Utility of different body composition indicators: demographic influences and associations with blood pressures and heart rates in adolescents (Heartfelt Study).

PRIMARY OBJECTIVE: To compare the utility of 10 commonly used body composition indicators (BCIs) in relation to demographic characteristics and cardiovascular risk factors. RESEARCH DESIGN: A cross-sectional, school sample was studied. SUBJECTS: Three hundred and eighty-four Black, White and Hispanic adolescents 11-16 years of age from Houston, Texas, USA (Heartfelt Study) were studied. METHODS: BCIs include impedance and skinfold estimates of fat-free mass (FFM); fat mass (FM) and per cent body fat (PBF); resistance mass index (RMI); body mass index (BMI); and waist and abdomen circumferences. The cardiovascular risk factors (blood pressures/heart rates) are summarized by factor analysis. Sexual maturity was clinically assessed. RESULTS: Two distinct classes of BCIs emerged with respect to demographic influences: (1) RMI, impedance and skinfold estimators, for which sexual dimorphism is evident, and (2) BMI and circumferences, for which it is not. All BCIs were strongly related to general (systolic) blood pressure, but only body fat variables were related to heart rates. Skinfold-derived FM, PBF and mid-body circumferences were the variables most strongly related to cardiovascular risk factors. CONCLUSIONS: RMI, impedance or skinfold estimators are necessary for research requiring an accurate description of body composition changes during adolescence and for assessing the role of lean and fat tissue in disease aetiology. A 2-skinfold method is just as effective as the more complicated impedance. Mid-body circumferences are closely related to blood pressures and heart rates, suggesting their importance as indicators of abdominal fat in adolescents.

Blood pressure and sexual maturity in adolescents: the Heartfelt Study.

This study investigates sexual maturity as a predictor of resting blood pressures independent of other known predictors, in 179 boys and 204 girls 11-16 years of age from the Heartfelt Study. The sample included youth of African (n = 140), Mexican (n = 117), and European and "other" (n = 126) backgrounds. Sexual maturity was assessed during clinical examination of three standard indicators for each sex. Systolic and diastolic blood pressures were higher in children of maturity stages IV and V, compared to stages I-III, in each gender/ethnic group (P < 0.01 in almost all groups). Boys and girls advanced in sexual maturity for their age group, had significantly higher systolic blood pressures (but not diastolic) than the less advanced in linear models that included height, body mass index (BMI), ethnicity, and age as co-predictors. Diastolic blood pressures were predicted by height in boys and by age and the BMI in girls. This analysis, using a very conservative approach, suggests that sexual maturity provides important and independent information on systolic blood pressure in adolescents. Further investigation of its role in 24-hr blood pressures and in blood pressures taken during physical and emotional stress, is recommended.

Strategies for combining and scaling sexual maturity indicators: the Heartfelt Study.

PRIMARY OBJECTIVE: To identify the best variable or combination of sexual maturity variables to use in investigations of adolescent health, and explore possible re-scaling of five-stage sexual maturity stages into dummy variables' ('advanced'/'delayed'). RESEARCH DESIGN: Cross-sectional. SUBJECTS: Tri-ethnic sample of 384 US adolescents 11-16 years of age (Heartfelt Study). METHODS: Sexual maturity variables are genital. breast and pubic hair stages obtained by clinical examination by nurse practitioners, testes size, menarche and age at menarche. RESULTS: Principal factor analysis of sexual maturity variables, height and age, revealed high commonality among the variables, as no more than a single factor appeared in 27 of 28 factor analyses (by sex and age groups). Genital stage (boys) and breast stage (girls) were most highly related to the first principal factor independent of age and ethnicity. ANOVA of 'key variables' indirectly reflecting endocrine function suggested that some stages could be combined. CONCLUSIONS: A single variable should suffice to describe sexual maturity at the studied ages, or variables could be combined in a (unstandardized) sexual maturity index (SMI): SMI (Girls)=0.998 x BREAST+0.900 x PUBIC HAIR + 1.815 x YEARS SINCE MENARCHE. SMI (Boys)= 1.104 x GENITAL + 1.328 x PUBIC HAIR + 5.997 x TESTES SIZE (mL).

Psychometric testing of the adolescent version of the Cook-Medley hostility scale.

