Methods and rationale to assess the efficacy of a parenting intervention targeting diet improvement and substance use prevention among Latinx adolescents

Abstract

Latinx adolescents are at higher risk for chronic diseases relative to adolescents of other ethnic groups, in part because of their lack of adherence to diet recommendations and their higher rates of substance use. Given the proximal influence of family factors during the developmental stage of adolescence, parenting interventions may be an effective way to promote healthy nutrition and substance use prevention simultaneously. This article describes the design and theoretical rationale of a study assessing the effects of Families Preparing the New Generation Plus (FPNG Plus), a 10-week culturally-tailored nutrition and substance use prevention parenting program, on diet and substance use outcomes among Latinx middle school students (6^th–8^th grade). The 3-arm cluster randomized controlled trial compares FPNG Plus (substance use prevention and healthy nutrition), FPNG (substance use prevention only), and a comparison condition (focusing on academic success) in 1,494 parent-child dyads from 18 schools, randomized at the school level. Adolescents and parents will complete surveys pre- and post-intervention, and 16-weeks after program participation, regarding diet behaviors, substance use, and parenting practices. A random subsample of 126 dyads (42 from each program), will participate in additional data collection to assess the home food environment, detailed dietary intake (via two 24-h recalls), and provide biomarkers of cardiometabolic risk (blood pressure, total cholesterol and HbA1c). If successful, this study will provide evidence contributing to helping Latinx parents assist their adolescent children develop and maintain long-lasting positive lifestyle behaviors in order to prevent concurrent substance use and diet-related chronic diseases.

1. Introduction

Latinx adolescents are at increased risk for cardiometabolic disease (i.e. cardiovascular disease, type 2 diabetes) because of their increasing overweight and obesity rates, lack of adherence to nutrition and physical activity recommendations, and greater rates of tobacco and illicit drug use than their non-Latinx counterparts [1,2]. Behavior change interventions promoting healthy nutrition and substance use prevention for Latinx adolescents have been implemented in school settings with limited parental engagement [3–5]. However, interventions targeting adolescents tend to have a greater impact when the entire family is involved [6–8]. The role of parents is particularly important due to their ability to create a home environment that promotes healthful behaviors (including substance use prevention and healthy nutrition), and parents’ role as providers of resources to the family (including food). Cross-sectional evidence suggests that familial factors (e.g., parenting feeding style, frequency of family meals, food insecurity, acculturation, and resiliency) are associated with adolescents’ weight status and healthy nutrition [9–12]. Whereas parenting has been used as an efficacious strategy for substance use prevention among Latinx adolescents [7,13], few studies have used a family approach to address healthy nutrition. Whether parenting interventions are an effective way to promote healthy nutrition and substance use prevention simultaneously is unknown. The integration of multiple levels or domains of influence (e.g. simultaneously assessing outcomes at the biological, family or household level and within other domains within the ecological framework) is needed to enhance intervention effects for preventing, reducing and eventually eliminating health disparities.

Families Preparing the New Generation (FPNG) is an efficacious parenting intervention to increase parent-child communication and family functioning as a means to prevent substance use in Latinx adolescents [7,13]. Based on epidemiological data and feedback from FPNG community partners, there is a pressing need to integrate healthy nutrition into the FPNG curriculum in order to make a greater impact on the health needs of Latinx adolescents. Using a community-based participatory research (CBPR) approach [14], the study team developed a nutrition-enhanced version of the intervention, now called Families Preparing the New Generation Plus (FPNG Plus). FPNG Plus was developed in partnership with parents and adolescents from the target population to weave culturally acceptable nutrition improvement strategies into the existing parenting intervention. The purpose of the project described herein is to test the efficacy of the enhanced intervention over time through a 3-arm cluster randomized controlled trial comparing FPNG Plus (substance use prevention and healthy nutrition), FPNG (substance use prevention only), and a comparison condition (focusing on academic success) on adolescents’ substance use and nutrition outcomes. The study will also assess mediating effects of parenting strategies and moderating effects of sociocultural factors. Finally, an exploratory aim of the study will evaluate effects at the biological and environmental level through assessing the preliminary effects of FPNG Plus, relative to FPNG and the comparison condition, on modifiable cardiometabolic disease risk factors (glycosylated hemoglobin [HbA1c], total cholesterol, blood pressure, body weight) and the home food environment (availability of fruit, vegetables, and sugar-laden foods) in a subsample of participants.

2. Theoretical approach

2.1. The role of parents in substance use and nutrition behaviors

Parents are a primary change agent for the prevention of substance use and improvements in nutrition behaviors. Many parenting-related factors have a bearing on adolescent substance use and nutrition behaviors [15–17]. Effective parenting practices, such as parental monitoring and involvement, are associated with reduced adolescent substance use [15–18]. Family functioning, such as parental attachment, parent-child communication, and family connectedness, are also associated with reduced risk of substance use [19–21]. Additionally, familismo (the centerness of family in Latinx cultures) is associated with reduced risk of substance use [17,22]. Conversely, poor family functioning and family problems are risk factors for substance use [23].

