Genome-wide association study identifies novel loci for type 2 diabetes-attributed end-stage kidney disease in African Americans

BACKGROUND

End-stage kidney disease (ESKD) is a significant public health concern disproportionately affecting African Americans (AAs). Type 2 diabetes (T2D) is the leading cause of ESKD in the USA, and efforts to uncover genetic susceptibility to diabetic kidney disease (DKD) have had limited success. A prior genome-wide association study (GWAS) in AAs with T2D-ESKD was expanded with additional AA cases and controls and genotypes imputed to the higher density 1000 Genomes reference panel. The discovery analysis included 3432 T2D-ESKD cases and 6977 non-diabetic non-nephropathy controls (N = 10,409), followed by a discrimination analysis in 2756 T2D non-nephropathy controls to exclude T2D-associated variants.

RESULTS

Six independent variants located in or near RND3/RBM43, SLITRK3, ENPP7, GNG7, and APOL1 achieved genome-wide significant association (P < 5 × 10-8) with T2D-ESKD. Following extension analyses in 1910 non-diabetic ESKD cases and 908 non-diabetic non-nephropathy controls, a meta-analysis of 5342 AA all-cause ESKD cases and 6977 AA non-diabetic non-nephropathy controls revealed an additional novel all-cause ESKD locus at EFNB2 (rs77113398; P = 9.84 × 10-9; OR = 1.94). Exclusion of APOL1 renal-risk genotype carriers identified two additional genome-wide significant T2D-ESKD-associated loci at GRAMD3 and MGAT4C. A second variant at GNG7 (rs373971520; P = 2.17 × 10-8, OR = 1.46) remained associated with all-cause ESKD in the APOL1-negative analysis.

CONCLUSIONS

Findings provide further evidence for genetic factors associated with advanced kidney disease in AAs with T2D.

Metabolomic profiling to improve glomerular filtration rate estimation: a proof-of-concept study

BACKGROUND

Estimation of glomerular filtration rate (GFR) using estimated glomerular filtration rate creatinine (eGFRcr) is central to clinical practice but has limitations. We tested the hypothesis that serum metabolomic profiling can identify novel markers that in combination can provide more accurate GFR estimates.

METHODS

We performed a cross-sectional study of 200 African American Study of Kidney Disease and Hypertension (AASK) and 265 Multi-Ethnic Study of Atherosclerosis (MESA) participants with measured GFR (mGFR). Untargeted gas chromatography/dual mass spectrometry- and liquid chromatography/dual mass spectrometry-based quantification was followed by the development of targeted assays for 15 metabolites. On the log scale, GFR was estimated from single- and multiple-metabolite panels and compared with eGFR using the Chronic Kidney Disease Epidemiology equations with creatinine and/or cystatin C using established metrics, including the proportion of errors >30% of mGFR (1-P30), before and after bias correction.

RESULTS

Of untargeted metabolites in the AASK and MESA, 283 of 780 (36%) and 387 of 1447 (27%), respectively, were significantly correlated (P ≤ 0.001) with mGFR. A targeted metabolite panel eGFR developed in the AASK and validated in the MESA was more accurate (1-P30 3.7 and 1.9%, respectively) than eGFRcr [11.2 and 18.5%, respectively (P < 0.001 for both)] and estimating GFR using cystatin C (eGFRcys) [10.6% (P = 0.02) and 9.1% (P < 0.05), respectively] but was not consistently better than eGFR using both creatinine and cystatin C [3.7% (P > 0.05) and 9.1% (P < 0.05), respectively]. A panel excluding creatinine and demographics still performed well [1-P30 6.4% (P = 0.11) and 3.4% (P < 0.001) in the AASK and MESA] versus eGFRcr.

CONCLUSIONS

Multimetabolite panels can enable accurate GFR estimation. Metabolomic equations, preferably excluding creatinine and demographic characteristics, should be tested for robustness and generalizability as a potential confirmatory test when eGFRcr is unreliable.

Associations between lipids and subclinical coronary atherosclerosis

OBJECTIVE

Whether HIV modifies the relationship of serum lipids with coronary atherosclerosis and coronary plaque subtypes is uncertain. We examined the associations between traditional lipids and coronary atherosclerosis among HIV-infected (HIV+) and HIV-uninfected (HIV-) men.

DESIGN

The Multicenter AIDS Cohort Study is an observational cohort with a total of 429 HIV+ and 303 HIV- men who had non-contrast cardiac computed tomography performed to measure coronary artery calcium and coronary computed tomography angiography to measure coronary stenosis, coronary plaque presence, and composition.

METHODS

We used multivariable adjusted prevalence ratios to examine the relationship between the SD difference in each lipid parameter and coronary atherosclerosis.

RESULTS

Total cholesterol (TC)/HDL-cholesterol had the strongest associations with coronary atherosclerosis regardless of HIV status. Overall, lipid parameters were most strongly associated with the presence of mixed plaque, stenosis more than 50%, and coronary artery calcium for both HIV+ and HIV- men. HIV+ men had similar, but weaker associations, between lipid parameters and coronary atherosclerosis compared with HIV- men. The strongest association was between the TC/HDL-cholesterol and stenosis more than 50% for both HIV+ [prevalence ratios 1.25 per SD (95% confidence interval 1.07-1.43)] and HIV- men [prevalence ratios 1.46 per SD (95% confidence interval 1.08-1.85)].

