Statins increase the risk of new-onset type 2 diabetes mellitus. We aimed to assess whether this increase in risk is a consequence of inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the intended drug target.
We used single nucleotide polymorphisms in the HMGCR gene, rs17238484 (for the main analysis) and rs12916 (for a subsidiary analysis) as proxies for HMGCR inhibition by statins. We examined associations of these variants with plasma lipid, glucose, and insulin concentrations; bodyweight; waist circumference; and prevalent and incident type 2 diabetes. Study-specific effect estimates per copy of each LDL-lowering allele were pooled by meta-analysis. These findings were compared with a meta-analysis of new-onset type 2 diabetes and bodyweight change data from randomised trials of statin drugs. The effects of statins in each randomised trial were assessed using meta-analysis.
Data were available for up to 223 463 individuals from 43 genetic studies. Each additional rs17238484-G allele was associated with a mean 0·06 mmol/L (95% CI 0·05–0·07) lower LDL cholesterol and higher body weight (0·30 kg, 0·18–0·43), waist circumference (0·32 cm, 0·16–0·47), plasma insulin concentration (1·62%, 0·53–2·72), and plasma glucose concentration (0·23%, 0·02–0·44). The rs12916 SNP had similar effects on LDL cholesterol, bodyweight, and waist circumference. The rs17238484-G allele seemed to be associated with higher risk of type 2 diabetes (odds ratio [OR] per allele 1·02, 95% CI 1·00–1·05); the rs12916-T allele association was consistent (1·06, 1·03–1·09). In 129 170 individuals in randomised trials, statins lowered LDL cholesterol by 0·92 mmol/L (95% CI 0·18–1·67) at 1-year of follow-up, increased bodyweight by 0·24 kg (95% CI 0·10–0·38 in all trials; 0·33 kg, 95% CI 0·24–0·42 in placebo or standard care controlled trials and −0·15 kg, 95% CI −0·39 to 0·08 in intensive-dose vs moderate-dose trials) at a mean of 4·2 years (range 1·9–6·7) of follow-up, and increased the odds of new-onset type 2 diabetes (OR 1·12, 95% CI 1·06–1·18 in all trials; 1·11, 95% CI 1·03–1·20 in placebo or standard care controlled trials and 1·12, 95% CI 1·04–1·22 in intensive-dose vs moderate dose trials).
The increased risk of type 2 diabetes noted with statins is at least partially explained by HMGCR inhibition.
The funding sources are cited at the end of the paper.
Left ventricular (LV) mass and LV ejection fraction (EF) are major independent predictors of future cardiovascular disease. The association of LV mass with future LVEF in younger populations has not been studied. We investigated the relation of LV mass index (LVMI) at age 23 to 35 years to LV function after 20 years of follow-up in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. CARDIA is a longitudinal study that enrolled young adults in 1985–1986. We included participants with echocardiographic examinations at both years-5 and -25. LVMI and LVEF were assessed using M-mode echocardiography at year-5 and using both M-mode and 2-dimensional images at year-25. Statistical analytic models assessed the correlation between LVMI and LV functional parameters both cross-sectionally and longitudinally. A total of 2,339 participants were included. The mean LVEF at year-25 was 62%. Although there was no cross-sectional correlation between LVMI and LVEF at year-5, there was a small, but statistically significant negative correlation between LVMI at year-5 and LVEF 20 years later (r = −0.10, p < 0.0001); this inverse association persisted for LVMI in the multivariable model. High LVMI was an independent predictor of systolic dysfunction (LVEF < 50%) 20 years later (odds ratio 1.46, p = 0.0018). In conclusion, we have shown that LVMI in young adulthood in association with chronic risk exposure impacts systolic function in middle age; the antecedents of heart failure may occur at younger ages than previously thought.
left ventricular mass; left ventricular ejection fraction; echocardiography; left ventricular remodeling
The timing of menopause is associated with multiple chronic diseases. Tools to predict this milestone have relevance for clinical and research purposes. Among infertile women, a positive relationship exists between antral follicle count (AFC) and response to controlled ovarian hyperstimulation, a marker of ovarian reserve. However, a relationship between AFC and menopause that is age-independent has not been demonstrated. Thus, our objective was to evaluate the relationship between AFC measured in women at ages 34–49 and incident natural menopause over 7-years of follow-up.
The Coronary Artery Risk Development in Young Adults (CARDIA) study is a longitudinal community-based study (Chicago, Illinois; Birmingham, Alabama; Minneapolis, Minnesota; and Oakland, California) begun in 1985–1986. In 2002–03, the CARDIA Women’s Study measured FSH levels and performed a transvaginal ultrasound protocol that included AFC (2mm–10mm follicles on both ovaries). Incident natural menopause was assessed by survey in 2005–06 and 2009–10.
