EAL

HD: Food Security (2011)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To test a comprehensive model, grounded in social cognitive theory (SCT) and empirical data
To explain fruit and vegetable intake among adolescents
To identify specific correlates of intake.

Inclusion Criteria:

Adolescents from middle schools and high schools in the urban and suburban school districts of the St. Paul/Minneapolis area of Minnesota
School districts serving ethnically and socio-economically diverse populations.

Exclusion Criteria:

School involved in other related studies.

Description of Study Protocol:

Recruitment

Middle schools and high schools in the urban and suburban school districts of St. Paul/Minneapolis area of Minnesota were invited to participate in the study.

Design

Survey data and anthropometric data were collected from participants
- Trained staff distributed surveys within school classes
- Assessed height and weight in a private area
Dietary intake was assessed with food frequency and factors hypothesized to be potential correlates of dietary intake were assessed with the Project EAT survey. Developed for this study, the survey was a 221-item survey assessing range of socio-environmental, personal and behavioral factors hypothesized to be associated with dietary intake among adolescents. The response rate for the survey was 81.5%
Fruit and vegetable intake was assessed with the 149-item Youth and Adolescent Food Frequency Questionnaire (YAQ).

Statistical Analysis

Structural Equation Modeling (SEM) was employed using Amos 4.0 software (allows for partially missing data utilizing a full information maximum likelihood technique)
Confirmatory factor analysis
Normed Fit Index
Root squared error of Approximations (RMSEA)
Pearson's correlations.

Data Collection Summary:

Timing of Measurements

One-time survey.

Dependent Variables

Fruit and vegetable intake.

Independent Variables

Socio-economic factors:
- Social support for healthy eating
- Family meal patterns
- Food security
- Family socio-economic status
- Home availability of fruits and vegetables
Personal factors:
- Taste preferences
- Health and nutrition attitudes
- Weight and body concerns
- BMI
- Self-efficacy to make healthy food choices
Behavioral factors:
- Meal frequency
- Weight control behavior
- Fast food intake.

Description of Actual Data Sample:

Initial N

4,746 adolescents:

50.2% boys
49.8% girls.

Attrition (final N)

3,957 (1,976 boys, 1,981 girls) with a total attrition of 789:

344 participants did not complete YAQ
261 had biologically implausible responses (energy intakes less than 400kcal per day or more than 7,000kcal per day)
133 had missing data for fruit and vegetable intake on the YAQ
51 answered less than 25% of survey items regarding economic, behavioral and personal questions.

Age

Mean age: 14.9±1.7 years.

Ethnicity

48.5% Caucasian
19.0% African American
19.2% Asian American
5.8% Hispanic
3.5% Native American
3.9% mixed/other.

Other Relevant Demographics

34.3% were in junior high school
65.7% were in high school.

Location

From 31 public middle and high schools in St. Paul/Minneapolis area of Minnesota.

Summary of Results:

Key Findings

Measurement model:
- Resulting factor loading and simple correlation
- All factor loadings are significant
- Home availability of fruits and vegetables is correlated with social support for healthy eating, family meal patterns and food security
- Taste preference in correlated with health and nutrition attitudes and self efficacy to make food choices perceived as healthy by adolescents
- Weight control behavior is highly correlated with weight and body concerns and meal frequency
Structural equation model for fruit and vegetable intake:
- Direct and indirect effects of factors on fruit and vegetable intake
- Only taste preference and home availability were found to be meaningful and statistically significant (P=0.01)
Interactions between home availability of fruit and vegetable and taste preferences:
- Availability of taste preference was included into the model
- The interaction term was highly significant (P<0.001) based on the procedure of Wall and Amemiya
- This increased the amount of explained variability in fruit and vegetable intake by only 1%
- The fitted relationship indicates that when the availability of fruits and vegetables within the home is low, intake patterns do not differ regardless of taste preferences
- In contrast, even when taste preferences for fruits and vegetables are low, if fruits and vegetables are available within the home, intake increases.

Author Conclusion:

Interventions to increase fruits and vegetable intake in adolescents need to target socio-economic factors such as greater availability of fruits and vegetables.

Funding Source:

Government:

Maternal and Child Health Bureau

Reviewer Comments:

Not applicable.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	Yes
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	N/A
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes