Faculty Bibliography
Searched for:
Department/Unit:Population Health
Total Results:
13249
Bone Mineral Density and Progression of Subclinical Atherosclerosis in African-Americans With Type 2 Diabetes
CONTEXT:Relative to European Americans, calcified atherosclerotic plaque (CP) is less prevalent and severe in African-Americans (AAs). OBJECTIVE:Predictors of progression of CP in the aorta, carotid, and coronary arteries were examined in AAs over a mean 5.3 ± 1.4-year interval. DESIGN:This is the African American-Diabetes Heart Study. SETTING:A type 2 diabetes (T2D)-affected cohort was included. PARTICIPANTS:A total of 300 unrelated AAs with T2D; 50% female, mean age 55 ± 9 years, baseline hemoglobin A1c 8.1 ± 1.8% was included. MAIN OUTCOME MEASURES:Glycemic control, renal parameters, vitamin D, and computed tomography-derived measures of adiposity, vascular CP, and volumetric bone mineral density (vBMD) in lumbar and thoracic vertebrae were obtained at baseline and follow-up. RESULTS:CP increased in incidence and quantity/mass in all three vascular beds over the 5-year study (P < .0001). Lower baseline lumbar and thoracic vBMD were associated with progression of abdominal aorta CP (P < .008), but not progression of carotid or coronary artery CP. Lower baseline estimated glomerular filtration rate was associated with progression of carotid artery CP (P = .0004), and higher baseline pericardial adipose volume was associated with progression of coronary artery (P = .001) and aorta (P = .0006) CP independent of body mass index. There was a trend for an inverse relationship between change in thoracic vBMD and change in aortic CP (P = .05). CONCLUSIONS:In this longitudinal study, lower baseline thoracic and lumbar vBMD and estimated glomerular filtration rate and higher pericardial adipose volumes were associated with increases in CP in AAs with T2D. Changes in these variables and baseline levels and/or changes in glycemic control, albuminuria, and vitamin D were not significantly associated with progression of CP.
PMCID:5095232
PMID: 27552541
ISSN: 1945-7197
CID: 4318542
Common scientific and statistical errors in obesity research
This review identifies 10 common errors and problems in the statistical analysis, design, interpretation, and reporting of obesity research and discuss how they can be avoided. The 10 topics are: 1) misinterpretation of statistical significance, 2) inappropriate testing against baseline values, 3) excessive and undisclosed multiple testing and "P-value hacking," 4) mishandling of clustering in cluster randomized trials, 5) misconceptions about nonparametric tests, 6) mishandling of missing data, 7) miscalculation of effect sizes, 8) ignoring regression to the mean, 9) ignoring confirmation bias, and 10) insufficient statistical reporting. It is hoped that discussion of these errors can improve the quality of obesity research by helping researchers to implement proper statistical practice and to know when to seek the help of a statistician.
PMID: 27028280
ISSN: 1930-739x
CID: 4318472
Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function
Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways.
PMID: 26831199
ISSN: 2041-1723
CID: 4318462
APOE Genotypes Associate With Cognitive Performance but Not Cerebral Structure: Diabetes Heart Study MIND
OBJECTIVE:Dementia is a debilitating illness with a disproportionate burden in patients with type 2 diabetes (T2D). Among the contributors, genetic variation at the apolipoprotein E locus (APOE) is posited to convey a strong effect. This study compared and contrasted the association of APOE with cognitive performance and cerebral structure in the setting of T2D. RESEARCH DESIGN AND METHODS:European Americans from the Diabetes Heart Study (DHS) MIND (n = 754) and African Americans from the African American (AA)-DHS MIND (n = 517) were examined. The cognitive battery assessed executive function, memory, and global cognition, and brain MRI was performed. RESULTS:In European Americans and African Americans, the APOE E4 risk haplotype group was associated with poorer performance on the modified Mini-Mental Status Examination (P < 0.017), a measure of global cognition. In contrast to the literature, the APOE E2 haplotype group, which was overrepresented in these participants with T2D, was associated with poorer Rey Auditory Verbal Learning Test performance (P < 0.032). Nominal associations between APOE haplotype groups and MRI-determined cerebral structure were observed. CONCLUSIONS:Compared with APOE E3 carriers, E2 and E4 carriers performed worse in the cognitive domains of memory and global cognition. Identification of genetic contributors remains critical to understanding new pathways to prevent and treat dementia in the setting of T2D.
