminuria: A Population-Based Study 
PLoS ONE  2014;9(12):e114970.
Background
Serum γ - glutamyltransferase (GGT) is implicated in the pathogenesis of endothelial dysfunction and atherosclerosis. Albuminuria is a marker of endothelial damage and correlated with structural and functional integrity of the vasculature. Our objective was to evaluate the association between serum GGT level and prevalence of albuminuria in a Chinese population.
Materials and Methods
We conducted a population-based cross-sectional study in 9,702 subjects aged 40 years or older. Increased urinary albumin excretion was defined according to the urinary albumin-to-creatinine ratio (ACR) ranges greater or equal than 30 mg/g. Low-grade albuminuria was defined according to the highest quartile of ACR in participants without increased urinary albumin excretion.
Results
The prevalence of low-grade albuminuria and increased urinary albumin excretion were respectively 23.4% and 6.6% in this population and gradually increased across the sex-specific serum GGT quartiles (all P for trend <0.05). In logistic regression analysis, compared with subjects in the lowest quartile of serum GGT level, the adjusted odds ratios (ORs) in the highest quartile was 1.22 [95% confidence interval (CI), 1.04–1.43] for low-grade albuminuria and 1.55 (95% CI, 1.18–2.04) for increased urinary albumin excretion. In subgroup analysis, significant relationship of serum GGT level with both low-grade albuminuria and increased urinary albumin excretion were detected in women, younger subjects, overweight subjects and in those with hypertension or glomerular filtration rate greater than 90 (all P <0.05).
Conclusion
Serum GGT level is associated with urinary albumin excretion in middle-aged and elderly Chinese.
doi:10.1371/journal.pone.0114970
PMCID: PMC4263709  PMID: 25500578
8.  Prevalence, determinants and co-morbidities of chronic kidney disease among First Nations adults with diabetes: results from the CIRCLE study 
BMC Nephrology  2012;13:57.
Background
Indigenous peoples worldwide are experiencing elevated rates of type 2 diabetes and its complications. To better understand the disproportionate burden of diabetic end stage renal disease (ESRD) among Canadian First Nations people (FN), we examined prevalence, determinants, and co-morbidities of chronic kidney disease (CKD) within this population.
Methods
The 2007 Canadian FN Diabetes Clinical Management and Epidemiologic (CIRCLE) study conducted a cross-sectional national medical chart audit of 885 FN adults with type 2 diabetes to assess quality of diabetes care. In this sub-study, participants were divided by estimated glomerular filtration rate (eGFR in ml/min/1.73 m2), as well as by albuminuria level in those with eGFRs = > 60. Those with eGFRs = > 60 and negative albuminuria were considered to have normal/near normal kidney function (non-CKD). Using univariate and logistic regression analysis, they were compared with participants having eGFRs = > 60 plus albuminuria (CKD-alb) and with participants having eGFRs <60 (CKD-eGFR <60).
Results
While 84.5% of total CIRCLE participants had eGFRs = > 60, almost 60% of the latter had CKD-alb. Of the 15.5% of total participants with CKD-eGFR <60, 80% had eGFRs 30–60 (Stage 3 CKD) but over 10% (1.6% of total participants) had ESRD. Independent determinants of CKD-alb were male gender and increasing diabetes duration, systolic BP, A1C and total cholesterol. These plus smoking rates also discriminated between FN with micro- and macro-albuminuria. Independent determinants of CKD-eGFR <60 were increasing age at diabetes diagnosis, diabetes duration, total cholesterol and systolic BP. However, participants with CKD-eGFR <60 also displayed a decreasing mean age of diabetes diagnosis as eGFR declined. Micro-vascular co-morbidities were significantly associated with CKD-alb but both micro- and macro-vascular co-morbidities were associated with CKD-eGFR <60. Only 35-40% of participants with CKD used insulin.
Conclusions
High prevalences of CKD-alb and early CKD-eGFR <60 among diabetic FN were largely related to modifiable and treatable risk factors. However, an earlier age of diabetes diagnosis and longer duration of diabetes characterized those with ESRD. These findings suggest that a failure to meet current standards of diabetes care interacting with an age-related survival benefit contribute to the disproportionate burden of ESRD among FN and possibly other Indigenous peoples.
doi:10.1186/1471-2369-13-57
PMCID: PMC3438064  PMID: 22776036
Indigenous peoples; Aboriginal; First Nations; Diabetes; Chronic kidney disease; End stage renal disease; Risk factors.
9.  Advanced Glycation Urinary Protein-Bound Biomarkers and Severity of Diabetic Nephropathy in Man 
American Journal of Nephrology  2011;34(4):347-355.
Background/Aims
The formation of advanced glycation end products (AGEs) is accelerated in patients with diabetic nephropathy. The aim of this study was to ascertain if the urinary excretion of proteins modified by advanced glycation can be used as biomarkers for albuminuria in individuals with type 1 or type 2 diabetes.
