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author:("psat, Bruce M")
1.  Assessing Risk Prediction Models Using Individual Participant Data From Multiple Studies 
Pennells, Lisa | Kaptoge, Stephen | White, Ian R. | Thompson, Simon G. | Wood, Angela M. | Tipping, Robert W. | Folsom, Aaron R. | Couper, David J. | Ballantyne, Christie M. | Coresh, Josef | Goya Wannamethee, S. | Morris, Richard W. | Kiechl, Stefan | Willeit, Johann | Willeit, Peter | Schett, Georg | Ebrahim, Shah | Lawlor, Debbie A. | Yarnell, John W. | Gallacher, John | Cushman, Mary | Psaty, Bruce M. | Tracy, Russ | Tybjærg-Hansen, Anne | Price, Jackie F. | Lee, Amanda J. | McLachlan, Stela | Khaw, Kay-Tee | Wareham, Nicholas J. | Brenner, Hermann | Schöttker, Ben | Müller, Heiko | Jansson, Jan-Håkan | Wennberg, Patrik | Salomaa, Veikko | Harald, Kennet | Jousilahti, Pekka | Vartiainen, Erkki | Woodward, Mark | D'Agostino, Ralph B. | Bladbjerg, Else-Marie | Jørgensen, Torben | Kiyohara, Yutaka | Arima, Hisatomi | Doi, Yasufumi | Ninomiya, Toshiharu | Dekker, Jacqueline M. | Nijpels, Giel | Stehouwer, Coen D. A. | Kauhanen, Jussi | Salonen, Jukka T. | Meade, Tom W. | Cooper, Jackie A. | Cushman, Mary | Folsom, Aaron R. | Psaty, Bruce M. | Shea, Steven | Döring, Angela | Kuller, Lewis H. | Grandits, Greg | Gillum, Richard F. | Mussolino, Michael | Rimm, Eric B. | Hankinson, Sue E. | Manson, JoAnn E. | Pai, Jennifer K. | Kirkland, Susan | Shaffer, Jonathan A. | Shimbo, Daichi | Bakker, Stephan J. L. | Gansevoort, Ron T. | Hillege, Hans L. | Amouyel, Philippe | Arveiler, Dominique | Evans, Alun | Ferrières, Jean | Sattar, Naveed | Westendorp, Rudi G. | Buckley, Brendan M. | Cantin, Bernard | Lamarche, Benoît | Barrett-Connor, Elizabeth | Wingard, Deborah L. | Bettencourt, Richele | Gudnason, Vilmundur | Aspelund, Thor | Sigurdsson, Gunnar | Thorsson, Bolli | Kavousi, Maryam | Witteman, Jacqueline C. | Hofman, Albert | Franco, Oscar H. | Howard, Barbara V. | Zhang, Ying | Best, Lyle | Umans, Jason G. | Onat, Altan | Sundström, Johan | Michael Gaziano, J. | Stampfer, Meir | Ridker, Paul M. | Michael Gaziano, J. | Ridker, Paul M. | Marmot, Michael | Clarke, Robert | Collins, Rory | Fletcher, Astrid | Brunner, Eric | Shipley, Martin | Kivimäki, Mika | Ridker, Paul M. | Buring, Julie | Cook, Nancy | Ford, Ian | Shepherd, James | Cobbe, Stuart M. | Robertson, Michele | Walker, Matthew | Watson, Sarah | Alexander, Myriam | Butterworth, Adam S. | Angelantonio, Emanuele Di | Gao, Pei | Haycock, Philip | Kaptoge, Stephen | Pennells, Lisa | Thompson, Simon G. | Walker, Matthew | Watson, Sarah | White, Ian R. | Wood, Angela M. | Wormser, David | Danesh, John
American Journal of Epidemiology  2013;179(5):621-632.
Individual participant time-to-event data from multiple prospective epidemiologic studies enable detailed investigation into the predictive ability of risk models. Here we address the challenges in appropriately combining such information across studies. Methods are exemplified by analyses of log C-reactive protein and conventional risk factors for coronary heart disease in the Emerging Risk Factors Collaboration, a collation of individual data from multiple prospective studies with an average follow-up duration of 9.8 years (dates varied). We derive risk prediction models using Cox proportional hazards regression analysis stratified by study and obtain estimates of risk discrimination, Harrell's concordance index, and Royston's discrimination measure within each study; we then combine the estimates across studies using a weighted meta-analysis. Various weighting approaches are compared and lead us to recommend using the number of events in each study. We also discuss the calculation of measures of reclassification for multiple studies. We further show that comparison of differences in predictive ability across subgroups should be based only on within-study information and that combining measures of risk discrimination from case-control studies and prospective studies is problematic. The concordance index and discrimination measure gave qualitatively similar results throughout. While the concordance index was very heterogeneous between studies, principally because of differing age ranges, the increments in the concordance index from adding log C-reactive protein to conventional risk factors were more homogeneous.
PMCID: PMC3927974  PMID: 24366051
C index; coronary heart disease; D measure; individual participant data; inverse variance; meta-analysis; risk prediction; weighting
2.  Evidence of Heterogeneity by Race/Ethnicity in Genetic Determinants of QT Interval 
Epidemiology (Cambridge, Mass.)  2014;25(6):790-798.
QT-interval (QT) prolongation is an established risk factor for ventricular tachyarrhythmia and sudden cardiac death. Previous genome-wide association studies in populations of the European descent have identified multiple genetic loci that influence QT, but few have examined these loci in ethnically diverse populations.
Here, we examine the direction, magnitude, and precision of effect sizes for 21 previously reported SNPs from 12 QT loci, in populations of European (n=16,398), African (n=5,437), American Indian (n=5,032), Hispanic (n=1,143), and Asian (n=932) descent as part of the Population Architecture using Genomics and Epidemiology (PAGE) study. Estimates obtained from linear regression models stratified by race/ethnicity were combined using inverse-variance weighted meta-analysis. Heterogeneity was evaluated using Cochran's Q test.
