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

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

To assess the outcomes of health behavior interventions, focusing on the elementary school environment, classroom curricula, and home programs, for the primary prevention of cardiovascular disease.

School-level aims:

  • decrease fat (to 30% total energy) and sodium (to 600-1000 mg/svg) in food service lunch
  • increase moderate-vigorous PA in PE (to 40% class time)

Individual-level aims:

  • primary  - decrease blood cholesterol (basis of sample size calc; expected difference = 5.1 mg/dl)
  • secondary - change psychosocial factors, self-reported dietary fat and sodium intakes, time engaged in moderate-vigorous PA, and systolic BP
Inclusion Criteria:
  • Schools – near one of four study centers, ethnic distribution (criteria not specified), food service potential for intervention, commitment to offering PE >90 min/wk, participate in 3-y study & cooperate with random assignment
  • Subjects – agree to provide blood sample at baseline and f/u
Exclusion Criteria:
None provided
Description of Study Protocol:

96 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).


  • Student education – Adventures of Hearty Hear and Friends, Go for Health-4, & go for Health-5 for grades 3, 4, & 5, respectively (16 lessons/y of 30-40 min ea by classroom teachers that emphasized eating habits [grades 3-5], PA [grades 4-5], & smoking [grade 5]; classroom teachers trained 1-1.5 days/y)
  • Moderate to vigorous PA (40% of PE) by PE specialists & classroom teachers trained 1-1.5 days/y)
  • Modified school lunch - ‘Eat Smart” (30% kcals from fat, 10% from sat fat, Na 600-1000 mg/svg, while maintaining recommended levels of other nutrients; food service personnel received 1-day training session at beginning of each school year + monthly f/u visits and booster sessions )
  • ±Home programs (19 packet curricula and 2 family fun nights over 3 y)

Safety & quality control monitored by respective committees throughout study.

Statistical Analysis: (described elsewhere)

  • Single-stage, mixed-modeling to account for randomization at school level while most outcome data were collected by repeated measure of individuals
  • School-level analyses – by repeated measures ANCOVA
  • Individual-level analyses – by mixed-model ANCOVA

No adjustment of p values for multiple comparisons or multiple outcome measures, since no appropriate denominator for the type I error rate was feasible, given the multiple research questions addressed

Data Collection Summary:

Dependent Variables

Dependent – School level:

  • Program implementation (described elsewhere)
  • Macro & micronutrients in school lunch (recipe & menu analysis)
  • PE length & PA type (System for Observing Fitness Instruction Time or SOFIT)

Dependent – Individual level:

  • Dietary knowledge, intentions, usual food choices, social reinforcement & support, self-efficacy (Health Behavior Questionnaire)
  • Daily food & nutrient intake (24-hr recall) – in subsample of 30 students per school
  • Type, duration, and intensity of selected leisure time PA, TV watching & video games (Self-administered Physical Activity Checklist) – in 5th graders only
  • Blood lipids – total, HDL cholesterol & apolipoprotein B (non-fasting sample)  - in 45% randomly selected subsample
  • Blood pressure
  • Skinfolds (TSF, SSF)
  • BMI (measured wt, ht)
  • Aerobic fitness (9-min run test)

Independent Variables

  • CATCH program group (see above)

Control Variables

School level:

  • Observation days within semester & lessons within observation days
  • Location of the lesson (inside, outside)
  • Specialty of the teacher (PE, classroom)

Individual level:

  • Baseline value
  • Gender
  • Ethnicity
  • CATCH field site
  • Random effect of school with site and intervention group
  • Age, Ht, BMI as predictors of risk factors
  • Weather conditions as predictor of 9-min test run
Description of Actual Data Sample:

Original Sample: not well described

Withdrawals/Drop-Outs:  not well described:  “A substantial number of students left the district prior to the end of the study but were tracked within a 100-mile radius and underwent measurements to enable analysis according to the intention to treat principle.”

