Increase Font Size Decrease Font Size View as PDF Print

Frenn M, Malin S, Bansal N, Delgado M, Greer Y, Havice M, Ho M, Schweizer H. Addressing health disparities in middle school students' nutrition and exercise. J Community Health Nurs. 2003 Spring; 20 (1): 1-14.

PubMed ID: 12581939
Study Design:
Non-Randomized Controlled Trial
C - Click here for explanation of classification scheme.
NEUTRAL: See Research Design and Implementation Criteria Checklist below.
Research Purpose:
  • To determine if a four-session Internet and video intervention with healthy snack and gym labs impacted dietary fat intake and weekly moderate and vigorous physical activity
  • Researchers also sought to determine if there were differences to the intervention in regard to race, gender, income level or school attended or to the number of sessions attended or use of the gym lab.
Inclusion Criteria:
  • Inclusion criteria included being a seventh or eighth grade student attending one of two participating urban middle schools in the Midwest
  • Marquette University's Institutional Review Board reviewed and approved this study.
Exclusion Criteria:

No explicit exclusion criteria stated. 

Description of Study Protocol:


Entire classrooms of seventh and eighth grade students (from two urban middle schools in the Midwest) were recruited to intervention or control groups based on classroom assignment to prevention diffusion of the intervention to the control group.


This study utilized a quasi-experimental design with assignment to group by classroom.

Dietary Intake/Dietary Assessment Methodology

  • Dietary intake was measured by using the Food Habits Questionnaire. This instrument includes a 21-item series of questions about consumption of high- and low-fat foods with a five-option response format. Low-fat items were reverse scored and an algorithm used to calculate percentage of fat, such that the resulting total score indicated percentage of fat in diet during the last month.
  • This instrument was found to have the same distributions of stage of change to low-fat diet when tested with Block’s Food Frequency Questionnaire (FFQ) modified to increase sensitivity to high fat foods
  • An interviewer read the survey aloud while students marked responses on their own copies.

Blinding Used

No discussion of blinding.


  • The intervention was conducted in four Internet sessions plus a healthy snack session and a gym class (one school only) of approximately 50 minutes (six total sessions). Interventions were delivered in the classroom computer lab.
  • For students identified as "Pre-contemplation" and "Contemplation" stages according to the Transtheoretical and Health Promotion models, Internet and video sessions focused on raising awareness of current eating and exercise, identifying benefits of both low-fat diet and exercise and overcoming barriers to consuming low-fat diets and participating in exercise
  • For those identified as "Preparation," "Action" and "Maintenance" students were prepared as "peer models" and led the healthy snack and exercise labs with the assistance of senior nursing students and faculty.

 Statistical Analysis: 

  • Descriptive statistics were used to examine percentage fat in diet and duration of moderate
    and vigorous activity
    • Child and Adolescent Activities Log (CAAL) activities include those of mild, moderate and vigorous intensity activities. Moderate intensity and vigorous activity were included in analysis because these reflect Healthy People 2010 goals for adolescents. Total activity was also analyzed, because this has value for improving health.
  • Statistical Package for the Social Sciences (SPSS) General Linear Model was used with age as a covariate to compare participants on variables by sex, race, eligibility for free or reduced fee lunch (proxy for family income) and school, as well as interactions among these demographic characteristics with response to the intervention
  • Pre-test data on each measure were subtracted from post-test data to create a difference score for analysis
  • The number of sessions with answers recorded in notebooks and online were summed.


Data Collection Summary:

Timing of Measurements

Variables were measured before the intervention and immediately after.

Dependent Variables

  • Decrease in dietary fat intake (Measured using the Food Habits Questionnaire)
  • Greater duration of weekly moderate and vigorous physical activity (Measured using the Child and Adolescent Activity Log (CAAL)).

Independent Variables

  • Benefits of low-fat diet
  • Barriers to low-fat diet
  • Access to low-fat food
  • Benefits of exercise
  • Barriers to exercise
  • Exercise access.