Hostility, a phenomenon that has been linked to cardiovascular disease and all-cause mortality, is often measured by the Cook-Medley hostility (Ho) scale. Although there is an adolescent version of the Ho scale, it has had little testing with only Anglo-American samples. This pilot study tested the reliability and validity of the adolescent version of the Ho scale with a multiethnic sample of adolescents. Sixty adolescents participated. Reliability was measured using Chronbach's alpha. The Ho scale was correlated with the Speilberger State-Trait Anger Expression Inventory (1988) scales to determine concurrent validity. A factor analysis assessed construct validity; content validity was assessed by analyzing tape-recorded descriptions of a circumstance that provoked anger, as remembered by each adolescent. Internal consistency reliability was .75. The hostility measure was most highly correlated with anger expression (r = .62, p = .000) and trait anger (r = .50, p = .000). The factor analysis generated three factors (suspicious alienation, cynical aggression and justified mistrust), that accounted for 34.5% of the variance. The content analysis resulted in five anger-provoking themes: aggression, unfulfilled personal expectations, mistrust/lying, criticism of effort, and rejection. The majority of items in the scale (74%) were related to one of the themes.

School-based interventions for primary prevention of cardiovascular disease: evidence of effects for minority populations.

The purposes of this review were to analyze and evaluate the results of school-based studies that have used population-wide approaches for primary prevention of cardiovascular diseases and to assess the extent to which strategies tested to date have been effective for minority populations in the United States. The literature included in the review was restricted to studies published between 1986 and August 1999; they sampled elementary, middle, or high school students and incorporated a control or comparison group. There were no consistent effects of school-based interventions on blood pressure, lipid profiles, or measures of body mass and obesity. There was evidence that changes in knowledge and health behaviors occurred. Findings are interpreted within the context of population-wide approaches to prevention, and recommendations for future research directions are discussed.

Stress-induced alterations of blood pressure and 24 h ambulatory blood pressure in adolescents.

OBJECTIVE: To examine the extent to which ambulatory blood pressure was predicted by blood pressure levels exhibited during talking segments of a laboratory protocol and by resting blood pressures in male and female adolescents from three ethnic groups: African, European and Hispanic Americans. DESIGN: This was a laboratory-field study incorporating an experimental study of reactivity of blood pressure during a laboratory protocol and an observational study of 24h ambulatory blood pressure (ABP) monitoring. METHODS: Resting blood pressure, reactivity of blood pressure, 24h ABP, and activity, height, and maturation of a multi-ethnic sample of 373 male and female adolescents aged 11-16 years were measured. A mixed-effects model for repeated measures was the statistical approach, with systolic and diastolic blood pressures as separate, dependent variables. RESULTS: Percentiles of ABP by sex, ethnic group, and height are presented. High and mixed blood pressure reactors in the laboratory had higher levels of 24h ABP and higher levels of blood pressure load during the daytime. African Americans had higher ABP than did European and Hispanic Americans. CONCLUSIONS: Blood pressure measured during laboratory tasks that require talking might be useful as a screening device to identify adolescents with high blood pressures. Further study will be necessary in order to quantify the sensitivity of the laboratory protocol as an indicator of high blood pressure compared with casual measurement of blood pressures. If laboratory patterns of blood pressure could be used to predict which individuals have high levels of blood pressure during the course of daily activities, the laboratory protocol would be a useful screening tool, identifying high-risk individuals.

Adolescent blood pressure, anger expression and hostility: possible links with body fat.

An uncertain relation between health and angry/hostile behaviour exists in the literature on adolescents. With data from a pilot study, one possible reason for this is explored: health measures such as blood pressure as well as angry/hostile behaviours may change with, or depend upon physical maturity, body size and body fatness. The sample consists of 60 African-, Hispanic-, and Anglo-American adolescents (15 to 16 years of age) drawn from a public school in Houston, TX. Using resting diastolic blood pressure as a model, in a sex stratified analysis, the following conclusions were reached: Physical maturity in girls and body height in boys were related to ethnicity in the sample and were confounders of the blood pressure and anger relationship. In girls secretive anger ('anger-in') and hostility were associated with increased body fat; expressive anger ('anger-out') in boys is associated with increased conicity (central body fat distribution) (p < 0.01). These associations were independent of height and physical maturity. Hostility was not significantly related to diastolic blood pressure in boys after adjusting for height and conicity. 'Anger-in' was significantly and positively related to diastolic blood pressure in girls (p < 0.01). This relationship was strongly mediated by per cent body fat, because the association of 'anger-in' and blood pressure was no longer statistically significant when the model included body fat. The results suggest that measures of physical maturity and more refined measures of body fat and body fat distribution should be considered in studies attempting to link adolescent blood pressure with anger expression.