CONCLUSION

The associations between lipids and coronary atherosclerosis tended to be weaker for HIV+ compared with HIV- men, although TC/HDL had the strongest association for both HIV+ and HIV- men. A weaker association between lipid levels and coronary atherosclerosis for HIV+ men may contribute to the decreased discrimination of cardiovascular disease risk observed in HIV+ individuals.

Inflammatory biomarkers and subclinical carotid atherosclerosis in HIV-infected and HIV-uninfected men in the Multicenter AIDS Cohort Study

BACKGROUND

HIV-infected persons have an increased risk of atherosclerosis relative to uninfected individuals. Inflammatory processes may contribute to this risk. We evaluated the associations of 10 biomarkers of systemic inflammation (CRP, IL-6, sTNF-αR1 and 2), monocyte activation (CCL2, sCD163, sCD14), coagulation (fibrinogen, D-dimer), and endothelial dysfunction (ICAM-1) with subclinical carotid atherosclerosis among participants in the Multicenter AIDS Cohort Study (MACS).

METHODS

Carotid plaque and intima media thickness (IMT) in the common carotid (CCA-IMT) and bifurcation region were assessed by B mode ultrasound among 452 HIV-infected and 276 HIV-uninfected men from 2010-2013. Associations between levels of each biomarker and presence of focal plaque and IMT were assessed by logistic and linear regression models, adjusting for demographics, risk behaviors, traditional cardiovascular disease (CVD) risk factors, and HIV disease characteristics.

RESULTS

Compared to HIV-uninfected men, HIV-infected men had significantly higher levels of 8 of the 10 biomarkers. Overall, men with sCD163, CCL2, IL-6, and CRP levels in the highest quintile had approximately 2 times the odds of carotid plaque relative to those with levels in the lowest quintile, independent of demographic and CVD risk factors. Fibrinogen levels were positively associated with CCA-IMT while ICAM-1, CCL2, and sTNF-αR1 levels were positively associated with bifurcation-IMT. Among HIV-uninfected men, higher levels of sTNF-αR2 were positively associated with CCA-IMT, fibrinogen with bifurcation-IMT and carotid plaque, and ICAM-1 with carotid plaque.

CONCLUSION

In addition to greater levels of systemic inflammation, heightened monocyte activation (sCD163, CCL2) may contribute to the burden of atherosclerosis among HIV-infected persons.

The Impact of Past and Current Alcohol Consumption Patterns on Progression of Carotid Intima-Media Thickness Among Women and Men Living with HIV Infection

BACKGROUND

The relationship between alcohol consumption and atherosclerosis has not been sufficiently examined among people living with HIV (PLWH).

METHODS

We analyzed data from PLWH in the Women's Interagency HIV Study (WIHS; n = 1,164) and the Multicenter AIDS Cohort Study (MACS; n = 387) with no history of cardiovascular disease (CVD). Repeated measures of intima-media thickness of the right common carotid artery (CCA-IMT) were assessed using B-mode ultrasound from 2004 to 2013. Current alcohol consumption was collected at time of CCA-IMT measurement and was categorized according to gender-specific weekly limits. Group-based trajectory models categorized participants into past 10-year consumption patterns (1994 to 2004). Multivariate generalized estimating equations were conducted to assess the association of past and current alcohol use patterns on change in CCA-IMT by cohort, controlling for age, race, cigarette and illicit drug use, probable depression, HIV RNA viral load, antiretroviral therapy exposure, and hepatitis C coinfection.

RESULTS

Among the WIHS, past heavy alcohol consumption was associated with increased CCA-IMT level over time (β = 8.08, CI 0.35, 15.8, p = 0.04), compared to abstinence. Among the MACS, compared to abstinence, all past consumption patterns were associated with increased CCA-IMT over time (past low: β = 15.3, 95% CI 6.46, 24.2, p < 0.001; past moderate: β = 14.3, CI 1.36, 27.2, p = 0.03; past heavy: β = 21.8, CI 4.63, 38.9, p = 0.01). Current heavy consumption was associated with decreased CCA-IMT among the WIHS (β = -11.4, 95% CI -20.2, -2.63, p = 0.01) and MACS (β = -15.4, 95% CI -30.7, -0.13, p = 0.04). No statistically significant time by consumption pattern effects were found.

CONCLUSIONS

In both cohorts, 10-year heavy consumption was associated with statistically significant increases in carotid artery thickness, compared to abstinence. Long-term patterns of drinking at any level above abstinence were particularly significant for increases in IMT among men, with heavy consumption presenting with the greatest increase. Our results suggest a potentially different window of risk among past and current heavy drinkers. Further studies are needed to determine whether alcohol consumption level is associated with intermediate measures of atherosclerosis. Alcohol screening and interventions to reduce heavy consumption may benefit PLWH who are at risk of CVD.

