Serum 25-hydroxyvitamin D, diabetes, and ethnicity in the third national health and nutrition examination survey

OBJECTIVE— To determine the association between serum 25-hydroxyvitamin D (25OHD) and diabetes risk and whether it varies by ethnicity.
RESEARCH DESIGN AND METHODS— We performed an analysis of data from participants who attended the morning examination of the Third National Health and Nutrition Examination Survey (1988–1994), a cross-sectional survey of a nationally representative sample of the U.S. population. Serum levels of 25OHD, which reflect vitamin D status, were available from 6,228 people (2,766 non-Hispanic whites, 1,736 non-Hispanic blacks, and 1,726 Mexican Americans) aged ≥20 years with fasting and/or 2-h plasma glucose and serum insulin measurements.
RESULTS— Adjusting for sex, age, BMI, leisure activity, and quarter of year, ethnicityspecific odds ratios (ORs) for diabetes (fasting glucose ≥7.0 mmol/l) varied inversely across quartiles of 25OHD in a dose-dependent pattern (OR 0.25 [95% CI 0.11– 0.60] for non-Hispanic whites and 0.17 [0.08–0.37] for Mexican Americans) in the highest vitamin D quartile (25OHD ≥81.0 nmol/l) compared with the lowest 25OHD (≥43.9 nmol/l). This inverse association
was not observed in non-Hispanic blacks. Homeostasis model assessment of insulin resistance (loge) was inversely associated with serum 25OHD in Mexican Americans (P ≥ 0.0024) and non-Hispanic whites (P≥0.058) but not non-Hispanic blacks (P≥0.93), adjusting for confounders.
CONCLUSIONS— These results show an inverse association between vitamin D status and diabetes, possibly involving insulin resistance, in non-Hispanic whites and Mexican Americans. The lack of an inverse association in non-Hispanic blacks may reflect decreased sensitivity to vitamin D and/or related hormones such as the parathyroid hormone.

The relationships between insomnia, sleep apnoea and depression: findings from the American National Health and Nutrition Examination Survey, 2005-2008.

Objective: To determine the association between insomnia, obstructive sleep apnoea (OSA), and comorbid insomnia- OSA and depression, while controlling for relevant lifestyle and health factors, among a large population-based sample of US adults. Method: We examined a sample of 11,329 adults (≥18 years) who participated in the National Health and Nutrition Examination Survey (NHANES) during the years 2005-2008. Insomnia was classified via a combination of self-reported positive physician diagnosis and high-frequency 'trouble falling asleep', 'waking during the night', 'waking too early', and 'feeling unrested during the day'. OSA was classified as a combination of a positive response to a physician-diagnosed condition, in addition to a high frequency of self-reported nocturnal 'snoring', 'snorting/stopping breathing' and 'feeling overly sleepy during the day'. Comorbid insomnia-OSA was further assessed by combining a positive response to either insomnia (all), or sleep apnoea (all), as classified above. Depressive symptomology was assessed by the Patient Health Questionnaire-9 (PHQ-9), with scores of >9 used to indicate depression. Odds ratios (ORs) and 95% confidence intervals (CIs) for sleep disorders and depression were attained from logistic regression modelling adjusted for sex, age, poverty level, smoking status and body mass index (BMI). Results: Those who reported insomnia, OSA or comorbid insomnia-OSA symptoms reported higher rates of depression (33.6%, 22.2%, 27.1%, respectively), and consistently reported poorer physical health outcomes than those who did not report sleep disorders. After adjusting for sex, age, poverty level, smoking status and BMI (kg/m2), insomnia (OR 6.57, 95% CI 3.89-11.11), OSA (OR 5.14, 95% CI 3.14-8.41) and comorbid insomnia-OSA (OR 6.67, 95% CI 4.44-10.00) were associated with an increased likelihood of reporting depression. © The Royal Australian and New Zealand College of Psychiatrists 2014.