In our sample (n=456), median AFC and FSH were 5 (IQR 2–9) and 7.8 mIU/mL (IQR 5.6–11.0), respectively, at a mean age of 42 (range 34–49) in 2002–03. 101 women reported natural menopause by 2009–10. In Cox models, current smoking, stable menses, FSH>13, and AFC ≤4 were independently associated with incident natural menopause. Compared to AFC >4, those with AFC ≤4 were nearly twice as likely to have undergone menopause over 7-years of follow-up (HR 1.89, 95% CI 1.19–3.02) after adjustment for covariates.
AFC is independently associated with natural menopause over 7-years of follow-up after controlling for other markers of ovarian aging.
Antral Follicle Count; Menopause; Ovarian Aging; Ovarian Reserve; FSH
In this study, the authors determined the prevalence and extent of cardiovascular disease (CVD) risk factors and subclinical CVD in four US Hispanic subgroups, as well as associations between the CVD risk factors and subclinical CVD in these groups. Participants were 1,437 Hispanic men and women enrolled in the Multi-Ethnic Study of Atherosclerosis in 2000–2002. Fifty-six percent were Mexican-American, 12% were Dominican-American, 14% were Puerto Rican-American, and 18% were Other Hispanic-American. All participants underwent clinical examinations for coronary artery calcium, thoracic aortic calcium, carotid intimal-medial thickness, ankle-brachial index, left ventricular mass, and left ventricular size. Mexican Americans had the highest levels of coronary artery calcium, thoracic aortic calcium, and carotid intimal-medial thickness, while Puerto Rican Americans had the highest prevalence of an ankle-brachial index less than 1.0 and levels of left ventricular mass. The magnitudes of the associations between coronary artery calcium and age, sex, and body mass index were similar across all Hispanic subgroups. However, there were differences in the magnitude and significance of the associations between coronary artery calcium and hypertension, hypercholesterolemia, and cigarette smoking among the different Hispanic subgroups. This finding was also present for the other subclinical CVD measures. These results suggest a differential relationship between risk factors and either prevalence or extent of subclinical disease by Hispanic subgroup.
atherosclerosis; cardiovascular diseases; ethnic groups; Hispanic Americans; risk factors
Perimenopause significantly impacts women’s health, but is under-researched due to challenges in assessing perimenopause status. Using CARDIA data, we compared the validity of six approaches for classifying perimenopause status in order to better understand the performance of classification techniques which can be applied to general cohort data. Specifically, we examined the validity of a self-reported question concerning changes in menstrual cycle length and two full prediction models using all available data concerning menstrual cycles as potential indicators of perimenopause. The validity of these three novel methods of perimenopause classification were compared to three previously established classification methods.
For each method, women were classified as pre- or peri-menopausal at Year 15 of follow-up (ages 32–46). Year 15 perimenopause status was then used to predict Year 20 post-menopausal status (yes/no) to estimate measures of validity and area under the curve.
The validity of the methods varied greatly, with four having an area under the curve greater than 0.8.
When designing studies, researchers should collect the data required to construct a prediction model for classifying perimenopause status that includes age, smoking status, vasomotor symptoms, and cycle irregularities as predictors. The inclusion of additional data regarding menstrual cycles can be used to construct a full prediction model which may offer improved validity. Valid classification methods that use readily available data are needed to improve the scientific accuracy of research regarding perimenopause, promote research on this topic, and inform clinical practices.
menopause; perimenopause; sensitivity; specificity; validity
Genome-wide association studies (GWAS) in European Americans have reported several SNPs in the lipoprotein lipase (LPL) gene associated with plasma levels of HDL-C and triglycerides. However, the influences of the LPL SNPs on longitudinal changes of these lipids have not been systematically examined.
Methods and Results
Based on data from 2045 African American and 2116 European American young adults in the CARDIA Study, we investigated cross-sectional and longitudinal associations of lipids with 8 LPL SNPs, including two that have been reported in GWAS. Plasma levels of HDL-C and triglycerides were measured at seven examinations during 20 years of follow-up. In European Americans, rs328 (Ser447Stop), rs326 and rs13702 were significantly associated with cross-sectional interindividual variations in triglycerides and HDL-C (p<0.005) and with their longitudinal changes over time (p < 0.05). The minor alleles in rs326, rs328, and rs13702 that predispose an individual to lower triglycerides and higher HDL-C levels at young adulthood further slow down the trajectory increase in triglycerides and decrease in HDL-C during 20 years of follow-up. In African Americans, these 3 SNPs were significantly associated with triglycerides but only rs326 and rs13702 associated with HDL-C (p<0.008). Rs328 showed a stronger association in European Americans than African Americans and adjustment for it did not remove all of the associations for the other SNPs. Longitudinal changes in either trait did not differ significantly by SNP genotypes in African Americans.