Ethnic, geographic and dietary differences in arsenic exposure in the multi-ethnic study of atherosclerosis (MESA)

Differences in residential location as well as race/ethnicity and dietary habits may result in differences in inorganic arsenic (iAs) exposure. We investigated the association of exposure to iAs with race/ethnicity, geography, and dietary intake in a random sample of 310 White, Black, Hispanic, and Chinese adults in the Multi-Ethnic Study of Atherosclerosis from 6 US cities with inorganic and methylated arsenic (ΣAs) measured in urine. Dietary intake was assessed by food-frequency questionnaire. Chinese and Hispanic race/ethnicity was associated with 82% (95% CI: 46%, 126%) and 37% (95% CI: 10%, 70%) higher urine arsenic concentrations, respectively, compared to White participants. No differences were observed for Black participants compared to Whites. Urine arsenic concentrations were higher for participants in Los Angeles, Chicago, and New York compared to other sites. Participants that ate rice ≥2 times/week had 31% higher urine arsenic compared to those that rarely/never consumed rice. Participants that drank wine ≥2 times/week had 23% higher urine arsenic compared to rare/never wine drinkers. Intake of poultry or non-rice grains was not associated with urinary arsenic concentrations. At the low-moderate levels typical of the US population, exposure to iAs differed by race/ethnicity, geographic location, and frequency of rice and wine intake.

Associations of variants In the hexokinase 1 and interleukin 18 receptor regions with oxyhemoglobin saturation during sleep

Sleep disordered breathing (SDB)-related overnight hypoxemia is associated with cardiometabolic disease and other comorbidities. Understanding the genetic bases for variations in nocturnal hypoxemia may help understand mechanisms influencing oxygenation and SDB-related mortality. We conducted genome-wide association tests across 10 cohorts and 4 populations to identify genetic variants associated with three correlated measures of overnight oxyhemoglobin saturation: average and minimum oxyhemoglobin saturation during sleep and the percent of sleep with oxyhemoglobin saturation under 90%. The discovery sample consisted of 8,326 individuals. Variants with p < 1 × 10(-6) were analyzed in a replication group of 14,410 individuals. We identified 3 significantly associated regions, including 2 regions in multi-ethnic analyses (2q12, 10q22). SNPs in the 2q12 region associated with minimum SpO2 (rs78136548 p = 2.70 × 10(-10)). SNPs at 10q22 were associated with all three traits including average SpO2 (rs72805692 p = 4.58 × 10(-8)). SNPs in both regions were associated in over 20,000 individuals and are supported by prior associations or functional evidence. Four additional significant regions were detected in secondary sex-stratified and combined discovery and replication analyses, including a region overlapping Reelin, a known marker of respiratory complex neurons.These are the first genome-wide significant findings reported for oxyhemoglobin saturation during sleep, a phenotype of high clinical interest. Our replicated associations with HK1 and IL18R1 suggest that variants in inflammatory pathways, such as the biologically-plausible NLRP3 inflammasome, may contribute to nocturnal hypoxemia.

Efficient Variant Set Mixed Model Association Tests for Continuous and Binary Traits in Large-Scale Whole-Genome Sequencing Studies

With advances in whole-genome sequencing (WGS) technology, more advanced statistical methods for testing genetic association with rare variants are being developed. Methods in which variants are grouped for analysis are also known as variant-set, gene-based, and aggregate unit tests. The burden test and sequence kernel association test (SKAT) are two widely used variant-set tests, which were originally developed for samples of unrelated individuals and later have been extended to family data with known pedigree structures. However, computationally efficient and powerful variant-set tests are needed to make analyses tractable in large-scale WGS studies with complex study samples. In this paper, we propose the variant-set mixed model association tests (SMMAT) for continuous and binary traits using the generalized linear mixed model framework. These tests can be applied to large-scale WGS studies involving samples with population structure and relatedness, such as in the National Heart, Lung, and Blood Institute's Trans-Omics for Precision Medicine (TOPMed) program. SMMATs share the same null model for different variant sets, and a virtue of this null model, which includes covariates only, is that it needs to be fit only once for all tests in each genome-wide analysis. Simulation studies show that all the proposed SMMATs correctly control type I error rates for both continuous and binary traits in the presence of population structure and relatedness. We also illustrate our tests in a real data example of analysis of plasma fibrinogen levels in the TOPMed program (n = 23,763), using the Analysis Commons, a cloud-based computing platform.

Carotid Artery Echolucency, Texture Features, and Incident Cardiovascular Disease Events: The MESA Study

Background We hypothesized that measures of common carotid artery echolucency and grayscale texture features were associated with cardiovascular disease ( CVD ) risk factors and could predict CVD events. Methods and Results Using a case-cohort design, we measured common carotid artery ultrasound images from 1788 participants in Exam 1 of the MESA study (Multi-Ethnic Study of Atherosclerosis) to derive 4 grayscale features: grayscale median, entropy, gray level difference statistic-contrast, and spatial gray level dependence matrices-angular second moment. CVD risk factor associations were determined by linear regression. Cox proportional hazard models with inverse selection probability weighting and adjustments for age, sex, race/ethnicity, CVD risk factors, and C-reactive protein were used to determine if standardized values for grayscale median, entropy, gray level difference statistic-contrast, and spatial gray level dependence matrices-angular second moment could predict incident coronary heart disease, stroke, and total CVD events over a median 13 years follow-up. Participants were mean ( SD ) 63.1 (10.3) years of age, 52.6% female, 32.1% white, 27.8% black, 23.3% Hispanic, and 16.8% Chinese. There were 283 coronary heart disease, 120 stroke, and 416 CVD events. Several associations of grayscale features with CVD risk factors were identified. In fully adjusted models, higher gray level difference statistic-contrast was associated with a lower risk of incident coronary heart disease (hazard ratio 0.82, 95% CI 0.71-0.94, padj=0.005) and CVD events (hazard ratio 0.87, 95% CI 0.77-0.98, padj=0.018); higher spatial gray level dependence matrices-angular second moment was associated with a higher risk of CVD events (hazard ratio 1.09, 95% CI 1.00-1.19, padj=0.044). Conclusions Gray level difference statistic-contrast and spatial gray level dependence matrices-angular second moment predicted CVD events independent of risk factors, indicating their potential use as biomarkers to assess future CVD risk.