Regarding diet behaviors, positive norms such as parental modeling and encouragement of healthy food consumption, support of family meals, and parental monitoring of junk food, have been associated with greater fruit and vegetable intake, lower consumption of unhealthy foods and snacks, and greater overall diet quality in adolescents [24–30]. In contrast, inappropriate parental modeling and permissive feeding have been associated with increased consumption of fat- and sugar-laden foods and beverages [24,29].

In addition to traditional parenting factors, grocery shopping and the availability of healthy or unhealthy food at home are key factors influencing the quality of the children’s diet. Healthier environments are generally associated with greater intake of healthy foods, such as fresh fruits and vegetables, and lower consumption of their unhealthy counterparts, such as sugar-containing snack foods and beverages, among children and adolescents [24–26,28,29,31–36]. Whereas information on how the home food environment influences diet behaviors among Latinxs is limited, research consistently supports that parental feeding practices and food availability are associated with children’s dietary quality and health outcomes [37–40].

Behavioral change interventions for Latinx adolescents tend to have a greater impact when the other family members are involved [6–8]. The role of parents is particularly important due to their ability to create a home environment that promotes healthy behaviors (including substance use prevention and healthy nutrition), and parents’ role as providers of resources to the family (including food). When targeting nutrition, involving parents and children together has been a successful strategy because of the strong role parents play in modeling and facilitating children’s behaviors [41–43]. Although the home food environment has a localized and direct impact on food choice, and consequently health [44,45], the focus of nutrition interventions on environmental influences at the household level has been limited [25]. The present study follows an ecological systems approach [46]. The ecological systems theory accounts for the different ecosystems that influence children development. It identifies family, peers, and school (microsystem), the interactions between them (the mesosystem) and broader systems such as culture of origin (macrosystem) as influencing children’s attitudes and behaviors toward the outcomes of interest in this study [46]. In addition, the ecological systems theory integrates person-environment interrelations through a biosocial perspective [47].

2.2. Acculturative stress and substance use and nutrition behaviors among Latinx adolescents

Acculturative stress has been identified as a factor that may hasten the erosion of health as immigrants adapt to American culture. Acculturation stressors reported by Mexican heritage and other Latinx adolescents have been categorized into six domains: (1) immigration, (2) communication and language, (3) school and academic, (4) peer, (5) family, and (6) social and economic [48]. These domains are interrelated, as family disruption is often a consequence of acculturative adaptation and acculturative stress and can operate as a pathway to adverse health outcomes. Substance use rates, deteriorating diet quality, and related negative health consequences appear to increase significantly with acculturation [49–62].

Longer residence time in the U.S. results in individuals abandoning more traditional dietary patterns and shifting to processed foods, lower intake of fresh fruits and vegetables, and high added sugars intake [12,50,59,63,64]. These changes in nutrition practices are associated with increases in body mass index, and higher diabetes and cardiovascular disease risk [65,66]. Moreover, acculturative stress has been identified to affect the substance use of Latinx adolescents disproportionally and adversely [67]. Lack of familiarity with mainstream American culture and the discriminatory environment that exists in many communities and schools further limits the ability of many Mexican heritage adolescents and parents to seek help and to benefit from existing prevention efforts [68,69]. Because 95% of children of immigrants are U.S. born, there is a need to address possible ecodevelopmental influences –beyond individual factors – that place these children at risk, and prevent the erosion or disappearance of the original protective factors connected to their culture of origin [70].

2.3. Addressing substance use and unhealthy diet behaviors in Latinx adolescents from an ecodevelopmental framework

Adolescence is a critical period for the adoption of behaviors relevant to health and provides an opportunity for the acquisition and maintenance of life-long health trajectories [71]. A useful approach to examine health related behaviors such as substance use and diet is the Ecodevelopmental Theory. This theory derives from Bronfenbrenner’s work [46] and more specifically focuses on the multiple, interacting social contexts that influence ethnic minority adolescent development [72,73]. Risk and resiliency for Latinx adolescents emerge from interdependent relationships across proximal and distal nested systems [74], including the broad social structures and forces that influence parents and adolescents (e.g., cultural processes, migration, residential instability, socioeconomic inequality). Proximal and distal systems interact to influence adolescent health behaviors and biological vulnerability [73,75–78]. Knowledge of these interactions helps identify strategies for improving family functioning, parenting skills, the home environment, and the neighborhood social environment as a means to strengthen adolescent health behaviors and reduce biological vulnerability [79,80]. Positive support within and between these systems facilitates positive health outcomes, while conflict within or among them increases vulnerability to risky health behaviors.