Predictors of ambulatory blood pressure: identification of high-risk adolescents.

Within a life span perspective on prevention, adolescence was conceptualized as a pivotal transition in the evolution of risk for hypertension and other cardiovascular morbidity. Resting blood pressure (BP), BP reactivity, and 24-hour ambulatory BP were measured in a multiethnic sample of 41 male and female adolescents aged 15 to 16 years old. Results were consistent with the hypothesis that BP levels during reactivity testing would be better predictors of ambulatory BP than levels of BP measured at rest using a standard protocol. Ethnic group differences in ambulatory BP were statistically significant. The findings warrant further study and may provide a means for early identification of adolescents at risk for developing high BP.

Genetic and environmental influences on cardiovascular disease risk factors in adolescents.

BACKGROUND: Although there is consensus that prevention of cardiovascular diseases is a worthwhile activity and that these efforts should begin in childhood, some controversies remain about the efficacy and timing of preventive efforts. OBJECTIVE: To differentiate the cardiovascular risk factors that have a potential to respond to environmental and lifestyle modification. METHODS: The sample consisted of 56 monozygotic and 29 same-sex dyzogotic twin pairs, equally distributed by gender with a mean age of 12.62 years. Systolic and diastolic blood pressure, triceps skinfold thickness, body mass, and fasting blood specimens for lipid profiles were collected during home visits. Teachers rated the subjects' Type A behaviors using the Matthews Youth Test for Health. RESULTS: Statistically significant estimates of genetic variance were obtained for cholesterol, triglycerides, high-density lipoprotein cholesterol, systolic and diastolic blood pressure, and body mass index. Compared with the previous phase of this longitudinal study, higher estimates of genetic variance were observed for components of the lipid profile and blood pressure and lower estimates were observed for Type A behavior variables. CONCLUSIONS: Overall, the genetic influence on risk factors was moderate, leading to the conclusion that the potential to modify risk profiles during the transition from childhood to adolescence is substantial. Attitudes, behaviors, and environmental inducements that establish and maintain healthy lifestyles over long period should be the focus of interventions and further research.

Blood pressure reactivity in urban youth during angry and normal talking.

Distinctions between male and female adult patterns of cardiovascular disease are well established. Although risk for cardiovascular disease begins early in life, little research has been focused on the beginning of gender difference patterns. This pilot study examined blood pressure reactivity, gender, and biologic maturity in adolescents talking about angry life circumstances and the usual progression of their day. Systolic and diastolic blood pressure increased during talking, and the addition of biologic maturity to the analysis distinguished males from females. Males had higher systolic blood pressures than did females throughout the protocol, and, generally, mature subjects had higher systolic and diastolic blood pressures than did less mature subjects. These pilot data confirm the effects of talking on blood pressure. The data suggest that biologic maturity enhances understanding of gender differences in adolescent blood pressure reactivity and continued study of the gender-blood pressure reactivity distinctions in adolescents may further understanding of adult patterns of gender differences in cardiovascular disease.

Guidelines for selecting outcome measures: lifestyle modification for stage 1 hypertension.

Lifestyle modification is the recommended intervention for stage 1 hypertension. Advanced practice nurses are well positioned to guide lifestyle modification, and they are well prepared to measure outcomes related to the intervention. Selection of an appropriate outcome measure begins with matching the measure to the intervention. Matching is reliant on identification of the system of ideas and the research database guiding the intervention. This article proposes guidelines for selecting an outcome measure for use with individuals in practice settings. The guidelines are then applied in the selection of an outcome measure for lifestyle modification in stage 1 hypertension.

Primary prevention of cardiovascular disease risk factors: review and implications for population-based practice.

This review analyzed the results of population-based intervention studies targeting primary prevention of cardiovascular disease risk factors among children and adolescents in the United States. In general, the findings indicate that cardiovascular disease risk factors may be amenable to interventions in school-based programs. Although the interventions have small effects on risk factor outcomes, they should be interpreted within the context of population-based approaches that ultimately may have a greater impact on disease prevention than much larger effects among the small proportion of individuals at the highest levels of risk.