Of 21 SNPs, seven showed consistent direction of effect across all five populations, and an additional nine had estimated effects that were consistent across four populations. Despite consistent direction of effect, nine of 16 SNPs had evidence (P < 0.05) of heterogeneity by race/ethnicity. For these 9 SNPs, linkage disequilibrium plots often indicated substantial variation in linkage disequilibrium patterns among the various racial/ethnic groups, as well as possible allelic heterogeneity.
These results emphasize the importance of analyzing racial/ethnic groups separately in genetic studies. Furthermore, they underscore the possible utility of trans-ethnic studies to pinpoint underlying casual variants influencing heritable traits such as QT.
PMCID: PMC4380285  PMID: 25166880
3.  Drug-Gene Interactions of Antihypertensive Medications and Risk of Incident Cardiovascular Disease: A Pharmacogenomics Study from the CHARGE Consortium 
PLoS ONE  2015;10(10):e0140496.
Hypertension is a major risk factor for a spectrum of cardiovascular diseases (CVD), including myocardial infarction, sudden death, and stroke. In the US, over 65 million people have high blood pressure and a large proportion of these individuals are prescribed antihypertensive medications. Although large long-term clinical trials conducted in the last several decades have identified a number of effective antihypertensive treatments that reduce the risk of future clinical complications, responses to therapy and protection from cardiovascular events vary among individuals.
Using a genome-wide association study among 21,267 participants with pharmaceutically treated hypertension, we explored the hypothesis that genetic variants might influence or modify the effectiveness of common antihypertensive therapies on the risk of major cardiovascular outcomes. The classes of drug treatments included angiotensin-converting enzyme inhibitors, beta-blockers, calcium channel blockers, and diuretics. In the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, each study performed array-based genome-wide genotyping, imputed to HapMap Phase II reference panels, and used additive genetic models in proportional hazards or logistic regression models to evaluate drug-gene interactions for each of four therapeutic drug classes. We used meta-analysis to combine study-specific interaction estimates for approximately 2 million single nucleotide polymorphisms (SNPs) in a discovery analysis among 15,375 European Ancestry participants (3,527 CVD cases) with targeted follow-up in a case-only study of 1,751 European Ancestry GenHAT participants as well as among 4,141 African-Americans (1,267 CVD cases).
Although drug-SNP interactions were biologically plausible, exposures and outcomes were well measured, and power was sufficient to detect modest interactions, we did not identify any statistically significant interactions from the four antihypertensive therapy meta-analyses (Pinteraction > 5.0×10−8). Similarly, findings were null for meta-analyses restricted to 66 SNPs with significant main effects on coronary artery disease or blood pressure from large published genome-wide association studies (Pinteraction ≥ 0.01). Our results suggest that there are no major pharmacogenetic influences of common SNPs on the relationship between blood pressure medications and the risk of incident CVD.
PMCID: PMC4627813  PMID: 26516778
4.  Association of exome sequences with plasma C-reactive protein levels in >9000 participants 
Human Molecular Genetics  2014;24(2):559-571.
C-reactive protein (CRP) concentration is a heritable systemic marker of inflammation that is associated with cardiovascular disease risk. Genome-wide association studies have identified CRP-associated common variants associated in ∼25 genes. Our aims were to apply exome sequencing to (1) assess whether the candidate loci contain rare coding variants associated with CRP levels and (2) perform an exome-wide search for rare variants in novel genes associated with CRP levels. We exome-sequenced 6050 European-Americans (EAs) and 3109 African-Americans (AAs) from the NHLBI-ESP and the CHARGE consortia, and performed association tests of sequence data with measured CRP levels. In single-variant tests across candidate loci, a novel rare (minor allele frequency = 0.16%) CRP-coding variant (rs77832441-A; p.Thr59Met) was associated with 53% lower mean CRP levels (P = 2.9 × 10−6). We replicated the association of rs77832441 in an exome array analysis of 11 414 EAs (P = 3.0 × 10−15). Despite a strong effect on CRP levels, rs77832441 was not associated with inflammation-related phenotypes including coronary heart disease. We also found evidence for an AA-specific association of APOE-ε2 rs7214 with higher CRP levels. At the exome-wide significance level (P < 5.0 × 10−8), we confirmed associations for reported common variants of HNF1A, CRP, IL6R and TOMM40-APOE. In gene-based tests, a burden of rare/lower frequency variation in CRP in EAs (P ≤ 6.8 × 10−4) and in retinoic acid receptor-related orphan receptor α (RORA) in AAs (P = 1.7 × 10−3) were associated with CRP levels at the candidate gene level (P < 2.0 × 10−3). This inquiry did not elucidate novel genes, but instead demonstrated that variants distributed across the allele frequency spectrum within candidate genes contribute to CRP levels.
PMCID: PMC4334838  PMID: 25187575
5.  GWAS of Longevity in CHARGE Consortium Confirms APOE and FOXO3 Candidacy 
The genetic contribution to longevity in humans has been estimated to range from 15% to 25%. Only two genes, APOE and FOXO3, have shown association with longevity in multiple independent studies.
We conducted a meta-analysis of genome-wide association studies including 6,036 longevity cases, age ≥90 years, and 3,757 controls that died between ages 55 and 80 years. We additionally attempted to replicate earlier identified single nucleotide polymorphism (SNP) associations with longevity.
In our meta-analysis, we found suggestive evidence for the association of SNPs near CADM2 (odds ratio [OR] = 0.81; p value = 9.66 × 10−7) and GRIK2 (odds ratio = 1.24; p value = 5.09 × 10−8) with longevity. When attempting to replicate findings earlier identified in genome-wide association studies, only the APOE locus consistently replicated. In an additional look-up of the candidate gene FOXO3, we found that an earlier identified variant shows a highly significant association with longevity when including published data with our meta-analysis (odds ratio = 1.17; p value = 1.85×10−10).
We did not identify new genome-wide significant associations with longevity and did not replicate earlier findings except for APOE and FOXO3. Our inability to find new associations with survival to ages ≥90 years because longevity represents multiple complex traits with heterogeneous genetic underpinnings, or alternatively, that longevity may be regulated by rare variants that are not captured by standard genome-wide genotyping and imputation of common variants.
PMCID: PMC4296168  PMID: 25199915
Longevity; GWAS; FOXO3; APOE.