Ecodevelopmental Theory posits that parents and families play a primary role in the socialization of adolescents and directly influence adolescents across the other microsystems (e.g., parental monitoring of involvement with peers) [81]. Many family-related factors have a bearing on adolescent health behaviors including family connectedness, family cohesion, family support, parent-child communication, parental attachment, parental modeling, parental involvement, support of family meals, and parental monitoring [15–30,82]. Familismo is associated with reduced risk of health behaviors and improvements in health practices [22,83]. Conversely, poor family functioning and family problems are associated with risk factors for adolescents, like substance use [23]. Families also reflect socioeconomic assets and resources that influence housing, school, and neighborhood characteristics [82,84]. When families live in low socioeconomic, disadvantaged areas, opportunities for pro-social activities, interactions, and behaviors are diminished and replaced by feelings of stress, fear, and distrust further limiting healthy behaviors [85–90].

The Ecodevelopmental Theory provides broad-based approaches for investigating risk and resiliency in Latinx adolescent drug use and dietary behaviors, as these models can account for important familial and parent-child influences that characterize Latinx adolescents and families as they undergo acculturation processes [73,91–93]. As Latinx adolescents are called upon to navigate two distinct sets of cultural norms, promoting biculturalism may help them to sustain strong family, peer, and community ties, and reduce the likelihood of engaging in risky health behaviors [94]. Adolescents who are able to construct a culturally blended identity that adheres positively to both native and host cultures evidence the best outcomes across mental health, physical health, and relational domains [95]. However, the postulated parent-child gaps in communication resulting from differential rates of acculturation between Latinx parents and their children can interfere with effective parenting, induce social isolation of immigrant parents, compromise the ability to attain adequate social support, and disturb role relations as when parents rely on the adolescents to navigate arenas where English proficiency may be required. Stress related to forced assimilation, colonization, and acculturation has been cited as contributing to risk behaviors among Latinx adolescents [96]. When the disruptions and stress imposed by acculturation are managed effectively, such as when Latinx parents maintain active involvement in their child’s activities, fewer acculturation-based behavioral problems occur [97,98]. These are skills that can be taught, albeit only within programs that are grounded in their developmental and cultural experiences [99].

From an ecodevelopmental perspective, the present study aims to intervene in the family/parents ecosystem in order to optimize the health benefits at the child’s level. The assumption is that there are recent immigrant parents who are able to successfully manage the stressors related to acculturation, while others encounter more difficulties. Bringing parents together in small groups will provide a needed forum to share their experiences. The intervention will help parents identify and strengthen what it is working, learn new strategies to overcome challenges, and be actively engaged in their children healthy eating and substance use prevention.

3. Methods

This study was approved by the Institutional Review Board at Arizona State University (Protocol ID: STUDY00006797). All study-related materials are available in English and Spanish. This study is registered in ClinicalTrials.gov (Identifier: NCT03517111).

3.1. Study aims

The purpose of the project described herein is to test the efficacy of a nutrition-enhanced parenting intervention over time. It is proposed that by strengthening parent-child communication and family functioning, it is possible to impact two health behaviors (nutrition and substance use) simultaneously among Latinx adolescents and positively improve multiple health outcomes.

Specifically, we will: (1) test the efficacy of FPNG Plus relative to the original FPNG and the comparison condition on adolescents substance use and nutrition outcomes; (2) examine the mediating effects of parenting strategies (e.g., parental social support, enhancing family functioning, parenting skills) on the effects of the expanded (FPNG Plus) and the original (FPNG) interventions; (3) examine the moderator effects of sociocultural factors (e.g., acculturation, acculturation gaps, acculturative stress, food insecurity, and resiliency) on the efficacy of the two versions of FPNG both on parenting strategies and on specific adolescents substance use and nutrition outcomes; and (4) explore the preliminary effects of FPNG Plus, relative to FPNG and the comparison condition, on modifiable chronic disease risk factors and the home food environment in a subsample of participants.

3.2. Study design

Study aims will be achieved through a 3-arm group cluster randomized controlled trial comparing FPNG Plus (substance use prevention and healthy nutrition), FPNG (substance use prevention only), and the Realizing the American Dream (RAD) comparison condition (focusing on academic success) on adolescent substance use and nutrition outcomes (Figure 1). Each 10-week group-based intervention will be delivered to parents in local middle schools. A total of 1494 parent-child dyads will be recruited from 18 different schools (n=6 schools; 83 parent-child dyads per school; 498 dyads per condition). Randomization will occur at the school level, each school randomly assigned to one of the three conditions. Data collection from both parents and adolescents will take place at baseline (T1), immediately post-intervention at 10 weeks (T2), and at approximately 16 weeks post-intervention (T3). Parents will participate in one of the three intervention conditions and complete data collection procedures. Their adolescent children will only complete data collection procedures. Recruitment will occur in cohorts starting each consecutive semester to ensure reaching the target sample size.

Figure 1.

Three-arm group randomized controlled trial comparing FPNG Plus (substance use prevention and healthy nutrition), FPNG (substance use prevention only), and the Realizing the American Dream (RAD) comparison condition (focusing on academic success) on adolescent substance use and nutrition outcomes.

