Waist Circumference Measurement Methodology Study: National Health and Nutrition Examination Survey, 2016.

Objective This report compares five methods of waist circumference (WC) measurements: 1) the National Heart, Lung, and Blood Institute (NHLBI-WC); 2) the World Health Organization (WHO-WC); 3) the Multi-Ethnic Study of Atherosclerosis (MESA-WC) using Gulick II Plus tape; 4) the Multi-Ethnic Study of Atherosclerosis (MESA-WC) using Lufkin tape; and 5) assisted self-measurement over clothes (MESA-assisted). Method During 2016, measurements were obtained from 2,297 participants aged 20 and over, who participated in the National Health and Nutrition Examination Survey (NHANES). The mean differences and sensitivity and specificity for abdominal obesity (AO) were calculated between the NHLBI-WC (reference) and the other four WC measurements. Results The mean difference between NHLBI-WC and WHO-WC was 0.81 cm for men and 3.21 cm for women ( p ≤ 0.0125 for both); between NHLBI-WC and MESA-WC (Gulick) was -0.68 cm for men ( p ≤ 0.0125) and -0.89 cm for women; between NHLBI-WC and MESA-WC (Lufkin) was 0.02 cm for men and 0.08 cm for women; and between NHLBI-WC and MESA-assisted was -0.71 cm for men and 1.34 cm for women ( p ≤ 0.0125 for both). Sensitivity and specificity for AO, with NHLBI-WC as a reference, for men were greater than 90% for all methods; for women, sensitivity and specificity for AO for MESA-WC (Lufkin) were greater than 90%; for women, WHO-WC, MESAWC (Gulick), and MESA-assisted methods were greater than 85%.

Comparison of in-home collection of physical measurements and biospecimens with collection in a standardized setting: the health measures at home study.

OBJECTIVES: Collection of physical measurements and biospecimens in the home may be an efficient way to obtain objective health measurements. This study assesses differences between collection in the home and a standardized setting. METHODS: Participants had physical measurements and biospecimens taken in the National Health and Nutrition Examination Survey mobile examination center (MEC). Then, they had height and weight measured in the MEC using portable equipment. In the home, participants had height, weight, and blood pressure measured and dried blood spots collected using portable equipment. Two complete examinations were done in the home: one by a health technician and one by a field interviewer. RESULTS: Home environments were less standardized and presented more challenges to examiners. Correlations between all four height measurements and all four weight measurements were higher than 99%. Mean differences in height (0.3 cm) and weight (0.4 kg) were small but statistically significant. The home measurements perfectly or near-perfectly classified participants as obese relative to the standardized MEC examination. CONCLUSIONS: The selected physical measurements can be collected in the home by field interviewers using portable equipment. Before adding home collection of physical measurements to household interview surveys, further research should be done to examine the impact of these changes on interviewer training, participant recruitment, and participant response rates.

Comparison of blood pressure measurements obtained in the home setting: analysis of the Health Measures at Home Study.

BACKGROUND: Automated blood pressure (BP) devices have been used in the home for self-management purposes and are increasingly being used in population-based research. Although these devices are convenient and affordable and may be used by inexperienced lay personnel, the potential impact of an examiner's skill level on the results needs to be evaluated quantitatively. The aim of this study was to compare BP measurements obtained in a home setting by personnel with healthcare experience with those obtained by personnel without healthcare experience. In addition, the percent agreement in high blood pressure (HBP) classification between the home BP measurement by the field interviewer (FI) and measurements obtained in a standardized environment was examined. METHODS: The Health Measures at Home Study was a pilot study carried out among 128 adult participants recruited from the National Health and Nutrition Examination Survey. The Health Measures at Home Study provided the opportunity to compare the BP values obtained with an automated device in a home setting by both experienced health technicians (HTs) with those obtained by FIs who had no healthcare experience. Differences between measurements obtained by the HT and measurements obtained by the FI were assessed using paired t-tests, Pearson's correlations, and Bland-Altman plots. Percent agreement and κ-statistics were used to assess agreement in HBP classification between examiners in the home. Measurements obtained by the FI were also compared with those obtained in the National Health and Nutrition Examination Survey mobile exam center (MEC) by a physician using percent agreement and κ-statistics. RESULTS: There was a high correlation in both systolic blood pressure (SBP; r=0.903) and diastolic blood pressure (DBP; r=0.894) between measurements obtained by HTs and those obtained by FIs. The mean SBP and DBP obtained by the FIs (SBP, 119.0±14.4 mmHg; DBP, 71.9±9.8 mmHg) were significantly higher than the HT measurements (SBP, 117.0±12.7 mmHg; DBP, 69.9.9±9.2 mmHg). In the home, the FI classified 11.7% as having HBP, whereas the HT classified 7.0%. The percent of individuals classified as having HBP by the physician in the MEC was 10.2% of the participants. CONCLUSION: Operationally, FIs could take BP measurements in the home; however, there were some differences between measurements obtained by the FI and HT. The absolute difference between measurements obtained by the FI and those obtained by the HT in the home showed that measurements obtained by the FI tended to be higher than the HT, but the magnitude of these differences was less than 5 mmHg. The HT classified 7.0% of HBP whereas the FI classified 11.7% of HBP. Similarly, the FI and the MEC physician classified a different percent of individuals with HBP. Further investigation is warranted to determine the cause of these small but significant absolute differences between measurements obtained by the FI and HT.