Our data suggest that aging interacts with LPL gene variants to influence the longitudinal lipid variations and there is population-related heterogeneity in the longitudinal associations.
lipids; genetics; epidemiology; LPL gene
Electrocardiographic indices reflecting left ventricular hypertrophy are associated with incident diabetes in clinical populations at risk for coronary heart disease. We tested whether electrocardiographically determined left ventricular mass was positively associated with incident diabetes in a population sample.
RESEARCH DESIGN AND METHODS
Coronary Artery Risk Development in Young Adults (CARDIA) study participants (n = 4,739) were followed from 1985–1986 to 2010–2011 for incident diabetes. Validated sex- and race-specific formulas were applied to standard electrocardiograms to determine left ventricular mass.
Over 25 years, 444 participants developed diabetes (9.4%). After adjustment for demographic, behavioral, and clinical covariates, participants in the highest quartile of left ventricular mass index (LVMI) were twice as likely to develop diabetes than participants in the lower three quartiles (hazard ratio 2.61 [95% CI 2.16–3.17]). Neither Cornell voltage nor Cornell voltage product was associated with incident diabetes in fully adjusted models.
Electrocardiographically determined LVMI may be a useful noninvasive marker for identifying adults at risk for diabetes.
We evaluated the cross-sectional association between race and hysterectomy prevalence in a population-based cohort of US women and investigated participant characteristics associated with racial differences.
The cohort consisted of 1863 Black and White women in the Coronary Artery Risk Development in Young Adults (CARDIA) study from 2000 to 2002 (years 15 and 16 after baseline). We used logistic regression to examine unadjusted and multivariable adjusted odds ratios.
Black women demonstrated greater odds of hysterectomy compared with White women (odds ratio [OR]=3.52; 95% confidence interval [CI]=2.52, 4.90). Adjustment for age, educational attainment, perceived barriers to accessing medical care, body mass index, polycystic ovarian syndrome, tubal ligation, depressive symptoms, age at menarche, and geographic location minimally altered the association (OR=3.70; 95% CI=2.44, 5.61). In a subset of the study population, those with directly imaged fibroids, the association was minimally attenuated (OR=3.47; 95% CI=2.23, 5.40).
In both unadjusted and multivariable adjusted models, Black women, compared with White women, had increased odds of hysterectomy that persisted despite adjustment for participant characteristics. The increased odds are possibly related to decisions to undergo hysterectomy.
There has been reduced active smoking, decreased societal acceptance for smoking indoors, and changing smoking policy since the mid-1980s. We quantified passive smoke exposure trends and their relationship with workplace policy.
We studied 2,504 CARDIA participants (blacks and whites, 18–30 years old when recruited in 1985–86 from four US cities, reexamination 2, 5, 7, 10, and 15 years later) who never reported smoking and attended exams at 10 or 15 years.
In non-smokers with a college degree (n = 1,581), total passive smoke exposure declined from 16.3 hr/wk in 1985/86 to 2.3 hr/wk in 2000/01. Less education tended to be associated with more exposure at all timepoints for example, in high school or less (n = 349) 22.2 hours/wk in 1985/86 to 8.5 hr/wk in 2000/01. Those who experienced an increase in the restrictiveness of self-reported workplace smoking policy from 1995/96 to 2000/01 were exposed to almost 3 hours per week less passive smoke than those whose workplace policies became less restrictive in this time period.
The increasing presence of restrictive workplace policies seemed to be a component of the substantial decline in self-reported passive smoke exposure since 1985.
Environmental Tobacco Smoke Pollution; Occupational Health; Passive Smoking; Socioeconomic factors
Data supporting physical activity guidelines to prevent long-term weight gain are sparse, particularly during the period when the highest risk of weight gain occurs.
To evaluate the relationship between habitual activity levels and changes in body mass index (BMI) and waist circumference over 20 years.