Randomization to treatment conditions (FPNG Plus, FPNG, or comparison [RAD]) will occur at the school level. School eligibility will be dependent on the following criteria: (1) public school offering 6^th, 7^th, and 8^th grades with at least 65 students per grade; (2) located in Maricopa County, AZ; (3) having at least 60% of Latinx students; (4) receiving Title I funds from the federal government to assist in meeting student’s education needs; and (5) willing to offer one of the three programs to their students’ parents at their facilities. From the 18 participating schools, 6 each will be randomized into one of the three conditions. The schools will be clustered by geographic location (3 schools per cluster) and within each cluster, schools will be sorted by the estimated number of Hispanic 7^th grade students from largest to smallest. School demographic information was obtained from the U.S. Department of Education Public Elementary/Secondary School Universe Survey CCD School Database [100]. Within each cluster, schools will be given a random number, and the school with the highest random number will be randomized into FPNG Plus, second highest into FPNG, and lowest into RAD. Stratified randomization on site characteristics and ethnic composition is not expected to be necessary because the sites are very homogeneous in these respects, but this assumption will be verified.

3.3. Study setting

The study will be conducted in partnership with Arizona State University’s American Dream Academy (ADA), an established organization with the infrastructure to deliver the intervention to the families of middle-school children. ADA is a multi-site community program serving 4,000 families a year, mainly through the delivery of Realizing the American Dream (RAD), and other academic success programs with no substance use prevention or nutrition content. ADA programs are delivered in participating schools from the Phoenix Metropolitan area that contract with ADA to offer the programs to their students’ parents through trained facilitators. Since 2006, ADA has delivered programs in 250 schools. ADA has a demonstrated record of successfully recruiting and retaining thousands of Latinx parents into RAD, in part due to the work of their state-of the-art call center staffed with experienced bilingual and bicultural personnel.

3.4. Participants

The study will recruit parent-child dyads consisting of one parent and one adolescent enrolled in 6^th, 7^th or 8^th grade at the time of recruitment. Following inclusiveness policies from our community partner, the ADA, parents of children enrolled in other grades will also be included if interested in the program, but their children will not be part of the study. Adults will be eligible to participate if they are 18 years of age or older, are the parent/caregiver/guardian of an eligible adolescents, or a parent of a child enrolled in participating schools who expresses interest in the program.

Participant recruitment will occur in cohorts starting every consecutive semester in up to 9 different schools at the time to ensure reaching the study sample size. The study team will provide ADA with general “invitation scripts” to be used by the trained operators of the ADA phone call center describing the study and inviting parents and their children to participate. Because FPNG and FPNG Plus are specifically designed for parents of 6^th–8^th grade children, additional recruitment activities will take place to increase visibility of the programs and target families who have a child in those grades. These activities include: meeting with the 6^th–8^th grade teachers to explain the study; getting permission to present in their classrooms; handing out take-home flyers for the students; placing additional phone calls to parents of 6^th–8^th graders to give them additional information about the study; and attending school events (e.g., meet the teacher day, school open house, curriculum night) to advertise the programs.

Interested parents will be invited to the initial intervention session. A trained team member will read aloud the study consenting documents while parents follow along. The team member will then explain in more detail the study procedures and what is being asked of participating parents and children, after which they will have the chance to ask questions. Interested participants will be asked to provide written consent to participate, and initial survey data collection will take place. If participating parents have a child in 6^th–8^th grade, they will also be asked to provide consent for their child to participate in data collection procedures. Adolescents will be asked to provide written assent prior to data collection. Parents will also be asked to consent for optional data collection procedures (in order to be eligible for randomization to be part of the subsample). Parents do not have to agree to be part of the subsample in order to be part of the overall study (i.e., complete the surveys). Parents who are interested in the program but do not want to consent for the study will be welcome to attend the program but will not be involved in data collection procedures.

3.5. Intervention programs

FPNG Plus curriculum adaptation

The original FPNG curriculum was adapted to incorporate nutrition content in all intervention sessions, with a primary emphasis on how to apply parenting strategies that are already part of FPNG to diet-related behaviors. FPNG Plus supports dietary change and aligns with adolescent values of autonomy (e.g. increasing communication with family members to talk about healthy eating and how it can help them feel better about themselves [i.e., how eating breakfast can help them improve performance in sports]). FPNG Plus was designed to help parents reinforce life skills and other proactive behaviors with their children (i.e., how to avoid junk food, particularly in response to peer-pressure, monitoring availability of unhealthful foods in the home, shopping together for fruits, vegetables and healthy snacks, or joining a community garden as a family). The nutrition content is consistent with current diet recommendations for the U.S. population [101,102], and mainly focuses on increasing fruit and vegetable intake, and reducing consumption of sugar-laden processed foods. The FPNG Plus curriculum also includes themes for addressing potential food insecurity (e.g., healthy eating on a tight budget, healthy food access) and issues related to body image. Core components of the original FPNG curriculum were preserved, e.g. overall structure, topics, and skills training in the use of substance use prevention strategies.

