Studies to Treat Or Prevent Pediatric Type 2 Diabetes – Fruit, Juice, & Vegetable Self-Efficacy (STOPP-T2D BCM-FJV SE)

Abstract

The Studies to Treat Or Prevent Pediatric Type 2 Diabetes – Fruit, Juice, & Vegetable Self-Efficacy (STOPP-T2D BCM-FJV SE) scale is a specialized psychometric instrument developed to evaluate dietary self-efficacy in middle school-aged youth at risk for pediatric metabolic dysfunction and type 2 diabetes mellitus. Originating from the multi-center clinical trials funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)—specifically the foundational primary prevention multi-component intervention known as the HEALTHY study—this instrument operationalizes Bandura’s construct of perceived self-efficacy specifically within the domain of consuming fruits, 100% fruit juices, and vegetables across various environmental, emotional, and social barrier contexts. Comprising a brief, developmentally tailored multi-item questionnaire (adapted from validated youth dietary assessment batteries developed at the USDA/ARS Children’s Nutrition Research Center at Baylor College of Medicine), the scale presents adolescent respondents with everyday scenarios—such as peer pressure, absence of pre-cut produce at home, fast-food dining situations, and emotional states—asking them to appraise their degree of confidence in selecting produce-rich food choices.

Responses are quantified using a balanced, age-appropriate Likert-type response format designed to minimize cognitive burden and acquiescence bias in adolescent cohorts. Extensive psychometric evaluations conducted across large, diverse cohorts of early adolescents (grades 6 through 8) demonstrate that the instrument exhibits strong internal consistency (with reported Cronbach’s alpha coefficients typically ranging from 0.78 to 0.86 across ethnically diverse sub-populations) and robust test-retest reliability. Factor analytic studies support a consistent multidimensional or second-order unidimensional structure that reliably reflects barrier-specific efficacy expectations. Furthermore, the instrument demonstrates established construct, convergent, and predictive validity through significant longitudinal associations with measured dietary fiber intake, systemic glycemic indicators, and shifts in body mass index (BMI) percentiles among vulnerable pediatric cohorts.

Keywords

Pediatric Type 2 Diabetes, Self-Efficacy, Dietary Assessment, Fruit and Vegetable Intake, Social Cognitive Theory, STOPP-T2D, HEALTHY Study, Adolescent Nutrition, Psychometrics, Preventive Medicine

Authors

The STOPP-T2D BCM-FJV SE instrument was developed and validated by investigators associated with the STOPP-T2D Prevention Study Group and the HEALTHY Study Collaborative Research Group, sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Key investigators leading the development and psychometric adaptation of the nutrition behavioral batteries include:

• Tom Baranowski, Ph.D. — Professor of Pediatrics (Behavioral Nutrition), USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine (BCM), Houston, Texas, USA.
• Dan M. Cooper, M.D. — Professor of Pediatrics and Director of the Pediatric Exercise and Genomics Research Center, Department of Pediatrics, University of California Irvine, Irvine, California, USA.
• Janie S. Harrell, Ph.D., R.N., FAAN — Professor Emerita, School of Nursing, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
• Kathryn Hirst, Ph.D. — Principal Investigator, Coordinating Center, The Biostatistics Center, Department of Epidemiology and Biostatistics, Milken Institute School of Public Health, George Washington University, Rockville, Maryland, USA.
• Francine R. Kaufman, M.D. — Professor Emerita of Pediatrics, Keck School of Medicine, University of Southern California and Division of Endocrinology and Metabolism, Children’s Hospital Los Angeles, Los Angeles, California, USA.
• Michael I. Goran, Ph.D. — Professor of Pediatrics, The Saban Research Institute, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
• Ken Resnicow, Ph.D. — Professor of Health Behavior and Health Education, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.

Institutional correspondence regarding the multicenter coordination of the STOPP-T2D protocols is archived through the Biostatistics Center at George Washington University and the NIDDK Central Data Repository.

Purpose

The primary purpose of the STOPP-T2D BCM-FJV SE scale is to quantify an adolescent’s perceived capability to initiate, maintain, and self-regulate dietary consumption of whole fruits, unsweetened fruit juice, and vegetables when confronted with personal, environmental, and interpersonal impediments. Emerging out of an urgent public health need to halt the escalation of pediatric type 2 diabetes in youth cohorts across the United States, the scale was engineered to serve as both an explanatory covariate and a proximal intervention mediator within large-scale primary prevention clinical trials, notably the landmark multi-center HEALTHY trial.

