Mona A. Eissa

Trajectories of Fat Mass Index, Fat Free–Mass Index, and Waist Circumference in Children: Project HeartBeat!

BACKGROUND Body composition and fat distribution change dramatically during adolescence. Data based on longitudinal studies to describe these changes are limited. The aim of this study was to describe age-related changes in fat free-mass index (FFMI) and fat mass index (FMI), which are components of BMI, and waist circumference (WC) in participants of Project HeartBeat!, a longitudinal study of children. METHODS Anthropometric measurements and body composition data were obtained in a mixed longitudinal study of 678 children (49.1% female, 20.1% black), initially aged 8, 11, and 14 years, every 4 months for 4 years (1991-1995). Trajectories of change from ages 8 to 18 years were measured for FFMI, FMI, and WC. Because of the small number of observations for black participants, trajectories for this group were limited to ages 8.5-15 years. RESULTS Body mass index, FFMI, and WC increased steadily with age for all race-gender cohorts. However, in nonblack girls, FFMI remained constant after about age 16 years. For black boys and girls, FFMI was similar at age 8.5 years but increased more steeply for black boys by age 15 years. In girls, FMI showed an upward trend until shortly after age 14 years, when it remained constant. In boys, FMI increased between age 8 years and age 10 years, and then decreased. CONCLUSIONS The extent to which each component of BMI contributes to the changes in BMI depends on the gender, race, and age of the individual. Healthcare providers need to be aware that children who show upward deviation of BMI or BMI percentiles may have increases in their lean body mass rather than in adiposity.

Comparison of the actigraph versus patients' diary information in defining circadian time periods for analyzing ambulatory blood pressure monitoring data.

Background >Assessment of 24‐h changes in blood pressure is one of the unique features that ambulatory blood pressure monitoring (ABPM) can provide. Most studies agree that sleep/wake periods should be based on patients’ actual sleep and wake times. Actual wake and sleep time determinations are often based on patients’ diary information. Several publications indicate that actigraphy is, at least, as accurate as activity diary in determining sleep/wake periods. Objectives To compare subjects’ compliance with actigraphy and diary keeping and to compare actigraphy and diary data in determination of sleep and wake times, mean blood pressures, classification of hypertension, and assessment of nocturnal dipping status. Methods We evaluated ABPM studies of 62 subjects. Blood pressure data were obtained using Spacelabs monitors for 24 h. Sleep and wake times were determined by both the actigraph and patients’ activity diary. Results In the 62 studies, 56 subjects had successful actigraphy (90%), 44 had activity diary completion (71%), and 38 subjects had both (61%). There was no statistically significant difference between the mean wake and sleep onset using the two methods, but up to 3 hours’ difference in wake or sleep onset was noted in some studies. Although the two methods did not significantly affect the calculated systolic blood pressure (SBP) or diastolic blood pressure (DBP) loads in either awake or sleep periods, approximately 55% of the subjects’ dipping status was changed when diary information on sleep time was used compared to actigraph. Conclusions Our data indicate that in children and young adults, compliance with the actigraph was superior to diary completion and use of the actigraphy method rather than diary information changed the interpretation of some ABPM data. Our study suggested that actigraphy is superior to diary keeping in providing the information needed for appropriate interpretation of some ABPM data.

Screening for eligibility in the study of antihypertensive medication in children: experience from the Ziac Pediatric Hypertension Study

BACKGROUND The FDA Modernization Act has resulted in an increase in pediatric trials of antihypertensive medications. As experience is limited in children to guide the planning of these studies, we reviewed data from the Ziac Pediatric Hypertension Study to determine patterns of early study termination to help future studies. METHODS For inclusion, subjects aged 6 to 17 years were required to have an average systolic blood pressure (SBP) or diastolic blood pressure (DBP) above the 95th percentile at the last of three visits during 2 weeks of single-blind placebo screening. Early study termination was defined as early termination for any reason. Screening termination was defined as normalization of blood pressure (BP) during the placebo screening phase. RESULTS Early study termination rate was 27% (38 of 140 subjects). The most common reason was screening termination due to normalization of BP, accounting for 63% of all early study terminations. Among screening termination subjects who completed three screening visits, SBP was higher (P < .001) at visit 1 (129+/-8 mm Hg) than at visit 2 (123+/-7 mm Hg) or visit 3 (121+/-8 mm Hg), but did not differ between visits 2 and 3. Screening termination occurred in 15% with isolated SBP hypertension, and 21% with isolated DBP hypertension. At randomization, 83% had SBP hypertension and 53% had DBP hypertension. CONCLUSIONS These data suggest that SBP hypertension should be part of inclusion criteria to increase enrollment and reduce the rate of screening termination, and that 1-week placebo screening is necessary and sufficient to minimize inclusion of transiently hypertensive subjects.