PMCID:5127235
PMID: 27703028
ISSN: 1935-5548
CID: 4318572
Deceased-Donor Apolipoprotein L1 Renal-Risk Variants Have Minimal Effects on Liver Transplant Outcomes
BACKGROUND:Apolipoprotein L1 gene (APOL1) G1 and G2 renal-risk variants, common in populations with recent African ancestry, are strongly associated with non-diabetic nephropathy, end-stage kidney disease, and shorter allograft survival in deceased-donor kidneys (autosomal recessive inheritance). Circulating APOL1 protein is synthesized primarily in the liver and hydrodynamic gene delivery of APOL1 G1 and G2 risk variants has caused hepatic necrosis in a murine model. METHODS:To evaluate the impact of these variants in liver transplantation, this multicenter study investigated the association of APOL1 G1 and G2 alleles in deceased African American liver donors with allograft survival. Transplant recipients were followed for liver allograft survival using data from the Scientific Registry of Transplant Recipients. RESULTS:Of the 639 liver donors evaluated, 247 had no APOL1 risk allele, 300 had 1 risk allele, and 92 had 2 risk alleles. Graft failure assessed at 15 days, 6 months, 1 year and total was not significantly associated with donor APOL1 genotype (p-values = 0.25, 0.19, 0.67 and 0.89, respectively). CONCLUSIONS:In contrast to kidney transplantation, deceased-donor APOL1 G1 and G2 risk variants do not significantly impact outcomes in liver transplantation.
PMCID:4824450
PMID: 27054572
ISSN: 1932-6203
CID: 4318492
A Comparison of Composite Reliability Estimators: Coefficient Omega Confidence Intervals in the Current Literature
Coefficient omega and alpha are both measures of the composite reliability for a set of items. Unlike coefficient alpha, coefficient omega remains unbiased with congeneric items with uncorrelated errors. Despite this ability, coefficient omega is not as widely used and cited in the literature as coefficient alpha. Reasons for coefficient omega's underutilization include a limited knowledge of its statistical properties. However, consistent efforts to understand the statistical properties of coefficient omega can help improve its utilization in research efforts. Here, six approaches for estimating confidence intervals for coefficient omega with unidimensional congeneric items were evaluated through a Monte Carlo simulation. The evaluations were made through simulation conditions that mimic realistic conditions that investigators are likely to face in applied work, including items that are not normally distributed and small sample size(s). Overall, the normal theory bootstrap confidence interval had the best performance across all simulation conditions that included sample sizes less than 100. However, most methods had sound coverage with sample sizes of 100 or more.
PMCID:5965559
PMID: 29795872
ISSN: 1552-3888
CID: 4318752
APOL1 Genotype and Kidney Transplantation Outcomes From Deceased African American Donors
BACKGROUND:Two apolipoprotein L1 gene (APOL1) renal-risk variants in donors and African American (AA) recipient race are associated with worse allograft survival in deceased-donor kidney transplantation (DDKT) from AA donors. To detect other factors impacting allograft survival from deceased AA kidney donors, APOL1 renal-risk variants were genotyped in additional AA kidney donors. METHODS:The APOL1 genotypes were linked to outcomes in 478 newly analyzed DDKTs in the Scientific Registry of Transplant Recipients. Multivariate analyses accounting for recipient age, sex, race, panel-reactive antibody level, HLA match, cold ischemia time, donor age, and expanded criteria donation were performed. These 478 transplantations and 675 DDKTs from a prior report were jointly analyzed. RESULTS:Fully adjusted analyses limited to the new 478 DDKTs replicated shorter renal allograft survival in recipients of APOL1 2-renal-risk-variant kidneys (hazard ratio [HR], 2.00; P = 0.03). Combined analysis of 1153 DDKTs from AA donors revealed donor APOL1 high-risk genotype (HR, 2.05; P = 3 × 10), older donor age (HR, 1.18; P = 0.05), and younger recipient age (HR, 0.70; P = 0.001) adversely impacted allograft survival. Although prolonged allograft survival was seen in many recipients of APOL1 2-renal-risk-variant kidneys, follow-up serum creatinine concentrations were higher than that in recipients of 0/1 APOL1 renal-risk-variant kidneys. A competing risk analysis revealed that APOL1 impacted renal allograft survival, but not recipient survival. Interactions between donor age and APOL1 genotype on renal allograft survival were nonsignificant. CONCLUSIONS:Shorter renal allograft survival is reproducibly observed after DDKT from APOL1 2-renal-risk-variant donors. Younger recipient age and older donor age have independent adverse effects on renal allograft survival.