Design, Setting, and Participants
The Coronary Artery Risk Development in Young Adults (CARDIA) study is a prospective longitudinal study with 20 years of follow-up, 1985-86 to 2005-06. Habitual activity was defined as maintaining high, moderate, and low activity levels based on sex-specific tertiles of activity scores at baseline. Participants comprised a population-based multi-center cohort (Chicago, Illinois; Birmingham, Alabama; Minneapolis, Minnesota; and Oakland, California) of 3554 men and women aged 18 to 30 years at baseline.
Main Outcome Measures
Average annual changes in BMI and waist circumference
Over 20 years, maintaining high levels of activity was associated with smaller gains in BMI and waist circumference compared with low activity levels after adjustment for race, baseline BMI, age, education, cigarette smoking status, alcohol use, and energy intake. Men maintaining high activity gained 2.6 fewer kilograms (+ 0.15 BMI units per year; 95 % confidence interval [CI] 0.11-0.18 vs +0.20 in the lower activity group; 95% CI, 0.17-0.23) and women maintaining higher activity gained 6.1 fewer kilograms (+0.17 BMI units per year; 95 % CI, 0.12-0.21 vs. +0.30 in the lower activity group; 95 % CI, 0.25-0.34). Men maintaining high activity gained 3.1 fewer centimeters in waist circumference (+0.52 cm per year; 95 % CI, 0.43-0.61 cm vs 0.67 cm in the lower activity group; 95 % CI, 0.60-0.75) and women maintaining higher activity gained 3.8 fewer centimeters (+0.49 cm per year; 95 % CI, 0.39-0.58 vs 0.67 cm in the lower activity group; 95 % CI, 0.60-0.75).
Maintaining high activity levels through young adulthood may lessen weight gain as young adults transition to middle age, particularly in women.
Genome-wide association studies (GWAS) have identified 36 loci associated with body mass index (BMI), predominantly in populations of European ancestry. We conducted a meta-analysis to examine the association of >3.2 million SNPs with BMI in 39,144 men and women of African ancestry, and followed up the most significant associations in an additional 32,268 individuals of African ancestry. We identified one novel locus at 5q33 (GALNT10, rs7708584, p=3.4×10−11) and another at 7p15 when combined with data from the Giant consortium (MIR148A/NFE2L3, rs10261878, p=1.2×10−10). We also found suggestive evidence of an association at a third locus at 6q16 in the African ancestry sample (KLHL32, rs974417, p=6.9×10−8). Thirty-two of the 36 previously established BMI variants displayed directionally consistent effect estimates in our GWAS (binomial p=9.7×10−7), of which five reached genome-wide significance. These findings provide strong support for shared BMI loci across populations as well as for the utility of studying ancestrally diverse populations.
Slow heart rate recovery (HRR) from a graded exercise treadmill test (GXT) is a marker of impaired parasympathetic reactivation that is associated with elevated mortality. Our objective was to test whether demographic, behavioral or coronary heart disease (CHD) risk factors during young adulthood were associated with the development of slow HRR.
Participants from the Coronary Artery Risk Development in Young Adults study underwent symptom-limited maximal GXT using a modified Balke protocol at baseline (1985–86) and 20-year follow-up (2005–06) examinations. HRR was calculated as the difference between peak heart rate (HR) and HR two-minutes following cessation of the GXT. Slow HRR was defined as 2-minute HRR < 22 beats·min−1.
In 2,730 participants who did not have slow HRR at baseline, mean HRR was 44 beats*min−1 (SD = 11) at baseline and declined to 40 beats·min−1 (SD=12) in 2005–06; slow HRR developed in 5% (n=135) of the sample by 2005–06. Female sex, black race, fewer years of education, obesity, cigarette smoking, higher depressive symptoms, higher fasting glucose, hypertension, metabolic syndrome and physical inactivity and low fitness were each associated with incident slow HRR. In a multivariable model higher BMI, larger waist, low education, fasting glucose and current smoking remained significantly associated with incident slow HRR. Increasing BMI (per SD higher) over follow-up and incident hypertension, diabetes and metabolic syndrome (in the subsets of participants who were free from those conditions at baseline), were each associated with a significantly elevated odds of incident slow HRR.
On average, HRR declines with aging; however, the odds of having slow HRR in early middle age is significantly associated with traditional CHD risk factors.
Epidemiology; Cardiovascular Disease; Exercise; Autonomic Nervous System
Cardiovascular disease is the number one killer of women. Identifying women at risk of cardiovascular disease has tremendous public health importance. Early menopause is associated with increased cardiovascular disease events in some predominantly white populations, but not consistently. Our objective was to determine if a self-reported early menopause (menopause at an age <46) identifies women as at risk for future coronary heart disease or stroke.