Intervention programs curricula

Table 1 includes lists of topics covered in each of the sessions for the three intervention curricula.

Table 1.

Curricula of intervention programs

Week	Topic	Objectives
RAD (Control)
1	Introduction	Welcome participants Highlight the importance of being involved in the RAD program
2	You make the difference	Learn about the changes that occur in middle school students Learn how to commit to success and make expectations clear “Success Ladder”
3	Being a partner with your school	Discuss Step 1 of Academic Success Plan Learn how to prepare for a parent-teacher conference Learn how child’s school and the wider school system operate
4	Academic standards and performance requirements	Discuss Step 2 of Academic Success Plan Learn practical ways to help child prepare for standardized tests Learn about requirements, academic standards, high school curriculum, and important terms related to these
5	Communication and discipline	Discuss Step 3 of Academic Success Plan Learn how to use and maintain effective two-way communication with child Establish firm, fair, and consistent discipline
6	Self-esteem and motivation	Discuss Step 4 of Academic Success Plan Learn effective ways to motivate children and build their self-esteem Learn about university admission requirements
7	Reading and responsibility	Discuss Step 5 of Academic Success Plan Learn practical ways to teach children about responsibility Understand how important reading is to overall academic success
8	Your academic success plan	Put Academic Success Plan into action and learn how to maintain it until your child graduates from college
9	Community forum	Provide an opportunity to ask questions to the school principal
10	Graduation	Recognize participants for their work and involvement in the program
Original FPNG
1	Introduction	Welcome participants Highlight the importance of being involved in the FPNG program
2	You are not alone	Identify parent and family social networks Discuss different roles parents have in raising children Identify goals participants have for their children
3	Introduction to keepin’ it Real	Learn the differences between norms and values Learn about keepin’ it REAL program and practice the strategies Learn the ABCD Problem Solving method
4	Knowing your child’s world	Learn about the stages of adolescent development Discuss how diversity and social environment affect adolescent development
5	Communicating with your child	Identify obstacles and solutions to communication Learn to communicate in an effective and positive way Identify pro-social and anti-social behaviors and how parents can promote pro-social behaviors
6	Receiving and giving support	Learn how to ask for and accept help as it relates to raising children Identify the components of a supportive relationship and its role in preventing risky behaviors
7	Managing your child’s behavior effectively	Learn about effective behavior management and identifying criteria for establishing rules Make the connection between norms and values and guiding their children’s behavior
8	Talking to teens about risky behaviors	Review the prevalence of risk behaviors of adolescents country-wide and state-wide Learn about harm reduction Prepare for sensitive conversations with adolescents
9	Putting it all together	Review concepts from the previous seven sessions through a “Jeopardy”-style review game
10	Graduation	Recognize participants for their work and involvement in the program
FPNG Plus
1	You are not alone	Identify parent and family social networks Discuss different roles parents have in raising children Identify goals participants have for their children
2	Introduction to keepin’ it REAL	Learn the differences between norms and values Learn about keepin’ it REAL program and practice the strategies Learn the ABCD Problem Solving method
3	Introduction to nutrition	Learn about MyPlate and current diet recommendations Learn how to read the nutrition facts label Learn how to identify healthy and unhealthy snack options
4	Knowing your child’s world	Learn about the stages of adolescent development Discuss how diversity and social environment affect adolescent development
5	Communicating with your child	Identify obstacles and solutions to communication Learn to communicate in an effective and positive way Identify pro-social and anti-social behaviors and how parents can promote pro-social behaviors
6	Parenting and healthy eating
7	Receiving and giving support	Learn how to ask for and accept help as it relates to raising children Identify the components of a supportive relationship and its role in preventing risky behaviors
8	Managing your child’s behavior effectively	Learn about effective behavior management and identifying criteria for establishing rules Make the connection between norms and values and guiding their children’s behavior
9	Talking to teens about risky behaviors	Review the prevalence of risk behaviors (including nutrition-related ones) of adolescents country-wide and state-wide Learn about harm reduction Prepare for sensitive conversations with adolescents
10	Putting it all together	Review concepts from the previous nine sessions through a “Jeopardy”-style review game

The control program, Realizing the American Dream (RAD), is centered around helping participants’ children achieve academic success. Parents learn the importance of being involved in their children’s education; receive information and resources regarding academic standards in Arizona; learn how to implement effective discipline; and create a success plan that will help their child move on to the next step in their education.

The original Families Preparing a New Generation (FPNG) program is designed to help parents raise healthy children who lead pro-social lives and avoid the use of substances. Parents learn about the importance of social support and resources available to help them as they raise their children; using different styles for effective communication; strategies for effective behavior control; strategies for adolescents to avoid the use of substances; information about the stages of child development; and the social, emotional, academic, and physical changes that adolescents face.

The Families Preparing the New Generation Plus (FPNG Plus) program, was designed to include the same topics as the original FPNG, with the addition of two entirely new workshops focused on healthy eating and parenting strategies to promote healthy eating behaviors. Lessons from the original FPNG curriculum have comparable content and objectives, but include activities and examples that focus on nutrition and healthy eating practices.