Food sources of total energy and nutrients among U.S. infants and toddlers: national health and nutrition examination survey 2005-2012

Understanding the dietary intakes of infants and toddlers is important because early life nutrition influences future health outcomes. The aim of this study was to determine the dietary sources of total energy and 16 nutrients in a nationally representative sample of U.S. infants and toddlers aged 0-24 months. Data from the 2005-2012 National Health and Nutrition Examination Survey were analyzed. Dietary intake was assessed in 2740 subjects using one 24-h dietary recall. The population proportion was used to determine the contribution of foods and beverages to nutrient intakes. Overall infant formulas and baby foods were the leading sources of total energy and nutrients in infants aged 0-11.9 months. In toddlers, the diversity of food groups contributing to nutrient intakes was much greater. Important sources of total energy included milk, 100% juice and grain based mixed dishes. A number of foods of low nutritional quality also contributed to energy intakes including sweet bakery products, sugar-sweetened beverages and savory snacks. Overall non-flavored milks and ready-to-eat cereals were the most important contributors to micronutrient intakes. In conclusion this information can be used to guide parents regarding appropriate food selection as well as inform targeted dietary strategies within public health initiatives to improve the diets of infants and toddlers.

Cross-continental comparison of national food consumption survey methods—A narrative review

Food consumption surveys are performed in many countries. Comparison of results from those surveys across nations is difficult because of differences in methodological approaches. While consensus about the preferred methodology associated with national food consumption surveys is increasing, no inventory of methodological aspects across continents is available. The aims of the present review are (1) to develop a framework of key methodological elements related to national food consumption surveys, (2) to create an inventory of these properties of surveys performed in the continents North- America, South-America, Asia and Australasia, and (3) to discuss and compare these methodological properties cross-continentally. A literature search was performed using a fixed set of search terms in different databases. The inventory was completed with all accessible information from all retrieved publications and corresponding authors were requested to provide additional information where missing. Surveys from ten individual countries, originating from four continents are listed in the inventory. The results are presented according to six major aspects of food consumption surveys. The most common dietary intake assessment method used in food consumption surveys worldwide is the 24-HDR (24 h dietary recall), occasionally administered repeatedly, mostly using interview software. Only three countries have incorporated their national food consumption surveys into continuous national health and nutrition examination surveys.

Cardiovascular surveys : manual of operations

Cardiovascular disease (CVD) is the leading cause of death and hospitalization in both men and women in nearly all countries of Europe. The most frequent forms of CVD are those of an atherosclerotic origin, mainly ischaemic heart disease, stroke and heart failure. The magnitude of the problem contrasts with the usual paucity and poor quality of data available on incidence and prevalence of CVD, except for few rigorous but limited studies.

The objectives of the health interview and health examination surveys (HIS/HES) are to evaluate the frequency and the distribution of the disease, to evaluate trends and treatment effectiveness, to estimate risk factors distribution and prevalence of high risk conditions and to monitor prevention programmes.

According to the EUROCISS project (EUROpean Cardiovascular Surveillance Set) recommendations, surveys are aimed at describing the prevalence of the following CVD conditions: myocardial infarction, heart failure, angina pectoris, peripheral arterial disease, stroke, and ischaemic heart disease.

HIS and HES were developed to supplement information collected from routine databases and population-based registers to implement consistent public health policies. HIS can be repeated periodically in a new sample of the population, or can follow up over time the population recruited at baseline. Procedures and methods to collect information from participants include self-administered questionnaires, direct interviewer-administered questions and telephone interviews. A minimum set of questions to be administered every year, along with a longer, more detailed module to be administered periodically are recommended to evaluate CVD prevalence. The addition of HES provides more detailed and objective information that can be used to improve estimates regarding prevalence of both risk factors and disease status.

The selection of more specialized CVD-specific tests will depend on the objective the survey is designed to achieve, the assumed response rate and the cost and time considerations. For HES on CVD the minimum required is to perform the following measurements: height, weight, blood pressure, waist circumference, total and high density lipoprotein-cholesterol and glucose assay in a nonfasting blood sample. The next appropriate step would be to perform an electrocardiogram. High costs usually make HES difficult to carry out.