Methods
Community-based patients with type 1 (n = 68) or type 2 diabetes (n = 216) attending a diabetes clinic of a tertiary referral hospital were classified as having normoalbuminuria (Normo, albumin excretion rate (AER) <20 μg/min), microalbuminuria (Micro, AER 20–200 μg/min) or macroalbuminuria (Macro, AER ≥200 μg/min). Serum and urine AGE-modified proteins were measured.
Results
In patients with both type 1 diabetes and type 2 diabetes, there was a clear association between the degree of albuminuria and urinary AGE-modified proteins (p < 0.0001). Exclusive to patients with type 1 diabetes, urinary excretion of the AGE carboxymethyllysine correlated with AER, whereas patients with type 2 diabetes and macroalbuminuria had an increase in urinary methylglyoxal, an AGE intermediate. These changes were independent of isotopic glomerular filtration rate levels. Serum concentrations of AGEs or soluble receptor for AGEs were not consistently associated with albuminuria in either type 1 or type 2 diabetes.
Conclusions
Urinary excretion of proteins modified by AGEs may be useful biomarkers of albuminuria in individuals with type 1 and type 2 diabetes, warranting prospective investigation in larger diabetic cohorts.
doi:10.1159/000331064
PMCID: PMC3182043  PMID: 21876347
Advanced glycation end products; Diabetic nephropathy; Albuminuria; Carboxymethyllysine; Methylglyoxal; Urinary biomarkers
10.  Racial and Ethnic Differences in Albuminuria in Individuals With Estimated GFR Greater Than 60 mL/min/1.73 m2: 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 ≥ 60 mL/min/1.73 m2, not on regular dialysis, and without previous kidney transplant. Albuminuria (urine albumin-creatinine ratio [ACR] ≥ 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 prevalence was 8% (n = 2303) in whites, 11% (n = 2310) 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 odds ratio 1.93, 95% confidence interval 1.70–2.20), then Asians (1.42, 1.26–1.61), African Americans (1.38, 1.29–1.47), and Hispanics (1.19, 1.08–1.31).
Conclusions
In the KEEP study population, albuminuria prevalence was higher among African Americans, Hispanics, Asians, and American Indians/Alaska Natives than among non-Hispanic whites, suggesting a need for screening for early detection of kidney damage, especially among people at increased risk, in the community primary care setting.
doi:10.1053/j.ajkd.2009.09.034
PMCID: PMC3507474  PMID: 20172444
11.  Hyperuricemia Is an Independent Risk Factor for New Onset Micro-Albuminuria in a Middle-Aged and Elderly Population: A Prospective Cohort Study in Taiwan 
PLoS ONE  2013;8(4):e61450.
Background
Hyperuricemia is now regarded as a risk factor for cardiovascular disease. Micro-albuminuria is associated with increased risk for cardiovascular disease and chronic kidney disease. We hypothesized that elevated serum uric acid (UA) is associated with development of micro-albuminuria in the general population.
Methodology/Principal Findings
We conducted a community-based prospective cohort study. A total of 1862 subjects from southern Taiwan, all older than 40 years, were screened and 993 of these participants without micro-albuminuria were followed for 4 years. Urinary albumin-to-creatinine ratio was measured two times per year. A multiple linear regression model indicated that serum UA was independently associated with ln(ACR) after adjustment for 8 factors (age, sex, and 6 metabolic metrics) (β = 0.194, p<0.01). Logistic regression analysis indicated that each 1 mg/dL increase of UA was associated with a 1.42-fold increased risk of micro-albuminuria after adjustment for the same 8 factors (OR = 1.42, 95% CI: 1.27–1.59, p<0.01). A Cox regression model using subjects with serum UA less than 5 mg/dL as reference group indicated higher hazard ratios (HRs) only found in subjects with serum UA more than 7 mg/dL (HR = 3.54, 95% CI: 2.11–5.93, p<0.01) and not in subjects with serum UA of 5 to 7 mg/dL (HR = 1.30, 95% CI: 0.82–2.07, p = 0.15).
Conclusion
Hyperuricemia is significantly associated with micro-albuminuria in middle-aged and elderly males and females from a general population in Taiwan. Elevated serum UA is an independent predictor for development of micro-albuminuria in this population.
doi:10.1371/journal.pone.0061450
PMCID: PMC3634806  PMID: 23637835
12.  Combined Association of Albuminuria and Cystatin C–Based Estimated GFR With Mortality, Coronary Heart Disease, and Heart Failure Outcomes: The Atherosclerosis Risk in Communities (ARIC) Study 
Background
Serum cystatin C level has been shown to have a stronger association with clinical outcomes than serum creatinine level. However, little is known about the combined association of cystatin C–based estimated glomerular filtration rate (eGFRcys) and albuminuria with clinical outcomes, particularly at levels lower than current chronic kidney disease (CKD) cutoffs.
Study Design
Prospective cohort.
Setting & Participants
10,403 ARIC (Atherosclerosis Risk in Communities) Study participants followed up for a median of 10.2 years.
Predictor
eGFRcys, albuminuria.