The study population came from the Multi-Ethnic Study of Atherosclerosis, a longitudinal, ethnically diverse cohort study of US men and women aged 45 to 84 years enrolled in 2000–2002 and followed up until 2008. The association between a personal history of early menopause (either natural menopause or surgical removal of ovaries at an age <46) and future coronary heart disease and stroke was assessed in 2509 women (ages 45–84, 987 White, 331 Chinese, 641 Black, 550 Hispanic) from the Multi-Ethnic Study Atherosclerosis, who were free of cardiovascular disease at baseline.
693/2509 (28%) of women reported either surgical or natural early menopause. In survival curves, women with early menopause had worse coronary heart disease and stroke-free survival (log rank p=<0.008 and 0.0158). In models adjusted for age, race/ethnicity, Multi-Ethnic Study Atherosclerosis site and traditional cardiovascular disease risk factors, this risk for coronary heart disease and stroke remained (HR 2.08, 95% CI 1.17, 3.70 and 2.19, 95% CI 1.11, 4.32, respectively).
Early menopause is positively associated with coronary heart disease and stroke in a multiethnic cohort, independent of traditional cardiovascular disease risk factors.
Early Menopause; Coronary Heart Disease; Stroke
Central obesity, measured by waist circumference (WC) or waist-hip ratio (WHR), is a marker of body fat distribution. Although obesity disproportionately affects minority populations, few studies have conducted genome-wide association study (GWAS) of fat distribution among those of predominantly African ancestry (AA). We performed GWAS of WC and WHR, adjusted and unadjusted for BMI, in up to 33,591 and 27,350 AA individuals, respectively. We identified loci associated with fat distribution in AA individuals using meta-analyses of GWA results for WC and WHR (stage 1). Overall, 25 SNPs with single genomic control (GC)-corrected p-values<5.0×10−6 were followed-up (stage 2) in AA with WC and with WHR. Additionally, we interrogated genomic regions of previously identified European ancestry (EA) WHR loci among AA. In joint analysis of association results including both Stage 1 and 2 cohorts, 2 SNPs demonstrated association, rs2075064 at LHX2, p = 2.24×10−8 for WC-adjusted-for-BMI, and rs6931262 at RREB1, p = 2.48×10−8 for WHR-adjusted-for-BMI. However, neither signal was genome-wide significant after double GC-correction (LHX2: p = 6.5×10−8; RREB1: p = 5.7×10−8). Six of fourteen previously reported loci for waist in EA populations were significant (p<0.05 divided by the number of independent SNPs within the region) in AA studied here (TBX15-WARS2, GRB14, ADAMTS9, LY86, RSPO3, ITPR2-SSPN). Further, we observed associations with metabolic traits: rs13389219 at GRB14 associated with HDL-cholesterol, triglycerides, and fasting insulin, and rs13060013 at ADAMTS9 with HDL-cholesterol and fasting insulin. Finally, we observed nominal evidence for sexual dimorphism, with stronger results in AA women at the GRB14 locus (p for interaction = 0.02). In conclusion, we identified two suggestive loci associated with fat distribution in AA populations in addition to confirming 6 loci previously identified in populations of EA. These findings reinforce the concept that there are fat distribution loci that are independent of generalized adiposity.
Central obesity is a marker of body fat distribution and is known to have a genetic underpinning. Few studies have reported genome-wide association study (GWAS) results among individuals of predominantly African ancestry (AA). We performed a collaborative meta-analysis in order to identify genetic loci associated with body fat distribution in AA individuals using waist circumference (WC) and waist to hip ratio (WHR) as measures of fat distribution, with and without adjustment for body mass index (BMI). We uncovered 2 genetic loci potentially associated with fat distribution: LHX2 in association with WC-adjusted-for-BMI and at RREB1 for WHR-adjusted-for-BMI. Six of fourteen previously reported loci for waist in EA populations were significant in AA studied here (TBX15-WARS2, GRB14, ADAMTS9, LY86, RSPO3, ITPR2-SSPN). These findings reinforce the concept that there are loci for body fat distribution that are independent of generalized adiposity.
Sex hormones are thought to play an important role in the pathophysiology of depressive disorders in women. This study assessed the associations of total testosterone (T), bioavailable T, estradiol (E2), dehydroepiandrosterone (DHEA) and sex hormone binding globulin (SHBG) with depressive symptoms stratified on postmenopausal stage to determine whether associations were strongest for early postmenopausal women.