Standardization of measurements, training of personnel and quality control are essential to assure reliable data. A high response rate is extremely important, as nonrespondents tend to have different health characteristics from the rest of the sample and their omission therefore results in bias.

This manual of operations is intended for health professionals and policy makers and provides a standardized and simple model for the implementation of a CVD survey.

Comparing trends in BMI and waist circumference

The nature of excess body weight may be changing over time to one of greater central adiposity. The aim of this study is to determine whether BMI and waist circumference (WC) are increasing proportionately among population subgroups and the range of bodyweight, and to examine the public health implications of the findings. Our data are from two cross-sectional surveys (the US National Health and Nutrition Examination Studies (NHANES) in 1988–1994 (NHANES III) and 2005–2006), from which we have used samples of 15,349 and 4,176 participants aged ≥20 years. Between 1988–1994 and 2005–2006 BMI increased by an average of 1.8 kg/m2 and WC by 4.7 cm (adjusted for sex, age, race-ethnicity, and education). The increase in WC was more than could be attributed simply to increases in BMI. This independent increase in WC (of on average, 0.9 cm) was consistent across the different BMI categories, sexes, education levels, and race-ethnicity groups. It occurred in younger but not older age groups. Overall in each BMI category, the prevalence of low-risk WC decreased and the prevalence of increased-risk or substantially increased-risk WC increased. These results suggest that the adverse health consequences associated with obesity may be increasingly underestimated by trends in BMI alone. Since WC is closely linked to adverse cardiovascular outcomes, it is important to know the prevailing trends in both of these parameters.

Understanding the role of mediating risk factors and proxy effects in the association between socio-economic status and untreated hypertension

The association between socio-economic status (SES) and untreated hypertension varies according to a country's level of development and racial/ethnic group. We sought to confirm this variation in women from China and the United States (US) as well as to investigate the impact of SES on several mediating risk factors. We also investigate the extent to which SES explains racial/ethnic differences in untreated hypertension in the US. We used cross-sectional data from 1814 non-pregnant women in China (China Health and Nutrition Survey (CHNS), 1997) and 3266 non-pregnant women in the United States (National Health and Nutrition Examination Survey (NHANES III), 1988–1994) respectively. A variety of statistical modelling techniques was used to predict untreated hypertension as a function of several mediating factors and to simulate the impact of changes in SES. The age-adjusted prevalence of untreated hypertension was significantly higher (p<0.01) for low-income White and Black women compared to Mexican American or Chinese women. Untreated hypertension was not significantly associated with income or education in Mexican Americans or women in China. Obesity and light physical activity had the largest mediating effect on the association between SES and untreated hypertension for all racial/ethnic groups. However, this effect was not as strong as the proxy effect of income and education. SES did not completely explain racial/ethnic differences in hypertension in the US. While SES was more strongly associated with hypertension in Blacks than Whites, Blacks were still 1.97 (95% CI 1.47–2.64) times more likely to have untreated hypertension than Whites after adjusting for SES differences. The association between SES and untreated hypertension varied by country and racial/ethnic group. An important explanation for this variation was the differential effect of SES on mediating risk factors. SES disparities between Whites and Blacks in the US partly explain differences in the prevalence of untreated hypertension between these racial/ethnic groups.

Bone mineral density reference ranges for Australian men : Geelong Osteoporosis Study

Summary : A large population-based random sample of Australian white men was used to provide normative bone mineral density (BMD) data at multiple anatomical sites. The femoral neck BMD data are very similar to those obtained in USA non-Hispanic white males participating in the National Health and Nutrition Examination Survey III (NHANES III). The reference ranges will be suitable for similar populations.

Introduction : To provide normative BMD data for Australian men derived from a large population-based random sample.

Methods : An age-stratified random sample of men was recruited from the Australian electoral rolls (n = 1,467 aged 20–97 years). BMD was quantified at multiple sites using Lunar densitometers.