6.  Trans-ethnic meta-analysis of white blood cell phenotypes 
Human Molecular Genetics  2014;23(25):6944-6960.
White blood cell (WBC) count is a common clinical measure used as a predictor of certain aspects of human health, including immunity and infection status. WBC count is also a complex trait that varies among individuals and ancestry groups. Differences in linkage disequilibrium structure and heterogeneity in allelic effects are expected to play a role in the associations observed between populations. Prior genome-wide association study (GWAS) meta-analyses have identified genomic loci associated with WBC and its subtypes, but much of the heritability of these phenotypes remains unexplained. Using GWAS summary statistics for over 50 000 individuals from three diverse populations (Japanese, African-American and European ancestry), a Bayesian model methodology was employed to account for heterogeneity between ancestry groups. This approach was used to perform a trans-ethnic meta-analysis of total WBC, neutrophil and monocyte counts. Ten previously known associations were replicated and six new loci were identified, including several regions harboring genes related to inflammation and immune cell function. Ninety-five percent credible interval regions were calculated to narrow the association signals and fine-map the putatively causal variants within loci. Finally, a conditional analysis was performed on the most significant SNPs identified by the trans-ethnic meta-analysis (MA), and nine secondary signals within loci previously associated with WBC or its subtypes were identified. This work illustrates the potential of trans-ethnic analysis and ascribes a critical role to multi-ethnic cohorts and consortia in exploring complex phenotypes with respect to variants that lie outside the European-biased GWAS pool.
PMCID: PMC4245044  PMID: 25096241
7.  Associations of NINJ2 Sequence Variants with Incident Ischemic Stroke in the Cohorts for Heart and Aging in Genomic Epidemiology (CHARGE) Consortium 
PLoS ONE  2014;9(6):e99798.
Stroke, the leading neurologic cause of death and disability, has a substantial genetic component. We previously conducted a genome-wide association study (GWAS) in four prospective studies from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium and demonstrated that sequence variants near the NINJ2 gene are associated with incident ischemic stroke. Here, we sought to fine-map functional variants in the region and evaluate the contribution of rare variants to ischemic stroke risk.
Methods and Results
We sequenced 196 kb around NINJ2 on chromosome 12p13 among 3,986 European ancestry participants, including 475 ischemic stroke cases, from the Atherosclerosis Risk in Communities Study, Cardiovascular Health Study, and Framingham Heart Study. Meta-analyses of single-variant tests for 425 common variants (minor allele frequency [MAF] ≥ 1%) confirmed the original GWAS results and identified an independent intronic variant, rs34166160 (MAF = 0.012), most significantly associated with incident ischemic stroke (HR = 1.80, p = 0.0003). Aggregating 278 putatively-functional variants with MAF≤ 1% using count statistics, we observed a nominally statistically significant association, with the burden of rare NINJ2 variants contributing to decreased ischemic stroke incidence (HR = 0.81; p = 0.026).
Common and rare variants in the NINJ2 region were nominally associated with incident ischemic stroke among a subset of CHARGE participants. Allelic heterogeneity at this locus, caused by multiple rare, low frequency, and common variants with disparate effects on risk, may explain the difficulties in replicating the original GWAS results. Additional studies that take into account the complex allelic architecture at this locus are needed to confirm these findings.
PMCID: PMC4069013  PMID: 24959832
8.  Telomere Length and the Risk of Atrial Fibrillation: Insights into the Role of Biological versus Chronological Aging 
Advanced age is the most important risk factor for atrial fibrillation (AF), however the mechanism remains unknown. Telomeres, regions of DNA that shorten with cell division, are considered reliable markers of biological aging. We sought to examine the association between leukocyte telomere length (LTL) and incident AF in a large population-based cohort using direct LTL measurements and genetic data. To further explore our findings, we compared atrial cell telomere length (ATL) and LTL in cardiac surgery patients.
Methods and Results
Mean LTL and the TERT rs2736100 single nucleotide polymorphism (SNP) were assessed as predictors of incident AF in the Cardiovascular Health Study (CHS). Among the surgical patients, within subject comparison of ATL versus LTL was assessed. Among 1639 CHS participants, we observed no relationship between mean LTL and incident AF prior to and after adjustment for potential confounders (adjusted hazard ratio [HR] 1.09; 95% CI: 0.92–1.29, p=0.299); chronologic age remained strongly associated with AF in the same model. No association was observed between the TERT rs2736100 SNP and incident AF (adjusted HR: 0.95; 95% CI: 0.88–1.04, p=0.265). In 35 cardiac surgery patients (26 with AF), ATL was longer than LTL (1.19 ± 0.20 versus 1.02 ± 0.25 [T/S ratio], p< 0.001), a finding that remained consistent within the AF subgroup.
Our study revealed no evidence of an association between LTL and incident AF and no evidence of relative atrial cell telomere shortening in AF. Chronological aging independent of biological markers of aging is the primary risk factor for AF.