Intervention program delivery, fidelity and retention

All three intervention programs (FPNG+, FPNG, and RAD) will be manualized and delivered as indicated by ADA’s trained community facilitators in group settings at participating schools (about 15 parents per group). Study team members will observe 20–25% of the total workshops per semester; these will be randomly chosen, but for FPNG+, at least one of the nutrition sessions will be observed with each facilitator. Fidelity checks will be recorded on standardized forms that contain a checklist with all the activities in the lesson, as well as questions regarding what was added or skipped, how parents and facilitator interacted, and how many parents completed the assigned homework from the prior week. If drift occurs, the team member will provide feedback to the facilitator after the workshop; if more than three activities are not completed correctly, the team will re-train the facilitator in coordination with the ADA program manager.

Parents who complete the program and their families will be invited to a graduation ceremony where participants will receive certificates of recognition for their participation. Additional retention strategies will include calling parents who miss a session in order to re-engage with them and invite them to the next session, and incentivizing perfect attendance with the opportunity to participate in a raffle at the end of the program.

Facilitator training

Facilitators from the ADA will undergo extensive training to implement the three programs reliably. All ADA facilitators are also required to attend 8-hour training sessions twice per year in order to discuss facilitation skills and review program updates. They also attend monthly mandatory meetings to learn about updates in logistics and ADA programming.

Specific training for FPNG (8 hours) and FPNG Plus (12 hours, allowing additional time to discuss nutrition-related content) includes content designed to understand program-related concepts, as well as instruction designed to enhance facilitation skills. The trainings were designed by curriculum, facilitation, and content experts from the research team (MH, AG, SVL, BVL). The training sessions will follow the same type of progression and layout of the curriculum workshops, so facilitators become familiar with lesson development and why each lesson follows a certain pattern. Facilitators will learn the theoretical foundations of the program, how to work with adult learners and create a successful learning environment, and practice all the workshops in the curriculum they are assigned to. In order to enable learning of the content and become familiar with the curriculum activities, the training sessions will utilize multiple active learning strategies, including videos, role-plays, discussions, activity sheets, games and a practicum.

3.6. Data collection and measures

Data collection from both parents and adolescents will take place at baseline (T1), immediately post-intervention at 10 weeks (T2), and at approximately 16 weeks post-intervention (T3). All parents and adolescents will be asked to complete a survey to collect information on substance use and nutrition outcomes regardless of intervention condition at the adolescents’ school. Additional data will be gathered from a random subsample of 126 families (42 per condition) at the same time points (T1, T2 and T3) to explore the preliminary effects of FPNG+ on modifiable chronic disease risk factors and the home food environment. These data will be collected at participants’ homes by a team of trained research technicians during times at which both parent and adolescents will be available. During this data collection home visit the following procedures will take place: (1) measurement of parent and child body weight, height, and blood pressure; (2) collection of a finger prick blood sample from parent and child for measurement of HbA1c and total cholesterol using portable point-of-care devices; and (3) completion of a home food inventory to record availability of fruit, vegetables, and sugar-laden foods. Parents and adolescents from the subsample will also be asked to complete 2 unannounced 24-hour diet recalls over the phone for assessment of diet intake.

Survey

Self-administered surveys will be available in Spanish and English so the respondent can complete them in the language he/she chooses without needing to request the accommodation and will be administered using an electronic tablet on a Qualtrics (Qualtrics, Provo, UT, USA) platform. If participants cannot read in either language, a Research Assistant will read the questions to them. The surveys will include items to collect sociodemographic information (T1 only) and instruments for assessment of the outcomes described below (T1, T2 and T3). The surveys will be saved locally on the tablet, and uploaded to the main Qualtrics server when wi-fi access is available, after which the data will no longer be available on the tablet.

Main outcomes

Data on the recent use of substances (amount and frequency of alcohol, cigarettes, e-cigarettes, marijuana, and inhalants) will be collected with individual items modeled after Likert scale items used by Flannery, et al. [103]. Drug resistance strategies measures, validated by Hecht, et al. [104], will assess adolescents’ responses to substance use offers in the last 30 days and likely responses to hypothetical situations of risks, as well as adolescents’ anti-drug norms [3]. Intake of fruit, vegetable, and sugar-laden foods will be assessed with the NCI Dietary Screener Questionnaire [105], a short (26-item) instrument used to estimate frequency of intake of select food groups (fruit & vegetables, fiber & whole grains, added sugars, dairy, calcium-containing foods, and red meat & processed meat). This questionnaire has been validated for use with the general population and with Latinos [106,107].

