Chronic disease risk factors among children. The 'Know Your Body' study

A public health vs a risk-based intervention to improve cardiovascular health in elementary school children: the Cardiovascular Health in Children Study

OBJECTIVES

This study sought to determine the population effects of both classroom-based and risk-based interventions designed to reduce cardiovascular disease risk factors in children.

METHODS

Elementary school children (n = 2109; age range: 7-12 years) were randomized by school to a classroom-based intervention for all third and fourth graders, a risk-based intervention only for those with 1 or more cardiovascular disease risk factors, or a control group. The 8-week interventions involved both knowledge--attitude and physical activity components.

RESULTS

School-level analyses showed that physical activity in the risk-based group and posttest knowledge in the classroom-based group were significantly higher than in the control group. With regard to trends shown by individual-level analyses, cholesterol dropped more in the classroom-based than in the control group, and skinfold thickness decreased 2.9% in the classroom-based group and 3.2% in the risk-based group (as compared with a 1.1% increase in the control group).

CONCLUSIONS

Both classroom-based and risk-based interventions had positive effects on physical activity and knowledge, with trends toward reduced body fat and cholesterol. However, the classroom-based approach was easier to implement and evidenced stronger results than the risk-based intervention.

Prevalence and correlates of early smoking among elementary schoolchildren in multiethnic, low-income inner-city neighborhoods

PURPOSE

The prevalence and correlates of early smoking were investigated among schoolchildren in grades 4-6 living in multiethnic, low-income neighborhoods in Montreal.

METHODS

As part of the evaluation of a school-based heart health promotion program, baseline data on the prevalence of early smoking were collected from 2285 students aged 9-13 years in 24 inner-city elementary schools during May-June 1993.

RESULTS

Overall, 28.7% of boys and 20.3% of girls had smoked. Girls began trying later than boys, but by age 13 the prevalence of experimental or regular smoking by girls overtook that of boys. Univariately, ever smoking varied considerably by family origin, from 2.1% among Vietnamese girls, to 35.8% among Portuguese boys. In multivariate analysis, age, perceived smoking habits of friends, and smoking by family members, were strong correlates of smoking. Being of Asian family origin was negatively associated with smoking. None of the indicators of social class were significantly associated with ever smoking.

CONCLUSIONS

Smoking prevention should begin with children even younger than age 9 in multiethnic, low-income, inner-city neighborhoods. With the exception of a lower prevalence of smoking among Asian children, ethnicity and social class were not strong influences on early smoking behavior in this population.

Healthy Start: a comprehensive health education program for preschool children

BACKGROUND

Healthy Start is a 3-year demonstration and education research project designed to evaluate the effectiveness of a multidimensional cardiovascular (CV) risk reduction intervention in preschool centers over a 3-year period of time.

METHODS

Two primary interventions are employed. The first is the preschool food service intervention program designed to reduce the total fat in preschool meals and snacks to less than 30% of calories and reduce the saturated fat to less than 10% of calories. The second major intervention is a comprehensive preschool health education curriculum, focused heavily on nutrition.

RESULTS

Effectiveness of the intervention will be determined through evaluation of changes in dietary intake of preschool children at school meals and snacks, especially with respect to intake of total and saturated fat. Evaluation of the education component will include assessment of program implementation by teachers, assessment of changes in nutrition knowledge by preschool children, and assessment of changes in home meals that children consume (total and saturated fat content). Blood cholesterol will be evaluated semiannually to evaluate changes that may be due to modification of dietary intake. Growth and body fatness will also be assessed.

CONCLUSIONS

While substantial efforts have targeted CV risk reduction and health education for elementary school children, similar efforts aimed at preschool children have been lacking. The rationale for beginning CV risk reduction programs for preschool children is based upon the premise that risk factors for heart disease are prevalent by 3 years of age and tend to track over time, most commonly hypercholesterolemia and obesity, both related to nutrition. Since the behavioral antecedents for nutritional risk factors begin to be established very early in life, it is important to develop and evaluate new educational initiatives such as Healthy Start, aimed at the primary prevention of cardiovascular risk factors in preschool children. The purpose of this publication is to describe the rationale and methods for the Healthy Start project.

Relationships among black families' cardiovascular disease risk factors

BACKGROUND

As participants in the District of Columbia Studies of Children's Activity and Nutrition (D.C. SCAN), 262 black mothers and two of each mother's children (3-4 and 8-10 years of age) were measured in their homes for selected cardiovascular disease risk factors: serum total cholesterol, systolic and diastolic blood pressures, height and weight for body mass index, fitness (sum of pulses), activity, and triceps and subscapular skinfolds.

RESULTS

For each measure, mothers in the highest quartile were more likely to have children who were also in the highest quartile, and mothers in the lowest quartile were more likely to have children who were in the lowest quartile. For the physiological measures, (with the exception of systolic blood pressure), correlations tended to be stronger between the siblings than between the younger child and the mother, and older siblings' physiological measures contributed to the prediction of younger siblings' physiological measures after controlling for mothers' physiological measures. Relationships between family cardiovascular disease risk factor history and children's serum total cholesterol, and systolic and diastolic blood pressure levels tended to be gender related; i.e., family cardiovascular disease risk factors on the mother's side were more likely to be related to levels among the female but not the male children and vice versa. When personal characteristics were controlled for, the family's cardiovascular disease history was related more strongly to the younger than to the older sibling's systolic and diastolic blood pressure levels.

CONCLUSIONS

Results tend to substantiate the importance of screening and counseling other family members, especially a child of the same gender as the parent with a cardiovascular disease or an elevated risk factor level.

Influence of parents' physical activity levels on activity levels of young children

To determine the relationship between activity levels of parents and those of their young children, we monitored physical activity with a mechanical device, the Caltrac accelerometer, in one hundred 4- to 7-year-old children and in 99 of their mothers and 92 of their fathers. During 1 year in the Framingham Children's Study, data were obtained for an average of more than 10 hours per day for 8.6 +/- 1.8 days for the children, for 8.3 +/- 2.1 days for their mothers, and for 7.7 +/- 2.3 days for their fathers. Children of active mothers (average Caltrac accelerometer counts per hour greater than the median) were 2.0 times as likely to be active as children of inactive mothers (95% confidence interval = 0.9, 4.5); the relative odds ratio of being active for the children of active fathers was 3.5 (95% confidence interval = 1.5, 8.3). When both parents were active, the children were 5.8 times as likely to be active (95% confidence interval = 1.9, 17.4) as children of two inactive parents. Possible mechanisms for the relationship between parents' and child's activity levels include the parents' serving as role models, sharing of activities by family members, enhancement and support by active parents of their child's participation in physical activity, and genetically transmitted factors that predispose the child to increased levels of physical activity.

Cardiovascular risk factor prevention in black school children: the "Know Your Body" evaluation project

A longitudinal study of the effectiveness of the "Know Your Body" (KYB) program in reducing coronary heart disease risk factors was begun among black students in the District of Columbia in 1983. Subjects were in grades four through six at nine schools stratified on socioeconomic status and randomized into one control and two intervention groups. At baseline, 1,041 students were measured for systolic and diastolic blood pressure, ponderosity, triceps skinfold thickness, postexercise pulse recovery rate, serum thiocyanate, serum total cholesterol, and serum HDL cholesterol. Significant net changes in individual values occurred in the favorable direction at one or all four annual follow-up reexaminations for systolic blood pressure, diastolic blood pressure, HDL cholesterol, HDL/total cholesterol ratio, serum thiocyanate, and fitness. Favorable changes in diastolic blood pressure and serum thiocyanate were observed at all reexaminations, and these were substantiated by analyses that used the school grade as the unit of analysis. Intervention students who were judged to have had the best KYB teachers showed significant favorable net changes in total serum cholesterol after one year. Results are consistent with other evaluations of the Know Your Body program suggesting that KYB may reduce chronic disease risk in diverse school populations, and that increased efforts should be made to improve implementation methods.