PMCID: PMC4294941  PMID: 25381796
atrial fibrillation; aging; genetics; telomere genetics
9.  The transcriptional landscape of age in human peripheral blood 
Peters, Marjolein J. | Joehanes, Roby | Pilling, Luke C. | Schurmann, Claudia | Conneely, Karen N. | Powell, Joseph | Reinmaa, Eva | Sutphin, George L. | Zhernakova, Alexandra | Schramm, Katharina | Wilson, Yana A. | Kobes, Sayuko | Tukiainen, Taru | Ramos, Yolande F. | Göring, Harald H. H. | Fornage, Myriam | Liu, Yongmei | Gharib, Sina A. | Stranger, Barbara E. | De Jager, Philip L. | Aviv, Abraham | Levy, Daniel | Murabito, Joanne M. | Munson, Peter J. | Huan, Tianxiao | Hofman, Albert | Uitterlinden, André G. | Rivadeneira, Fernando | van Rooij, Jeroen | Stolk, Lisette | Broer, Linda | Verbiest, Michael M. P. J. | Jhamai, Mila | Arp, Pascal | Metspalu, Andres | Tserel, Liina | Milani, Lili | Samani, Nilesh J. | Peterson, Pärt | Kasela, Silva | Codd, Veryan | Peters, Annette | Ward-Caviness, Cavin K. | Herder, Christian | Waldenberger, Melanie | Roden, Michael | Singmann, Paula | Zeilinger, Sonja | Illig, Thomas | Homuth, Georg | Grabe, Hans-Jörgen | Völzke, Henry | Steil, Leif | Kocher, Thomas | Murray, Anna | Melzer, David | Yaghootkar, Hanieh | Bandinelli, Stefania | Moses, Eric K. | Kent, Jack W. | Curran, Joanne E. | Johnson, Matthew P. | Williams-Blangero, Sarah | Westra, Harm-Jan | McRae, Allan F. | Smith, Jennifer A. | Kardia, Sharon L. R. | Hovatta, Iiris | Perola, Markus | Ripatti, Samuli | Salomaa, Veikko | Henders, Anjali K. | Martin, Nicholas G. | Smith, Alicia K. | Mehta, Divya | Binder, Elisabeth B. | Nylocks, K Maria | Kennedy, Elizabeth M. | Klengel, Torsten | Ding, Jingzhong | Suchy-Dicey, Astrid M. | Enquobahrie, Daniel A. | Brody, Jennifer | Rotter, Jerome I. | Chen, Yii-Der I. | Houwing-Duistermaat, Jeanine | Kloppenburg, Margreet | Slagboom, P. Eline | Helmer, Quinta | den Hollander, Wouter | Bean, Shannon | Raj, Towfique | Bakhshi, Noman | Wang, Qiao Ping | Oyston, Lisa J. | Psaty, Bruce M. | Tracy, Russell P. | Montgomery, Grant W. | Turner, Stephen T. | Blangero, John | Meulenbelt, Ingrid | Ressler, Kerry J. | Yang, Jian | Franke, Lude | Kettunen, Johannes | Visscher, Peter M. | Neely, G. Gregory | Korstanje, Ron | Hanson, Robert L. | Prokisch, Holger | Ferrucci, Luigi | Esko, Tonu | Teumer, Alexander | van Meurs, Joyce B. J. | Johnson, Andrew D.
Nature Communications  2015;6:8570.
Disease incidences increase with age, but the molecular characteristics of ageing that lead to increased disease susceptibility remain inadequately understood. Here we perform a whole-blood gene expression meta-analysis in 14,983 individuals of European ancestry (including replication) and identify 1,497 genes that are differentially expressed with chronological age. The age-associated genes do not harbor more age-associated CpG-methylation sites than other genes, but are instead enriched for the presence of potentially functional CpG-methylation sites in enhancer and insulator regions that associate with both chronological age and gene expression levels. We further used the gene expression profiles to calculate the ‘transcriptomic age' of an individual, and show that differences between transcriptomic age and chronological age are associated with biological features linked to ageing, such as blood pressure, cholesterol levels, fasting glucose, and body mass index. The transcriptomic prediction model adds biological relevance and complements existing epigenetic prediction models, and can be used by others to calculate transcriptomic age in external cohorts.
Ageing increases the risk of many diseases. Here the authors compare blood cell transcriptomes of over 14,000 individuals and identify a set of about 1,500 genes that are differently expressed with age, shedding light on transcriptional programs linked to the ageing process and age-associated diseases.
PMCID: PMC4639797  PMID: 26490707
10.  Lower risk of cardiovascular events in postmenopausal women taking oral estradiol compared with oral conjugated equine estrogens 
JAMA internal medicine  2014;174(1):25-31.
Little is known about the comparative cardiovascular safety of oral hormone therapy (HT) products, which impedes women from making informed safety decisions about HT treatment of menopausal symptoms.
To compare the relative clinical cardiovascular safety of 2 commonly used oral estrogen drugs, conjugated equine estrogens (CEE) and estradiol (E2).
Population-based, case-control study from 2003 to 2009 comparing cardiovascular event risk associated with current CEE and E2 use.
Large health maintenance organization where the preferred formulary estrogen changed from CEE to E2 during the course of data collection.
384 postmenopausal women 30-79 years of age using oral HT.
Incident venous thrombosis (VT) was the primary clinical outcome and incident myocardial infarction (MI) and ischemic stroke were secondary outcomes. As validation, an intermediate clotting phenotype, endogenous thrombin potential-based normalized activated protein C sensitivity ratio (nAPCsr), was measured in plasma of controls.
We studied 68 VT, 67 MI, and 48 stroke cases, and 201 matched controls; all were current users of oral CEE or E2. In adjusted analyses, compared with current oral E2 use, current oral CEE use was associated with an increased VT risk (OR: 2.08; 95% CI: 1.02-4.27; p-value 0.045), an increased MI risk that did not reach statistical significance (OR: 1.87; 95% CI: 0.91-3.84; p=0.086), and was not associated with stroke risk (OR: 1.13; 95% CI: 0.55-2.31; p=0.736). Among controls (n=140), compared with E2 users, CEE users had higher nAPCsrs (p=0.0002), indicating a stronger clotting propensity.
In an observational study of oral HT users, CEE use was associated with a higher risk of incident VT and possibly MI than E2 use. This risk differential was supported by biologic data. These findings need replication and suggest that various oral estrogen drugs may be associated with different levels of cardiovascular risk.
PMCID: PMC4636198  PMID: 24081194
11.  Risk Factors for Cardiovascular Disease across the Spectrum of Older Age: The Cardiovascular Health Study 
Atherosclerosis  2014;237(1):336-342.
The associations of some risk factors with cardiovascular disease (CVD) are attenuated in older age; whereas others appear robust. The present study aimed to compare CVD risk factors across older age.
Participants (n=4,883) in the Cardiovascular Health Study free of prevalent CVD, were stratified into three age groups: 65–74, 75–84, 85+ years. Traditional risk factors included systolic blood pressure (BP), LDL-cholesterol, HDL-cholesterol, obesity, and diabetes. Novel risk factors included kidney function, C-reactive protein (CRP), and N-terminal pro-B-type natriuretic peptide (NT pro-BNP).