Collection and laboratory methods for dried blood spots for hemoglobin A1c and total and high-density lipoprotein cholesterol in population-based surveys.

BACKGROUND: The Health Measures at Home Study was a study designed to evaluate the feasibility of incorporating dried blood spots (DBS) collection into the National Health Interview Survey and to compare the proficiencies between field interviewers and health technicians in obtaining DBS. METHODS: DBS collection and venipuncture were attempted on 125 participants. The DBS were collected in the participant's home and venous blood was collected in the National Health and Nutrition Examination Survey (NHANES) mobile examination center. The DBS results were compared to venous results in the NHANES for the measurements of hemoglobin A1c (HbA1c) and total and high-density lipoprotein (HDL) cholesterol. RESULTS: Field interviewers and health technicians were able to collect the DBS for greater than 95% of participants. For DBS, health technicians and field interviewers were highly correlated for HbA1c (r=0.92) and total cholesterol (r=0.89), but not for HDL cholesterol (r=0.72). The DBS results of interviewers and health technicians compared to the venous method for HbA1c (r=0.90), but did not compare well for HDL cholesterol (r=0.64-0.66) and total cholesterol (r=0.65-0.67). CONCLUSION: DBS was comparable to venous HbA1c, but not for total and HDL cholesterol. Health technicians and field interviewers had similar performance for DBS methods, except HDL cholesterol.

Strength and body weight in US children and adolescents.

BACKGROUND AND OBJECTIVES: Regular aerobic and muscle-strengthening physical activity in youth has been positively associated with health and may help prevent obesity. The purpose of this study is to provide reference values on 4 core, upper, and lower body measures of muscle strength among US children and adolescents and to investigate the association between these measures of strength and weight status. METHODS: We assessed muscular strength using 4 different tests (plank, modified pull-up, knee extension, and grip strength) in 1224 youth aged 6 to 15 years collected during the 2012 National Health and Nutrition Examination Survey National Youth Fitness Survey. Mean and median estimates are provided by gender, age, and weight status. Weight status was defined based on standard categories of obesity, overweight, normal weight, and underweight using the gender-specific BMI-for-age Centers for Disease Control and Prevention growth charts. RESULTS: There were significant positive trends with age for each of the strength tests (P < .001) except the modified pull-up among girls. The length of time the plank was held decreased as weight status increased for both girls and boys (P < .001). As weight status increased the number of modified pull-ups decreased (P < .001 boys and girls). Scores on the knee extension increased as weight status increased (P < .01). Grip strength increased as weight status increased (P < .01). CONCLUSIONS: Increasing weight status had a negative association with measures of strength that involved lifting the body, but was associated with improved performances on tests that did not involve lifting the body.

Measures of muscular strength in U.S. children and adolescents, 2012.

KEY FINDINGS: Data from the National Health and Nutrition Examination Survey, National Youth Fitness Survey. There were no significant differences by sex in core, lower, or upper body measures of strength for younger boys and girls. In contrast, adolescent boys had higher values than adolescent girls on all measures of strength. Adolescent boys and girls had higher scores than younger boys and girls on the core and lower body strength measures and upper body strength as measured by the grip strength test. Adolescent boys completed more modified pull-ups, a measure of upper body strength, than younger boys. There was no significant difference in the number of modified pull-ups completed between adolescent and younger girls. In 2008, the federal government released the Physical Activity Guidelines for Americans, which provide guidance on the types and amounts of physical activities that provide substantial health benefits for Americans of all ages. Regular physical activity reduces the risk of many adverse health outcomes and helps control the percentage of body fat in children and adolescents (1). This report provides the first nationally representative data on core, upper body, and lower body measures of muscle strength among U.S. children and adolescents aged 6-15 years by sex and age group.

Abdominal obesity, body mass index, and hypertension in US adults: NHANES 2007-2010.

BACKGROUND: Both abdominal obesity, defined as waist circumference (WC) ≥ 102 cm for men and WC ≥ 88 cm for women and increased body mass index (BMI; kg/m²) are known to be associated with hypertension. The aim of this study was to examine the independent and the combined relationship between abdominal obesity and increased BMI and hypertension by age, race, and gender in a national sample. METHODS: This report is based on national level cross-sectional data for adults aged 18 years and older (11,145 participants) from the US National Health and Nutrition Examination Survey (NHANES) 2007-2010. RESULTS: Abdominal obesity, after adjusting for BMI categories and other covariables, was independently associated with hypertension. That is, survey participants classified as abdominally obese had almost 50% increased odds of being hypertensive (odds ratio (OR) 1.51, 95% confidence interval (CI) 1.27-1.81) after controlling for BMI. After adjusting for covariables, the groups of individuals classified as abdominally obese and normal BMI; as abdominally obese and overweight; and abdominally obese and obese each had a progressive increase in the odds of hypertension when compared with individuals who had a normal BMI and no abdominal obesity (OR 1.81, 95% CI 1.28-2.57, OR 1.87, 95% CI 1.55-2.25, and OR 3.23, 95% CI 2.63-3.96, respectively). CONCLUSIONS: Abdominal obesity is independently associated with hypertension after adjusting for BMI. After adjusting for covariables and parameterizing BMI categories and abdominal obesity the new variable showed a progressive increase in the odds of hypertension. Both BMI and WC should be included in models assessing hypertension risks.