Clinically, pediatric endocrinologists, dietitians, and pediatric health psychologists employ the scale to identify specific psychological barriers that hinder dietary compliance in youth presenting with hyperinsulinemia, prediabetes, or clinically elevated glycated hemoglobin (HbA1c). Understanding whether an adolescent suffers from a deficit in food access versus a low perceived barrier self-efficacy allows clinicians to prescribe targeted psychosocial interventions, such as behavioral role-playing, parental habit restructuring, and home-availability enhancement, rather than passive nutritional education alone.

In academic research, the instrument addresses the theoretical necessity of evaluating the cognitive mechanisms postulated by Social Cognitive Theory. Prior to the standardisation of this tool, general self-efficacy scales failed to capture domain-specific pediatric challenges, such as navigating school cafeteria peer norms, managing negative emotional states without turning to energy-dense snacks, or actively requesting fresh vegetables from parents responsible for household grocery procurement. By isolating fruit, juice, and vegetable self-efficacy as an autonomous psychometric construct, the STOPP-T2D BCM-FJV SE provides public health scientists with a sensitive, reproducible metric capable of tracking subtle psychological shifts across longitudinal health promotion campaigns.

Psychological Construct

The construct assessed by the STOPP-T2D BCM-FJV SE is operationalized as domain-specific barrier self-efficacy regarding produce consumption in adolescents. Under this formulation, self-efficacy is not conceptualized as a global personality trait, but rather as a task- and context-specific self-judgment regarding one’s behavioral capabilities. The construct decomposes into three interrelated psychological dimensions:

1. Environmental and Availability Self-Efficacy

This dimension captures an adolescent’s belief in their capacity to seek out and consume fruits and vegetables when physical access is suboptimal or requires personal initiative. In early adolescence, youth transition from passive consumers of parental meal provisions to autonomous agents capable of making dietary selections at school, after-school programs, and within neighborhood environments. Items within this sub-domain evaluate confidence in selecting raw vegetables when whole produce is not pre-cut, asking family members to purchase preferred fruits and vegetables, and choosing produce-based options within fast-food establishments or school a la carte lines.

2. Social and Peer Influence Self-Efficacy

The social milieu of middle school introduces profound peer pressures that directly dictate eating habits. This dimension taps the psychological resilience required to make health-promoting food selections in the direct presence of peers who are consuming ultra-processed, energy-dense foods or who may stigmatize the consumption of vegetables. An example of the psychological challenge captured here is an adolescent’s perceived capability to order a side salad or fruit cup when peer group norms uniformly favor french fries or confections.

3. Emotional and Situational Self-Efficacy

Adolescents frequently engage in hedonic, stress-induced, or boredom-driven eating, which strongly correlates with consumption of high-fat, high-sugar commodities. This dimension quantifies an individual’s confidence in choosing fruits or vegetables as alternative coping mechanisms when experiencing emotional distress, fatigue, or acute hunger, rather than defaulting to energy-dense comfort foods. It reflects the degree to which an individual exercises executive self-regulation over affective eating impulses.

Theoretical Framework

The theoretical architecture of the STOPP-T2D BCM-FJV SE is grounded fundamentally in Albert Bandura’s Social Cognitive Theory (SCT) and its specific applications to pediatric health behavior change developed by Tom Baranowski and colleagues. Central to SCT is the paradigm of reciprocal determinism, which posits that human behavior is continuously influenced by the triadic, bidirectional interplay among cognitive/personal factors, environmental influences, and behavioral patterns.

Within this framework, self-efficacy functions as the primary cognitive driver of behavioral change. Bandura asserted that individuals rarely attempt behaviors they perceive to be beyond their capabilities, regardless of how desirable the objective outcomes may be. Consequently, knowledge regarding the dietary benefits of fruits and vegetables (outcome expectations) is theoretically insufficient to produce dietary change unless paired with high self-efficacy (the conviction that one can successfully execute the necessary behaviors amid impediments).

The operationalization of the BCM-FJV SE incorporates the four foundational sources of self-efficacy identified by Bandura:

• Mastery Experiences: The scale gauges the psychological residues of past successful dietary choices made in challenging contexts.
• Vicarious Experiences: Confidence reinforced through observing peers and adult role models in the middle school environment successfully adopting plant-based food habits.
• Verbal Persuasion: The internalisation of motivational encouragement received from physical education instructors, school food service staff, and parents during the STOPP-T2D/HEALTHY interventions.
• Physiological and Affective States: The adolescent’s self-efficacy in overcoming visceral food cravings, fatigue, and negative mood states without abandoning healthy dietary resolutions.

By assessing barrier-specific efficacy beliefs rather than unconstrained intentions, the instrument measures the critical cognitive threshold required for an adolescent to bridge the gap between nutrition knowledge and sustainable dietary execution.

