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


Webber LS, Osganian SK, Feldman HA, Wu M, McKenzie TL, Nichaman M, Lytle LA, Edmundson E, Cutler J, Nader PR, Luepker RV. Cardiovascular risk factors among children after a 2 1/2 –year intervention – The CATCH study. Prev Med 1996; 25: 432-41.

Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To compare differences between control and intervention CATCH groups and present differences on the basis of ethnicity, gender and site.

Inclusion Criteria:
All 3rd grade students in selected schools invited.
Exclusion Criteria:
None provided
Description of Study Protocol:

24 schools randomized (after baseline measurements complete) to control or intervention; Intervention schools further randomized into 2 equal subgroups (half receiving family-based program and other half not).

Intervention: (see Luepker, 1996 for details)

  • Student education
  • Moderate to vigorous PA in PE
  • Modified school lunch
  • ±Home programs

Statistical Analysis:

  • Data pooled for both intervention groups because no difference
  • Skinfolds log-transformed
  • Mixed-model ANOCOVA used
Data Collection Summary:

Dependent – Individual level

  • Blood lipids – total, HDL cholesterol & apolipoprotein B (non-fasting sample)
  • Blood pressure
  • Skinfolds (TSF, SSF)
  • BMI (measured wt, ht)


  • Original CATCH program group (see above)

Control Variables (for BMI & skinfolds)

  • Age
  • Site
  • Gender
  • Ethnicity
  • Intraclass correlation within school & student
  • Gender x ethnicity interaction
  • Baseline value.
Description of Actual Data Sample:

Original Sample: 5106 children, grade 3 (60.4% of available population) from 10 C & 14 I (half with and half without family component) public schools [no explanation for why different numbers of schools from Luepker, 1996 and Nader, 1999; in acknowledgements thank staff from 96 schools in 12 districts]

Withdrawals/Drop-Outs:  1087 children (reasons not specified); no differences, after adjusting for covariates, in baseline measures with 4019 f/u participants except 0.7 y older (p<0.001)and 8 mm taller (no p value provided)

Final Sample: 4019 students, grade 5 (79% of original sample) 

Location: San Diego, CA; Houston, TX; New Orleans, LA, Minneapolis, MN

Duration:  2.5 year intervention (fall 1991-spring 1994)

Race/Ethnicity:  Original and final cohort = 30.1% minority

SES:  not described

Summary of Results:


  • 79.6% W, 79,8% H, 75.1% AA, 76.8% Asian, 64.0% Native American
  • 83.9% TX, 81.1% MN, 77.7% LA, 73.1% CA
  • 78.1% control, 79.6% school intervention, 78.7% school + family intervention


  • 0 difference in BMI for W & H children
  • BMI in AA children
  • 0 difference in TSF or SSF (all ethnic groups)
  • Differential effects by ethnicity:  AA children were heavier and had greater triceps and subscapular skinfold thicknesses than did C and H children.
  • Differential effects by gender:  boys had greater skinfolds than girls; girls, particularly AA girls, were taller, perhaps reflective of the earlier growth spurts.

Other Physiological Measures:

  • 0 difference in heart rate or BP
  • 0 difference in blood lipids

Differential effects by gender:  boys had greater total and HDL-cholesterol, and apolipoprotein-b levels than girls; girls had greater heart rates than boys.  No differences between boys and girls were noted for blood pressure levels. 

Author Conclusion:

CATCH positively affected the school environment and the health behaviors of the children. Although these changes did not translate to significant changes in risk factors at these ages, they have the potential for promoting positive health behaviors into adulthood.   In addition, the differential effects noted by gender and ethnic group add to the body of the literature on the epidemiology of risk factors during childhood and may enhance the development of more specific intervention programs.

Funding Source:
Government: National Heart Lung and Blood Institute of the US Public Health Service
Reviewer Comments:


  • Large sample size (CATCH is largest school-based randomized trial ever conducted), protocols well described.


  • Did not adjust for maturation,
  • unclear why difference in number of schools reported compared to other CATCH papers,
  • no blinded assessment,
  • no analysis of relationship between behavior change and adiposity,
  • dose (1-2 sessions of 40 min per week for 12-15 weeks) and duration of intervention might not have been enough.

Other Comments:

Although not explicitly stated in the paper, prevention of OB was not a goal of CATCH, but rather aimed to avoid growth inhibition

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? No
  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 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? 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.) Yes
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? Yes
4. Was method of handling withdrawals described? No
  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? Yes
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? 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.) Yes
  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? Yes
  5.5. In diagnostic study, were test results blinded to patient history and other test results? Yes
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? Yes
  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? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? No
  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? Yes
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? ???
  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? No
  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)? No
  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