Outcomes
Mortality, coronary heart disease (CHD), and heart failure, as well as a composite of any of these separate outcomes.
Results
Both decreased eGFRcys and albuminuria were associated independently with the composite outcome, as well as mortality, CHD, and heart failure. Although eGFRcys of 75-89 mL/min/1.73 m2 in the absence of albuminuria (albumin-creatinine ratio [ACR] <10 mg/g) or albuminuria with ACR of 10-29 mg/g with normal eGFRcys (90-104 mL/min/1.73 m2) was not associated significantly with any outcome compared with eGFRcys of 90-104 mL/min/1.73 m2 and ACR <10 mg/g, the risk of each outcome was significantly higher in those with both eGFRcys of 75-89 mL/min/1.73 m2 and ACR of 10-29 mg/g (for mortality, HR of 1.4 [95% CI, 1.1-2.0]; for CHD, HR of 1.9 [95% CI, 1.4-2.6]; for heart failure, HR of 1.8 [95% CI, 1.2-2.7]). Combining the 2 markers improved risk classification for all outcomes (P < 0.001), even in those without overt CKD.
Limitations
Only one measurement of cystatin C.
Conclusions
Mildly decreased eGFRcys and mild albuminuria independently contributed to the risk of mortality, CHD, and heart failure. Even minimally decreased eGFRcys (75-89 mL/min/1.73 m2) is associated with increased risk in the presence of mild albuminuria. Combining the 2 markers is useful for improved risk stratification even in those without clinical CKD.
doi:10.1053/j.ajkd.2012.03.011
PMCID: PMC3582350  PMID: 22537422
Epidemiology; kidney; outcomes
13.  Association of Chronic Kidney Disease with Atrial Fibrillation Among Adults in the United States: Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study 
Background
Atrial fibrillation (AF) is common among patients with end-stage renal disease, but few data are available on its prevalence among adults with chronic kidney disease (CKD) of lesser severity.
Methods and Results
We evaluated the association of CKD with electrocardiogram-detected AF among 26,917 participants in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study, a population-based cohort of African-American and white US adults ≥45 years of age. Estimated glomerular filtration rate (eGFR) was calculated using the abbreviated Modification of Diet in Renal Disease study equation and albuminuria was defined as a urinary albumin to creatinine ratio ≥30 mg/g. Participants were categorized by renal function: no CKD (eGFR ≥60 ml/min/1.73m2 without albuminuria, n=21,081), stage 1–2 CKD (eGFR ≥60 ml/min/1.73m2 with albuminuria n=2,938), stage 3 CKD (eGFR 30 to 59 ml/min/1.73m2, n=2,683) and stage 4–5 CKD (eGFR <30 ml/min/1.73m2, n=215). The prevalence of AF among participants without CKD, and with stage 1–2, stage 3, and stage 4–5 CKD was 1.0%, 2.8%, 2.7% and 4.2%, respectively. Compared to participants without CKD, the age, race, sex adjusted odds ratios for prevalent AF were 2.67 (95% CI 2.04 – 3.48), 1.68 (95% CI 1.26 – 2.24) and 3.52 (95% CI 1.73–7.15) among those with stage 1–2, stage 3 and stage 4–5 CKD. The association between CKD and prevalent AF remained statistically significant after further multivariable adjustment and was consistent across numerous subgroups.
Conclusions
- Regardless of severity, CKD is associated with an increased prevalence of AF among US adults.
doi:10.1161/CIRCEP.110.957100
PMCID: PMC3049935  PMID: 21076159
chronic kidney disease; atrial fibrillation; electrocardiography
14.  Low Income and Albuminuria Among REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study Participants 
Background
Albuminuria is an important risk factor for progressive CKD and is more prevalent among black than among white adults. We sought to determine the association between low income and albuminuria, and if this association differs for blacks and whites.
Study Design
Cross-sectional study.
Setting & Participants
9,144 black and 13,684 white U.S. adults aged 45 years and older in the population-based REasons for Geographic and Racial Differences in Stroke (REGARDS) study.
Predictors
Self-reported annual household income category (≥$75,000, 35,000 – $74,999, $20,000 – $34,999, and <$20,000); black and white race.
Outcomes & Measurements
Albuminuria defined as high (30 to 300 mg/g) or very high (>300 mg/g) urinary albumin-creatinine ratio (ACR). Multinomial logistic regression used to examine the race-stratified association between categories of income and albuminuria (normal, high, or very high ACR).
Results
Overall, geometric mean ACR was 10.2 mg/g, and was higher for blacks (11.8 mg/g) than for whites (9.3 mg/g), p <0.001. Lower income was associated with a higher prevalence of albuminuria for both whites and blacks in unadjusted analyses. After adjustment for demographics, lifestyle factors, comorbid illnesses and estimated glomerular filtration rate, there was a trend towards a stronger association between lower income levels and high ACR among blacks [ORs of 1.38 (95% CI, 1.07 – 1.77), 1.36 (95% CI, 1.05 – 1.75), and 1.58 (95% CI, 1.21–2.05), for income levels of $35,000 – $74,999, $20,000 – $34,999, and <$20,000, respectively; reference group is those with income ≥$75,000] compared to whites [ORs of 0.95 (95% CI, 0.81 – 1.12), 0.95 (95% CI, 0.79 – 1.14), and 1.26 (95% CI, 1.02 – 1.55), respectively]; P interaction 0.08 between race and income. Results were similar for very high ACR, and subgroups of participants with diabetes or hypertension.