Overweight and Central Adiposity in School-Age Children and Links With Hypertension

The purpose of this study of school-age children was to estimate prevalence and interrelationships of overweight, central adiposity, and hypertension. It included 1,070 children in kindergarten through sixth grade (67% Hispanic, 26% African American, mean age = 8.9 years). Measures included body mass index (BMI), waist circumference (WC), systolic and/or diastolic hypertension identified by measurements on three separate occasions. Percentage overweight (BMI >or=95th percentile) was 28.7%, 17.9% were at risk of overweight, 28.8% had WC >or=90th percentile, and 9.4% had elevated (>or=90th percentile) systolic and/or diastolic blood pressure (BP). If we had screened only for BMI and examined those with BMI >or=85th percentile or underweight for hypertension, we would have missed 26% of the children with persistently elevated BP. WC explained variance in elevated BP not explained by BMI (p < .001). Measurement of WC is easily incorporated in a school-based screening protocol.

The association of variants in the FTO gene with longitudinal body mass index profiles in non-Hispanic white children and adolescents

OBJECTIVE:To investigate possible age-related changes in associations between polymorphisms in the fat mass and obesity-associated (FTO) gene and higher body mass index (BMI).DESIGN AND SUBJECTS:Multilevel mixed regression models were used to examine associations between four FTO variants and longitudinal BMI profiles in non-Hispanic white and African American children and adolescents 8–17 years of age from two different longitudinal cohort studies, the Bogalusa Heart Study (BHS) and Project HeartBeat! (PHB). In the BHS, there were 1551 examinations of 478 African Americans and 3210 examinations of 1081 non-Hispanic whites; in PHB, there were 971 examinations of 131 African Americans and 4458 examinations of 505 non-Hispanic whites.RESULTS:In African Americans, no significant FTO associations with BMI were found. In non-Hispanic whites, linkage disequilibrium among all four variants made haplotype analysis superfluous, so we focused on the single-nucleotide polymorphism, rs9939609. In longitudinal multilevel models, the A/A genotype of rs9939609 was associated with higher BMI in non-Hispanic whites in both cohorts at all ages. A significant age-by-genotype interaction found only in the BHS cohort predicted that in those with the A/A genotype, BMI would be ∼0.7 kg m−2 higher at age 8 and ∼1.6 kg m−2 higher at age 17 than in those with A/T or T/T genotypes. The design of PHB limited follow-up of any single individual to 4 years, and may have reduced the ability to detect any age-by-genotype interaction in this cohort.CONCLUSIONS:The A/A genotype of rs9939609 in the FTO gene is associated with higher longitudinal BMI profiles in non-Hispanic whites from two different cohorts. The association may change with age, with the A/A genotype being associated with a larger BMI difference in late adolescence than in childhood, though this was observed only in the BHS cohort and requires verification.

Evaluation of AAP guidelines for cholesterol screening in youth: Project HeartBeat!

BACKGROUND The American Academy of Pediatrics (AAP) criterion for screening for hypercholesterolemia in children is family history of hypercholesterolemia or cardiovascular disease or BMI > or =85th percentile. This paper aims to determine the sensitivity, specificity, and positive predictive value (PPV) of dyslipidemia screening using AAP criteria along with either family history or BMI. METHODS Height, weight, plasma total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, and family history were obtained for 678 children aged 8, 11, and 14 years, enrolled from 1991 to 1993 in Project HeartBeat!. Sensitivity, specificity, and PPV screening of each lipid component using family history alone, BMI > or =85th percentile alone, or family history and/or BMI > or =85th percentile, were calculated using 2008 AAP criteria (total cholesterol, LDL-C, and triglycerides > or =90th percentile; HDL-C <10th percentile). RESULTS Sensitivity of detecting abnormal total cholesterol, LDL-C, HDL-C, and triglycerides using family history alone ranged from 38% to 43% and significantly increased to 54%-66% using family history and/or BMI. Specificity significantly decreased from approximately 65% to 52%, and there were no notable changes in PPV. In black children, cholesterol screening using the BMI > or =85th percentile criterion had higher sensitivity than when using the family history criterion. In nonblacks, family history and/or BMI > or =85th percentile had greater sensitivity than family history alone. CONCLUSIONS When the BMI screening criterion was used along with the family history criterion, sensitivity increased, specificity decreased, and PPV changed trivially for detection of dyslipidemia. Despite increased screening sensitivity by adding the BMI criterion, a clinically significant number of children still may be misclassified.

Systolic and fourth- and fifth-phase diastolic blood pressure from ages 8 to 18 years: Project HeartBeat!

BACKGROUND Systolic and fourth-phase and fifth-phase diastolic blood pressure (SBP, DBP4, DBP5) have appeared to differ in their patterns of age-related change, and SBP and DBP5 differ in their respective associations with anthropometric variables. Project HeartBeat! investigated trajectories of change in SBP, DBP4, and SBP5 with age and their relationships with indices of adiposity, controlling for energy intake, physical activity, and sexual maturation. METHODS Project HeartBeat! was a mixed longitudinal study in 678 black and white girls and boys aged 8, 11, or 14 years at first examination, followed at 4-month intervals for up to 4 years (1991-1995). A statistical model was estimated for the trajectory of change in each blood pressure measure from ages 8 to 18 years. RESULTS For SBP, DBP4, and DBP5, the trajectories were sigmoid, parabolic, and linear in form, respectively. SBP and DBP4 differed significantly by gender; DBP4 and DBP5 were significantly related to race. Adjusted for age, gender, and race, all relationships of adiposity-related variables (percent body fat, abdominal circumference, skinfold thickness, and BMI and its fat and fat-free components) with SBP were positive and significant. Corresponding relationships for DBP4 were notably weaker but significant, and for DBP5, weak or not significant. After adjusting for diet, physical inactivity, and maturation, no DBP5 relationship with adiposity indices remained significant. CONCLUSIONS SBP, DBP4, and DBP5 are distinct in patterns of change with age, relationships to gender and race, and patterns of association with multiple anthropometric indices related to adiposity.

Sleep duration and its association with ambulatory blood pressure in a school-based, diverse sample of adolescents

BACKGROUND Evidence is accumulating that sleep duration is related to blood pressure (BP) and hypertensive status, but the strength of the association varies by age, and findings are inconsistent for adolescents. This cross-sectional study tested the hypothesis that sleep duration, both during the night and during naps, would be negatively associated with ambulatory systolic BP (SBP) and diastolic BP (DBP) measured over 24 hours in adolescents. METHODS In this ethnically diverse (37% non-Hispanic black, 31% Hispanic, 29% non-Hispanic white, 3% other), school-based sample of 366 adolescents aged 11-16 years, ambulatory BP was measured every 30 minutes for 24 hours on a school day; actigraphy was used to measure sleep duration. Covariables included demographic factors, anthropometric indices, physical activity, and position and location at the time of each BP measurement. Mixed models were used to test day and night sleep duration as predictors of 24-hour SBP and DBP, controlling for covariables. RESULTS The mean sleep duration was 6.83 (SD = 1.36) hours at night, and 7.23 (SD = 1.67) hours over 24 hours. Controlling for duration of sleep during the day and covariables, each additional hour of nighttime sleep was associated with lower SBP (-0.57; P < 0.0001); controlling for nighttime sleep duration and covariables, each additional hour of daytime sleep was associated with lower SBP (-0.73; P < 0.001) and lower DBP (-0.50; P < 0.001). CONCLUSIONS Longer sleep duration was significantly associated with lower ambulatory SBP and DBP in adolescents. The findings have potential implications for cardiovascular health in this age group.

Changes in Fasting Lipids during Puberty.

OBJECTIVE To describe longitudinal changes in plasma lipid levels and pubertal stage in youths from age 8-18 years, in Project HeartBeat! STUDY DESIGN Fasting blood samples and pubertal stage, using physical assessment of secondary sex characteristics, were obtained every 4 months for up to 4 years in a mixed longitudinal study of 633 children (49.1% female, 20.1% black), initially aged 8, 11, and 14 years. Total cholesterol, low density lipoprotein-cholesterol, high density lipoprotein-cholesterol, triglycerides (TG), and nonhigh density lipoprotein-cholesterol measurements were obtained. Data were collected from 1991-1995. RESULTS Pubertal stage correlations with age varied among all race-sex groups (range, r = 0.61-0.70), and a given pubertal stage could represent a range of 5 years or more of chronological age. Throughout puberty, levels of total cholesterol, low density lipoprotein-cholesterol, and nonhigh density lipoprotein-cholesterol decreased, TG in males increased, and high density lipoprotein-cholesterol and TG in females showed no changes. Within a given pubertal stage, plasma lipid levels tended to differ by race, sex, or both. CONCLUSIONS Lipid levels change markedly by pubertal stage, and patterns differ by sex and race. Chronological age ranges widely within a given pubertal stage and is an insensitive indicator of pubertal stage and the related changes in lipid levels. Pubertal development should be considered when determining screening criteria to identify youths with adverse blood lipid levels.

The cost of screening adolescents for overweight and hypertension using a community partnership model.

OBJECTIVES (1) Determine the prevalence of overweight and high blood pressure (BP) among middle and high school students over a 2-year period and, (2) measure the cost and initial outcomes of screening. DESIGN Cost and outcome description using a cross-sectional design sample. The target population was 12- to 19-year-old healthy students attending grades 7 through 12 at 3 proximal schools located in a large urban school district in Texas. RESULTS Of 2,338 students screened, 925 (39.6%) had a body mass index (BMI)>or=85th percentile and 504 (21.6%) had BMIs>or=95th percentile for age and gender. There were 346 students (14.8%) with BMIs>or=85th percentile and systolic blood pressure (SBP)>or=95th percentile for age, gender, and height. The cost of the 2-year screening program was