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

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

KOPS (an ongoing 8 y follow-up study) aims to reduce the mean BMI in the whole population by concerted school interventions directed at children, parents and teachers. In addition, family intervention is directed at high risk individuals (eg children of obese parents) as well as at overweight and obese individuals to prevent weight gain and/or to reduce body weight.

Inclusion Criteria:
There were no eligibility criteria except willingness to participate.
Exclusion Criteria:

Children with incomplete datasets were excluded.

Description of Study Protocol:

A control group and two intervention groups were followed. Interventions took place at schools for all children, parents and teachers as in families of overweight and obese children and parents.

The school intervention aimed at nutrition education and health promotion for all children, their parents as well as their teachers was performed in the intervention schools every year. The behavioral and educational messages given to all children and their parents were:

  1. Eat fruit & vegetables each day,
  2. Reduce the intake of high fat foods,
  3. Keep active at least 1 hour a day,
  4. Decrease TV consumption to less than 1 hour a day.

An 8 h course of nutrition education including so called “active breaks” was offered by a skilled nutritionist together with a teacher. The messages were also addresses to their parents at a parent’s evening. Teachers were trained regularly by a structured nutrition education program within a continuation class.  Every alternating year school changed and the control school became intervention schools and vice versa.

In addition, family intervention plus a structured sports program were offered to families with overweight or obese children and also to families with normal weight children but obese parents. Families with overweight and obese children and/or obese parents (BMI > 30) were offered a face-to-face counseling and support program within the family environment. It consisted of 3-5 home visits organized by a nutritionist.

Data Collection Summary:


  • Change in fat mass: Overweight & Obesity, defined as triceps skinfold thickness as a parameter of fat mass (90th TSF percentile was used as a cut-off value (14.5 & 12.9 mm for girls & boys, respectively),
  • Change in BMI for children (measured ht & wt),
  • Body composition (bioelectrical impedance analysis),
  • Dietary intake (food frequency),
  • Activity (questionnaire)



The effect of the intervention.


  • age,
  • education,
  • current marital state,
  • employment,
  • social state,
  • ethnicity (questionnaire),
  • parent’s BMI
  • body composition.

Control Variables

Schools were matched for socio-demographical variables.

Statistical Analysis

Not reported

Description of Actual Data Sample:

Original Sample: 2440 5-7-y-old children were recruited (30.2% of the total population of 5-7 y.o. children examined by the school physician) and a full data set was obtained from 1640 children.

Between 1996 & 2000, school interventions targeted a total of 414 children and their parents as well as 30 teachers. In addition, 92 out of 368 eligible families completed the family intervention program.

Final Sample: 297 children had complete baseline data and 1-yr f/u data (136 in the intervention group & 161 in the control group).

# of schools n/s; # of male/female n/s.

Location: city of Kiel, northwest Germany

Race/Ethnicity: N/A

SES: N/A – note control schools were socio-demographically-matched.

Summary of Results:

3 month follow-up

The short-term effects were studied for all children within 3 months after the end of the interventions.

Fruit & Vegetable Intake

Regarding family intervention daily fruit & vegetable consumption increased by 50% (from 50% to 60% of the children). Changes were significant at P<0.05. Note: actually number of servings was NOT stated.

Dietary fat

The frequency of daily intake of low fat foods increased from 20 to 50%. Changes were significant at P<0.05. Again, note: actually number of servings was NOT indicated – and how low fat foods were defined was also NOT indicated.

TV watching

An increase in PA was associated with a decrease in TV watching from a mean value of 1.9 h to 1.6 h/d. Changes were significant at P<0.05.

After 1 year

The nutritional state of children in the intervention schools was reassessed after a period of 1 year. Data were compared to nutritional state of children in control schools.

Fat Mass

There was a significant change in fat mass in both groups. When compared with children of intervention schools children of control schools showed disproportionate increases in the median TSF (mean values 13.0 vs 11.3 mm at 1 yr follow-up, P<0.01) as well as in percentage fat mass of overweight children (increased by 3.6 vs 0.4%, P<0.05). No group differences in the distribution of TSF were observed at baseline.

Author Conclusion:

Author’s words from the discussion:

"First results of KOPS are promising. Besides health promotion, a better school education and social support seem to be promising strategies for future interventions."

Funding Source:
Schwartauer Werke AG (Bad Schwartau), Team Success AG (Selent), , Hansa Tiefkuhlmenu (Hilter), Data Input (Frankfurt), Wirtschaftliche VereinigungZucker (Bonn)
Food Company:
Commodity Group:
Foundation associated with industry:
Reviewer Comments:

It was unclear why so few of the students were available for the intervention. 1640 children had complete datasets yet only 297 children had completed the year in the intervention or control school.

Only 92 of 368 eligible families completed the family intervention program.  It's unclear whether intent-to-treat analysis was done.

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? No
  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) 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? 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? 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? No
  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.) ???
  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? ???
  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? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  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? 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)? ???
  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? N/A
  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