Limitations
Cross-sectional design; not all REGARDS participants provided their annual income.
Conclusions
Lower income may be more strongly associated with albuminuria among blacks than among whites, and may be a determinant of racial disparities in albuminuria.
doi:10.1053/j.ajkd.2012.05.010
PMCID: PMC3448844  PMID: 22694949
Race; albuminuria; poverty; chronic kidney disease; socioeconomic status; disparity
15.  Associations of kidney disease measures with mortality and end-stage renal disease in individuals with and without hypertension: a meta-analysis 
Lancet  2012;380(9854):1649-1661.
Background
Hypertension is the most prevalent comorbidity in individuals with chronic kidney disease (CKD). It is unknown, however, whether the association of the CKD measures, estimated glomerular filtration rate (eGFR) and albuminuria, with mortality or end-stage renal disease (ESRD) differs by hypertensive status.
Methods
We performed a meta-analysis of 45 cohorts (25 general population, 7 high-risk and 13 CKD cohorts), including 1,127,656 participants (364,344 with hypertension). Adjusted hazard ratios (HRs) for all-cause mortality (84,078 deaths from 40 cohorts) and ESRD (7,587 events from 21 cohorts) by hypertensive status were obtained for each study and pooled using random-effects models.
Findings
Low eGFR and high albuminuria were associated with mortality in both non-hypertensive and hypertensive individuals in the general population and high-risk cohorts. Mortality risk was higher in hypertensives as compared to non-hypertensives at preserved eGFR but a steeper relative risk gradient among non-hypertensives than hypertensives at eGFR range 45-75 ml/min/1.73m2 led to similar mortality risk at lower eGFR. With a reference eGFR of 95 mL/min/1.73m2 in each group to explicitly assess interaction, adjusted HR for all-cause mortality at eGFR 45 mL/min/1.73m2 was 1.77 (95% CI, 1.57-1.99) in non-hypertensives versus 1.24 (1.11-1.39) in hypertensives (P for overall interaction =0.0003). Similarly, for albumin-creatinine ratio (ACR) of 300 mg/g (vs. 5 mg/g), HRs were 2.30 (1.98-2.68) in non-hypertensives versus 2.08 (1.84-2.35) in hypertensives (P for overall interaction=0.019). Similar results were observed for cardiovascular mortality. The associations of eGFR and albuminuria with ESRD, however, did not differ by hypertensive status. Results in CKD cohorts were comparable to results in general and high-risk population cohorts.
Interpretation
Low eGFR and elevated albuminuria were more strongly associated with mortality among individuals without hypertension than in those with hypertension, but the associations with ESRD were similar. CKD should be considered at least an equally relevant risk factor for mortality and ESRD in non-hypertensive as it is in hypertensive individuals.
Funding
The US National Kidney Foundation (sources include Abbott and Amgen).
doi:10.1016/S0140-6736(12)61272-0
PMCID: PMC3993095  PMID: 23013600
16.  The Association of Chronic Kidney Disease Complications by Glomerular Filtration Rate and Albuminuria: A Cross-sectional Analysis 
Clinical nephrology  2013;80(1):29-39.
Background
Albuminuria is strongly associated with future risk for cardiovascular and kidney outcomes, and has been proposed to be included in the classification of chronic kidney disease (CKD) along with glomerular filtration rate (GFR). Few data are available on whether albuminuria is associated with concurrent complications of CKD.
Study Design
Cross-Sectional
Setting & Participants
The Modification of Diet in Renal Disease (MDRD) Study examined the effects of dietary protein restriction and blood pressure control on the progression of kidney disease. This analysis includes 1665 participants screened for the MDRD Study.
Predictors
Urine albumin-creatinine ratio (ACR) and measured GFR using urinary clearance of iothalamate.
Outcomes & Measurements
Associations between ACR categories and GFR categories with anemia, acidosis, hyperphosphatemia and hypertension were evaluated using log-binomial regression.
Results
Mean GFR (±SD) was 39 ml/min/1.73m2 (± 21) and the median (25th–75th percentile) ACR was 161 (38–680) mg/g. In multivariable models adjusted for age, sex, race, kidney disease etiology and GFR, higher ACR levels were not associated with any complication. For example, comparing ACR > 300 mg/g versus < 30 mg/g, the prevalence ratio (95% CI) for anemia was 0.98 (0.81–1.20), acidosis 1.13 (0.86–1.48), hyperphosphatemia 1.69 (0.91–3.17) and hypertension 1.04 (0.97–1.12). Lower levels of GFR were associated with all complications. For example, GFR levels < 30 ml/min/1.73m2 versus GFR levels 60–89 ml/min/1.73m2 were associated with prevalence ratios (95% CI) of anemia 4.35 (3.18–5.96), acidosis 5.31 (3.41–8.29), hyperphosphatemia 23.8 (7.71–73.6) and hypertension 1.21 (1.10–1.32).
