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1.  Risk of Hyperkalemia in Nondiabetic Patients With Chronic Kidney Disease Receiving Antihypertensive Therapy 
Transplantation  2011;92(7):10.1097/TP.0b013e31822dc36b.
The incidence and factors associated with hyperkalemia in patients with chronic kidney disease (CKD) treated with angiotensin converting enzyme inhibitors (ACEIs) and other antihypertensive drugs was investigated using the African American Study of Kidney Disease and Hypertension (AASK) database.
A total of 1094 nondiabetic adults with hypertensive CKD (glomerular filtration rate [GFR], 20–65 mL/min/1.73 m2) were followed for 3.0 to 6.4 years in the AASK trial. Participants were randomly assigned to ACEI, β-blocker (BB), or dihydropyridine calcium channel blocker (CCB). The outcome variables for this analysis were a serum potassium level higher than 5.5 mEq/L (to convert to millimoles per liter, multiply by 1.0), or a clinical center initiated hyperkalemia stop point.
A total of 6497 potassium measurements were obtained, and 80 events in 51 subjects were identified (76 events driven by a central laboratory result and 4 driven by a clinical center–initiated hyperkalemia stop point). Compared with a GFR higher than 50 mL/min/1.73 m2, after multivariable adjustment, the hazard ratio (HR) for hyperkalemia in patients with a GFR between 31 and 40 mL/min/1.73 m2 and a GFR lower than 30 mL/min/1.73 m2 was 3.61 (95% confidence interval [CI], 1.42–9.18 [P=.007]) and 6.81 (95% CI, 2.67–17.35 [P<.001]), respectively; there was no increased risk of hyperkalemia if GFR was 41 to 50 mL/min/1.73 m2. Use of ACEIs was associated with more episodes of hyperkalemia compared with CCB use (HR, 7.00; 95% CI, 2.29–21.39 [P<.001]) and BB group (HR, 2.85; 95% CI, 1.50–5.42 [P=.001]). Diuretic use was associated with a 59% decreased risk of hyperkalemia.
In nondiabetic patients with hypertensive CKD treated with ACEIs, the risk of hyperkalemia is small, particularly if baseline and follow-up GFR is higher than 40 mL/min/1.73 m2. Including a diuretic in the regimen may markedly reduce risk of hyperkalemia.
PMCID: PMC3831506  PMID: 21832957
2.  Genetic Association and Gene-Gene Interaction Analyses in African American Dialysis Patients With Nondiabetic Nephropathy 
African Americans (AAs) have increased susceptibility to non-diabetic nephropathy relative to European Americans.
Study Design
Follow-up of a pooled genome-wide association study (GWAS) in AA dialysis patients with nondiabetic nephropathy; novel gene-gene interaction analyses.
Setting & Participants
Wake Forest sample: 962 AA nondiabetic nephropathy cases; 931 non-nephropathy controls. Replication sample: 668 Family Investigation of Nephropathy and Diabetes (FIND) AA nondiabetic nephropathy cases; 804 non-nephropathy controls.
Individual genotyping of top 1420 pooled GWAS-associated single nucleotide polymorphisms (SNPs) and 54 SNPs in six nephropathy susceptibility genes.
APOL1 genetic association and additional candidate susceptibility loci interacting with, or independently from, APOL1.
The strongest GWAS associations included two non-coding APOL1 SNPs, rs2239785 (odds ratio [OR], 0.33; dominant; p = 5.9 × 10−24) and rs136148 (OR, 0.54; additive; p = 1.1 × 10−7) with replication in FIND (p = 5.0 × 10−21 and 1.9 × 10−05, respectively). Rs2239785 remained significantly associated after controlling for the APOL1 G1 and G2 coding variants. Additional top hits included a CFH SNP(OR from meta-analysis in above 3367 AA cases and controls, 0.81; additive; p = 6.8 × 10−4). The 1420 SNPs were tested for interaction with APOL1 G1 and G2 variants. Several interactive SNPs were detected, the most significant was rs16854341 in the podocin gene (NPHS2) (p = 0.0001).
Non-pooled GWAS have not been performed in AA nondiabetic nephropathy.