There were 1,498 composite CVD events (stroke, myocardial infarction, and cardiovascular death) over 5 years. The associations of high systolic BP and diabetes appeared strongest, though both were attenuated with age (p-values for interaction = 0.01 and 0.002, respectively). The demographic-adjusted hazard ratios (HR) for elevated systolic BP were 1.79 (95% confidence interval: 1.49, 2.15), 1.59 (1.37, 1.85) and 1.10 (0.86, 1.41) in participants aged 65–74, 75–84, 85+, and for diabetes, 2.36 (1.89, 2.95), 1.55 (1.27, 1.89), 1.51 (1.10, 2.09). The novel risk factors had consistent associations with the outcome across the age spectrum; low kidney function: 1.69 (1.31, 2.19), 1.61 (1.36, 1.90), and 1.57 (1.16, 2.14) for 65–74, 75–84, and 85+ years, respectively; elevated CRP: 1.54 (1.28, 1.87), 1.33 (1.13, 1.55), and 1.51 (1.15, 1.97); elevated NT pro-BNP: 2.67 (1.96, 3.64), 2.71 (2.25, 3.27), and 2.18 (1.43, 3.45).
The associations of most traditional risk factors with CVD were minimal in the oldest old, whereas diabetes, eGFR, CRP, and NT pro-BNP were associated with CVD across older age.
PMCID: PMC4254262  PMID: 25303772
aging; epidemiology; risk factors
12.  Plasma phospholipid and dietary α-linolenic acid, mortality, CHD and stroke: the Cardiovascular Health Study 
The British journal of nutrition  2014;112(7):1206-1213.
Previous studies have suggested that long-chain n-3 fatty acids derived from seafood are associated with a lower risk of mortality, CHD and stroke. Whether α-linolenic acid (ALA, 18: 3n-3), a plant-derived long-chain essential n-3 fatty acid, is associated with a lower risk of these outcomes is unclear. The aim of the present study was to examine the associations of plasma phospholipid and dietary ALA with the risk of mortality, CHD and stroke among older adults who participated in the Cardiovascular Health Study, a cohort study of adults aged ≥65 years. A total of 2709 participants were included in the plasma phospholipid ALA analysis and 2583 participants were included in the dietary ALA analysis. Cox regression was used to assess the associations of plasma phospholipid and dietary ALA with the risk of mortality, incident CHD and stroke. In minimally and multivariable-adjusted models, plasma phospholipid ALA was found to be not associated with the risk of mortality, incident CHD or stroke. After adjustment for age, sex, race, enrolment site, education, smoking status, diabetes, BMI, alcohol consumption, treated hypertension and total energy intake, higher dietary ALA intake was found to be associated with a lower risk of total and non-cardiovascular mortality; on comparing the highest quintiles of dietary ALA with the lowest quintiles, the HR for total mortality and non-cardiovascular mortality were found to be 0·73 (95 % CI 0·61, 0·88) and 0·64 (95 % CI 0·52, 0·80), respectively. Dietary ALA was found to be not associated with the risk of cardiovascular mortality, incident CHD or stroke. In conclusion, the results of the present suggest study that dietary ALA, but not plasma phospholipid ALA, is associated with a lower risk of total and non-cardiovascular mortality in older adults.
PMCID: PMC4192018  PMID: 25159901
Fatty acids; α-Linolenic acid; Mortality; CVD
13.  Associations of Circulating Lymphocyte Subpopulations with Type 2 Diabetes: Cross-Sectional Results from the Multi-Ethnic Study of Atherosclerosis (MESA) 
PLoS ONE  2015;10(10):e0139962.
Distinct lymphocyte subpopulations have been implicated in the regulation of glucose homeostasis and obesity-associated inflammation in mouse models of insulin resistance. Information on the relationships of lymphocyte subpopulations with type 2 diabetes remain limited in human population-based cohort studies.
Circulating levels of innate (γδ T, natural killer (NK)) and adaptive immune (CD4+ naive, CD4+ memory, Th1, and Th2) lymphocyte subpopulations were measured by flow cytometry in the peripheral blood of 929 free-living participants of the Multi-Ethnic Study of Atherosclerosis (MESA). Cross-sectional relationships of lymphocyte subpopulations with type 2 diabetes (n = 154) and fasting glucose and insulin concentrations were evaluated by generalized linear models.
Each standard deviation (SD) higher CD4+ memory cells was associated with a 21% higher odds of type 2 diabetes (95% CI: 1–47%) and each SD higher naive cells was associated with a 22% lower odds (95% CI: 4–36%) (adjusted for age, gender, race/ethnicity, and BMI). Among participants not using diabetes medication, higher memory and lower naive CD4+ cells were associated with higher fasting glucose concentrations (p<0.05, adjusted for age, sex, and race/ethnicity). There were no associations of γδ T, NK, Th1, or Th2 cells with type 2 diabetes, glucose, or insulin.
A higher degree of chronic adaptive immune activation, reflected by higher memory and lower naive CD4+ cells, was positively associated with type 2 diabetes. These results are consistent with a role of chronic immune activation and exhaustion augmenting chronic inflammatory diseases, and support the importance of prospective studies evaluating adaptive immune activation and type 2 diabetes.
PMCID: PMC4601795  PMID: 26458065
14.  Circulating Omega-6 Polyunsaturated Fatty Acids and Total and Cause-Specific Mortality: The Cardiovascular Health Study 
Circulation  2014;130(15):1245-1253.
While omega-6 polyunsaturated fatty acids(n-6 PUFA) have been recommended to reduce CHD, controversy remains about benefits vs. harms, including concerns over theorized pro-inflammatory effects of n-6 PUFA. We investigated associations of circulating n-6 PUFA including linoleic acid(LA, the major dietary PUFA), γ-linolenic acid(GLA), dihomo-γ-linolenic acid(DGLA), and arachidonic acid(AA),with total and cause-specific mortality in the Cardiovascular Health Study, a community-based US cohort.