A Comparison of the Liver Fat Score and CT Liver-to-Spleen Ratio as Predictors of Fatty Liver Disease by HIV Serostatus

Background and Aim

Non-alcoholic fatty liver disease (NAFLD) is common among HIV-infected (HIV+) adults. The Liver Fat Score (LFS) is a non-invasive, rapid, inexpensive diagnostic tool that uses routine clinical data and is validated against biopsy in HIV-uninfected (HIV-) persons. CT liver-to-spleen (L/S) attenuation ratio is another validated method to diagnose NAFLD. We compared NAFLD prevalence using the LFS versus L/S ratio among Multicenter AIDS Cohort Study participants to assess the LFS's performance in HIV+vs. HIV-men.

Methods

In a cross-sectional analysis of men reporting<3 alcoholic drinks daily (308 HIV+, 218 HIV-), Spearman correlations determined relationships between LFS and L/S ratio by HIV serostatus. Multivariable regression determined factors associated with discordance in LFS- and L/S ratio-defined NAFLD prevalence.

Results

NAFLD prevalence by LFS and L/S ratio were 28%/15% for HIV+men and 20%/19% for HIV-men, respectively. Correlations between LFS and L/S ratio were weaker among HIV+than HIV-men, but improved with increasing BMI and exclusion of HCV-infected men. LFS and L/S ratio discordance occurred more frequently and across BMI strata among HIV+men, but predominantly at BMI<30 kg/m² among HIV-men. In multivariate analysis, only lower total testosterone levels were significantly associated with discordance.

Conclusion

NAFLD prevalence was similar by LFS and L/S ratio identification among HIV-men, but dissimilar and with frequent discordance between the two tests among HIV+men. As discordance may be multifactorial, biopsy data are needed to determine the best non-invasive diagnostic test for NAFLD in HIV+persons.

Sex Hormones and Change in N-Terminal Pro-B-Type Natriuretic Peptide Levels: The Multi-Ethnic Study of Atherosclerosis

Context

Sex hormones may influence sex differences in cardiovascular disease (CVD). N-terminal pro-B-type natriuretic peptide (NT-proBNP), a predictor of CVD, is higher in women than men, which may relate to sex hormones.

Objective

To evaluate whether total testosterone (T), bioavailable T, free T, estradiol, dehydroepiandrosterone (DHEA), and SHBG are associated with NT-proBNP.

Design

Cohort study.

Participants

Cross-sectional sample included 2371 postmenopausal women and 2688 men free of CVD, of which 2041 women and 2348 men were included longitudinally.

Main Outcome Measures

NT-proBNP at baseline (2000 to 2002) and one or more repeat NT-proBNPs (through 2012). Analyses adjusted for CVD risk factors.

Results

Women had higher NT-proBNP than men (median 79.9 vs 38.5 pg/mL). Cross-sectionally, higher bioavailable T, free T, DHEA, and lower SHBG levels were independently associated with lower NT-proBNP among both women and men (all P < 0.05). Higher total T in women and estradiol in men were also associated with lower NT-proBNP (both P < 0.05). Longitudinally, in women, higher total T, bioavailable T, free T, DHEA, and lower estradiol and SHBG were associated with greater 10-year increase in NT-proBNP (all P < 0.05). In men, higher free T and estradiol were associated with greater NT-proBNP increase (both P < 0.05).

Conclusions

A more androgenic sex hormone pattern was inversely associated with NT-proBNP cross-sectionally and may contribute to sex differences in NT-proBNP. Longitudinally, a more androgenic sex hormone pattern was associated with greater increase in NT-proBNP in women, which may reflect a mechanism for CVD risk after menopause.

Predictors of electrocardiographic QT interval prolongation in men with HIV

OBJECTIVE

HIV-infected (HIV+) individuals may be at increased risk for sudden arrhythmic cardiac death. Some studies have reported an association between HIV infection and prolongation of the electrocardiographic QT interval, a measure of ventricular repolarisation, which could potentiate ventricular arrhythmias. We aimed to assess whether HIV+ men have longer QT intervals than HIV-uninfected (HIV-) men and to determine factors associated with QT duration.

METHODS

We performed resting 12-lead ECGs in 774 HIV+ and 652 HIV- men in the Multicenter AIDS Cohort Study (MACS). We used multivariable linear and logistic regression analyses to assess associations between HIV serostatus and Framingham corrected QT interval (QTc), after accounting for potential confounders. We also determined associations among QTc interval and HIV-related factors in HIV+ men. In a subgroup of participants, levels of serum markers of inflammation were also assessed.

RESULTS

After adjusting for demographics and risk factors, QTc was 4.0 ms longer in HIV+ than HIV- men (p<0.001). Use of antiretroviral therapy (ART), specific ART drug class use and other HIV-specific risk factors were not associated with longer QTc. Among the subgroup with inflammatory biomarker measurements, higher interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1) and B-cell activating factor levels were independently associated with longer QTc and their inclusion partially attenuated the HIV effect.

CONCLUSIONS

HIV+ men had longer QTc, which was associated with higher levels of systemic inflammatory factors. This longer QTc may contribute to the increased risk for sudden arrhythmic cardiac death in some HIV+ individuals.

Carotid artery atherosclerosis is associated with mortality in HIV-positive women and men

OBJECTIVE

Among people with HIV, there are few long-term studies of noninvasive ultrasound-based measurements of the carotid artery predicting major health events. We hypothesized that such measurements are associated with 10-year mortality in the Women's Interagency HIV Study (WIHS) and Multicenter AIDS Cohort Study (MACS), and that associations differ by HIV serostatus.

DESIGN

Nested cohort study.

METHODS

Participants without coronary heart disease underwent B-mode carotid artery ultrasound, with measurement of common carotid artery intima-media thickness (IMT); carotid artery plaque (focal IMT > 1.5 mm) at six locations; and Young's modulus of elasticity, a measure of arterial stiffness. We examined all-cause mortality using Cox models, controlling for demographic, behavioral, cardiometabolic, and HIV-related factors.

RESULTS

Among 1722 women (median age 40 years, 90% nonwhite, 71% HIV-positive) and 1304 men (median age 50, 39% nonwhite, 62% HIV-positive), 11% died during follow-up. Mortality was higher among HIV-positive women [19.9 deaths/1000 person-years, 95% confidence interval (CI) 14.7-28.8] than HIV-positive men (15.1/1000, 95% CI 8.3-26.8). In adjusted analyses, plaque was associated with mortality (hazard ratio 1.44, 95% CI 1.10-1.88) regardless of HIV serostatus, and varied by sex (among women, hazard ratio 1.06, 95% CI 0.74-1.52; among men; hazard ratio 2.19, 95% CI 1.41-3.43). The association of plaque with mortality was more pronounced among HIV-negative (hazard ratio 3.87, 95% 1.95-7.66) than HIV-positive participants (hazard ratio 1.35, 95% CI 1.00-1.84). Arterial stiffness was also associated with mortality (hazard ratio 1.43 for highest versus lowest quartile, 95% CI 1.02-2.01). Greater common carotid artery-IMT was not associated with mortality.

CONCLUSION

Carotid artery plaque was predictive of mortality, with differences observed by sex and HIV serostatus.

Lp-PLA2, scavenger receptor class B type I gene (SCARB1) rs10846744 variant, and cardiovascular disease

BACKGROUND

We previously reported association of SCARB1 SNP rs10846744 with common carotid IMT (cIMT) and cardiovascular disease (CVD) events. Since rs10846744 has been reported in association with Lp-PLA2 mass and activity, we hypothesized that inflammatory pathways might mediate the association of rs10846744 with atherosclerosis.

METHODS

We first examined association of rs10846744 in CVD in multiple large-scale consortium-based genome-wide association studies. We further examined 27 parameters of interest, including Lp-PLA2 mass and activity, inflammatory markers, and plasma phospholipid fatty acids, and fatty acid ratios in participants from the Multi-Ethnic Study of Atherosclerosis (MESA), as potential mediators in the pathway linking rs10846744 with cIMT and incident CVD. Finally, we examined the association of rs10846744 with Lp-PLA2 activity, cardiovascular outcomes, and interaction with the Lp-PLA2 inhibitor, darapladib, in the Stabilization of Atherosclerotic Plaque by Initiation of Darapladib Therapy (STABILITY) and Stabilization of Plaque using Darapladib-Thrombolysis in Myocardial Infarction 52 (SOLID-TIMI 52) studies.

RESULTS

SCARB1 rs10846744 was associated with coronary artery disease events in CARDIoGRAMplusC4D (odds ratio 1.05; 95% CI [1.02, 1.07]; P = 1.4x10-4). In combined analysis across race/ethnic groups in MESA, rs10846744 was associated with Lp-PLA2 mass (P = 0.04) and activity (P = 0.001), homocysteine (P = 0.03), LDL particle number (P = 0.01), docosahexaenoic acid [DHA] (P = 0.01), docosapentaenoic acid [DPA] (P = 0.04), DPA/ eicosapentaenoic acid [EPA] ratio (P = 0.002), and DHA/EPA ratio (P = 0.008). Lp-PLA2 activity was identified as a mediator of rs10846744 with cIMT in a basic model (P = 8x10-5), but not after adjustment for CVD risk factors. There was no interaction or modifier effect of the Lp-PLA2 inhibitor darapladib assignment on the relationship between rs10846744 and major CVD events in either STABILITY or SOLID-TIMI 52.

SUMMARY

SCARB1 rs10846744 is significantly associated with Lp-PLA2 activity, atherosclerosis, and CVD events, but Lp-PLA2 activity is not a mediator in the association of rs10846744 with cIMT in MESA.

Association of endogenous sex hormone levels with coronary artery calcium progression among post-menopausal women in the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Sex differences in the incidence and manifestation of cardiovascular disease (CVD) suggest the involvement of sex hormones in disease pathogenesis. Coronary artery calcium (CAC) and its progression, measured by non-contrast cardiac computed tomography, are markers of subclinical atherosclerosis and predict CVD, even among low-risk women. We hypothesized that sex hormone levels were associated with CAC progression among women in the Multi-Ethnic Study of Atherosclerosis.