Results : Age-related differences in BMD were best predicted by linear relationships at the spine and hip and by quadratic functions at the whole body and forearm. At the spine, a small age-related increase in mean BMD was observed. Although in the subset with no spinal abnormalities, there was a decrease of 0.003 g/cm² per year from age 20. At the hip sites, mean BMD decreased at 0.001–0.006 g/cm² per year from age 20. At the forearm and whole body, BMD peaked at 41–47 years. Apart from a small difference in men greater than or equal to 80 years, the Australian femoral neck BMD data are not different to those obtained in USA non-Hispanic white males participating in NHANES III and were generally similar to those of large studies from Canada (CaMos) and Spain.

Conclusions : These data supply BMD reference ranges at multiple anatomical sites that will be applicable to white Australian men and similar populations such as USA non-Hispanic white men.

Light-intensity physical activity and cardiometabolic biomarkers in US adolescents

Active commuting to school and association with physical activity and adiposity among US youth

Background: Walking or bicycling to school (ie, active commuting) has shown promise for improving physical activity and preventing obesity in youth. Our objectives were to examine, among US youth, whether active commuting was inversely associated with adiposity and positively associated with moderate-to-vigorous physical activity (MVPA). We also examined whether MVPA mediated the relationships between active commuting and adiposity.

Methods: Using data of participants aged 12 to 19 years from the US National Health and Nutrition Examination Survey 2003 to 2004 (n = 789 unweighted), we constructed multiple linear regression models that controlled for dietary energy intake and sociodemographics. The main exposure variable was active commuting. The outcomes were BMI z-score, waist circumference, skinfolds and objectively measured MVPA. The product-of-coefficients method was used to test for mediation.

Results: Active commuting was inversely associated with BMI z-score (β = –0.07, P = .046) and skinfolds (β = –0.06, P = .029), and positively associated with overall daily (β = 0.12, P = .024) and before- and after-school (β = 0.20, P < .001) MVPA. Greater before- and after-school MVPA explained part of the relationship between active commuting and waist circumference (Sobel z = –1.98, P = .048).

Conclusions: Active commuting was associated with greater MVPA and lower measures of adiposity among US youth. Before- and after-school MVPA mediated the relationships between active commuting and waist circumference.

Body fatness charts based on BMI and waist circumference

Objective To present percent body fat (PBF) charts based on body mass index (BMI) and waist circumference (WC) which can supplement current public health guidelines for obesity. Methods Based on data from the National Health and Nutrition Examination Survey (NHANES) III for 18- to 65-year-olds, a semi-parametric spline approach was utilized, in which no specific functional forms for BMI and WC are assumed, to depict graphically the relationship between BMI, WC, and PBF. Four distinct PBF charts were created, categorized by gender and ethnicity which are based on data from 2,170 white females, 1,902 African American females, 1,905 white males, and 1,635 African American males. Results PBF prediction based on the semi-parametric spline model outperformed competing linear models. For men, BMI is largely inconsequential, and WC plays a primary role in determining PBF levels. For women, the interaction between BMI and WC is more complex. To have low body fat, women would need to watch both their BMI and WC measurements carefully. Conclusions PBF charts, which incorporate information from three dimensions that are as simple to read as a BMI chart to help determine a person's level of fatness, were proposed.

Fusing data mining, machine learning and traditional statistics to detect biomarkers associated with depression

BACKGROUND: Atheoretical large-scale data mining techniques using machine learning algorithms have promise in the analysis of large epidemiological datasets. This study illustrates the use of a hybrid methodology for variable selection that took account of missing data and complex survey design to identify key biomarkers associated with depression from a large epidemiological study.

METHODS: The study used a three-step methodology amalgamating multiple imputation, a machine learning boosted regression algorithm and logistic regression, to identify key biomarkers associated with depression in the National Health and Nutrition Examination Study (2009-2010). Depression was measured using the Patient Health Questionnaire-9 and 67 biomarkers were analysed. Covariates in this study included gender, age, race, smoking, food security, Poverty Income Ratio, Body Mass Index, physical activity, alcohol use, medical conditions and medications. The final imputed weighted multiple logistic regression model included possible confounders and moderators.