Control Variables

  • Race
  • Sex (gender)
  • Income level
  • School attended.
Description of Actual Data Sample:
  • Initial N: Sample included 341 students
    • Not all subjects completed instruments
    • For those with recorded data, 56 were males and 68 were females
  • Attrition (final N): This is unclear. Researchers stated that study was limited by the number of participants who completed all instruments with less than 20% missing data
  • Age: 12-15 years; Of those who completed instruments:
    • 90 were in seventh grade
    • 33 were in eighth grade
  • Ethnicity: Of those with recorded data:
    • 58 were African-American
    • 47 were White
    • Nine Asian
    • Four Hispanic
    • Four Native American
  • Other relevant demographics: Sample was two low-middle income urban schools in the Midwest
  • Anthropometrics: No discussion
  • Location: Urban city in the Midwest.
Summary of Results:
  • The difference in percentage fat between the intervention and control groups as a whole was not significant
    • Mean percentage of fat was 31% for the intervention group and 32% for the control group on both pre- and post-tests
  • Both control and intervention groups decreased their amount of moderate and vigorous activity, but the level of decrease in moderate and vigorous was less among the intervention group (-8.58 minutes) as compared to the control (-37.61 minutes; P=0.024)
  • The statistical analysis with significant interactions demonstrate that the effect of intervention varies from race to race and from boys to girls. Both the low-fat diet and physical activity aspects of the intervention resulted in significantly better outcomes for all but one racial subgroup in girls, who have the greatest risk of obesity later in life.
    • Percentage of fat in food was reduced significantly P=0.018 for Black, White and Black/Native American girls in the intervention group
  • Individual school analysis demonstrated that the number of sessions students responded to the Internet program online or in their notebook were associated with a decrease in their percentage fat in diet
  • The gym lab was only conducted in the first school. When demographic variables, as well as difference in exercise stage, pros and cons, were regressed on differences in total activity, the only significant variable was whether or not a physical activity lab was used (P=0.002) with an adjusted R2=0.24; F(9, 28)=2.325; P=0.042. Those with the peer-led gym lab increased their total physical activity, whereas those with only the Internet and video intervention decreased their total physical activity, but not as much as those in the control group.


Author Conclusion:
  • Interventions delivered through Internet and video may enable reduction of health disparities in students by encouraging those most at risk to consume 30% or less calories from fat and to engage in moderate and vigorous physical activity
  • The exercise session with peer-led, physical activity lab was effective in increasing moderate and vigorous activity. The Internet content alone prevented decrease in exercise to the degree it occurred in the control group. Adding an additional Internet session focused on exercise may be helpful, because Internet sessions can be administered across many schools with less personnel and without access to a gym. Most important, the intervention examined in this study significantly reduced percentage of dietary fat among girls, who are at greatest risk of obesity in later life.
Reviewer Comments:

A total of 341 students were included in the sample, but the study was limited by the number of participants who completed all instruments with less than 20% missing data. The resulting sample did not permit analysis of both diet and exercise variables in the same equation.

Research Design and Implementation 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)
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to nutrition or dietetics practice?
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies)
Validity Questions
1. Was the research question clearly stated?
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated?
  1.3. Were the target population and setting specified?
2. Was the selection of study subjects/patients free from bias?
  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?
  2.2. Were criteria applied equally to all study groups?
  2.3. Were health, demographics, and other characteristics of subjects described?
  2.4. Were the subjects/patients a representative sample of the relevant population?
3. Were study groups comparable?
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?
  3.3. Were concurrent controls used? (Concurrent preferred over historical controls.)
  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?
  3.5. If case control or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?
4. Was method of handling withdrawals described?
  4.1. Were follow-up methods described and the same for all groups?
  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%.)
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for?
  4.4. Were reasons for withdrawals similar across groups?
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study?
5. Was blinding used to prevent introduction of bias?
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?
  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.)
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status?
  5.5. In diagnostic study, were test results blinded to patient history and other test results?
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were intervening factors described?
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied?
  6.2. In observational study, were interventions, study settings, and clinicians/provider described?
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured?
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described?
  6.6. Were extra or unplanned treatments described?
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?
  6.8. In diagnostic study, were details of test administration and replication sufficient?
7. Were outcomes clearly defined and the measurements valid and reliable?
  7.1. Were primary and secondary endpoints described and relevant to the question?
  7.2. Were nutrition measures appropriate to question and outcomes of concern?
  7.3. Was the period of follow-up long enough for important outcome(s) to occur?
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?
  7.5. Was the measurement of effect at an appropriate level of precision?
  7.6. Were other factors accounted for (measured) that could affect outcomes?
  7.7. Were the measurements conducted consistently across groups?
8. Was the statistical analysis appropriate for the study design and type of outcome indicators?
  8.1. Were statistical analyses adequately described and the results reported appropriately?
  8.2. Were correct statistical tests used and assumptions of test not violated?
  8.3. Were statistics reported with levels of significance and/or confidence intervals?
  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)?
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?
  8.6. Was clinical significance as well as statistical significance reported?
  8.7. If negative findings, was a power calculation reported to address type 2 error?
9. Are conclusions supported by results with biases and limitations taken into consideration?
  9.1. Is there a discussion of findings?
  9.2. Are biases and study limitations identified and discussed?
10. Is bias due to study’s funding or sponsorship unlikely?
  10.1. Were sources of funding and investigators’ affiliations described?
  10.2. Was the study free from apparent conflict of interest?