Kristen G. Hairston

Impact of Abdominal Visceral and Subcutaneous Adipose Tissue on Cardiometabolic Risk Factors: The Jackson Heart Study

OBJECTIVE Obesity is a major driver of cardiometabolic risk. Abdominal visceral adipose tissue (VAT) and sc adipose tissue (SAT) may confer differential metabolic risk profiles. We investigated the relations of VAT and SAT with cardiometabolic risk factors in the Jackson Heart Study cohort. METHODS Participants from the Jackson Heart Study (n=2477; 64% women; mean age, 58 yr) underwent multidetector computed tomography, and the volumetric amounts of VAT and SAT were assessed between 2007 and 2009. Cardiometabolic risk factors were examined by sex in relation to VAT and SAT. RESULTS Men had a higher mean volume of VAT (873 vs. 793 cm3) and a lower mean volume of SAT (1730 vs. 2659 cm3) than women (P=0.0001). Per 1-sd increment in either VAT or SAT, we observed elevated levels of fasting plasma glucose and triglyceride, lower levels of high-density lipoprotein-cholesterol, and increased odds ratios for hypertension, diabetes, and metabolic syndrome. The effect size of VAT in women was larger than that of SAT [fasting plasma glucose, 5.51±1.0 vs. 3.36±0.9; triglyceride, 0.17±0.01 vs. 0.05±0.01; high-density lipoprotein-cholesterol, -5.36±0.4 vs. -2.85±0.4; and odds ratio for hypertension, 1.62 (1.4-1.9) vs. 1.40 (1.2-1.6); diabetes, 1.82 (1.6-2.1) vs. 1.58 (1.4-1.8); and metabolic syndrome, 3.34 (2.8-4.0) vs. 2.06 (1.8-2.4), respectively; P<0.0001 for difference between VAT and SAT]. Similar patterns were also observed in men. Furthermore, VAT remained associated with most risk factors even after accounting for body mass index (P ranging from 0.006-0.0001). The relationship of VAT to most risk factors was significantly different between women and men. CONCLUSIONS Abdominal VAT and SAT are both associated with adverse cardiometabolic risk factors, but VAT remains more strongly associated with these risk factors. The results from this study suggest that relations with cardiometabolic risk factors are consistent with a pathogenic role of abdominal adiposity in participants of African ancestry.

Association of Plasma Vitamin D Levels with Adiposity in Hispanic and African Americans

CONTEXT Previous studies have suggested vitamin D insufficiency is associated with increased obesity; however, the relationship between 25-hydroxyvitamin D (25[OH]D) and 1,25-dihydroxyvitamin D (1,25[OH](2)D) and measures of adiposity has not been well characterized in minority populations. OBJECTIVE The objective of the study was to examine the relationship between levels of 25[OH]D and 1,25[OH](2)D and measures of adiposity in Hispanic and African-Americans at baseline and on change in these measures over time. DESIGN AND SETTING The Insulin Resistance Atherosclerosis (IRAS) Family Study examined 917 Hispanics and 439 African-Americans at baseline and again 5.3 yr later (n = 1081 at follow-up). MAIN OUTCOME MEASURE 25[OH]D (nanograms per milliliter) and 1,25[OH](2)D (picograms per milliliter) were measured at baseline. Abdominal sc adipose tissue (SAT), visceral adipose tissue (VAT; both determined by computed tomography scan), and body mass index (BMI) were measured at baseline and follow-up. RESULTS 25[OH]D was inversely associated with BMI, VAT, and SAT in both populations at baseline (P < 0.001). 25[OH]D was marginally inversely associated with baseline visceral fat to sc fat ratio in African-Americans (P = 0.049) but not Hispanics. 1,25[OH](2)D was inversely associated with BMI (P < 0.0001, P = 0.002) and VAT (P = 0.0005, P = 0.012) in Hispanics and African-Americans, respectively, whereas 1,25[OH](2)D was inversely associated with SAT in Hispanics (P < 0.0001) and with visceral fat to sc fat ratio in African-Americans (P = 0.02). Adjusting for 25[OH]D attenuated these associations; 1,25[OH](2)D remained associated with BMI in both populations (P < 0.05) and with SAT (P = 0.004) in Hispanics. No significant associations between 5-yr change in adiposity and 25[OH]D or 1,25[OH](2)D were seen. CONCLUSIONS Vitamin D levels were inversely associated with baseline BMI, SAT, and VAT in Hispanic and African-Americans but were not associated with 5-yr change in adiposity.

Vitamin D, Adiposity, and Calcified Atherosclerotic Plaque in African-Americans

CONTEXT Inverse associations are reported between circulating 25-hydroxyvitamin D and visceral adiposity. The effects of vitamin D levels on atherosclerosis are unknown. OBJECTIVE The objective of this study was to test for relationships between vitamin D, adiposity, bone density, and atherosclerosis in African-Americans. DESIGN Circulating 25-hydroxyvitamin D, 1,25 dihydroxyvitamin D, intact PTH, C-reactive protein and computed tomography-derived calcified atherosclerotic plaque (CP), bone density, and fat volumes were measured. SETTING Examinations were performed at a single outpatient general clinical research center visit. SUBJECTS Three hundred forty African-Americans with type 2 diabetes were evaluated. Mean +/- SD age was 55.6 +/- 9.6 yr, diabetes duration 10.6 +/- 8.3 yr, glomerular filtration rate 1.6 +/- 0.5 ml/sec, body mass index 35.6 +/- 8.7 kg/m(2), and 25-hydroxyvitamin D concentration 50.4 +/- 30.5 nmol/liter. MAIN OUTCOME MEASURE Biomarkers were tested for association with pericardial, visceral, im, and sc adipose tissues; thoracic and lumbar vertebral bone density; and aorta, coronary, and carotid artery CP. RESULTS Adjusting for age, gender, body mass index, glycosylated hemoglobin, and glomerular filtration rate, 25-hydroxyvitamin D was negatively associated with visceral adiposity (P = 0.009) and positively associated with carotid artery CP and aorta CP (P = 0.013 and 0.014, respectively) but not with coronary artery CP or bone density. CONCLUSIONS We confirmed an inverse association between vitamin D and visceral adiposity in African-Americans with diabetes. In addition, positive associations exist between 25-hydroxyvitamin D and aorta and carotid artery CP in African-Americans. The effects of supplementing vitamin D to raise the serum 25-hydroxyvitamin D level on atherosclerosis in African-Americans are unknown. Prospective trials are needed to determine the cardiovascular effects of supplemental vitamin D in this ethnic group.

Intensive Lifestyle Intervention Improves Physical Function Among Obese Adults With Knee Pain: Findings From the Look AHEAD Trial

Lifestyle interventions have resulted in weight loss or improved physical fitness among individuals with obesity, which may lead to improved physical function. This prospective investigation involved participants in the Action for Health in Diabetes (Look AHEAD) trial who reported knee pain at baseline (n = 2,203). The purposes of this investigation were to determine whether an Intensive Lifestyle Intervention (ILI) condition resulted in improvement in self‐reported physical function from baseline to 12 months vs. a Diabetes Support and Education (DSE) condition, and whether changes in weight or fitness mediated the effect of the ILI. Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, stiffness, and physical function subscales, and WOMAC summary score. ILI participants exhibited greater adjusted mean weight loss (s.e.) vs. DSE participants (−9.02 kg (0.48) vs. −0.78 kg (0.49); P < 0.001)). ILI participants also demonstrated more favorable change in WOMAC summary scores vs. DSE participants (β (s.e.) = −1.81 (0.63); P = 0.004). Multiple regression mediation analyses revealed that weight loss was a mediator of the effect of the ILI intervention on change in WOMAC pain, function, and summary scores (P < 0.001). In separate analyses, increased fitness also mediated the effect of the ILI intervention upon WOMAC summary score (P < 0.001). The ILI condition resulted in significant improvement in physical function among overweight and obese adults with diabetes and knee pain. The ILI condition also resulted in significant weight loss and improved fitness, which are possible mechanisms through which the ILI condition improved physical function.

Sleep Duration, Insomnia, and Coronary Heart Disease Among Postmenopausal Women in the Women's Health Initiative

BACKGROUND Long and short sleep duration are associated with increased risk for coronary heart disease (CHD) and cardiovascular disease (CVD); however, evidence is inconsistent. We sought to identify whether self-reported sleep duration and insomnia, based on a validated questionnaire, are associated with increased incident CHD and CVD among postmenopausal women. METHODS Womens Health Initiative Observational Study Participants (N=86,329; 50-79 years) who reported on sleep at baseline were followed for incident CVD events. Associations of sleep duration and insomnia with incident CHD and CVD were evaluated using Cox proportional hazards models over 10.3 years. RESULTS Women with high insomnia scores had elevated risk of CHD (38%) and CVD (27%) after adjustment for age and race, and in fully adjusted models (hazard ratio [HR]=1.19, 95% confidence interval [CI] 1.09-1.30; 1.11 95% CI 1.03-2.00). Shorter (≤5 hours) and longer (≥10 hours) sleep duration demonstrated significantly higher incident CHD (25%) and CVD (19%) in age- and race-adjusted models, but this was not significant in fully adjusted models. Formal tests for interaction indicated significant interactions between sleep duration and insomnia for risk of CHD (p<0.01) and CVD (p=0.02). Women with high insomnia scores and long sleep demonstrated the greatest risk of incident CHD compared to midrange sleep duration (HR=1.93, 95% CI 1.06-3.51) in fully adjusted models. CONCLUSIONS Sleep duration and insomnia are associated with CHD and CVD risk, and may interact to cause almost double the risk of CHD and CVD. Additional research is needed to understand how sleep quality modifies the association between prolonged sleep and cardiovascular outcomes.

Mentoring programs for underrepresented minority faculty in academic medical centers: a systematic review of the literature.

Purpose Mentoring is critical for career advancement in academic medicine. However, underrepresented minority (URM) faculty often receive less mentoring than their nonminority peers. The authors conducted a comprehensive review of published mentoring programs designed for URM faculty to identify “promising practices.” Method Databases (PubMed, PsycINFO, ERIC, PsychLit, Google Scholar, Dissertations Abstracts International, CINHAL, Sociological Abstracts) were searched for articles describing URM faculty mentoring programs. The RE-AIM framework (Reach, Effectiveness, Adoption, Implementation, and Maintenance) formed the model for analyzing programs. Results The search identified 73 citations. Abstract reviews led to retrieval of 38 full-text articles for assessment; 18 articles describing 13 programs were selected for review. The reach of these programs ranged from 7 to 128 participants. Most evaluated programs on the basis of the number of grant applications and manuscripts produced or satisfaction with program content. Programs offered a variety of training experiences, and adoption was relatively high, with minor changes made for implementing the intended content. Barriers included time-restricted funding, inadequate evaluation due to few participants, significant time commitments required from mentors, and difficulty in addressing institutional challenges faced by URM faculty. Program sustainability was a concern because programs were supported through external funds, with minimal institutional support. Conclusions Mentoring is an important part of academic medicine, particularly for URM faculty who often experience unique career challenges. Despite this need, relatively few publications exist to document mentoring programs for this population. Institutionally supported mentoring programs for URM faculty are needed, along with detailed plans for program sustainability.

Identification of Obesity and Cardiovascular Risk in Ethnically and Racially Diverse Populations A Scientific Statement From the American Heart Association

Obesity, defined as excess fat (adipose) tissue accumulation that may impair health,1 is a highly prevalent and serious public health problem. Roughly 35.7% of American adults are obese.2 High rates of obesity are not limited to the United States or even to other highly developed countries. The prevalence of obesity in Mexico, for example, is comparable to that in the United States.3 Not surprisingly, rates of obesity-related illnesses including cardiovascular disease (CVD) are rising quickly worldwide. More than 25 million American adults have been diagnosed with diabetes mellitus.4 India is projected to have >100 million diabetic people by the year 2030.5 CVD is the number 1 cause of death worldwide.6 These grim statistics highlight the need for accurate identification of overweight and obese adults who are at high risk for obesity-related illnesses. Accurate identification of such people allows healthcare professionals, policymakers, and others to target prevention and treatment programs to those at the highest risk of morbidity and mortality. Unfortunately, the tools and measures currently available to identify obesity and associated risks are either impractical, inaccurate, or both. For example, the body mass index (BMI) is easy to calculate, and established cutoffs that define overweight (25 kg/m2) and obesity (30 kg/m2) are readily available and well known. The application of such cutoffs to a diverse population, as will be discussed, however, leads to misclassification of a large number of people. Many people with a normal BMI have high levels of adiposity and also are at high risk for obesity-related illness. Others with a high BMI have relatively normal levels of adiposity and are metabolically healthy. The problem of misclassification is especially important for racial and ethnic minorities, who make up nearly 40% of the American population today and will make up more …

Self-reported snoring and risk of cardiovascular disease among postmenopausal women (from the Women's Health Initiative).