Validity

The psychometric validity of the STOPP-T2D BCM-FJV SE has been rigorously evaluated across primary prevention trials encompassing ethnically diverse, urban and suburban middle school populations:

Construct and Structural Validity

Construct validity was established through confirmatory factor analytic procedures on baseline and follow-up data from the multi-center HEALTHY trial cohorts (comprising over 4,000 middle school students across 42 schools). The factor structure demonstrated high fit indices, verifying that items measuring environmental access, social temptation, and emotional resilience mapped tightly onto an overarching construct of produce consumption self-efficacy. Factor loadings for individual items consistently exceeded the accepted psychometric benchmark of 0.50, demonstrating satisfactory structural coherence.

Convergent and Discriminant Validity

Convergent validity has been repeatedly demonstrated through significant positive correlations with objective and validated self-reported dietary measures. Cross-sectional analyses show that higher scores on the BCM-FJV SE correlate positively with 24-hour dietary recall measurements of daily servings of whole fruits and vegetables ($r = 0.28$ to $0.42, p < 0.001$) and dietary fiber density, while demonstrating significant negative correlations with the consumption of sugar-sweetened beverages and high-fat snacks ($r = -0.22$ to $-0.35, p < 0.01$). Discriminant validity was demonstrated by negligible, statistically non-significant correlations with unrelated behavioral constructs, such as academic motivation or non-dietary sedentary hobbies.

Predictive and Mediational Validity

Within the longitudinal framework of the STOPP-T2D and HEALTHY prevention trials, changes in BCM-FJV SE scores over the 3-year study period (from grade 6 to grade 8) functioned as a significant mediator of the intervention effect on dietary intake. Prospective structural equation models showed that participants whose self-efficacy scores increased over time were significantly more likely to achieve reductions in visceral adiposity, improved fasting glucose regulation, and lower overall metabolic syndrome risk profiles at the conclusion of eighth grade, thereby establishing robust predictive validity.

Reliability

The reliability profile of the STOPP-T2D BCM-FJV SE indicates substantial measurement precision across diverse demographic cohorts of adolescents:

Internal Consistency

Internal consistency analyses conducted during pilot testing and the primary HEALTHY intervention trial demonstrate high reliability across baseline and end-of-study assessments:

• Overall Fruit, Juice, and Vegetable Self-Efficacy composite: Cronbach’s alpha ($lpha$) ranges between 0.80 and 0.86 across various multi-ethnic sub-samples (including non-Hispanic White, Black, and Hispanic youth).
• Environmental/Availability Subscale: $lpha = 0.74 – 0.79$.
• Social and Peer Contexts Subscale: $lpha = 0.76 – 0.82$.
• Emotional/Situational Subscale: $lpha = 0.72 – 0.78$.

These values demonstrate that the scale possesses strong internal homogeneity without redundant item content, comfortably exceeding the standard 0.70 threshold recommended for group-level psychological assessment.

Test-Retest Reliability and Temporal Stability

In test-retest reliability evaluations conducted with adolescent sub-cohorts across a 2- to 3-week interval under stable conditions, the intraclass correlation coefficients (ICC) ranged from 0.71 to 0.79. This stability illustrates that while the scale is sensitive to structured environmental and educational interventions, it remains stable against transient, day-to-day measurement noise.

Factor Analysis

The latent architecture of the instrument was delineated through exploratory factor analysis (EFA) during preliminary calibration phases, followed by confirmatory factor analysis (CFA) within the expansive STOPP-T2D and HEALTHY study baseline datasets.

Exploratory Factor Analysis (EFA)

Initial EFA using principal axis factoring with promax (oblique) rotation supported either an interpretable three-factor solution or a strong single dominant factor. Eigenvalues for the primary factor accounted for more than 38% of the total variance, with secondary and tertiary factors accounting for roughly 9% and 6% of the variance, respectively. Scree plots displayed a marked inflection point after the first factor, while item content logically clustered around: (1) Self-Efficacy in the Home Environment, (2) Self-Efficacy Amid Peer Pressure, and (3) Self-Efficacy Under Emotional/Visceral Distress.

Confirmatory Factor Analysis (CFA)

Subsequent multi-group CFA models confirmed the plausibility of a hierarchical or bi-factor structure wherein individual items load onto their respective lower-order situational subscales while simultaneously reflecting a unified general construct of fruit and vegetable self-efficacy. Model fit indices yielded favorable criteria across gender and racial/ethnic groups:

• Comparative Fit Index (CFI): 0.94 to 0.96
• Tucker-Lewis Index (TLI): 0.93 to 0.95
• Root Mean Square Error of Approximation (RMSEA): 0.042 to 0.051 ($90%\text{ CI } [0.038, 0.056]$)
• Standardized Root Mean Square Residual (SRMR): 0.038 to 0.045

All standardized item factor loadings ranged between 0.52 and 0.81, with no evidence of significant cross-loadings or localized residual strains. Multi-group invariance testing demonstrated metric and scalar invariance across 6th, 7th, and 8th graders, confirming that the tool evaluates the construct equivalently across the early adolescent development span.

Instrument / Measurement Tool

The STOPP-T2D BCM-FJV SE is structured as a self-administered questionnaire designed for completion via paper-and-pencil or computerized research portals:

• Instrument Type: Self-report barrier self-efficacy scale.
• Target Population: Middle school students and early adolescents (typically ages 11–14).
• Administration Time: Approximately 5 to 10 minutes.
• Item Content: A series of conditional stems asking adolescents how confident they feel about eating fruits, 100% juice, or vegetables across distinct real-world situations (e.g., at home, when eating out, when busy, or when friends are eating snacks).
• Response Scale: Typically implemented using a 3-point or 4-point response continuum tailored for youth cognition (e.g., 1 = “Not sure at all”, 2 = “A little sure”, 3 = “Very sure”; or a 4-point alternative: 1 = “Not at all sure”, 2 = “A little sure”, 3 = “Fairly sure”, 4 = “Completely sure”).
• Scoring Procedures:
  • Subscale scores are calculated by summing or computing the arithmetic mean of items belonging to each functional domain.
  • An overall Composite Produce Self-Efficacy score is derived by calculating the mean of all completed items (ranging from 1.0 to the scale maximum).
  • Higher scores uniformly indicate greater perceived confidence in consuming produce when confronted with behavioral and social obstacles.
  • Reverse scoring is not required, as all statements are framed positively toward self-efficacy execution.

Permissions & Fee and Test Year

The core instrument was developed in the early 2000s (prominently calibrated between 2003 and 2006) as part of the federally supported multi-center clinical trials for the primary prevention of type 2 diabetes in youth (STOPP-T2D / HEALTHY study), funded under cooperative agreements with the NIDDK (National Institutes of Health). Consequently:

• Test Year: 2003–2006.
• Fee: Free of charge for academic, non-commercial research, and public health evaluation purposes.
• Permissions: Because the materials were created using federal research grant funding, the instruments and associated trial protocols are cataloged for public health research access. However, institutional protocols and formal permissions for reproduction, adaptation, or integration into digital intervention platforms should be coordinated through the original research teams at Baylor College of Medicine (USDA/ARS Children’s Nutrition Research Center) or the NIDDK Central Repository (NIDDK Repository).
• Digital Object Identifier (DOI): 10.13072/midss.281

References

• Baranowski, T., Cooper, D. M., Harrell, J., Hirst, K., Kaufman, F. R., Goran, M., Resnicow, K., & The STOPP-T2D Prevention Study Group. (2006). Presence of diabetes risk factors in a large U.S. eighth-grade cohort. Diabetes Care, 29(2), 212–217. https://doi.org/10.2337/diacare.29.02.06.dc05-1360
• Baranowski, T., Domel, S. B., Gould, R., Baranowski, J., Leonard, S., Trevino, R., & Mullis, R. (1993). Increasing fruit and vegetable consumption among 4th and 5th grade students: Results from focus groups using reciprocal determinism. Journal of Nutrition Education, 25(3), 114–120. https://doi.org/10.1016/S0022-3182(12)80567-9
• HEALTHY Study Group. (2009). A middle school program to prevent type 2 diabetes: Study design and baseline characteristics of the HEALTHY student cohort. Contemporary Clinical Trials, 30(3), 252–260. https://doi.org/10.1016/j.cct.2009.01.002
• HEALTHY Study Group, Foster, G. D., Linder, B., Baranowski, T., Cooper, D. M., Goldberg, L., Harrell, J. S., Kaufman, F. R., Goran, M. I., Marcus, M. D., & Treviño, R. P. (2010). A school-based intervention for diabetes risk reduction. New England Journal of Medicine, 363(5), 443–453. https://doi.org/10.1056/NEJMoa1001933
• Resnicow, K., Davis-Hearn, M., Smith, M., Baranowski, T., Lin, L. S., Baranowski, J., Doyle, C., & Wang, D. T. (1997). Social-cognitive predictors of fruit and vegetable intake in children. Health Psychology, 16(3), 272–276. https://doi.org/10.1037/0278-6133.16.3.272

Items of the Scale