PWM: School-based Programs to Prevent Overweight (2006)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To present the design, implementation and the preliminary outcomes of 3 years of the program’s application from grade 1 through 3, on targeted variables such as children’s and parents’ health knowledge, and children’s physical fitness and physical activity out of school.

Inclusion Criteria:

All children registered in the first grade of primary schools throughout three counties of Crete in September 1992.

Exclusion Criteria:
None specified
Description of Study Protocol:

Preparatory phase: development of teaching materials using health profile component of “Know Your Body” program of American Health Foundation.

Classroom modules designed to develop behavioral capability, expectations, and self efficacy for healthful eating, physical activity and fitness; learning methods included modeling, self monitoring, skill development, verbal praise, cues and reinforcing messages.

Health and nutrition components conducted by classroom teacher, incorporating 13-17 hours of classroom material annually.

Physical fitness and activity component of 4-6 hours of classroom material per year delivered by physical education instructor and fitness oriented exercise sessions in playground.

Four 3 hour teacher orientation seminars used for training.

Parental involvement: two meetings with presentation on importance of relevant topics and encouragement of modification of parent and children dietary and exercise habits held annually at each intervention school; parents also given file with children’s screening results. Control group: no parental education sessions, results only mailed to parents with no meetings.

Data Collection Summary:


  • Health knowledge scores, anthropometric measurements, physical fitness, serum lipids, behavioral data concerning diet and physical activity.
  • Data collected during morning visits between 8:30am and 1pm; maximum of 30 pupils and parents screened each day by one large or two small teams of trained personnel.
  • Pupil’s health knowledge measured by multiple choice questionnaire with color illustrations at beginning and end of 3 year intervention period.
  • Parents asked to report children’s physical activities during two consecutive weekday afternoons and one weekend day through observation; parental report validity tested on subsample of 39 children using heart rate monitoring during corresponding hours of reported days.
  • Physical fitness assessed with use of EUROFIT Tests Protocol.
  • Body weight measured by digital scale, standing height measured with stadiometer, skinfold thicknesses measured with Lange skinfold caliper.
  • Parental data obtained through questionnaire.


Health and physical education intervention in class and on playground; structured program of physical activity and supervision by physical education instructor; parental involvement.

Control Variables


Statistical Analysis

Repeated measures ANOVA with covariates sex and parental education to measure health knowledge; ANOVA with covariates sex, height, weight at follow-up to measure physical fitness; multiple linear forward regression analysis to examine variance in physical fitness; regression analysis to compare improvement by gender and geographic area.

Description of Actual Data Sample:

Original Sample: total 4171 children in intervention group, 1510 children in control group; random sample of 538 children from 24 schools in intervention group and 424 children from 16 schools in control group selected for comparative evaluation (962 total - 509 boys and 453 girls)

Withdrawals/Drop-Outs: not specified

Final Sample: baseline from 962 (509M, 453F; participation rate at baseline 94%); after 3 year intervention, measures obtained for random subsample of 393 pupils – 231 from intervention group, 162 from control group (participation rate 92%)

Location: Crete - Iraklio and Rethimno counties for intervention, Chania county for control.

Race/Ethnicity: not specified

SES: 49.8% from urban areas, 50.2% from rural areas.

Summary of Results:

Statistically greater improvements in the intervention group observed for both children’s and parents’ health knowledge and children’s standing broad jump, situps, sit-and-reach, handgrip and endurance run test. Time spent on moderate to vigorous physical activities out of school significantly increased for intervention group children.

Statistically smaller increases in intervention group observed in suprailiac skinfold and BMI relative to control group.

Change in suprailiac skinfold 1.2 in intervention group and 2.5 in control group (p<.001).

Change in BMI 0.7 for intervention group and 1.7 in control group (p<.0005).

Author Conclusion:

Significantly smaller increase in BMI and suprailiac skinfold in intervention group might have resulted from intervention program.

Significant increase in children’s physical activity, physical fitness and smaller increase in body fat in intervention group might be related to increased health knowledge observed in this group and their parents.

Overall, results indicate that health education intervention can achieve short term effects in as young as 6 year old children.

Funding Source:
Government: European Union, Mediterranean Integrated Program of Crete
Foundation associated with industry:
Reviewer Comments:

Weaknesses: focused mainly on physical education with limited discussion of measures of adiposity.

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? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
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) No
  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 or comparisons used? (Concurrent preferred over historical control or comparison groups.) 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 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? No
  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? No
  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? 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? N/A
  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? 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? 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)? Yes
  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? No
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