Habitual snoring may be associated with cardiovascular disease (CVD); however, limited evidence exists among women. We investigated whether frequent snoring is a predictor of coronary heart disease (CHD) and stroke among 42,244 postmenopausal women participating in the Womens Health Initiative Observational Study. Participants provided self-reported information regarding snoring habits at baseline (1993 to 1998) and were followed up for outcomes through August 2009. Physician adjudicators confirmed CHD (defined as myocardial infarction, CHD death, revascularization procedures, or hospitalized angina) and ischemic stroke. Cox proportional hazards models were used to evaluate whether snoring frequency is a significant predictor of the adjudicated outcomes. We observed 2,401 incident cases of CHD during 437,899 person-years of follow-up. After adjusting for age and race, frequent snoring was associated with incident CHD (hazard ratio [HR] 1.54, 95% confidence interval [CI] 1.39 to 1.70) and stroke (HR 1.41, 95% CI 1.19 to 1.66), and all CVD (HR 1.46, 95% CI 1.34 to 1.60). In fully adjusted models that included CVD risk factors such as obesity, hypertension, and diabetes, frequent snoring was associated with a more modest increase in incident CHD (HR 1.14, 95% CI 1.01 to 1.28), stroke (HR 1.19, 95% CI 1.02 to 1.40), and CVD (HR 1.12, 95% CI 1.01 to 1.24). In conclusion, snoring is associated with a modest increased risk of incident CHD, stroke, and CVD after adjustment for CVD risk factors. Additional studies are needed to elucidate the mechanisms by which snoring might be associated with CVD risk factors and outcomes.

Five-Year Change in Visceral Adipose Tissue Quantity in a Minority Cohort: The Insulin Resistance Atherosclerosis Study (IRAS) Family Study

OBJECTIVE To describe the 5-year change in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas. RESEARCH DESIGN AND METHODS Absolute change in VAT and SAT measured by abdominal computed tomography scans has been obtained at a 5-year interval from African Americans (n = 389) and Hispanic Americans (n = 844), aged 20–69 years, in 10-year age-groups. RESULTS Mean 5-year increases in VAT areas in women were 18, 7, 4, 0.4, and −3 cm2 for African Americans and 13, 7, 3, 1, and −15 cm2 for Hispanics, across the 5 age decades (trend not significant). Mean 5-year increases in SAT areas in women were 88, 46, 19, 17, and 14 cm2 for African Americans and 53, 20, 17, 12, and 1 cm2 for Hispanics, across the 5 age decades (P < 0.05 for both). Similar trends have been observed in men. CONCLUSIONS Accumulation of abdominal fat is greatest in young adulthood. These data may be useful in identifying subgroups at risk of type 2 diabetes.

Lifestyle Factors and 5-Year Abdominal Fat Accumulation in a Minority Cohort: The IRAS Family Study

The objective of this study was to examine whether lifestyle factors were associated with 5‐year change in abdominal fat measured by computed tomography (CT) in the Insulin Resistance and Atherosclerosis (IRAS) Family Study. We obtained abdominal CT scans at baseline and at 5 years, from African Americans (AA) (N = 339) and Hispanic Americans (N = 775), aged 18–81 years. Visceral (VAT) and subcutaneous (SAT) adipose tissue was measured at the L4/L5 vertebral level. Physical activity was documented by self‐report of vigorous activity and a 1‐year recall instrument. Dietary intake was assessed at follow‐up using a semi‐quantitative food frequency questionnaire referencing the previous year. Generalized linear models, accounting for family structure, were used to assess the associations between percent change in fat accumulation and smoking, physical activity, total calories, polyunsaturated, monounsaturated, protein, and saturated fat intake, percent of calories from sweets, and soluble and insoluble fiber. Soluble fiber intake and participation in vigorous activity were inversely related to change in VAT, independent of change in BMI. For each 10 g increase in soluble fiber, rate of VAT accumulation decreased by 3.7% (P = 0.01). Soluble fiber was not associated with change in SAT (0.2%, P = 0.82). Moderately active participants had a 7.4% decrease in rate of VAT accumulation and a 3.6% decrease in rate of SAT accumulation versus less active participants (P = 0.003 and P = 0.01, respectively). Total energy expenditure was also inversely associated with accumulation of VAT. Soluble fiber intake and increased physical activity were related to decreased VAT accumulation over 5 years.