METHODS

We studied 2759 post-menopausal women (age 65 ± 9 years), free of baseline CVD, with baseline serum sex hormones and CAC measured at Exam 1 (2000-2002). Of this sample, 2427 had ≥1 follow-up CAC measurement through Exam 5 (2010-2012). Using mixed effects linear regression methods, we tested change in log[CAC+1] score by log[sex hormone] levels (continuous, comparing the 90th versus 10th percentiles). Models adjusted for demographics, lifestyle factors, cardiovascular risk factors, hormone therapy, and years since menopause.

RESULTS

At baseline, we found no associations between sex hormones and prevalent CAC. Over a median of 4.7 years, in fully-adjusted models, women with higher free testosterone levels had relatively greater CAC progression [Ratio 1.26 (95% CI 1.01-1.56)], whereas higher sex hormone binding globulin (SHBG) was associated with lower progression risk [0.80 (0.64-0.99). No associations were seen for total testosterone, estradiol, or dehydroepiandrosterone.

CONCLUSION

A more androgenic hormone profile of higher free testosterone and lower SHBG is associated with a greater CAC progression up to 10-years in post-menopausal women. Sex hormone levels may help identify women at increased risk for CVD who may benefit from additional risk-reducing strategies.

To T or not to T: Differences in Testosterone Use and Discontinuation by HIV Serostatus among Men who Have Sex with Men

OBJECTIVES

The aim of the study was to characterize contemporary patterns and correlates of testosterone therapy (TTh) use and discontinuation by HIV serostatus among men in the Multicenter AIDS Cohort Study (MACS).

METHODS

Self-reported testosterone use data were collected semiannually from 2400 (1286 HIV-infected and 1114 HIV-uninfected) men who have sex with men. Multivariable Poisson regression was used to estimate prevalence ratios for TTh use and predictors of TTh discontinuation (2012-2015).

RESULTS

Use was higher among HIV-infected compared with HIV-uninfected men in all age strata, with an age-adjusted prevalence of 17% vs. 5%, respectively (adjusted prevalence ratio 3.7; P < 0.001). Correlates of use in the multivariable model were similar by HIV serostatus: white race, the Los Angeles (LA) site, more than one recent sexual partner, non-smoking status, and higher American Heart Association/American College of Cardiology (AHA/ACC) cardiovascular disease (CVD) risk score category (approximately 70% of testosterone users were in the high-risk category). Compared with HIV-uninfected men, HIV-infected men more frequently reported building muscle mass as a motivation for testosterone use. The TTh discontinuation rate was 20.9/100 person-years [95% confidence interval (CI) 17.3, 25.0/100 person-years]. Relative to HIV-uninfected men, HIV-infected men were half as likely to discontinue (adjusted incidence rate ratio 0.4; P < 0.001). Discontinuation was 40% higher in the period after the US Food and Drug Administration (FDA) safety communication for testosterone in 2014, independent of co-factors (P = 0.06).

CONCLUSIONS

Given the high prevalence of both TTh use and CVD risk among HIV-infected men, the benefits and risks of TTh should be examined in future studies of aging HIV-infected men and monitored routinely in clinical practice.

Ten-year association of coronary artery calcium with atherosclerotic cardiovascular disease (ASCVD) events: the multi-ethnic study of atherosclerosis (MESA)

Aims

While coronary artery calcium (CAC) has been extensively validated for predicting clinical events, most outcome studies of CAC have evaluated coronary heart disease (CHD) rather than atherosclerotic cardiovascular disease (ASCVD) events (including stroke). Also, virtually all CAC studies are of short- or intermediate-term follow-up, so studies across multi-ethnic cohorts with long-term follow-up are warranted prior to widespread clinical use. We sought to evaluate the contribution of CAC using the population-based MESA cohort with over 10 years of follow-up for ASCVD events, and whether the association of CAC with events varied by sex, race/ethnicity, or age category.

Methods and results

We utilized MESA, a prospective multi-ethnic cohort study of 6814 participants (51% women), aged 45-84 years, free of clinical CVD at baseline. We evaluated the relationship between CAC and incident ASCVD using Cox regression models adjusted for age, race/ethnicity, sex, education, income, cigarette smoking status, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, diabetes, lipid-lowering medication, systolic blood pressure, antihypertensive medication, intentional physical exercise, and body mass index. Only the first event for each individual was used in the analysis. Overall, 500 incident ASCVD (7.4%) events were observed in the total study population over a median of 11.1 years. Hard ASCVD included 217 myocardial infarction, 188 strokes (not transient ischaemic attack), 13 resuscitated cardiac arrest, and 82 CHD deaths. Event rates in those with CAC = 0 Agatston units ranged from 1.3% to 5.6%, while for those with CAC > 300, the 10-year event rates ranged from 13.1% to 25.6% across different age, gender, and racial subgroups. At 10 years of follow-up, all participants with CAC > 100 were estimated to have >7.5% risk regardless of demographic subset. Ten-year ASCVD event rates increased steadily across CAC categories regardless of age, sex, or race/ethnicity. For each doubling of CAC, we estimated a 14% relative increment in ASCVD risk, holding all other risk factors constant. This association was not significantly modified by age, sex, race/ethnicity, or baseline lipid-lowering use.

Conclusions

Coronary artery calcium is associated strongly and in a graded fashion with 10-year risk of incident ASCVD as it is for CHD, independent of standard risk factors, and similarly by age, gender, and ethnicity. While 10-year event rates in those with CAC = 0 were almost exclusively below 5%, those with CAC ≥ 100 were consistently above 7.5%, making these potentially valuable cutpoints for the consideration of preventive therapies. Coronary artery calcium strongly predicts risk with the same magnitude of effect in all races, age groups, and both sexes, which makes it among the most useful markers for predicting ASCVD risk.