This follow-up of a pooled GWAS provides additional and independent evidence that APOL1 variants contribute to nondiabetic nephropathy in AAs and identified additional associated and interactive non-diabetic nephropathy susceptibility genes.
PMCID: PMC3259209  PMID: 22119407
African American; APOL1; CFH; end-stage renal disease; FIND; FSGS; hypertension
3.  Quality of Life and Psychosocial Factors in African Americans with Hypertensive Chronic Kidney Disease 
Health-related quality of life (HRQOL) is poorly understood in patients with chronic kidney disease (CKD) prior to end-stage renal disease. The association between psychosocial measures and HRQOL has not been fully explored in CKD, especially in African Americans. We performed a cross-sectional analysis of HRQOL and its association with sociodemographic and psychosocial factors in African Americans with hypertensive CKD.
There were 639 participants in the African American Study of Kidney Disease and Hypertension Cohort Study. The Short Form-36 was used to measure HRQOL. The Diener Satisfaction with Life Scale measured life satisfaction, the Beck Depression Inventory-II assessed depression, the Coping Skills Inventory-Short Form measured coping, and the Interpersonal Support Evaluation List-16 was used to measure social support.
Mean participant age was 60 years at enrollment, and 61% were male. Forty-two percent reported a household income below $15,000/year. Higher levels of social support, coping skills, and life satisfaction were associated with higher HRQOL, while unemployment and depression were associated with lower HRQOL (p<0.05). There was a significant positive association between higher estimated glomerular filtration rate (eGFR) with the Physical Health Composite (PHC) score (p=0.004) but not the Mental Health Composite (MHC) score (p=0.24).
Unemployment was associated with lower HRQOL, and lower eGFR was associated with lower PHC. African Americans with hypertensive CKD with better social support and coping skills had higher HRQOL. This study demonstrates an association between CKD and low HRQOL and highlights the need for longitudinal studies to further examine this association.
PMCID: PMC3240805  PMID: 22153804
4.  Elevated depressive affect is associated with adverse cardiovascular outcomes among African Americans with chronic kidney disease 
Kidney international  2011;80(6):670-678.
This study was designed to examine the impact of elevated depressive affect on health outcomes among participants with hypertensive chronic kidney disease in the African-American Study of Kidney Disease and Hypertension (AASK) Cohort Study. Elevated depressive affect was defined by Beck Depression Inventory II (BDI-II) thresholds of 11 or more, above 14, and by 5-Unit increments in the score. Cox regression analyses were used to relate cardiovascular death/hospitalization, doubling of serum creatinine/end-stage renal disease, overall hospitalization, and all-cause death to depressive affect evaluated at baseline, the most recent annual visit (time-varying), or average from baseline to the most recent visit (cumulative). Among 628 participants at baseline, 42% had BDI-II scores of 11 or more and 26% had a score above 14. During a 5-year follow-up, the cumulative incidence of cardiovascular death/hospitalization was significantly greater for participants with baseline BDI-II scores of 11 or more compared with those with scores <11. The baseline, time-varying, and cumulative elevated depressive affect were each associated with a significant higher risk of cardiovascular death/hospitalization, especially with a time-varying BDI-II score over 14 (adjusted HR 1.63) but not with the other outcomes. Thus, elevated depressive affect is associated with unfavorable cardiovascular outcomes in African Americans with hypertensive chronic kidney disease.
PMCID: PMC3237701  PMID: 21633409
AASK (African American Study of Kidney Disease and Hypertension); cardiovascular events; chronic kidney disease; depression
5.  Sociodemographic factors contribute to the depressive affect among African Americans with chronic kidney disease 
Kidney international  2010;77(11):1010-1019.