RESULTS: After the creation of 20 imputation data sets from multiple chained regression sequences, machine learning boosted regression initially identified 21 biomarkers associated with depression. Using traditional logistic regression methods, including controlling for possible confounders and moderators, a final set of three biomarkers were selected. The final three biomarkers from the novel hybrid variable selection methodology were red cell distribution width (OR 1.15; 95% CI 1.01, 1.30), serum glucose (OR 1.01; 95% CI 1.00, 1.01) and total bilirubin (OR 0.12; 95% CI 0.05, 0.28). Significant interactions were found between total bilirubin with Mexican American/Hispanic group (p = 0.016), and current smokers (p<0.001).

CONCLUSION: The systematic use of a hybrid methodology for variable selection, fusing data mining techniques using a machine learning algorithm with traditional statistical modelling, accounted for missing data and complex survey sampling methodology and was demonstrated to be a useful tool for detecting three biomarkers associated with depression for future hypothesis generation: red cell distribution width, serum glucose and total bilirubin.

Hair cortisol levels, perceived stress and body mass index in women and children living in socioeconomically disadvantaged neighborhoods: the READI study

Disadvantaged communities provide adverse psychosocial exposures that have been linked to high levels of stress, and this may provide one explanatory pathway linking socioeconomic disadvantage to obesity. This study used hair cortisol analysis to quantify associations between stress and body mass index (BMI), and between hair cortisol and perceived psychological stress levels, in women and children living in socioeconomically disadvantaged neighborhoods. Participants were a volunteer sample of 70 women from the Resilience for Eating and Activity Despite Inequality study, including 30 maternal-child pairs. Women self-reported body weight, height and perceived psychological stress using the Perceived Stress Scale (PSS), and provided hair samples for themselves and their child. Children's body weight and height were measured. Following extraction, hair cortisol levels were measured using enzyme-linked immunosorbent assay. Multiple linear regression models examined associations between stress and BMI, and between hair cortisol and perceived stress levels in women and children. Women's hair cortisol levels were not associated with their BMI or PSS scores. Women's PSS scores were positively associated with their BMI (p = 0.015). Within maternal-child pairs, mothers and children's hair cortisol levels were strongly positively associated (p = 0.006). Maternal hair cortisol levels and PSS scores were unrelated to their child's zBMI. Children's hair cortisol levels were not associated with their zBMI or with their mother's PSS score. Findings suggest that cortisol-based and perceived psychological measures of stress may be distinct among women and children living in disadvantaged neighborhoods. Perceived psychological measures may be more important predictors of weight-related risk.

Mediating effects of dietary intake on associations of TV viewing, body mass index and metabolic syndrome in adolescents

OBJECTIVE: Evidence suggests that TV viewing is associated with body mass index (BMI) and metabolic syndrome (MetS) in adolescents. However, it is unclear whether dietary intake mediates these relationships.

METHODS: A cross-sectional analysis was conducted in adolescents (12-19 years) participating in the 2003-2006 United States National Health and Nutrition Examination Survey. BMI z scores (zBMI) (n = 3,161) and MetS (n = 1,379) were calculated using age- and sex-specific criteria for adolescents. TV viewing (h/day) was measured via a self-reported questionnaire, and dietary intake was assessed using two 24-h recalls. Using the MacKinnon method, a series of mediation analyses were conducted examining five dietary mediators (total energy intake, fruit and vegetable intake, discretionary snacks, sugar-sweetened beverages and diet quality) of the relationships between TV viewing and zBMI and MetS.

RESULTS: Small positive relationships were observed between TV viewing and zBMI (β = 0.99, p < 0.001) and TV viewing and MetS (OR = 1.18, p = 0.046). No dietary element appeared to mediate the relationship between TV viewing and zBMI. However, sugar-sweetened beverage consumption and fruit and vegetable intake partially mediated the relationship between TV viewing and MetS, explaining 8.7% and 4.1% of the relationship, respectively.

CONCLUSIONS: These findings highlight the complexity of the relationships between TV viewing, dietary intake and cardiometabolic health outcomes, and that TV viewing should remain a target for interventions.