Location: Children's Nutrition Research CenterTitle: HEALTHY study rationale, design and methods: Moderating risk of type 2 diabetes in multi-ethnic middle school students ) Author
Submitted to: International Journal of Obesity
Publication Type: Review Article
Publication Acceptance Date: 11/25/2009
Publication Date: 11/25/2009
Citation: Hirst, K., Baranowski, T., Debar, L., Foster, G., Kaufman, F., Kennel, P., Linder, B., Schneider, M., Venditti, E., Yin, Z. 2009. HEALTHY study rationale, design and methods: moderating risk of type 2 diabetes in multi-ethnic middle school students. International Journal of Obesity. 33(Suppl 4):S4-S20. Interpretive Summary: The HEALTHY study is a multi-site middle school-based (called a cluster) cluster randomized clinical trial testing whether a large multi-component intervention can reduce middle school children’s risk factors for type 2 diabetes and obesity. This paper outlines the research design for the trial. There were 42 participating middle schools distributed across seven sites (6 per site), with 21 schools each randomized to treatment or control groups. The intervention includes 4 components: revising school food services to lower caloric content and enhance nutrition, revising physical education to increase minutes of moderate to vigorous physical activity; providing a health promotion classroom education; and providing a school social marketing component to draw students' attention to the other components and promote behavior change. This trial has a strong design and has a large enough sample to detect relatively small changes in the percent of children above the 85th percentile BMI. It is anticipated that because of this study various methods will be identified to prevent an increase of type 2 diabetes.
Technical Abstract: The HEALTHY primary prevention trial was designed and implemented in response to the growing numbers of children and adolescents being diagnosed with type 2 diabetes. The objective was to moderate risk factors for type 2 diabetes. Modifiable risk factors measured were indicators of adiposity and glycemic dysregulation: body mass index > or =85th percentile, fasting glucose > or =5.55 mmol l(-1) (100 mg per 100 ml) and fasting insulin > or =180 pmol l(-1) (30 microU ml(-1)). A series of pilot studies established the feasibility of performing data collection procedures and tested the development of an intervention consisting of four integrated components: (1) changes in the quantity and nutritional quality of food and beverage offerings throughout the total school food environment; (2) physical education class lesson plans and accompanying equipment to increase both participation and number of minutes spent in moderate-to-vigorous physical activity; (3) brief classroom activities and family outreach vehicles to increase knowledge, enhance decision-making skills and support and reinforce youth in accomplishing goals; and (4) communications and social marketing strategies to enhance and promote changes through messages, images, events and activities. Expert study staff provided training, assistance, materials and guidance for school faculty and staff to implement the intervention components. A cohort of students were enrolled in sixth grade and followed to end of eighth grade. They attended a health screening data collection at baseline and end of study that involved measurement of height, weight, blood pressure, waist circumference and a fasting blood draw. Height and weight were also collected at the end of the seventh grade. The study was conducted in 42 middle schools, six at each of seven locations across the country, with 21 schools randomized to receive the intervention and 21 to act as controls (data collection activities only). Middle school was the unit of sample size and power computation, randomization, intervention and primary analysis.