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Citation:

Haerens L, Deforche B, Maes L, Cardon G, Stevens V, De Bourdeaudhuij I. Evaluation of a 2-year physical activity and healthy eating intervention in middle school children. Health Educ Res. 2006; 21(6): 911-921.


PubMed ID: 17032704
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
POSITIVE: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

To evaluate the two-year effects of an intervention targeting physical activity and healthy eating in middle schools.

Inclusion Criteria:
  • Middle school children
  • Seventh and eighth graders.
Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment 

A random sample of 15 schools out of the 65 schools with technical and vocational education in West Flanders (Belgium) was selected to participate in this study.

Design

Group randomized controlled trial

Intervention

A school-based intervention program to promote healthy food and physical activity over two school years (October 2003 to June 2005) was developed.

Statistical Analysis

  • Data were analyzed using SPSS 12.0. Preliminary analyses consisted of descriptive statistics of sample characteristics.
  • Linear mixed models on baseline demographics and behaviors were used to conduct drop-out analyses with group (participating and not participating at follow-up) entered as a factor
  • To assess effects of the second intervention year per se, linear mixed models were applied on two-year post-measures of physical activity and eating behaviors, co-varying for one-year post-measurements (Post One to Post Two)
  • To assess two-year post-intervention effects, linear mixed models were then repeated, co-varying for pre-test values (Pre to Post Two). Since one-year post-intervention effects showed clear gender differences, all analyses were applied in boys and girls separately. Condition (intervention or control) was entered as a factor into the models
  • Schools were nested within condition to take into account possible school variance. All analyses were adjusted for age and SES
  • To assess specific differences in effects between intervention with parental involvement and intervention without parental involvement, linear mixed models analyses were repeated
  • P<0.05 were considered as statistically significant.
Data Collection Summary:

Timing of Measurements

  • Beginning of the first school year (Pre-test, September 2003)
  • Assessed at the end of the first school year (Post One, May to June 2004)
  • Repeated at the end of the second school year (Post Two, May to June 2005).

Dependent Variables

  • Physical activity was measured with questionnaires in the total sample and with accelerometers in a sub-sample of children
  • Fat intake, fruit, water and soft drink consumption were measured using food-frequency questionnaires.  

Independent Variables   

  • The 15 schools were randomly assigned to one of the intervention or control conditions (intervention with parental involvement, intervention alone or control condition)
  • In 10 schools, an intervention, combining environmental changes with computer-tailored feedback, was implemented over two school years
  • In five intervention schools, increased parental support was added.

Control Variables

  • Age
  • SES.
Description of Actual Data Sample:
  • Initial N: 2,840 (girls, 36.6%). The parents of 2,840 (95%) of the 2,991 pupils in seventh and eight grades signed an informed consent in which authorization was provided for their child to complete measurements
  • Attrition (final N): 2,287 (girls, 38.1%). Data of 704 children were lost through follow-up due to absence at measurements, children changing school or questionnaires filled out inaccurately
  • Age: 13.1±0.8 years
  • Anthropometrics: Pupils not participating at follow-up were significantly older and consumed significantly more soft drinks than pupils participating at follow-up
  • Location: West Flanders (Belgium).
Summary of Results:

Key Findings

  • Significant positive intervention effects on physical activity in both genders
  • No significant (NS) increase or decrease of the intervention effects on physical activity and eating behaviors was found as a result of the second intervention year per se (Post One to Post Two)
  • Effects of parental involvement on fat intake in girls showed that there were no significant differences between the intervention with parental support and that without parental support (F=0.4, P=0.6)
  • In boys, significant two-year post-baseline intervention effects on levels of physical activity, but not on eating behaviors, were found
  • School-related physical activity increased significantly more in the intervention groups compared with the control group (P<0.05)
  • Accelerometer data revealed a trend for significant lower decreases in physical activity of light intensity in the intervention groups (-6 minutes per day) compared with the control group (-39 minutes per day, P<0.001). Where time spent in MVPA remained stable in the intervention group, it significantly decreased (-18 minutes per day) in the control group (P<0.05)
  • In girls, significant two-year post-baseline intervention effects were found for both physical activity and eating behaviors
  • In girls, the physical activity intervention was effective in preventing decreases in physical activity of light intensity
  • Time spent in physical activity of light intensity decreased significantly less in the intervention groups (-2 minutes per day) compared with the control group (-20 minutes per day, P<0.05)
  • Decreases in fat intake and percent energy from fat were significantly higher in the intervention groups (-20g per day) when compared with the control group (-10g per day, P<0.05)
  • In the same line, percentage of energy taken from fat significantly decreased with 9% in the intervention group and with 5% in the control group (P<0.001).
Author Conclusion:
  • Physical activity and eating behaviors of middle school children can be improved by school-based strategies combining environmental and personal interventions
  • The use of personalized computer-tailored interventions seems to be a promising tool for targeting adolescents, but needs to be further explored.
Reviewer Comments:
  • Significant differences between participating and non-participating pupils.
  • Increased parental support added in five intervention schools, but not all intervention schools 
  • Authors note the following limitations:
    • Lack of process evaluation data on levels of parental involvement makes it hard to draw conclusions
    • High percentage of dropouts (25%)
    • Self-reported character of measurements of dietary intake and physical activity.

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)
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 nutrition or dietetics practice?
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?
Yes
  3.3. Were concurrent controls used? (Concurrent preferred over historical controls.)
Yes
  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?
N/A
  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.)
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?
Yes
  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?
???
  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?
No
  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?
Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described?
N/A
  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?
Yes
  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?
Yes
  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?
Yes
  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?
Yes
  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
 
 

Copyright American Dietetic Association (ADA).