Primary prevention of chronic disease among children: the school-based "Know Your Body" intervention trials

The "Know Your Body" project, initiated in 1975 with funding from the National Heart, Lung, and Blood and the National Cancer Institutes, was developed in response to the empirically-validated suggestion that the primary prevention of chronic disease should begin in childhood. The aim of the program is to favorably modify the population distributions of risk factors for these diseases through changes in their behavioral antecedents. The program is classroom-based and teacher-delivered, and consists of three primary intervention foci: diet, physical activity, and cigarette smoking prevention. The program was subjected to a field trial among two demographically dissimilar populations of schoolchildren in the New York City area. After five years of intervention in one of the populations, the program was associated with significant favorable changes in blood total cholesterol levels and dietary intake of total fat and carbohydrate. In both populations, the program was associated with significant favorable changes in knowledge. After six years of intervention, the program was associated with a significant net reduction in the rate of initiation of cigarette smoking. If these findings can be replicated among diverse populations of schoolchildren, they suggest that such programs may be effective in reducing the population risk for the future development of chronic disease.

Determinants of physical ability in 7th grade schoolchildren

The aim of the study was to determine factors associated with running time in children aged 12 years, according to sex and sexual maturation of girls. The physical ability was measured, using a 1000 meter run in a group of 942 boys and girls aged 12. In addition, data was collected on family sports activities and the children's sports activities, using questionnaires for parents and children. Before the 1000 meter run, physical examination was carried out. Nutrition habits of the family in the home and outside were self-reported in a questionnaire. The mean time for run in boys was shorter by 40 seconds than that for girls. Premenarche girls ran significantly faster than postmenarche girls (p less than 0.05). The best predictors for short running time were triceps skinfold thickness and sport motivation of the children. Weaker correlation was observed between food variables, family characteristics and running time. The highest prediction of running time by the measured variables was found for postmenarche girls, explained by the high correlation of running time with the behavioral variables. In boys and premenarche girls, the best predictors for running time were the physical and physiological characteristics of the children.

Quasi-experimental evaluation of the Los Angeles Know Your Body program: knowledge, beliefs, and self-reported behaviors

In 1981-1982 the Division of Cancer Control (Jonsson Comprehensive Cancer Center, University of California, Los Angeles) implemented a Know Your Body program in the Los Angeles and Santa Monica Unified School Districts. The results from this evaluation are based on analyses of over 1,400 elementary school children (ages 9-11 years) from 18 schools who were assigned to one of four comparison groups: (a) Know Your Body curriculum and health screening (N = 688 students/seven schools), (b) Know Your Body health screening only (N = 333 students/three schools), (c) Know Your Body curriculum only (N = 253 students/five schools), and (d) the control group (N = 234 students/three schools). Standardized questionnaires concerning health knowledge, beliefs, and (self-reported) behaviors were group-administered by teachers in January 1981 (pretest) and then again in March 1982 (post-test). The group receiving both the Know Your Body curriculum and the clinical screening scored higher than the control group on four out of six post-test knowledge measures, one out of three belief scales, and one out of four behavioral measures. The curriculum-only group scored higher than the control group on five out of six post-test knowledge measures and on two of three belief scales. The screening-only group did not score significantly higher than the control group on any of the outcome measures. Among children identified during the clinical screening (at pretest) as being at higher risk of developing chronic disease (N = 543), students receiving both the screening and the curriculum (N = 401) scored higher on four out of six knowledge measures and reported significantly lower consumption of both dairy products and high-cholesterol foods than "high-risk" students receiving only the clinical screening (N = 142).

Health lifestyle education in high schools. A three-year follow-up study

An experimental "healthy lifestyle programme" was initiated in Year 7 (first year of high school) in selected high schools in 1980 and was conducted over a three-year period. The programme had two main objectives: to influence attitudes and increase knowledge about health matters, in order to improve lifestyle; and to strengthen the general case for the more organized instruction of schoolchildren in this field. As part of the programme, children were given lessons on nutrition, physical activity and fitness, and on alcohol, tobacco and drugs. The programme was reasonably implemented in three of the four schools which took part in the experiment. Significant improvements, over three years, in attitudes and knowledge about health and nutrition and a reduction in cigarette smoking, were noted among children in schools where the programme had been implemented reasonably. The reasons for the partial success of the programme are discussed.