Limitations
Limited generalizability; lack of data on other complications that may be related to CKD.
Conclusions
Albuminuria is not associated with complications after controlling for GFR and thus would not affect clinical action plans for decisions regarding evaluation and treatment of complications.
PMCID: PMC4108165  PMID: 23803596
Albuminuria; GFR; CKD; complications
17.  Angiopoietin-2 Is Associated with Albuminuria and Microinflammation in Chronic Kidney Disease 
PLoS ONE  2013;8(3):e54668.
Although cardiovascular disease (CVD) is the leading cause of mortality in patients with chronic kidney disease (CKD), the pathophysiology is not thoroughly understood. Given that elevated albuminuria or circulating angiopoietin-2 associates with CVD and mortality in CKD patients, we were intrigued by the relationship between albuminuria and angiopoietin-2. A total of 416 patients with CKD stages 3 to 5 were stratified by urine albumin-creatinine ratio as normoalbuminuria (<30 mg/g), microalbuminuria (30–300 mg/g), or macroalbuminuria (>300 mg/g). The levels of plasma angiopoietin-2 and vascular endothelial growth factor (VEGF) increased, and soluble Tie-2 decreased in the subgroups of albuminuria; whereas angiopoietin-1 did not change. Linear regression showed a positive correlation between urine albumin-creatinine ratio (ACR) and plasma angiopoietin-2 (correlation coefficient r = 0.301, 95% confidence interval 0.211–0.386, P<0.0001), but not between ACR and VEGF or soluble Tie-2. Multivariate linear regression analysis showed that plasma angiopoietin-2 was independently associated with ACR (P = 0.025). Furthermore, plasma angiopoietin-2 was positively correlated with high sensitive C-reactive protein (r = 0.114, 95% confidence interval 0.018–0.208, P = 0.020). In conclusion, plasma angiopoietin-2 was associated with albuminuria and markers of systemic microinflammation in CKD patients. Although previous evidence has shown that angiopoietin-2 destabilizes vasculature and induces inflammation in different scenarios, further study will be required to delineate the role of angiopoietin-2 in albuminuria and microinflammation in CKD patients.
doi:10.1371/journal.pone.0054668
PMCID: PMC3585725  PMID: 23469160
18.  Prevalence and Determinants of Diabetic Nephropathy in Korea: Korea National Health and Nutrition Examination Survey 
Diabetes & Metabolism Journal  2014;38(2):109-119.
Background
Diabetic nephropathy is a leading cause of end stage renal disease and is associated with an increased risk of cardiovascular mortality. It manifests as albuminuria or impaired glomerular filtration rate (GFR), and the prevalence of diabetic nephropathy varies with ethnicity. The prevalence of diabetic nephropathy and its determinants in Korean adults have not previously been studied at the national level. This cross-sectional study was undertaken to ascertain the prevalence and determinants of albuminuria and chronic kidney disease (CKD) in Korean patients with diabetes.
Methods
The Korea National Health and Nutrition Examination Survey (KNHANES) V, conducted in 2011, was used to define albuminuria (n=4,652), and the dataset of KNHANES IV-V (2008-2011) was used to define CKD (n=21,521). Selected samples were weighted to represent the entire civilian population in Korea. Albuminuria was defined as a spot urine albumin/creatinine ratio >30 mg/g. CKD was defined as a GFR <60 mL/min/1.73 m2.
Results
Among subjects with diabetes, 26.7% had albuminuria, and 8.6% had CKD. Diabetes was associated with an approximate 2.5-fold increased risk of albuminuria, with virtually no difference between new-onset and previously diagnosed diabetes. Only systolic blood pressure was significantly associated with albuminuria, and old age, high serum triglyceride levels, and previous cardiovascular disease (CVD) were related with CKD in subjects with diabetes.
Conclusion
Korean subjects with diabetes had a higher prevalence of albuminuria and CKD than those without diabetes. Blood pressure was associated with albuminuria, and age, triglyceride level, and previous CVD were independent determinants of CKD in subjects with diabetes.
doi:10.4093/dmj.2014.38.2.109
PMCID: PMC4021298  PMID: 24851205
Albuminuria; Chronic renal disease; Diabetes mellitus; Diabetic nephropathy; Korea
19.  Genetic variation of Glucose Transporter-1 (GLUT1) and albuminuria in 10,278 European Americans and African Americans: a case-control study in the Atherosclerosis Risk in Communities (ARIC) Study 
BMC Medical Genetics  2011;12:16.
Background
Evidence suggests glucose transporter-1(GLUT1) genetic variation affects diabetic nephropathy and albuminuria. Our aim was to evaluate associations with albuminuria of six GLUT1 single nucleotide polymorphisms(SNPs), particularly XbaI and the previously associated Enhancer-2(Enh2) SNP.