Relation of Sex Hormone Levels With Prevalent and 10-Year Change in Aortic Distensibility Assessed by MRI: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Women experience a steeper decline in aortic elasticity related to aging compared to men. We examined whether sex hormone levels were associated with ascending aortic distensibility (AAD) in the Multi-Ethnic Study of Atherosclerosis.

METHODS

We studied 1,345 postmenopausal women and 1,532 men aged 45-84 years, who had serum sex hormone levels, AAD measured by phase-contrast cardiac magnetic resonance imaging, and ejection fraction>50% at baseline. Among these participants, 457 women and 548 men returned for follow-up magnetic resonance imaging 10-years later. Stratified by sex, and using mixed effects linear regression methods, we examined associations of sex hormones (as tertiles) with baseline and annual change in log-transformed AAD (mm Hg-110-3), adjusting for demographics, body size, lifestyle factors, mean arterial pressure, heart rate, hypertensive medication use (and in women, for hormone therapy use and years since menopause).

RESULTS

The mean (SD) age was 65 (9) for women and 62 (10) years for men. AAD was lower in women than men (P < 0.001). In adjusted cross-sectional analysis, the highest tertile of free testosterone (compared to lowest) in women was significantly associated with lower AAD [-0.10 (-0.19, -0.01)] and the highest tertile of estradiol in men was associated with greater AAD [0.12 (0.04, 0.20)]. There were no associations of sex hormones with change in AAD over 10 years, albeit in a smaller sample size.

CONCLUSIONS

Lower free testosterone in women and higher estradiol in men were associated with greater aortic distensibility at baseline, but not longitudinally. Sex hormone levels may account for differences in AAD between women and men.

Ethnic, Geographic, and Genetic Differences in Arsenic Metabolism at Low Arsenic Exposure: A Preliminary Analysis in the Multi-Ethnic Study of Atherosclerosis (MESA)

We investigated the effect of candidate variants in AS3MT (arsenic (III) methyltransferase) with urinary arsenic metabolites and their principal components in a subset of 264 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Urinary arsenic species, including inorganic arsenic (iAs), monomethylarsonate (MMA), dimethylarsinate (DMA), and arsenobetaine (Ab), were measured using high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) and corrected for organic sources from seafood consumption by regressing Ab on arsenic species using a validated method. Principal components of arsenic metabolism were also used as independent phenotypes. We conducted linear regression of arsenic traits with allelic dosage of candidate single nucleotide polymorphisms (SNPs) rs12768205 (G > A), rs3740394 (A > G), and rs3740393 (G > C) measured using Illumina MetaboChip. Models were stratified by non-Hispanic white vs. all other race/ethnicity and adjusted for age, sex, arsenic exposure, study site, and population stratification. Consistent with previous studies, rs12768205 showed evidence for strongest association (non-Hispanic white: iAs% -0.14 (P 0.83), MMA% -0.66 (0.49), DMA% 0.81(0.49); other race/ethnicity: 0.13 (0.71), -1.21 (0.09), 1.08 (0.20)). No association, however, passed the strict Bonferroni p-value. This was a novel study among an ethnically diverse population exposed to low arsenic levels.

Resting heart rate and the incidence and progression of valvular calcium: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND AND AIMS

Left-sided valvular calcification is associated with cardiovascular disease (CVD) morbidity and mortality. Resting heart rate (RHR) may influence valvular calcium progression through shear stress. Whether RHR, an established CVD risk factor, is associated with valvular calcium progression is unknown. We assessed whether RHR predicts incidence and progression of mitral annular calcium (MAC) and aortic valve calcium (AVC) in a community-based cohort free of CVD at baseline.

METHODS

RHR was obtained from baseline electrocardiograms of 5498 MESA participants. MAC and AVC were quantified using Agatston scoring from cardiac computed tomography scans obtained at baseline and at a second examination during follow-up. We examined associations of RHR with incident MAC/AVC and annual change in MAC/AVC scores, after adjusting for demographics, CVD risk factors, physical activity, and atrioventricular nodal blocker use.

RESULTS

At baseline, participants had mean age of 62 ± 10 years and mean RHR of 63 ± 10 bpm; 12.3% and 8.9% had prevalent AVC and MAC, respectively. Over a median of 2.3 years, 4.1% and 4.5% developed incident AVC and MAC, respectively. Each 10 bpm higher RHR was significantly associated with incident MAC [Risk Ratio 1.17 (95% CI 1.03-1.34)], but not incident AVC. However, RHR was associated with AVC progression [β = 1.62 (0.45-2.80) Agatston units/year for every 10 bpm increment], but not MAC progression.

CONCLUSIONS

Higher RHR was associated with MAC incidence and AVC progression, independent of traditional CVD risk factors. Future studies are needed to determine whether modification of RHR through lifestyle or pharmacologic interventions can reduce valvular calcium incidence or progression.