Methods and Results
Among 2,792 participants(age≥65y) free of CVD at baseline, plasma phospholipid n-6 PUFAwere measured at baseline using standardized methods. All-cause and cause-specific mortality, and total incident CHD and stroke, were assessed and adjudicated centrally. Associations of PUFA with risk were assessed by Cox regression. During 34,291 person-years of follow-up(1992–2010), 1,994 deaths occurred(678 cardiovascular deaths), with 427 fatal and 418 nonfatal CHD, and 154 fatal and 399 nonfatal strokes. In multivariable models, higher LA was associated with lower total mortality, with extreme-quintile HR=0.87(P-trend=0.005). Lower death was largely attributable to CVD causes, especially nonarrhythmic CHD mortality(HR=0.51, 95%CI=0.32–0.82, P-trend=0.001). Circulating GLA, DGLA, and AA were not significantly associated with total or cause-specific mortality; e.g., for AA and CHD death, the extreme-quintile HR was 0.97 (95%CI=0.70–1.34, P-trend=0.87). Evaluated semi-parametrically, LA showed graded inverse associations with total mortality(P=0.005). There was little evidence that associations of n-6 PUFA with total mortality varied by age, sex, race, or plasma n-3 PUFA. Evaluating both n-6 and n-3 PUFA, lowest risk was evident with highest levels of both.
High circulating LA, but not other n-6 PUFA, was inversely associated with total and CHD mortality in older adults.
PMCID: PMC4189990  PMID: 25124495
Fatty Acids; Omega-6; Cardiovascular diseases; Epidemiology; Mortality
15.  Integrating Genetic, Transcriptional, and Functional Analyses to Identify Five Novel Genes for Atrial Fibrillation 
Circulation  2014;130(15):1225-1235.
Atrial fibrillation (AF) affects over 30 million individuals worldwide and is associated with an increased risk of stroke, heart failure, and death. AF is highly heritable, yet the genetic basis for the arrhythmia remains incompletely understood.
Methods & Results
To identify new AF-related genes, we utilized a multifaceted approach, combining large-scale genotyping in two ethnically distinct populations, cis-eQTL mapping, and functional validation. Four novel loci were identified in individuals of European descent near the genes NEURL (rs12415501, RR=1.18, 95%CI 1.13 – 1.23, p=6.5×10−16), GJA1 (rs13216675, RR=1.10, 95%CI 1.06 – 1.14, p=2.2×10−8), TBX5 (rs10507248, RR=1.12, 95%CI 1.08 – 1.16, p=5.7×10−11), and CAND2 (rs4642101, RR=1.10, 95%CI 1.06 – 1.14, p=9.8×10−9). In Japanese, novel loci were identified near NEURL (rs6584555, RR=1.32, 95%CI 1.26–1.39, p=2.0×10−25) and CUX2 (rs6490029, RR=1.12, 95%CI 1.08–1.16, p=3.9×10−9). The top SNPs or their proxies were identified as cis-eQTLs for the genes CAND2 (p=2.6×10−19), GJA1 (p=2.66×10−6), and TBX5 (p=1.36×10−05). Knockdown of the zebrafish orthologs of NEURL and CAND2 resulted in prolongation of the atrial action potential duration (17% and 45%, respectively).
We have identified five novel loci for AF. Our results further expand the diversity of genetic pathways implicated in AF and provide novel molecular targets for future biological and pharmacological investigation.
PMCID: PMC4190011  PMID: 25124494
atrial fibrillation; genetics; epidemiology; expression; functional analysis; zebrafish
17.  Plasma Free Fatty Acids, Fatty Acid-binding Protein 4, and Mortality in Older Adults (From the Cardiovascular Health Study) 
The American journal of cardiology  2014;114(6):843-848.
Plasma free fatty acids (FFA) are largely derived from adipose tissue. Elevated levels of FFA and fatty acid-binding protein 4 (FABP4), a key cytoplasmic chaperone of fatty acids, have been associated with adverse cardiovascular outcomes but limited data are available on the relation of these biomarkers with cardiovascular and total mortality. We studied 4,707 participants with a mean age of 75 years who had plasma FFA and FABP4 measured in 1992–1993 as part of the Cardiovascular Health Study, an observational cohort of community dwelling older adults. Over a median follow-up of 11.8 years, 3,555 participants died. Cox proportional hazard regression was used to determine the association between FFA, FABP4, and mortality. In fully adjusted models, FFA were associated with dose-dependent significantly higher total mortality (hazard ratio (HR) per standard deviation (SD): 1.14, 95% confidence interval (CI) 1.09–1.18), but FABP4 levels were not (HR 1.04, 95% CI 0.98–1.09). In a cause-specific mortality analysis, higher concentrations of FFA were associated with significantly higher risk of death due to cardiovascular disease, dementia, infection, and respiratory causes, but not cancer or trauma. We did not find evidence of an interaction between FFA and FABP4 (p=0.45), but FABP4 appeared to be associated with total mortality differentially among men and women (HR 1.17 (1.08–1.26) for men, HR 1.02 (0.96–1.07) for women, interaction p-value <0.001). In conclusion, in a cohort of community-dwelling older individuals, elevated plasma concentrations of FFA, but not FABP4, were associated with cardiovascular and non-cardiovascular mortality.
PMCID: PMC4162821  PMID: 25073566
Fatty acids; Mortality; Epidemiology
18.  Systolic and Diastolic Blood Pressure, Incident Cardiovascular Events and Death in Elderly Persons: The Role of Functional Limitation in the Cardiovascular Health Study 
Hypertension  2014;64(3):472-480.
Whether limitation in ability to perform activities of daily living (ADL) or gait speed can identify elders in whom the association of systolic (SBP) and diastolic (DBP) blood pressure with cardiovascular events (CVD) and death differs is unclear.
We evaluated whether limitation in ADL or gait speed modify the association of SBP or DBP with incident CVD (N= 2,358) and death (N=3,547) in the Cardiovascular Health Study.
Mean age was 78 ± 5 and 21% reported limitation in ≥1 ADL. There were 778 CV events and 1,289 deaths over 9 years. Among persons without and with ADL limitation, SBP was associated with incident CVD: HR (per 10 mmHg increase) 1.08 (95% CI 1.03, 1.13) and 1.06 (0.97, 1.17), respectively. ADL modified the association of DBP with incident CVD. Among those without ADL limitation, DBP was weakly associated with incident CVD, HR 1.04 (0.79, 1.37) for DBP > 80, compared with <65 mmHg. Among those with ADL limitation, DBP was inversely associated with CVD: HR 0.65 (0.44, 0.96) for DBP 66–80 mmHg and HR 0.49 (0.25, 0.94) for DBP > 80, compared to DBP ≤ 65. Among persons with ADL limitation, a DBP 66–80 had the lowest risk for death, HR 0.72 (0.57, 0.91), compared with DBP ≤ 65. Associations did not vary by 15 feet walking speed
ADL can identify elders in whom diastolic hypotension is associated with higher CV risk and death. Functional status, rather than chronologic age alone, should inform design of hypertension trials in elders.