Methods
A two-stage case-control study was nested in a prospective cohort study of 2156 African Americans and 8122 European Americans with urinary albumin-to-creatinine ratio(ACR). Cases comprised albuminuria(N = 825; ≥ 30 μg/mg) and macroalbuminuria(N = 173; ≥ 300 μg/mg). ACR < 30 μg/mg classified controls(n = 9453). Logistic regression and odds ratios(OR) assessed associations. The evaluation phase(stage 1, n = 2938) tested associations of albuminuria(n = 305) with six GLUT1 SNPs: rs841839, rs3768043, rs2297977, Enh2(rs841847) XbaI(rs841853), and rs841858. Enh2 was examined separately in the replication phase(stage 2, n = 7340) and the total combined sample (n = 10,278), with all analyses stratified by race and type 2 diabetes.
Results
In European Americans, after adjusting for diabetes and other GLUT1 SNPs in stage 1, Enh2 risk genotype(TT) was more common in albuminuric cases(OR = 3.37, P = 0.090) whereas XbaI (OR = 0.94, p = 0.931) and remaining SNPs were not. In stage 1, the Enh2 association with albuminuria was significant among diabetic European Americans(OR = 2.36, P = 0.025). In African Americans, Enh2 homozygosity was rare(0.3%); XbaI was common(18.0% AA) and not associated with albuminuria. In stage 2(n = 7,340), Enh2 risk genotype had increased but non-significant OR among diabetic European Americans(OR = 1.66, P = 0.192) and not non-diabetics(OR = 0.99, p = 0.953), not replicating stage 1. Combining stages 1 and 2, Enh2 was associated with albuminuria(OR 2.14 [1.20-3.80], P = 0.009) and macroalbuminuria(OR 2.69, [1.02-7.09], P = 0.045) in diabetic European Americans. The Enh2 association with macroalbuminuria among non-diabetic European Americans with fasting insulin(OR = 1.84, P = 0.210) was stronger at the highest insulin quartile(OR = 4.08, P = 0.040).
Conclusions
As demonstrated with type 1 diabetic nephropathy, the GLUT1 Enh2 risk genotype, instead of XbaI, may be associated with type 2 diabetic albuminuria among European Americans, though an association is not conclusive. The association among diabetic European Americans found in stage 1 was not replicated in stage 2; however, this risk association was evident after combining all diabetic European Americans from both stages. Additionally, our results suggest this association may extend to non-diabetics with high insulin concentrations. Rarity of the Enh2 risk genotype among African Americans precludes any definitive conclusions, although data suggest a risk-enhancing role.
doi:10.1186/1471-2350-12-16
PMCID: PMC3034664  PMID: 21247498
20.  Age and the Association of Kidney Measures with Mortality and End-Stage Renal Disease 
Context
Chronic kidney disease (CKD) is prevalent in older individuals, but the risk implications of low estimated glomerular filtration rate (eGFR) and high albuminuria across the full age range are controversial.
Objective
To evaluate possible effect modification (interaction) of age on the association of estimated GFR and albuminuria with clinical risk examining both relative and absolute risk.
Design, Setting, Participants
We investigated 2,051,244 participants from 33 general population or high-risk (of vascular disease) cohorts and 13 CKD cohorts from Asia, Australesia, Europe, and North/South America conducted during 1972–2011 with mean follow-up time of 5.8 years (range 0–31 years).
Main Outcome Measures
Hazard ratios (HRs) of mortality and end-stage renal disease (ESRD) according to eGFR and albuminuria were meta-analyzed across age categories after adjusting for sex, race, cardiovascular disease, diabetes, systolic blood pressure, cholestserol, body mass index, and smoking. Absolute risks were estimated using HRs and average incidence rates.
Results
Mortality (112,325 deaths) and ESRD (8,411 events) risk were higher at lower eGFR and higher albuminuria in every age category. In general/high-risk cohorts, relative mortality risk for reduced eGFR decreased with increasing age: e.g., adjusted HRs (95% CI) at eGFR 45 vs. 80 ml/min/1.73m2 were 3.50 (2.55–4.81), 2.21 (2.02–2.41), 1.59 (1.42–1.77), and 1.35 (1.23–1.48) in age categories 18–54, 55–64, 65–74 and 75+ years, respectively (P-values for age interaction <0.05). Absolute risk differences for the same comparisons were higher at older age (9.0 [95% CI, 6.0–12.8], 12.2 [10.3–14.3], 13.3 [9.0–18.6], and 27.2 [13.5–45.5] excess deaths per 1,000 person-years, respectively). For increased albuminuria, reduction of relative risk with increasing age were less evident, while differences in absolute risk were higher in the older age categories (7.5 [95% CI, 4.3–11.9], 12.2 [7.9–17.6], 22.7 [15.3–31.6], and 34.3 [19.5–52.4] excess deaths per 1,000 person-years, respectively by age category, at ACR 300 mg/g compared to 10 mg/g). In CKD cohorts, adjusted relative hazards of mortality did not decrease with age. In all cohorts, ESRD relative risks and absolute risk differences at lower eGFR or higher albuminuria were comparable across age categories.