Observational and Genetic Associations of Resting Heart Rate With Aortic Valve Calcium

It is unknown if lifelong exposure to increased hemodynamic stress from an elevated resting heart rate (HR) may contribute to aortic valve calcium (AVC). We performed multivariate regression analyses using data from 1,266 Framingham Heart Study (FHS) Offspring cohort participants and 6,764 Multi-Ethnic Study of Atherosclerosis (MESA) participants. We constructed a genetic risk score (GRS) for HR using summary-level data in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) AVC Consortium to investigate if there was evidence in favor of a causal relation. AVC was present in 39% of FHS Offspring cohort participants and in 13% of MESA cohort participants. In multivariate adjusted models, participants in the highest resting HR quartiles had significantly greater prevalence of AVC, with a prevalence ratio of 1.19 (95% confidence interval [CI] 0.99 to 1.44) for the FHS Offspring cohort and 1.32 (95% CI 1.12 to 1.63) for the MESA cohort, compared with those in the lowest quartile. There was a similar increase in the prevalence of AVC per standard deviation increase in resting HR in both FHS Offspring (prevalence ratio 1.08, 95% CI 1.01 to 1.15) and MESA (1.10, 95% CI 1.03 to 1.17). In contrast with these observational findings, a HR associated GRS was not significantly associated with AVC. Although our observational analysis indicates that a higher resting HR is associated with AVC, our genetic results do not support a causal relation. Unmeasured environmental and/or lifestyle factors associated with both increased resting HR and AVC that are not fully explained by covariates in our observational models may account for the association between resting HR and AVC.

Abstract 470: Ultrasound Carotid Plaque Features, Cardiovascular Disease Risk Factors and Events: the Multi-Ethnic Study of Atherosclerosis

Background: Grayscale ultrasound atherosclerotic plaque characteristics may predict cardiovascular disease (CVD) events, though they have not been investigated in a large primary prevention cohort. This study determined if CVD risk factors were associated with carotid plaque ultrasound characteristics and if these characteristics could predict future coronary heart disease (CHD) and stroke/transient ischemic attack (TIA) events in a multi-ethnic cohort free of known CVD at baseline.

Methods: We measured carotid artery total plaque area (TPA) and grayscale carotid plaque features (grayscale median, black areas, and discrete white areas) at baseline in participants of the Multi-Ethnic Study of Atherosclerosis that had B-mode carotid ultrasound examinations. There were 2205 participants with images available for TPA analyses and 1703 with images available for grayscale analyses. Multivariable linear regression analysis was used to examine relationships between baseline ultrasound carotid plaque features and CVD risk factors. Cox proportional hazards models were used to assess their ability to predict incident CHD and stroke/TIA events over an average follow-up of 13.3 years. The predictive characteristics of TPA and carotid plaque features were compared to carotid plaque score and coronary artery calcification (CAC) score.

Results: Participants were mean (standard deviation) 65.4 (9.6) years old, 49% male, 39% White, 28% Black, 22% Hispanic, and 11% Chinese. Mean TPA (27.7 [24.7] mm 2 ), but not grayscale plaque features, were associated with several CVD risk factors. In risk factor-adjusted models, TPA was the only plaque feature that predicted incident CHD events (HR 1.23; 95% CI 1.11-1.36; p<0.001) with C-statistics for CHD that were similar to carotid plaque score, but lower than CAC score. TPA did not independently predict stroke/TIA events. No gray scale plaque feature predicted future CHD or stroke/TIA events.

Conclusions: In middle-aged individuals free of known CVD, carotid TPA was associated with CVD risk factors and predicted incident CHD events while grayscale plaque features did not. For CHD, predictive characteristics of TPA were similar to carotid plaque score but lower than CAC score.

Genome-Wide Associations of Global Electrical Heterogeneity ECG Phenotype: The ARIC (Atherosclerosis Risk in Communities) Study and CHS (Cardiovascular Health Study)

BACKGROUND

ECG global electrical heterogeneity (GEH) is associated with sudden cardiac death. We hypothesized that a genome-wide association study would identify genetic loci related to GEH.

METHODS AND RESULTS

We tested genotyped and imputed variants in black (N=3057) and white (N=10 769) participants in the ARIC (Atherosclerosis Risk in Communities) study and CHS (Cardiovascular Health Study). GEH (QRS-T angle, sum absolute QRST integral, spatial ventricular gradient magnitude, elevation, azimuth) was measured on 12-lead ECGs. Linear regression models were constructed with each GEH variable as an outcome, adjusted for age, sex, height, body mass index, study site, and principal components to account for ancestry. GWAS identified 10 loci that showed genome-wide significant association with GEH in whites or joint ancestry. The strongest signal (rs7301677, near TBX3) was associated with QRS-T angle (white standardized β+0.16 [95% CI 0.13-0.19]; P=1.5×10-26), spatial ventricular gradient elevation (+0.11 [0.08-0.14]; P=2.1×10-12), and spatial ventricular gradient magnitude (-0.12 [95% CI -0.15 to -0.09]; P=5.9×10-15). Altogether, GEH-SNPs explained 1.1% to 1.6% of GEH variance. Loci on chromosomes 4 (near HMCN2), 5 (IGF1R), 11 (11p11.2 region cluster), and 7 (near ACTB) are novel ECG phenotype-associated loci. Several loci significantly associated with gene expression in the left ventricle (HMCN2 locus-with HMCN2; IGF1R locus-with IGF1R), and atria (RP11-481J2.2 locus-with expression of a long non-coding RNA and NDRG4).

CONCLUSIONS

We identified 10 genetic loci associated with ECG GEH. Replication of GEH GWAS findings in independent cohorts is warranted. Further studies of GEH-loci may uncover mechanisms of arrhythmogenic remodeling in response to cardiovascular risk factors.