60.4% of 5106 students participated in baseline measure; 79% (4019 of 5016) participated in f/u measures

Final Sample: 5106 students (school level data), 4019 students (most individual level data), 1182 (24-hr recall), 2995 (9-min test run), initially 3rd grade (mean age 8.76 y at baseline for 5106 students) and ending in 5th grade,  from 40 C & 56 I public schools from 12 school districts (equal numbers per study site)

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

Duration:  3 school y (fall 1991-spring 1994)

Race/Ethnicity:  69% W, 13% AA, 14% H

SES:  not described

Summary of Results:

Baseline comparison:

  • No differences between C & I groups by site, sex, or ethnic group
  • No differences in any endpoint between those who were and were not lost to followup
  • No differences in followup participation by intervention group or sex, although AA students and students in CA more likely to have dropped out

Program Implementation:

  • Training sessions attended by 86% school food service cooks, 94% PE specialists, 86% classroom teachers
  • >90% school food service guidelines met
  • >80% PE activities implemented
  • >88% of curriculum sessions completed
  • >70% families participated in some home curricula during each grade level
  • >63% families attended a family fun night
  • 100% of schools had family fun nights
  • >90% specified family fun night activities implemented

Intervention Effects:

School-level -

  • 70-75% school lunch participation
  •  fat in school lunch (from 38.7 to 31.9% in I vs. 38.9% to 36.2% in C schools, p<0.001)
  •  energy & saturated fat content in school lunch (p<0.01)
  • 0 difference in Na in school lunch (increased nonsignificantly in both C & I schools)
  •  K in school lunch (p<0.01)
  • 0 difference in PE length (mean = 30 min/lesson)
  •  PA intensity in PE (time spent at moderate to vigorous p<0.02, time spent at vigorous activity p<0.04)

Individual level -

  •  dietary knowledge, dietary intentions, self-reported food choice changes
  •  diet & PA self-efficacy at end of 3rd year (3rd grade?), but not at f/u
  •  dietary knowledge was only variable that differed b/t school + family & school-only groups
  •  rise in dietary energy (p<0.01)
  •  dietary fat (32.7% to 30.3% in I vs. 32.6% to 32.2% in C, p<0.01)
  •  saturated fat (p<0.01) and cholesterol (p<0.05)
  • 0 difference in Na intake
  • 0 difference in total PA (145.5 min in I vs. 154.8 min in C)
  •  vigorous PA (58.6 min in I vs. 46.5 min in C, p<0.003)
  • 0 change in BMI, TSF or SSF
  • 0 change in blood lipids ( cholesterol, but not significant)
  • 0 change in blood pressure
  • 0 change in 9-min test run
Author Conclusion:

The CATCH intervention was able to modify the fat content of school lunches, increase moderate-to-vigorous PA in PE, and improve eating and PA behaviors in children during 3 school years.

Review of the secondary end points suggests significant and consistent changes in targeted psychosocial factors, lower fat intake, and increased physical activity among children in the intervention schools, but not detectable changes in risk factors. 

Data on height and weight also suggest that this recommended eating pattern did not inhibit growth.

The lack of changes in cholesterol levels and other physiological risk factors, although disappointing, is not surprising . . .given the magnitude of the changes in food intake and physical activity across the population.

The secondary comparison in the study between the school-based programs and the school-plus-family program revealed only a modest benefit in dietary knowledge by adding the family component.  These findings suggest that a family-based program may also need to be more extensive or more intensive in implementation than was possible in the CATCH.

The CATCH intervention demonstrates that the policies and practices of schools can be changed without substantial new school resources and time.  The changes observed positively affected health behaviors and met national recommendations.  These changes, when spread across the entire school-based population, have the potential to produce long-term cardiovascular health benefits.  Moreover, these school-based programs were introduced with minimal but concentrated and effective training of existing school personnel and modest follow-up support from CATCH intervention staff.  The CATCH, therefore, provides an important model of a school-based health promotion program for the primary prevention of CVD that should be feasible and effective for American’s schools.

Funding Source:
Reviewer Comments:


  • Large sample size,
  • assessed program implementation,
  • protocols well-described,
  • review boards included,
  • educational + environmental intervention,
  • intention to treat analysis.


  • Did not adjust for maturation,
  • no blinded assessment,
  • no description of why children lost to follow-up,
  • unclear how 30 children/school selected for 24-hr recall diet assessment,
  • no analysis of relationship between behavior change and adiposity,
  • may not have had sufficient statistical power for cholesterol endpoint.

Other Comments:

Although not explicitly stated in the paper, prevention of obesity 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? ???
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? 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)? 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