Conclusions
Both low eGFR and high albuminuria were independently associated with mortality and ESRD regardless of age across a wide range of populations. Mortality showed lower relative risk but higher absolute risks differences at older age.
doi:10.1001/jama.2012.16817
PMCID: PMC3936348  PMID: 23111824
21.  Kidney Function, Albuminuria, and All-Cause Mortality in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study 
Background
Chronic kidney disease (CKD) and albuminuria are associated with increased risk of all-cause mortality.
Study Design
Prospective observational cohort study
Setting and Participants
17,393 participants (mean age, 64.3 ± 9.6 years) in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study.
Predictor
Estimated glomerular filtration rate (eGFR), urinary albumin-creatinine ratio (ACR).
Outcome
All-cause mortality (710 deaths); median duration of follow-up: 3.6 years.
Measurements and Analysis
Categories of eGFR (90– <120, 60–<90, 45–<60, 30–<45, and 15–<30 mL/min/1.73 m2) and urinary ACR (<10 mg/g or normal, 10–<30 mg/g or high normal, 30–300 mg/g or high, and >300 mg/g or very high). Cox’s proportional hazards models were adjusted for demographic factors, cardiovascular covariates, and hemoglobin.
Results
The background all-cause mortality rate for participants with normal ACR, eGFR of 90–<120 mL/min/1.73 m2 and no CHD was 4.3 deaths/1,000 person-years. Higher ACR was associated with an increased multivariable adjusted hazard ratio for all-cause mortality within each eGFR category. Reduced eGFR was associated with higher adjusted hazard ratio for all-cause mortality for participants with high normal (P value = 0.01) and high (P value <0.001) ACR values, but not for those with normal or very high ACR values.
Limitations
Only one laboratory assessment for serum creatinine and ACR was available
Conclusions
Increased albuminuria was an independent risk factor for all-cause mortality. Reduced eGFR was associated with increased mortality risk among those with high normal and high ACR. The mortality rate was low in the normal ACR group and increased in the very high ACR group but did not vary with eGFR in these groups.
doi:10.1053/j.ajkd.2010.05.017
PMCID: PMC2963678  PMID: 20692752
22.  Body mass index and metabolic factors predict glomerular filtration rate and albuminuria over 20 years in a high-risk population 
BMC Nephrology  2013;14:177.
Background
The number of individuals suffering from chronic kidney disease (CKD) is increasing. Therefore, early identification of modifiable predictors of CKD is highly desirable. Previous studies suggest an association between body mass index (BMI), metabolic factors and CKD.
Methods
Data of 241 high risk patients with information on renal function and albuminuria from the Renal Disease in Vorarlberg (RENVOR) study (2010–2011) were linked with long-term measurements of metabolic factors in the same patients from the population-based Vorarlberg Health Monitoring & Prevention Program (VHM&PP) cohort study (1988–2005). Actual estimated glomerular filtration rate (eGFR) and urinary albumin creatinine ratio (ACR) were determined. BMI, blood pressure, fasting glucose, total cholesterol, triglycerides and Gamma-glutamyltransferase (GGT) were available from previous health examinations performed up to 25 years ago. Linear regression models were applied to identify predictors of current renal function.
Results
At all-time points BMI was significantly inversely associated with actual eGFR and positively with actual albuminuria in men, but not in women. Serum GGT and triglycerides were significantly positively associated with albuminuria in men at all-time points. Fasting glucose levels more than 20 years earlier were associated with increased albuminuria in women and reduced eGFR in men, whereas at later time points it was associated with albuminuria in men.
Conclusions
BMI, serum GGT, and triglycerides are long-term predictors of renal function in men. In women however, anthropometric and metabolic parameters seem to be less predictive of eGFR and albuminuria.
doi:10.1186/1471-2369-14-177
PMCID: PMC3765663  PMID: 23962027
Body mass index; Glomerular filtration rate; Albuminuria; Obesity; Gamma glutamyltransferase; Epidemiology
23.  25-hydroxyvitamin D Levels and chronic kidney disease in the AusDiab (Australian Diabetes, Obesity and Lifestyle) study 
BMC Nephrology  2012;13:55.
Background
Low 25-hydroxy vitamin D (25(OH)D) levels have been associated with an increased risk of albuminuria, however an association with glomerular filtration rate (GFR) is not clear. We explored the relationship between 25(OH)D levels and prevalent chronic kidney disease (CKD), albuminuria and impaired GFR, in a national, population-based cohort of Australian adults (AusDiab Study).
Methods
10,732 adults ≥25 years of age participating in the baseline survey of the AusDiab study (1999–2000) were included. The GFR was estimated using an enzymatic creatinine assay and the CKD-EPI equation, with CKD defined as eGFR <60 ml/min/1.73 m2. Albuminuria was defined as a spot urine albumin to creatinine ratio (ACR) of ≥2.5 mg/mmol for men and ≥3.5 for women. Serum 25(OH)D levels of <50 nmol/L were considered vitamin D deficient. The associations between 25(OH)D level, albuminuria and impaired eGFR were estimated using multivariate regression models.