PMID: 26566060
ISSN: 1534-6080
CID: 4318422
Adiposity is inversely associated with hippocampal volume in African Americans and European Americans with diabetes
AIMS:To assess associations between body mass index (BMI), waist circumference (WC), and computed tomography-determined volumes of pericardial, visceral, and subcutaneous adipose tissue with magnetic resonance imaging-(MRI) based cerebral structure and cognitive performance in individuals with type 2 diabetes (T2D). METHODS:This study was performed in 348 African Americans (AAs) and 256 European Americans (EAs) with T2D. Associations between adiposity measures with cerebral volumes of white matter (WMV), gray matter (GMV), white matter lesions, hippocampal GMV, and hippocampal WMV, cognitive performance and depression were examined using marginal models incorporating generalized estimating equations. All models were adjusted for age, sex, education, smoking, HbA1c, hypertension, statins, cardiovascular disease, MRI scanner (MRI outcomes only), and time between scans; some neuroimaging measures were additionally adjusted for intracranial volume. RESULTS:Participants were 59.9% female with mean (SD) age 57.7(9.3)years, diabetes duration 9.6(6.8)years, and HbA1c 7.8(1.9)%. In AAs, inverse associations were detected between hippocampal GMV and both BMI (β [95% CI]-0.18 [-0.30, -0.07], P=0.0018) and WC (-0.23 [-0.35, -0.12], P=0.0001). In the full bi-ethnic sample, inverse associations were detected between hippocampal WMV and WC (P≤0.0001). Positive relationships were observed between BMI (P=0.0007) and WC (P<0.0001) with depression in EAs. CONCLUSIONS:In patients with T2D, adiposity is inversely associated with hippocampal gray and white matter volumes.
PMCID:5050135
PMID: 27615667
ISSN: 1873-460x
CID: 4318552
Factors influencing time to case registration for youth with type 1Â and type 2 diabetes: SEARCH for Diabetes in Youth Study
PURPOSE:The development of a sustainable pediatric diabetes surveillance system for the United States requires a better understanding of issues related to case ascertainment. METHODS:Using the SEARCH for Diabetes in Youth registry, we examined whether time from diabetes diagnosis to case registration differed by diabetes type, patient demographics, and the type of provider reporting the case to the study. Plots for time from diagnosis to registration were developed, and differences by key variables were examined using the log-rank test. RESULTS:Compared with time to registration for type 1 cases, it took 2.6 (95% confidence interval [CI], 2.5-2.6) times longer to register 50% of type 2 diabetes cases, and 2.3 (95% CI, 2.0-2.5) times longer to register 90% of type 2 cases. For type 1 diabetes cases, a longer time to registration was associated with older age, minority race/ethnicity, and cases, where the referring provider was not an endocrinologist. For type 2 diabetes cases, older age, non-Hispanic white race/ethnicity, and cases reported by providers other than an endocrinologist took longer to identify and register. CONCLUSIONS:These findings highlight the need for continued childhood diabetes surveillance to identify future trends and influences on changes in prevalence and incidence.
PMCID:5322941
PMID: 27664849
ISSN: 1873-2585
CID: 4318562
Relationships between measures of adiposity with subclinical atherosclerosis in patients with type 2 diabetes
OBJECTIVE:Assess cross-sectional relationships between body mass index (BMI), waist circumference (WC), pericardial (PAT), visceral (VAT), and subcutaneous adipose tissue (SAT) volumes with calcified plaque (CP) in African Americans (AAs) and European Americans (EAs) with type 2 diabetes. METHODS:Computed tomography measured PAT, VAT, SAT, and CP in coronary arteries (CAC), carotid arteries, and aorta. Generalized estimating equations models were fitted to test for associations between adiposity and CP, stratified by ethnicity while accounting for familial correlations. RESULTS:AAs (N = 753) vs. EAs (N = 562) had significantly lower PAT and VAT, despite equal or higher BMI. In multivariable models adjusting for age, gender, education, HbA1c, statins, smoking, cardiovascular disease, hypertension, nephropathy, and C-reactive protein, PAT positively associated with presence of CAC in AAs (P < 0.001), not EAs (P = 0.68; ethnicity interaction P < 0.01). Inverse associations were detected between SAT and severity of aorta CP (P < 0.01) in AAs and between BMI, WC, and SAT with severity of aorta CP in all participants. CONCLUSIONS:Ethnic- and gender-specific differences in BMI, WC, PAT, SAT, and VAT were present in AAs and EAs with diabetes. Only PAT was positively associated with CAC in AAs; paradoxical inverse associations were seen between several other adiposity measures and subclinical cardiovascular disease.
PMCID:4963287
PMID: 27356020
ISSN: 1930-739x
CID: 4318532