Women (N=1824) free of depressive symptoms at baseline (2000–2002) in the Multi-Ethnic Study of Atherosclerosis were categorized into tertiles of years postmenopause: T1, 0–10 years; T2, 11–20 years; and T3, 21–58 years. Multivariable-adjusted relative risks (RR) and 95% confidence intervals were computed for the incidence of depressive symptoms, as defined by a score of 16 or higher on the Center for Epidemiologic Studies Depression scale at examination 3 (2004–2005).
In analysis including all sex hormones, the RRs for incident depressive symptoms associated with 1 unit higher log(total T) was 0.57 (p=0.13), log(E2) was 0.78 (p=0.04), log(SHBG) was 1.84 (p=0.003) and log(DHEA) was 1.45 (p=0.08) in T1. Without adjustment for SHBG, the RR for log(bioavailable T) was 0.16 (p=0.04). However, in T2 and T3, there were no meaningful associations of hormone or SHBG levels with incident depressive symptoms. When stratified by HT use, results were consistent for HT users but attenuated for HT non-users.
In women early postmenopause, sex hormones were associated with incident depressive symptoms.
sex hormones; CES-D; depression; testosterone; estradiol; SHBG
Elevated plasma concentration of total homocysteine (tHcy) has been linked with many diseases. tHcy is associated with a variety of factors, including polymorphisms in genes involved in homocysteine metabolism. It is not clear whether US-mandated fortification of grain products with folic acid has affected the association of genetic variants with tHcy levels. We determined tHcy concentrations in sera from 997 Caucasians and 692 African Americans participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study before and after folic acid fortification. DNA was genotyped for variants present in four genes involved in homocysteine metabolism: cystathionine β-synthase (CBS) 844ins68, methionine synthase (MS) 2756A>G; methionine synthase reductase (MTRR) 66A>G, and methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C. A greater number of African Americans were homozygous for the MS 2756GG, MTRR 66GG and CBS 844ins68 genotypes compared to Caucasians, while prevalence of MTHFR 677TT and 1298CC genotypes was substantially lower in African Americans compared to Caucasians. The overall variance in tHcy levels at y 0, 7, and 15 that can be explained by the combined presence of all five variants increased slightly over time in Caucasians (17%, y 0; 21%, y 7 and 26%, y 15) and in African Americans (13%, y 0; 17% y 7; 18% y 15) largely due to decrease in tHcy variance.
Cystathionine B-synthase; folic acid; homocysteine; methylenetetrahydrofolate reductase; methionine synthase; methionine synthase reductase
Few studies to date have described the prevalence of electrocardiographic (ECG) abnormalities in a biracial middle-aged cohort.
Methods and Results
Participants underwent measurement of traditional risk factors and 12-lead ECGs coded using both Minnesota Code (MC) and Novacode (NC) criteria. Among 2585 participants, of whom 57% were women and 44% were black (mean age 45 years), the prevalence of major and minor abnormalities were significantly higher (all P<0.001) among black men and women compared to whites. These differences were primarily due to higher QRS voltage and ST/T wave abnormalities among blacks. There was also a higher prevalence of Q waves (MC 1-1, 1-2, 1-3) than described by previous studies. These racial differences remained after multivariate adjustment for traditional cardiovascular (CV) risk factors.
Black men and women have a significantly higher prevalence of ECG abnormalities, independent of traditional CV risk factors, than whites in a contemporary cohort middle-aged participants.
Meta-analyses of European populations has successfully identified genetic variants in over 100 loci associated with lipid levels, but our knowledge in other ethnicities remains limited. To address this, we performed dense genotyping of ∼2,000 candidate genes in 7,657 African Americans, 1,315 Hispanics and 841 East Asians, using the IBC array, a custom ∼50,000 SNP genotyping array. Meta-analyses confirmed 16 lipid loci previously established in European populations at genome-wide significance level, and found multiple independent association signals within these lipid loci. Initial discovery and in silico follow-up in 7,000 additional African American samples, confirmed two novel loci: rs5030359 within ICAM1 is associated with total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) (p = 8.8×10−7 and p = 1.5×10−6 respectively) and a nonsense mutation rs3211938 within CD36 is associated with high-density lipoprotein cholesterol (HDL-C) levels (p = 13.5×10−12). The rs3211938-G allele, which is nearly absent in European and Asian populations, has been previously found to be associated with CD36 deficiency and shows a signature of selection in Africans and African Americans. Finally, we have evaluated the effect of SNPs established in European populations on lipid levels in multi-ethnic populations and show that most known lipid association signals span across ethnicities. However, differences between populations, especially differences in allele frequency, can be leveraged to identify novel signals, as shown by the discovery of ICAM1 and CD36 in the current report.