PMCID: PMC4134400  PMID: 24935945
hypertension; elderly; functional status; cardiovascular
19.  The potential risks of expedited approval of drugs for acute bacterial infections 
JAMA internal medicine  2014;174(9):1436-1437.
PMCID: PMC4232183  PMID: 25023994
20.  Multiple rare alleles at LDLR and APOA5 confer risk for early-onset myocardial infarction 
Do, Ron | Stitziel, Nathan O. | Won, Hong-Hee | Jørgensen, Anders Berg | Duga, Stefano | Merlini, Pier Angelica | Kiezun, Adam | Farrall, Martin | Goel, Anuj | Zuk, Or | Guella, Illaria | Asselta, Rosanna | Lange, Leslie A. | Peloso, Gina M. | Auer, Paul L. | Girelli, Domenico | Martinelli, Nicola | Farlow, Deborah N. | DePristo, Mark A. | Roberts, Robert | Stewart, Alexander F.R. | Saleheen, Danish | Danesh, John | Epstein, Stephen E. | Sivapalaratnam, Suthesh | Hovingh, G. Kees | Kastelein, John J. | Samani, Nilesh J. | Schunkert, Heribert | Erdmann, Jeanette | Shah, Svati H. | Kraus, William E. | Davies, Robert | Nikpay, Majid | Johansen, Christopher T. | Wang, Jian | Hegele, Robert A. | Hechter, Eliana | Marz, Winfried | Kleber, Marcus E. | Huang, Jie | Johnson, Andrew D. | Li, Mingyao | Burke, Greg L. | Gross, Myron | Liu, Yongmei | Assimes, Themistocles L. | Heiss, Gerardo | Lange, Ethan M. | Folsom, Aaron R. | Taylor, Herman A. | Olivieri, Oliviero | Hamsten, Anders | Clarke, Robert | Reilly, Dermot F. | Yin, Wu | Rivas, Manuel A. | Donnelly, Peter | Rossouw, Jacques E. | Psaty, Bruce M. | Herrington, David M. | Wilson, James G. | Rich, Stephen S. | Bamshad, Michael J. | Tracy, Russell P. | Cupples, L. Adrienne | Rader, Daniel J. | Reilly, Muredach P. | Spertus, John A. | Cresci, Sharon | Hartiala, Jaana | Tang, W.H. Wilson | Hazen, Stanley L. | Allayee, Hooman | Reiner, Alex P. | Carlson, Christopher S. | Kooperberg, Charles | Jackson, Rebecca D. | Boerwinkle, Eric | Lander, Eric S. | Schwartz, Stephen M. | Siscovick, David S. | McPherson, Ruth | Tybjaerg-Hansen, Anne | Abecasis, Goncalo R. | Watkins, Hugh | Nickerson, Deborah A. | Ardissino, Diego | Sunyaev, Shamil R. | O’Donnell, Christopher J. | Altshuler, David | Gabriel, Stacey | Kathiresan, Sekar
Nature  2014;518(7537):102-106.
Myocardial infarction (MI), a leading cause of death around the world, displays a complex pattern of inheritance1,2. When MI occurs early in life, the role of inheritance is substantially greater1. Previously, rare mutations in low-density lipoprotein (LDL) genes have been shown to contribute to MI risk in individual families3–8 whereas common variants at more than 45 loci have been associated with MI risk in the population9–15. Here, we evaluate the contribution of rare mutations to MI risk in the population. We sequenced the protein-coding regions of 9,793 genomes from patients with MI at an early age (≤50 years in males and ≤60 years in females) along with MI-free controls. We identified two genes where rare coding-sequence mutations were more frequent in cases versus controls at exome-wide significance. At low-density lipoprotein receptor (LDLR), carriers of rare, damaging mutations (3.1% of cases versus 1.3% of controls) were at 2.4-fold increased risk for MI; carriers of null alleles at LDLR were at even higher risk (13-fold difference). This sequence-based estimate of the proportion of early MI cases due to LDLR mutations is remarkably similar to an estimate made more than 40 years ago using total cholesterol16. At apolipoprotein A-V (APOA5), carriers of rare nonsynonymous mutations (1.4% of cases versus 0.6% of controls) were at 2.2-fold increased risk for MI. When compared with non-carriers, LDLR mutation carriers had higher plasma LDL cholesterol whereas APOA5 mutation carriers had higher plasma triglycerides. Recent evidence has connected MI risk with coding sequence mutations at two genes functionally related to APOA5, namely lipoprotein lipase15,17 and apolipoprotein C318,19. When combined, these observations suggest that, beyond LDL cholesterol, disordered metabolism of triglyceride-rich lipoproteins contributes to MI risk.
PMCID: PMC4319990  PMID: 25487149
21.  Association of kidney disease measures with ischemic versus hemorrhagic strokes: Pooled analyses of 4 prospective community-based cohorts 
Background and purpose
Although low glomerular filtration rate (GFR) and albuminuria are associated with increased risk of stroke, few studies compared their contribution to risk of ischemic versus hemorrhagic stroke separately. We contrasted the association of these kidney measures with ischemic versus hemorrhagic stroke.
We pooled individual participant data from four community-based cohorts: three from the United States and one from The Netherlands. GFR was estimated by using both creatinine and cystatin C, and albuminuria was quantified by urinary albumin-to-creatinine ratio (ACR). Associations of eGFR and ACR were compared for each stroke type (ischemic vs. intraparenchymal hemorrhagic) using study-stratified Cox-regression.
