WIC and Obesity
The focus of this session, moderated by Patricia Crawford, was research on how the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) could have an impact on behaviors that contribute to childhood obesity. The two presenters (Robert Whitaker and Elsie Taveras) identified possible behavioral intervention targets and discussed different aspects of suggested research methods. The discussant (Sara Benjamin Neelon) raised a number of questions about the selection of behavioral intervention targets. The session did not address research on efforts by WIC to address obesity.
RESEARCH PROPOSALS FOR OBESITY PREVENTION AMONG CHILDREN IN WIC
Presenter: Robert C. Whitaker
Whitaker covered four key research findings and their implications for future research. In addition, he mentioned structural constraints in WIC that limit potential research designs, and he proposed a research agenda and a potential staged research design.
Key Research Findings
Four research findings have implications for the WIC research agenda, Whitaker said. They are:
Participation in WIC is not associated with obesity. Because of this, exposure to WIC alone is unlikely to either cause or protect against obesity, and body mass index (BMI) will not be a useful measure of a primary outcome (Hofferth and Curtin, 2005; Ploeg et al., 2008; Rose et al., 2006).
The prevalence of obesity in WIC children no longer seems to be increasing. Because favorable secular trends are likely to continue among WIC and non-WIC children, careful attention must be given to the control condition when designing studies (Sharma et al., 2009).
Within the WIC income range, higher income is associated with a greater rather than a lower prevalence of obesity. Thus qualitative studies are needed to examine the complex relationship between childhood obesity and household behaviors and resources (Anderson and Whitaker, 2010; Karp et al., 2005; Whitaker and Orzol, 2006).
Successful prevention or treatment interventions in young children require parental involvement. Therefore, parents should be the primary targets of interventions to prevent childhood obesity (Epstein et al., 1994; Golan and Crow, 2004; Golan et al., 2006).
Because WIC currently has no waivers or wait lists, it is challenging to develop feasible random assignment designs. Interventions must work within WIC’s three core functions: the provision of the food package, nutrition education, and referrals.
Proposed Research Agenda
Whitaker’s research proposal is given below, followed by his criteria for selecting target behaviors.
Develop and test the impact of a coordinated communication strategy among WIC, Head Start, and pediatricians on changing behaviors that help prevent obesity among children 12 to 60 months of age.
The target behaviors selected should meet three criteria, namely, that the behavior (1) has an effect on energy balance or weight, (2) is
Menu of Target Behaviors
unlikely to do harm, and (3) has a favorable effect on non-obesity outcomes, such as improving social well-being. The lack-of-harm criterion is especially important when the evidence of benefit is weak. The effect on outcomes other than obesity may provide the key to engaging parents and partners.
Whitaker’s menu for target behaviors appears in Box 3-1. According to Whitaker, behavior numbers 5 and 6 in this box, which have consistently been associated with a lower prevalence of obesity, also may lead to improvements in children’s moods and decreased aggressive behaviors—possible outcomes that may engage parents.
Potential Staged Design
Whitaker proposed a multistage research design in which each stage informs the next (Box 3-2). The first four stages entail the development of
Potential Multistage Research Design
Development of the Communication Strategy
Testing of the Communication Strategy
a communications strategy, which is tested in the fifth and sixth stages. The first stage is the most important. It includes framing messages on behavioral targets and reconciling differences between the frames1 held by those delivering and those receiving the messages. A key part of the fourth stage is a qualitative assessment of how well both the messages and the medium resonate with the messengers and the parents.
The pilot test (stage 5) would focus on assessing the acceptability, feasibility, and fidelity of delivering the message. If the results of the pilot test are unfavorable, stage 6 would not go forward. If the results of the first five stages warrant a controlled evaluation of the impact of the communication strategy (stage 6), this stage would probably be conducted using a group- or community-randomized design that compares traditional WIC services with WIC services plus an enhanced coordinated communication strategy. The primary outcome should be the target behavior or behaviors. A process and cost evaluation would be an important element of the study in order to determine how to implement the intervention on a larger scale and then to sustain it.