Preventing the onset of cigarette smoking in Norwegian adolescents: the Oslo youth study

As part of a 2-year multiple risk factor intervention study, a school-based, multicomponent smoking prevention program for 10- to 15-year-old students in Oslo, Norway, resulted in a significant reduction in the onset of smoking relative to a reference group. Based on reported smoking behavior, the intervention group (N = 278) experienced a smoking onset rate of 16.5% and the reference group (N = 208) a rate of 26.9%. Intervention students had a significantly larger increase in scores on a smoking knowledge index; they also reported a significantly larger increase in frequent exercise and a significantly smaller increase in consumption of alcoholic beverages. A stepwise discriminant analysis showed that the smoking prevention program was an important discriminator of smoking onset. In both reference and intervention groups, students who reported smoking at the follow-up survey had already displayed risk-taking tendencies at the time of the baseline survey 2 years earlier, whether or not they smoked at baseline. Follow-up smokers had more smoking friends and siblings at baseline and evidenced greater acceptability of smoking; they ate sweet, fatty, and salty snack foods more often, exercised less often, and drank more beer and hard liquor than students who were nonsmokers at the follow-up survey.

Baseline chronic disease risk factors in a racially heterogeneous elementary school population: The "Know Your Body" program, Los Angeles

The Los Angeles "Know Your Body" (KYB) program is an organized health education activity for children designed to encourage positive health behavior and discourage or interrupt behavioral patterns that are linked to illness, injury, disability, or death. Components of KYB include a 20-week curriculum; a survey of health knowledge, attitudes, and behaviors; in-service training for elementary school teachers; and a clinical screening that provides feedback to students on selected indices. As part of a KYB field demonstration in Los Angeles conducted by the UCLA Division of Cancer Control, Jonsson Comprehensive Cancer Center, 1,503 Los Angeles and Santa Monica-Malibu children ages 9-11 in grades 4 and 5 underwent baseline health screening evaluations in March 1981, measuring height, weight, triceps skinfold thickness, serum cholesterol, pulse rate recovery following exercise, and blood pressure. The population mean for serum cholesterol was 182.6 mg/dl, with no significant racial/ethnic, sex, or age differences. Significant racial/ethnic differences were found in obesity, with Hispanics having the highest prevalence, Asians the lowest. Black students scored significantly higher in pulse rate recovery following exercise, suggesting better relative cardiovascular fitness, and Asians scored lowest. Blacks were more likely to exceed the 95th percentile in diastolic and systolic blood pressure. Overall, 48% of the children had one or more chronic disease risk factors.

Can human behavior be modified?

Human behavior is constantly being modified, though not as rapidly or always in the direction that health professionals might wish. In cancer prevention and detection programs, human behavior is modified by several common interrelated methods: the mass media; face-to-face communications; risk-immunization measures; economic forces; and the enactment of laws and regulations. Information and education are the preferred methods and have over a period of time achieved encouraging results. Further emphasis should focus on improving communication skills of health professionals, especially physicians; the promotion of hospital health education programs; and the support of more effective school health education programs. They should keep the public informed about the latest scientific advances while guarding against oversimplifying scientific facts that can be misinterpreted. They must be aggressive in the battle against cancer quackery, and they must keep abreast of the self-care and self-help movements, supporting those that contribute to cancer prevention and detection.

Teaching children self-care for chronic disease prevention: obesity reduction and smoking prevention

A general health education program was developed for 1,252 students in six New York city area school districts. The purpose of the three-year project was to reduce the prevalence of risk factors associated with increased cardiovascular and cancer risk in adults. The curriculum included nutrition, antitobacco, and hypertension-control materials. A smaller, experimental intensive health behavior program was also developed for obese children (weight greater than or equal to 120% ideal for height, age, and sex). A smoking prevention program was offered to children with the aim of discouraging new smokers. Findings show that: 1) such a school-based primary disease prevention program is feasible and highly acceptable; and 2) reduction of obesity and new cigarette smoking occurred with intensive intervention involving small groups of students. On the other hand, a general health education itself had little effect in the total population in reducing the incidence of extreme clinical values (such as physical inactivity, high blood pressure, as well as smoking and obesity) for their age and sex. It is recommended that future programs for higher risk children concentrate on behavioral change rather than on general education.