Amongst 29,595 participants (mean age 61 [SD 12.5] years, 46% males, 17% black), 1,261 developed stroke (12% hemorrhagic) during 280,549 person-years. Low eGFR was significantly associated with increased risk of ischemic, but not hemorrhagic, stroke risk, while high ACR was associated with both stroke types. Adjusted HRs for ischemic and hemorrhagic stroke at eGFR of 45 (vs. 95) ml/min/1.73m2 were 1.30 (95% CI, 1.01–1.68) and 0.92 (0.47–1.81), respectively. In contrast, the corresponding HR for ACR 300 (vs. 5) mg/g were 1.62 (1.27–2.07) for ischemic and 2.57 (1.37–4.83) for hemorrhagic stroke, with significantly stronger association with hemorrhagic stroke (P =0.04). For hemorrhagic stroke, the association of elevated ACR was of similar magnitude as that of elevated systolic blood pressure.
Whereas albuminuria showed significant association with both stroke types, the association of decreased eGFR was only significant for ischemic stroke. The strong association of albuminuria with both stroke types warrants clinical attention and further investigations.
PMCID: PMC4517673  PMID: 24876078
22.  Conducting comparative effectiveness research on medications: the views of a practicing epidemiologist from the other Washington 
Value in Health  2011;15(2):394-396.
PMCID: PMC3310348  PMID: 22433773
effectiveness; evidence-based; hypertension; RECORD trial
23.  Genetic Variants Related to Height and Risk of Atrial Fibrillation 
American Journal of Epidemiology  2014;180(2):215-222.
Increased height is a known independent risk factor for atrial fibrillation (AF). However, whether genetic determinants of height influence risk is uncertain. In this candidate gene study, we examined the association of 209 height-associated single-nucleotide polymorphisms (SNPs) with incident AF in 3,309 persons of European descent from the Cardiovascular Health Study, a prospective cohort study of older adults (aged ≥65 years) enrolled in 1989–1990. After a median follow-up period of 13.2 years, 879 participants developed incident AF. The height-associated SNPs together explained approximately 10% of the variation in height (P = 6.0 × 10−8). Using an unweighted genetic height score, we found a nonsignificant association with risk of AF (per allele, hazard ratio = 1.01, 95% confidence interval: 1.00, 1.02; P = 0.06). In weighted analyses, we found that genetically predicted height was strongly associated with AF risk (per 10 cm, hazard ratio = 1.30, 95% confidence interval: 1.03, 1.64; P = 0.03). Importantly, for all models, the inclusion of actual height completely attenuated the genetic height effect. Finally, we identified 1 nonsynonymous SNP (rs1046934) that was independently associated with AF and may warrant future study. In conclusion, we found that genetic determinants of height appear to increase the risk of AF, primarily via height itself. This approach of examining SNPs associated with an intermediate phenotype should be considered as a method for identifying novel genetic targets.
PMCID: PMC4082343  PMID: 24944287
atrial fibrillation; cardiovascular disease; genetics; risk factors; risk prediction
24.  Effect of genetic variants associated with plasma homocysteine levels on stroke risk 
Background and Purpose
Elevated homocysteine (tHcy) levels are known to be associated with increased risk of ischemic stroke (IS). Given that both tHcy and IS are heritable traits, we investigated a potential genetic relationship between homocysteine levels and stroke risk by assessing 18 polymorphisms previously associated with tHcy levels for their association with IS and its subtypes.
Previous meta-analysis results from an international stroke collaborative network, METASTROKE, were utilized to assess association of the 18 tHcy associated SNPs in 12,389 IS cases and 62,004 controls. We also investigated the associations in regions located within 50kb from the 18 tHcy related SNPs, and the association of a genetic risk score including the 18 SNPs.
One SNP located in the RASIP1 gene and a cluster of three SNPs located at and near SLC17A3 were significantly associated with IS (P<0.0003) after correcting for multiple testing. For stroke subtypes, the sentinel SNP located upstream of MUT was significantly associated with SVD (small vessel disease) (P=0.0022), while one SNP located in MTHFR was significantly associated with LVD (large vessel disease) (P=0.00019). A genetic risk score including the 18 SNPs did not show significant association with IS or its subtypes.
This study found several potential associations with IS and its subtypes: an association of an MUT variant with SVD, an MTHFR variant with LVD, and associations of RASIP1 and SLC17A3 variants with overall IS.
PMCID: PMC4083192  PMID: 24846872
homocysteine; ischemic stroke; genetic association; genotype risk score
25.  Advanced Glycation/Glycoxidation Endproduct Carboxymethyl-Lysine and Incidence of Coronary Heart Disease and Stroke in Older Adults 
Atherosclerosis  2014;235(1):116-121.
Advanced glycation/glycoxidation endproducts (AGEs) accumulate in settings of increased oxidative stress – such as diabetes, chronic kidney disease and aging – where they promote vascular stiffness and atherogenesis, but the prospective association between AGEs and cardiovascular events in elders has not been previously examined.
To test the hypothesis that circulating levels of Nε-carboxymethyl-lysine (CML), a major AGE, increase the risk of incident coronary heart disease and stroke in older adults, we measured serum CML by immunoassay in 2,111 individuals free of prevalent cardiovascular disease participating in a population-based study of U.S. adults ages 65 and older.
During median follow-up of 9.1 years, 625 cardiovascular events occurred. CML was positively associated with incident cardiovascular events after adjustment for age, sex, race, systolic blood pressure, anti-hypertensive treatment, diabetes, smoking status, triglycerides, albumin, and self-reported health status (hazard ratio [HR] per SD [0.99 pmol/l] increase = 1.11, 95% confidence interval [CI]=1.03–1.19). This association was not materially attenuated by additional adjustment for C-reactive protein, estimated glomerular filtration rate (eGFR), and urine albumin/creatinine ratio. Findings were similar for the component endpoints of coronary heart disease and stroke.
In this large older cohort, CML was associated with an increased risk of cardiovascular events independent of a wide array of potential confounders and mediators. Although the moderate association limits CML’s value for risk prediction, these community-based findings provide support for clinical trials to test AGE-lowering therapies for cardiovascular prevention in this population.
PMCID: PMC4169874  PMID: 24825341
Advanced glycation endproducts; Carboxymethyl-lysine; Aging; Older Adults; Coronary Heart Disease; Stroke

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