Nongenetic influences of obesity on risk factors for cardiovascular disease during two phases of development.

Matched-pair analyses of twins were used to examine nongenetic influences of obesity on the lipid profile and systolic and diastolic blood pressure (cross-sectionally) during two phases of development--the school-age years (n = 73 twin pairs) and adolescence (n = 56 twin pairs)--and (longitudinally) in the transition between these two developmental phases. Data were collected during an early morning home visit. Results of the matched-pair t tests indicated significant environmental influences on obesity in both phases and in the transition (change in obesity) between these two phases. Intraindividual associations of obesity (kg/m3) and atherogenic lipids (total and LDL cholesterol) emerged during the school-age years. In adolescence, obesity was associated with HDL cholesterol and total triglyceride. Change in obesity (kg/m3) from the school-age years to adolescence was associated with total triglyceride. Results suggest an emphasis on obesity as part of CVD risk factor management in children and point to the importance of primary prevention early in life.

Assessing agreement between clinical measurement methods.

Nursing practice and research often require the use of one measurement method in place of another, creating the need to know how well one clinical measurement method approximates another. The usual statistical analyses for assessing agreement between measurement methods are the correlation coefficient and the paired t test. This article suggests that these statistical methods do not address the question of agreement. It proposes the limits of agreement as a more informative analysis when a researcher is interested in replacing one measurement method with another. The application of limits of agreement analysis to assess repeatability of one measurement method is also introduced.

Component analysis of the Structured Interview for assessment of Type A behavior in employed women.

Components of the Structured Interview in employed women and the overlap between these components and those identified by self-report measures of Type A behavior were investigated. The sample consisted of 177 employed, white females 26 to 52 years old; 48% were classified as Type A. Principal components factor analysis yielded five factors: Clinical Rating, Hurried-Drive, Impatience, Pressured-Competitiveness, and Expression of Anger. Some differences in the factor structure were noted for this sample of employed women, compared with previous studies of employed men, particularly with respect to anger and impatience. The behavioral components of the Structured Interview did not correlate with self-report measures of Type A behavior (Framingham Type A scale and the Jenkins Activity Scale). Implications for future studies of employed women are discussed.

Type A behavior in children: psychometric properties of the Matthews Youth Test for Health.

The purpose of this study was to investigate the psychometric properties of the Matthews Youth Test for Health (MYTH) as a measure of components of Type A behavior in school-age children. The sample consisted of 216 middle-class, white, 6 to 11 year old, same-sex twin children. Pairs were randomly split into two subgroups for cross-validation. The MYTH was completed by 88% of the children's teachers. The Perceived Competence Scale was completed by 118 of the 124 children 8 to 11 years old; a parallel form of this instrument was completed by teachers of 108 of these children. The 17 items of the MYTH instrument were factor analyzed. Two factors, Impatience-Aggression and Competitive Achievement-Striving, were derived and cross-validated. These MYTH factors were internally consistent and replicated previous studies of school-age children. The construct validity of the MYTH subscales was partially supported by evidence of relationships between these components of Type A behavior and teacher-ratings of the child's competence in specific domains. Children's ratings of their competence and perceptions of global self-worth were not related to total MYTH scores or subscale scores.

Genetics or environment? Type A behavior and cardiovascular risk factors in twin children.

The heritability of Type A behavior and other cardiovascular risk factors was investigated in twin school-age children. The purpose was to differentiate those risk factors that have the potential to respond to environmental and life-style changes. The sample consisted of 71 monozygotic and 34 same-sex, dizygotic twin pairs 6 to 11 years old residing in the Philadelphia metropolitan area. Systolic and diastolic blood pressure, triceps skinfold thickness, body mass, and fasting blood specimens for lipid profiles were collected during home visits. Teachers rated the children's Type A behavior and two of its subcomponents, impatience-aggression and competitive achievement-striving, using the Matthews Youth Test for Health. Statistically significant heritability estimates were found for Type A behavior and its subcomponents, triglycerides, systolic blood pressure, and body mass. Nevertheless, there was substantial environmental influence on these risk factors. The greatest environmental influence was observed for HDL-cholesterol, LDL-cholesterol, apolipoprotein-B and diastolic blood pressure.