Depression is common in end-stage renal disease and is associated with poor quality of life and higher mortality; however, little is known about depressive affect in earlier stages of chronic kidney disease. To measure this in a risk group burdened with hypertension and kidney disease, we conducted a cross-sectional analysis of individuals at enrollment in the African American Study of Kidney Disease and Hypertension Cohort Study. Depressive affect was assessed by the Beck Depression Inventory II and quality of life by the Medical Outcomes Study-Short Form and the Satisfaction with Life Scale. Beck Depression scores over 14 were deemed consistent with an increased depressive affect and linear regression analysis was used to identify factors associated with these scores. Among 628 subjects, 166 had scores over 14 but only 34 were prescribed antidepressants. The mean Beck Depression score of 11.0 varied with the estimated glomerular filtration rate (eGFR) from 10.7 (eGFR 50–60) to 16.0 (eGFR stage 5); however, there was no significant independent association between these. Unemployment, low income, and lower quality and satisfaction with life scale scores were independently and significantly associated with a higher Beck Depression score. Thus, our study shows that an increased depressive affect is highly prevalent in African Americans with chronic kidney disease, is infrequently treated with antidepressants, and is associated with poorer quality of life. Sociodemographic factors have especially strong associations with this increased depressive affect. Because this study was conducted in an African-American cohort, its findings may not be generalized to other ethnic groups.
PMCID: PMC3114445  PMID: 20200503
AASK (African American Study of Kidney Disease and Hypertension); chronic kidney disease; clinical epidemiology; depression; quality of life
6.  Genome-wide linkage scans for type 2 diabetes mellitus in four ethnically diverse populations; significant evidence for linkage on chromosome 4q in African Americans: the Family Investigation of Nephropathy and Diabetes (FIND) Research Group 
Previous studies have shown that, in addition to environmental influences, type 2 diabetes mellitus (T2DM) has a strong genetic component. The goal of the current study is to identify regions of linkage for T2DM in ethnically diverse populations.
Phenotypic and genotypic data were obtained from African American (AA; total number of individuals (N)=1004), American Indian (AI; N=883), European American (EA; N=537), and Mexican American (MA; N=1634) individuals from the Family Investigation of Nephropathy and Diabetes. Nonparametric linkage analysis, using an average of 4,404 SNPs, was performed in relative pairs affected with T2DM in each ethnic group. In addition, family-based tests were performed to detect association with T2DM.
Statistically significant evidence for linkage was observed on chromosomes 4q21.1 (LOD=3.13; genome-wide p=0.04) in AA. In addition, a total of eleven regions showed suggestive evidence for linkage (estimated at LOD>1.71), with the highest LOD scores on chromosomes 12q21.31 (LOD=2.02) and 22q12.3 (LOD=2.38) in AA, 2p11.1 (LOD=2.23) in AI, 6p12.3 (LOD=2.77) in EA, and 13q21.1 (LOD=2.24) in MA. While no region overlapped across all ethnic groups, at least five loci showing LOD>1.71 have been identified in previously published studies.
The results from this study provide evidence for the presence of genes affecting T2DM on chromosomes 4q, 12q, and 22q in AA, 6p in EA, 2p in AI, and 13q in MA. The strong evidence for linkage on chromosome 4q in AA provides important information given the paucity of diabetes genetic studies in this population.
PMCID: PMC2783577  PMID: 19795399
FIND; Type 2 Diabetes; linkage analysis; ethnicity
7.  A genome-wide admixture scan identifies MYH9 as a candidate locus associated with non-diabetic end stage renal disease in African Americans 
Nature genetics  2008;40(10):1185-1192.
End stage renal disease (ESRD) has a four times higher incidence in African Americans compared to European Americans. This led to the hypothesis that susceptibility alleles for ESRD have a higher frequency in West African than European gene pool. We performed a genome-wide admixture scan in 1,372 ESRD cases and 806 controls and demonstrated a highly significant association between excess African ancestry and non-diabetic ESRD (LOD 5.70) but not diabetic ESRD (LOD 0.47) on chromosome 22q12. Each copy of the European ancestral allele conferred a relative risk of 0.50 (95% credible interval 0.39 – 0.63) compared to African ancestry. Multiple common SNPs (allele frequency ranging from 0.2 to 0.6) in the gene that encodes non-muscle myosin heavy chain type II isoform A (MYH9) were associated with 2-4 times greater risk of non-diabetic ESRD and accounted for a large proportion of the excess risk of ESRD observed in African compared to European Americans.
PMCID: PMC2614692  PMID: 18794854

Results 1-7 (7)