Mediators

Family functioning will be assessed through three sets of indicators: (1) parental involvement [108], (2) parental self-agency [109], and (3) parental monitoring [110]. Each measure can be created into a mean scale. Parental involvement will measure the extent to which the parent is involved in the child’s life, and the Parent Self-Agency Measure [109] will gauge the parent’s sense of parenting competence and ability to positively influence the child’s development. Parental monitoring will assess the parents’ knowledge of the adolescent’s peers, activities, and whereabouts. To assess parent-child communication (including specifically about substance use and risky behaviors), we will utilize questions from the National Longitudinal Study of Adolescent Health (Add-Health) parent survey [111]. Family’s eating habits will be assessed as previously used by Berge et al. [112,113], and parental attitudes, beliefs and practices about feeding will be assessed using the Child Feeding Questionnaire [114]. Parents’ social support will be assessed with the 10-item Multidimensional Scale of Perceived Social Support (MSPSS) [115].

Moderators

The Acculturation Rating Scale for Mexican Americans–II (ARSMA-II) [116,117] will be used to measure acculturation related to language, ethnic identity, and ethnic interaction. The reliability, and validity of the ARSMA-II are well established in English and Spanish [116]. Acculturation-gaps will be computed from the ARSMA-II by subtracting the parent’s score from the adolescent’s score [118]. Acculturative stress will be assessed with the Pressure to Acculturate and Pressure Against Acculturation subscales of the Multidimensional Acculturative Stress Inventory [119], developed for use with Mexican heritage individuals living in the U.S. Food insecurity will be assessed using the 6-item Food Security Scale [120,121], a short screener that has been shown to have high specificity and sensitivity to identify household food insecurity. Resiliency will be assessed with the 10-item Connor-Davidson Resilience Scale [122], a validated instrument that has been used with English and Spanish-speaking adults to assess multiple dimensions of resilience.

Chronic disease risk factors

Body weight and height of parents and adolescents from the subsample will be collected in triplicate using light indoor clothing without shoes, using a standardized protocol. BMI for adults will be calculated in kg/m². For adolescents, weight and height will be used to determine BMI percentiles for age and sex based upon the 2000 CDC growth curves. Participants’ (parents and adolescents) blood pressure will be measured in triplicate using an automated blood pressure monitor (Omron IntelliSense HEM-907XL; Omron Healthcare, Inc.; Bannockburn, IL). A finger prick blood sample will be collected from parents and adolescents to measure total cholesterol and HbA1c. Total cholesterol will be measured as a marker of cardiovascular disease risk using the Accutrend Plus System (Roche Diagnostics; Indianapolis, IN), a point of care device that accurately measures cholesterol concentrations [123]. HbA1c will be measured as a marker of glycemic control and diabetes risk using the A1cNow+ system (PTS Diagnostics; Indianapolis, IN), an FDA-approved and National Glycohemoglobin Standardization Program-certified instrument that accurately measures HbA1c in point-of-care settings [124].

Diet and home food environment

Detailed nutrition variables of interest (energy, macronutrients, consumption of sugar-sweetened beverages, added sugars, servings of fruits and vegetables, and whole grains) from adolescents will be obtained using two unannounced 24-hour recalls administered via phone, reporting intake from one weekday and one weekend day, following a five-step multiple pass method [125]. The Nutrition Data System for Research (NDSR) software version 2019, developed by the Nutrition Coordinating Center (NCC), University of Minnesota, Minneapolis, MN, will be used to analyze dietary data. Dietary variables of interest include estimates of total energy intake, amount and percentage of energy provided by macronutrients, and intake of fruit, vegetables and sugar-containing foods. A modified version of the validated Home Food Inventory [126] will be used to assess availability and variety of fruit, vegetables, sugar-containing foods and beverages, snack foods, and breakfast cereals in the home. Modifications included cultural adaptations to include foods commonly consumed by Latinos (e.g., pan dulce, papaya, cactus pads), and inclusion of breakfast cereals. Although this instrument was developed for self-report, we will utilize research staff for data collection to minimize self-report bias.

3.7. Statistical analyses

Power calculations took into account design effects related to the clustering of outcome means by school sites. The total estimated sample size is 1494 parent-child dyads, across 18 schools. Based on data from the FPNG effectiveness trial, the level of clustering is low for our outcomes, including an intraclass correlation equal to 0.01, a student level R-square of 0.25, and a school level R-square of 0.03 [13]. Because the effect size for substance use outcomes (d=0.20; FPNG vs. C) is lower than the expected effect size for nutrition outcomes (d=0.78; prior non-related intervention study), the total sample size is calculated for substance use outcomes. Accounting for these parameters, the power of this design is 0.802. For the subsample, the estimated sample size is 126 households across 18 schools – 7 per school. The average effect size of .69 is calculated based upon prior work on home food availability of vegetables, fruits, and desserts. Given the above stated parameters, the power of this design is 0.814.

All analyses will be conducted using multilevel analyses in Mplus [127], with families clustered within schools. This analysis accounts for the clustering which, if uncorrected, may result in biased standard errors [128]. All analyses will employ a robust maximum likelihood estimator to adjust for any non-normality in the distributions of outcomes and to best control for Type I errors [129]. The analyses will also utilize full-information maximum likelihood (FIML) [130] to conduct intent-to-treat analyses that account and adjust for attrition and any item missing data.