Whereas it is well established that plasma lipid levels have substantial heritability within populations, it remains unclear how many of the genetic determinants reported in previous studies (largely performed in European American cohorts) are relevant in different ethnicities.
We tested a set of ∼50,000 polymorphisms from ∼2,000 candidate genes and genetic loci from genome-wide association studies (GWAS) for association with low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) in 25,000 European Americans and 9,000 African Americans in the National Heart, Lung, and Blood Institute (NHLBI) Candidate Gene Association Resource (CARe). We replicated associations for a number of genes in one or both ethnicities and identified a novel lipid-associated variant in a locus harboring ICAM1. We compared the architecture of genetic loci associated with lipids in both African Americans and European Americans and found that the same genes were relevant across ethnic groups but the specific associated variants at each gene often differed.
We identify or provide further evidence for a number of genetic determinants of plasma lipid levels through population association studies. In many loci the determinants appear to differ substantially between African Americans and European Americans.
In 2002 the United States Preventive Services Task Force and the American Heart Association recommended aspirin for the primary prevention of Coronary Heart Disease (CHD) in individuals with a Framingham risk score ≥ 6% or ≥ 10%, respectively. The regular use of aspirin (≥ 3 days per week) was examined in a cohort of 6452 White, Black, Hispanic, and Chinese individuals without cardiovascular disease in 2000-2002 and 5181 individuals from the same cohort in 2005-2007. Framingham risk scores were stratified into low (< 6%), increased (6% to 9.9%), and high risk (≥ 10%). In 2000-2002 the prevalence of aspirin use was 18% and 27% for those at increased and high risk, respectively. Whites (25%) used aspirin more than Blacks (14%), Hispanics (12%), or Chinese (14%) (P < 0.001) in the increased risk group. Corresponding prevalences for the high risk group were 38%, 25%, 17%, and 21%, respectively (P < 0.001). In 2005-2007 the prevalence of aspirin use was 31% and 44% for those at increased and high risk, respectively. Whites (41%) used aspirin more than Blacks (27%), Hispanics (24%), or Chinese (15%) in the increased risk group (P < 0.001). Corresponding prevalences for the high risk group were 53%, 43%, 38%, and 28%, respectively (P < 0.001). Racial/ethnic differences persisted after adjustment for age, gender, diabetes, income, and education. In conclusion, regular aspirin use in adults at increased and high risk for CHD remains suboptimal. Important racial/ethnic disparities exist for unclear reasons.
Framingham risk score; aspirin; coronary heart disease; race and ethnicity
To estimate whether women aged 19–32 who fulfilled National Institutes of Health (NIH) criteria for polycystic ovary syndrome (PCOS) would be at a higher risk for subsequent development of incident diabetes, dyslipidemia, and hypertension, and to estimate whether normal-weight women with PCOS would have the same degree of cardiovascular risk as overweight women with PCOS.
We estimated the association of PCOS with incident diabetes, dyslipidemia, and hypertension over a period of 18 years among 1,127 white women and black women in the Coronary Artery Risk Development In young Adults (CARDIA) cohort. We classified women at baseline (ages 20–32) based on self-reported symptoms and/or biochemical hyperandrogenism using NIH PCOS criteria. We estimated the association of PCOS and subsequent cardiovascular risk factors, independent of baseline body mass index (BMI), using multivariable logistic regression. Additionally, among 746 women with a second assessment of PCOS at ages 34–46, we estimated the association of persistent PCOS with cardiovascular risk factors.
Of 1,127 women, 53 (4.7%) met criteria for PCOS at ages 20–32. PCOS was associated with a twofold higher odds of incident diabetes (23.1% versus 13.1%; adjusted OR (AOR) 2.4, 1.2–4.9) and dyslipidemia (41.9% versus 27.7%; AOR 1.9, 1.0–3.6) over 18 years; the association with incident hypertension was not significant (26.9% versus 26.3%; AOR 1.7, 0.8–3.3). Normal-weight women with PCOS (n=31) had a threefold higher odds of incident diabetes compared to normal weight women without PCOS (AOR 3.1, 1.2–8.0). Compared to those without PCOS (n=11), women with persistent PCOS had the highest odds of diabetes (AOR 7.2, 1.1–46.5).
PCOS is associated with subsequent incident diabetes and dyslipidemia, independent of BMI. Diabetes risk may be greatest for women with persistent PCOS symptoms.