Results
30.7% of the study population had a 25(OH)D level <50 nmol/L (95% CI 25.6-35.8). 25(OH)D deficiency was significantly associated with an impaired eGFR in the univariate model (OR 1.52, 95% CI 1.07-2.17), but not in the multivariate model (OR 0.95, 95% CI 0.67-1.35). 25(OH)D deficiency was significantly associated with albuminuria in the univariate (OR 2.05, 95% CI 1.58-2.67) and multivariate models (OR 1.54, 95% CI 1.14-2.07).
Conclusions
Vitamin D deficiency is common in this population, and 25(OH)D levels of <50 nmol/L were independently associated with albuminuria, but not with impaired eGFR. These associations warrant further exploration in prospective and interventional studies.
doi:10.1186/1471-2369-13-55
PMCID: PMC3441805  PMID: 22759247
Albuminuria; Chronic kidney disease; Glomerular filtration rate; and Vitamin D
24.  Impacts of chronic kidney disease and albuminuria on associations between coronary heart disease and its traditional risk factors in type 2 diabetic patients – the Hong Kong diabetes registry 
Background
Glycated haemoglobin (HbA1c), blood pressure and body mass index (BMI) are risk factors for albuminuria, the latter in turn can lead to hyperlipidaemia. We used novel statistical analyses to examine how albuminuria and chronic kidney disease (CKD) may influence the effects of other risk factors on coronary heart disease (CHD).
Methods
A prospective cohort of 7067 Chinese type 2 diabetic patients without history of CHD enrolled since 1995 were censored on July 30th, 2005. Cox proportional hazard regression with restricted cubic spline was used to auto-select predictors. Hazard ratio plots were used to examine the risk of CHD. Based on these plots, non-linear risk factors were categorised and the categorised variables were refitted into various Cox models in a stepwise manner to confirm the findings.
Results
Age, male gender, duration of diabetes, spot urinary albumin: creatinine ratio, estimated glomerular filtration rate, total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and current smoking status were risk factors of CHD. Linear association between TC and CHD was observed only in patients with albuminuria. Although in general, increased HDL-C was associated with decreased risk of CHD, full-range HDL-C was associated with CHD in an A-shaped manner with a zenith at 1.1 mmol/L. Albuminuria and CKD were the main contributors for the paradoxically positive association between HDL-C and CHD for HDL-C values less than 1.1 mmol/L.
Conclusion
In type 2 diabetes, albuminuria plays a linking role between conventional risk factors and CHD. The onset of CKD changes risk associations between lipids and CHD.
doi:10.1186/1475-2840-6-37
PMCID: PMC2219954  PMID: 18053157
25.  Poor Glycemic Control in Diabetes and The Risk of Incident Chronic Kidney Disease Even in The Absence of Albuminuria and Retinopathy: The Atherosclerosis Risk in Communities (Aric) Study 
Archives of internal medicine  2008;168(22):2440-2447.
Background
Diabetic nephropathy is the leading cause of kidney failure in the US. The extent to which elevated glycated hemoglobin (HbA1c) is associated with increased risk of chronic kidney disease (CKD) in the absence of albuminuria and retinopathy, the hallmarks of diabetic nephropathy, is uncertain.
Methods
HbA1c was measured in 1,871 adults with diabetes followed for 11 years in the Atherosclerosis Risk in Communities Study. Incident CKD was defined as an estimated glomerular filtration rate (GFR) below 60 mL/min/1.73 m2 after 6 years of follow-up or a kidney disease-related hospitalization. We categorized HbA1c into 4 clinically relevant categories. Retinopathy and albuminuria were measured midway through follow-up.
Results
Higher HbA1c was strongly associated with risk of CKD in models adjusted for demographics, baseline GFR and cardiovascular risk factors. Compared to HbA1c values of <6.00%, HbA1cs of 6.00-7.00%, 7.00%-8.00%, and >8.00% had adjusted relative hazards of CKD of 1.4 (95% CI: 0.97-1.91), 2.5 (1.70-3.66) and 3.7 (2.76-4.90), respectively. Risk of CKD was higher among individuals with retinopathy and albuminuria, the association between HbA1c and incident CKD was observed even among those participants without either abnormality: adjusted relative hazards =1.46 (0.80-2.65), 1.17 (0.43-3.19) and 3.51 (1.67-7.40); p-trend=0.004.
Conclusion
We observed a positive association between HbA1c and incident CKD that was strong, graded, independent of traditional risk factors and present even in the absence of albuminuria and retinopathy. Hyperglycemia is an important indicator of risk of both diabetic nephropathy (with albuminuria or retinopathy) and of less specific forms of CKD.
doi:10.1001/archinte.168.22.2440
PMCID: PMC2766035  PMID: 19064828

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