We will use both baseline adjusted general linear model procedures (i.e., variants of multiple regression) and latent change modeling to test intervention efficacy. In all models, because the FPNG Plus is the intervention condition of interest, all analyses will use FPNG Plus as the reference group. The two remaining conditions (FPNG and Comparison) will be compared with the reference group. The first method will predict short-term (T2) and then long-term (T3) post-test outcome measures (e.g., adolescents substance use and diet outcomes), while controlling simultaneously for the baseline (T1) measure of the particular outcome. Latent-change models [131] will test whether and how changes over time in the outcomes differ significantly. Latent-change models will enable the assessment of change between T1 and T2 separately from change between T2 and T3. This examination will simultaneously test for improvements manifested during the course of the intervention (i.e., between T1 and T2) and for improvements maintained following the completion of the intervention (i.e., between T2 and T3).

For mediation analyses, we will employ multivariate linear regression path analyses [132,133]. Each mediation model will test the indirect path between the intervention condition at T1 and outcome measures at T3 (e.g., adolescents substance use and nutrition outcomes) mediated through family functioning, parenting strategies, and parents’ social support at T2. Mediation models will control for baseline (T1) measures of the particular mediator and outcome. We will employ a bias-corrected bootstrap approach to test the indirect effect [134].

The moderation effects of sociocultural factors on outcome measures will be tested employing mean centered interactions of the measures of acculturation, acculturative stress, food insecurity, and resiliency with the dummy variable contrasts of intervention conditions, following Aiken & West (1991) [135]. We will use baseline adjusted general linear model procedures to test for moderation. If significant moderation exists, we will use latent-change models to test whether and how changes over time in the outcomes differ significantly between adolescents who vary in the sociocultural moderating measures of interest (e.g., for those adolescents who are less and more acculturated).

Intervention effects on cardiometabolic risk factors and home food environment outcomes measured in the subsample will be tested through baseline adjusted regression models, including models that can appropriately analyze count data (e.g., Poisson, Negative Binomial). We will examine changes in short-term (T2) and long-term (T3) outcomes with dummy variable contrasts of intervention conditions, while controlling simultaneously for the baseline (T1) measure of the particular outcome.

4. Summary

There is an urgent need for successful strategies to improve diet quality and reduce substance use in Latinx adolescents. Few studies have used family-based or household-level environmental approaches to address diet improvement among Latinx adolescents. Moreover, community-based interventions involving the whole family have successfully addressed barriers that Latinos experience when attempting to access care [136,137]. Recent research also suggests that parenting programs with an emphasis on family functioning can prevent the onset of cardiometabolic diseases in early adolescence [138]. Healthy nutrition promotion strategies must align with adolescent food preferences, values of autonomy from adult control, and importance of peers [139–141].

The study described herein represents a substantive culturally grounded and multilevel approach to encourage preventive behaviors among Latinx adolescents by extending the scope and capitalizing on the success of an efficacious parenting intervention from one (substance use) to two conditions (substance use and healthy nutrition). The study focuses on Latinx adolescents, an underrepresented population, at a particularly vulnerable transition period in which future behaviors are established [72,73,142]. This supports adolescence as an optimal time to implement health promotion behavioral interventions. Of particular relevance is the focus on family and cultural values that are central to Latino cultures to promote relevant strategies for behavior modification more effectively, capitalizing on promoting existing behaviors, traditions, and rituals that are already compatible with acceptable behaviors.

The FPNG+ intervention will address multiple behavioral outcomes impacting cardiometabolic disease. Prior adolescent interventions have not focused on simultaneous modification of nutrition improvement and substance use prevention. This unique approach will underscore the success of a culturally grounded intervention, FPNG, by implementing parenting strategies and promoting family and cultural values to intervene in two behaviors known to impact cardiometabolic disease risk simultaneously, substance use and healthy nutrition, among Latinx adolescents. Involving parents is essential because of the central role of the family in Latino cultures, and given their primary responsibility for purchasing and preparing food for the family [17,22,143]. This multi-level intervention (focusing on individual-, family-, and household-level factors) is intended to influence several domains within an ecological framework (focus on biological, behavioral, and environmental outcomes) and capitalizes on a culturally grounded intervention that incorporates family-based approaches to healthy eating, thus ensuring that behavioral strategies will be acceptable not only to participants but also to family members.

Findings will contribute knowledge on how to design and test interventions to impact simultaneously more than one chronic condition and enhance the overall health of Latino communities. Findings will also support immigrant parents on how to engage in the prevention and reduction of health disparities among acculturating Latinx adolescents by preventing or delaying the onset of substance use and nutrition-related chronic conditions.

Abbreviations

ADA

American Dream Academy

CBPR

community-based participatory research

FPNG

Families Preparing the New Generation

HbA1c

glycosylated hemoglobin

RAD

Realizing the American Dream