In closing, Whitaker emphasized that any interventions that are part of the research agenda should target behaviors rather than BMI, that the target behaviors must matter to the WIC partners and to the parents, and that qualitative research is more important and feasible than quantitative research in the WIC setting.
RESEARCH OPPORTUNITIES IN WIC FOR CHILDHOOD OBESITY
Presenter: Elsie M. Taveras2
Although the most recent statistics show that the prevalence of childhood obesity has reached a plateau, the prevalence is still high, and obesity is affecting even the nation’s youngest children. In 2007–2008, the prevalence of high weight for recumbent length among U.S. children from birth to 2 years of age was 9.5 percent (Ogden et al., 2010), where “high” is defined as weights at or above the 95th percentile of the Centers for Disease Control and Prevention (CDC) growth charts (Kuczmarski et al., 2000). The prevalence of obesity varied by racial and ethnic background,
Proposed Targets for Behavioral Counseling—Prenatal to Early Childhood
ranging from 8.7 for non-Hispanic white to 12.5 for Hispanic girls and boys (Ogden et al., 2010). Severe obesity (BMI ≥35 kg/m2) was especially high for Black and Hispanic boys and for Black girls 2 to 19 years of age (Wang et al., 2010).
Relevant Research Findings
Box 3-3 offers a list of proposed targets for behavioral counseling and key references that provide the basis for the inclusion of those targets on the list. Racial and ethnic differences are present in all the early life risk factors for childhood obesity, with children who belong to racial or ethnic minority groups being affected disproportionately. Clearly, prevention must start early, and preventive interventions should be based on the best available evidence for the highest risk populations. WIC fits well with the effort to prevent obesity because of the population groups covered, the structure for screening nutritional status, the nutrition education provided, and the referrals for needed health and social services.
Proposed Research Agenda
Taveras proposed the following study: Develop and test the impact of coordinated surveillance and communication strategies among
WIC providers and obstetricians on promoting healthful behaviors during pregnancy to prevent childhood obesity and improve maternal health; and
WIC providers, home visitation programs, child care providers, and pediatricians on changing behaviors to help prevent excess weight gain among infants from birth to 12 months.
The targets of intervention during pregnancy would be maternal prepregnancy BMI, excessive gestational weight gain, maternal smoking, and gestational diabetes. The interventions would occur mainly during the inter-pregnancy interval. Taveras called for improving the surveillance of obesity-related risk factors; coordinated referrals and communication strategies; and improvements in parents’ ability to handle infant feeding, sleep, and media exposure. A very important communication goal would be to counter the myth that the pregnant woman needs to “eat for two.”
The targets of intervention during infancy would be excessive infant weight gain; breastfeeding initiation, continuation, and exclusivity; responsive feeding; portion sizes of bottles and solid food containers; outdoor physical activity; limiting television viewing and televisions in bedrooms; and improving sleep quality and duration. Taveras called for improved surveillance of infant weight gain using the CDC growth charts in combination with the identification of children at high risk of rapid growth and coordinated communication strategies to counter the myth that “bigger is better.” Other possible tactics involve education and support that would be directed mainly toward feeding practices and the promotion of physical activity and healthful sleep.
Possible Methodology for Impact Evaluation
Taveras supported the multistage design approach presented by Whitaker and focused on two possible evaluation methods: quasi-experiments and cluster-randomized controlled trials.
Quasi-experiments, as described by Gortmaker (2004), can have all the attributes of a randomized controlled trial, including pretest and posttest data. The key difference is the lack of random assignment to intervention and control groups. The success of the method depends on appropriate selection of the control sample (e.g., through propensity matching; see Chapter 10). Quasi-experiments make it possible to study programs and policies that are innovative, expensive, and difficult to implement.
Cluster-Randomized Controlled Trials
Cluster-randomized controlled trials are studies in which groups (clusters) are randomized rather than individuals. This method is useful when the intervention is applied to an entire group. Because of the randomization, such trials have better internal validity than quasi-experimental studies. They also allow the study of interventions that cannot be directed toward selected individuals. However, the design and analysis of cluster-randomized controlled trials are complex, the required sample sizes are large, the cost is high, and the long time it takes to obtain study results may preclude rapid evaluations of innovations.
Taveras said that WIC can play a substantial role in efforts to prevent childhood obesity during pregnancy, infancy, and early childhood—especially when WIC works in collaboration with partners such as obstetricians, home visitation programs, child care providers, and pediatricians. She concluded that those determining the research agenda should consider innovative study designs and methods as a way of overcoming the barriers to wide-scale intervention testing in WIC.
Discussant: Sara Benjamin Neelon
Questions Triggered by the Obesity Session Presentations
Benjamin Neelon asked all those present to consider the presentations by Whitaker and Taveras and think about four questions, and she provided her own responses, as follows:
What is WIC already doing and already doing well to prevent childhood obesity?
Response: Screening and measuring growth, addressing competing issues within families.
What can WIC do to include more obesity prevention within its current structure?
Response: Target various family members and caregivers, not just the mother.
Are there missed opportunities for obesity prevention within WIC?
Response: Reaching women during interconceptional periods, engaging fathers and partners.
Where does obesity prevention rank among other behavioral targets within WIC? How would you prioritize obesity prevention when you consider other health concerns?
Response: None provided.
Benjamin Neelon also asked attendees to consider behavioral targets according to three different considerations: (1) those that have the greatest effect on obesity prevention, (2) those that WIC is in a good position to address, and (3) those that are or should be integral to the mission of WIC. Some behavioral targets may move WIC nutritionists beyond their training and comfort zone. With these points in mind, Benjamin Neelon highlighted those behavioral intervention targets that she considered to be more promising—that is, the ones for which WIC could have a greater impact (see bolded items in Box 3-4).
According to Benjamin Neelon, WIC can play a substantial role in obesity prevention, although it cannot provide the entire answer. WIC needs to engage collaborative partners. Target behaviors must matter to partners and caregivers and must extend beyond weight and obesity. The research design should compare WIC to an enhanced form of WIC. Most importantly, a combination of qualitative and quantitative formative processes and impact evaluation will be needed to assess the effectiveness of new measures.
Behavioral Intervention Targetsa
Moderator: Patricia B. Crawford
The following topics were addressed during the discussion period:
Methods: Considerable evidence shows that quasi-experimental designs such as regression discontinuity and propensity scoring place large demands on the sample size, often requiring sample sizes much larger than those needed for randomized controlled trials (RCTs). When RCTs are feasible, they may be relatively simple and straightforward.
Healthy Habits for Life kits and the Around Food Insecurity program: These products of a partnership between the National WIC Association and the Sesame Workshop include evaluation components, and they tie in with suggestions for behavior change made during this session.
Efforts to encourage appropriate infant feeding (exclusive, long-term breastfeeding): These efforts tie together behaviors related to maternal health (postpartum fat loss) and infant health.
The screening component of WIC: (1) The use of the new World Health Organization growth charts results in identifying overweight children earlier than with the CDC growth charts. (2) Crowded living conditions can lead to positive responses to questions such as, “Is there a TV in the room in which your child sleeps?”
Formative research related to obesity prevention: This approach has value for 1-year-old children as well as for the older ones.
SUMMARY OF SUGGESTED RESEARCH TOPICS
The research proposals made during this session focused on developing and testing strategies to change behaviors linked with excess weight among infants and young children. Emphasis was placed on collaboration with a range of partners. The method proposed here would involve a multistage research design that would be used to identify target behaviors that matter to partners and caregivers and that extend beyond weight and obesity. The design would also help determine effective ways to address those behaviors. Both qualitative and quantitative research designs will be needed.
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