Lower extremity fat mass (LEFM) has been shown to be favorably associated with glucose metabolism. However, it is not clear whether this relationship is similar across varying levels of obesity. We hypothesized that lower amounts of LEFM is associated with higher insulin resistance (IR) and this association may vary according to weight status. Participants with available measures were examined from the Coronary Artery Risk Development in Young Adults study (CARDIA), a multi-center longitudinal study of the etiology of atherosclerosis in black and white men and women aged 38–50 years old in 2005–2006 (n = 1,579). The homeostasis model assessment of IR (HOMAIR) was calculated to estimate IR, regional adiposity was measured using dual energy X-ray absorptiometry (DXA), and weight status was defined according to BMI categories. Obese and overweight participants exhibited higher IR, total fat mass (FM), trunk FM (TFM), and LEFM compared to normal weight participants. After controlling for age, height, race, study center, education, smoking, and cardiorespiratory fitness (CRF), greater LEFM was significantly associated with higher IR only in normal weight men and women. Further adjustment for TFM revealed that lower LEFM was significantly associated with higher IR in overweight and obese men and women and the positive association in normal weight individuals was attenuated. These results suggest that excess adiposity in the lower extremities may attenuate the metabolic risk observed at a given level of abdominal adiposity in overweight and obese individuals. Weight status presents additional complexity since the metabolic influence of adipose tissue may not be homogenous across anatomic regions or level of obesity.
Adult height is a classic polygenic trait of high heritability (h2 ∼0.8). More than 180 single nucleotide polymorphisms (SNPs), identified mostly in populations of European descent, are associated with height. These variants convey modest effects and explain ∼10% of the variance in height. Discovery efforts in other populations, while limited, have revealed loci for height not previously implicated in individuals of European ancestry. Here, we performed a meta-analysis of genome-wide association (GWA) results for adult height in 20,427 individuals of African ancestry with replication in up to 16,436 African Americans. We found two novel height loci (Xp22-rs12393627, P = 3.4×10−12 and 2p14-rs4315565, P = 1.2×10−8). As a group, height associations discovered in European-ancestry samples replicate in individuals of African ancestry (P = 1.7×10−4 for overall replication). Fine-mapping of the European height loci in African-ancestry individuals showed an enrichment of SNPs that are associated with expression of nearby genes when compared to the index European height SNPs (P<0.01). Our results highlight the utility of genetic studies in non-European populations to understand the etiology of complex human diseases and traits.
Adult height is an ideal phenotype to improve our understanding of the genetic architecture of complex diseases and traits: it is easily measured and usually available in large cohorts, relatively stable, and mostly influenced by genetics (narrow-sense heritability of height h2∼0.8). Genome-wide association (GWA) studies in individuals of European ancestry have identified >180 single nucleotide polymorphisms (SNPs) associated with height. In the current study, we continued to use height as a model polygenic trait and explored the genetic influence in populations of African ancestry through a meta-analysis of GWA height results from 20,809 individuals of African descent. We identified two novel height loci not previously found in Europeans. We also replicated the European height signals, suggesting that many of the genetic variants that are associated with height are shared between individuals of European and African descent. Finally, in fine-mapping the European height loci in African-ancestry individuals, we found SNPs more likely to be associated with the expression of nearby genes than the SNPs originally found in Europeans. Thus, our results support the utility of performing genetic studies in non-European populations to gain insights into complex human diseases and traits.
To estimate the association of age with maximal heart rate (MHR).
Data were obtained in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Participants were black and white men and women aged 18-30 in 1985-86 (year 0). A symptom-limited maximal graded exercise test was completed at years 0, 7, and 20 by 4969, 2583, and 2870 participants, respectively. After exclusion 9622 eligible tests remained.
In all 9622 tests, estimated MHR (eMHR, beats/minute) had a quadratic relation to age in the age range 18 to 50 years, eMHR=179+0.29*age-0.011*age2. The age-MHR association was approximately linear in the restricted age ranges of consecutive tests. In 2215 people who completed both year 0 and 7 tests (age range 18 to 37), eMHR=189–0.35*age; and in 1574 people who completed both year 7 and 20 tests (age range 25 to 50), eMHR=199–0.63*age. In the lowest baseline BMI quartile, the rate of decline was 0.20 beats/minute/year between years 0-7 and 0.51 beats/minute/year between years 7-20; while in the highest baseline BMI quartile there was a linear rate of decline of approximately 0.7 beats/minute/year over the full age of 18 to 50 years.
Clinicians making exercise prescriptions should be aware that the loss of symptom-limited MHR is much slower at young adulthood and more pronounced in later adulthood. In particular, MHR loss is very slow in those with lowest BMI below age 40.
prediction equations; graded exercise test; mixed models; epidemiologic study