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

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

To influence health behavior and CVD risk factors in 13- to 15-year-old children in a two-year school- and community-based intervention in North Karelia, Finland.

Primary objectives:

  1. Prevent smoking
  2. Influence dietary habits to reduce serum cholesterol and blood pressure levels
    •  Total fat, saturated fat and cholesterol
    • Partially substitute saturated fat with polyunsaturated fat
    •  Vegetables and fiber
    •  Sodium.

Secondary objectives: (promoted with less intensity)

  1.  Physical activity
  2.  Prevent overweight
  3. Other principles of a healthy diet (e.g., ? sugar).


Inclusion Criteria:
  • Participated in both baseline and post-test survey
  • Had physical examinations.
Exclusion Criteria:

None described.

Description of Study Protocol:

Intervention Groups

  • Intensive direct intervention (II)
  • General community-wide intervention (CI)
  • Control (CL).

Sites of Intervention/Measurement

  • II - Two randomly selected schools (one rural, one urban)
  • CI – Rest of North Karelia county (evaluation in two schools [one urban, one rural] matched on municipality sociodemographics)
  • CL - Two matching schools in another nearby county.

Intervention Approach in II Schools

  • Based on WHO protocol (WHO, 1979) and the international ‘Know Your Body” (Williams, 1977) programs
  • Comprehensive educational activities to teach practical skills (not just health knowledge) and promote an environment supportive of the behavioral objectives
  • Aimed to involve children, homes, teachers and rest of community
  • Included practical preventive services by health personnel.

Anti-smoking program:

  • Aim: Resist social pressure to smoke
  • Administered by: Older peer leaders in classroom setting
  • Sessions: Ten 45-minute sessions over two-year included informative materials, skills training and role plays.

Dietary program:

  • Aim: Reduction of total fat and cholesterol intake, increase in polyunsaturated fat and dietary fiber consumption, and decrease in sodium intake (no set quantitative goals for individuals, rather aimed to change as much as feasible); at II schools
  • In school meals: Butter replaced by margarine, whole milk replaced by skim milk, butter milk or water; vegetable oil used for salad dressings and cooking, low-fat meat products promoted, fresh salad promoted and egg yolks avoided, food companies serving schools asked to reduced Na, and salt substitute used. Changes reduced the percentage of energy of fat from 37 to 32% fat and sodium was reduced by approximately 1g NaCl.
  • Administered by: Unknown; A nutritionist visited the homes of children in the upper 15th percentile of cholesterol and blood pressure distributions
  • Sessions: ‘Healthy diet discussed in some school lessons.’


  • Parent gatherings
  • Leaflets, posters, written recommendations, project magazine, general information through the mass medias
  • Screening results explained to children by school nurse
  • Special health passport used
  • Behavior change in different classes followed by repeated small surveys, results of which were displayed and discussed at school.

Intervention Approach in CI Schools

  • Same measures as above recommended to other schools in North Karelia
  • Provided training and materials.

Statistical Analysis

  • ANOVA: To test differences in three school pairs at baseline and post-test
  • T-test or X2 test: To compare changes between two intervention school pairs and control schools 
  • ANOCOVA: To control for baseline measures.
Data Collection Summary:

Dependent Variables

  • Diet (questionnaires of parents and children)
  • Urinary Na (to assess diet changes)
  • Smoking (questionnaire and serum thiocyanate)
  • Health knowledge (questionnaire)
  • Cholesterol (serum)
  • Blood pressure
  • BMI (measured weight and height by standardized protocol)
  • Triceps skinfold
  • Sexual maturity (Tanner staging).

Independent Variables

Intervention group (see above).

Control Variables

  • Gender (separate analyses)
  • Baseline values (in some analyses?).
Description of Actual Data Sample:
  • Original sample: 966 children (99.3% of all children in the six schools)
  • Withdrawals/Drop-outs: 115 children
    •  54% had left school
    •  40%  absent at school or did not want to participate
  • Final sample: 851 children (87% of boys and 90% of girls in original sample)
  • Age: 
    • 7th grade (mean 13.4 years) at baseline
    • 9th grade (15 years) at post-test
  • Location: County of North Karelia, Eastern Finland
  • Duration: 
    • Two years (Fall 1978 to  Fall 1980)
    • Baseline and post-test measures done in six weeks at same time of year
  • Race/Ethnicity: Finns
  • SES: Not described.
Summary of Results:


  • BMI: Non-significant (NS) differences
  • % Overweight (BMI greater than 24kg per m2): NS differences between the three groups at baseline or at follow-up [Proportion overweight was small, ~4%)
  • TSF: II > CI or Ctl among boys only (P<0.005); decreased in boys in CI and Ctl, but note that sexual maturity II < CI or Ctl  in boys (p<0.05)
  • Weight: CI < II and Ctl in girls (P<0.005)
  • Height: NS differences.


  • Boys: II (change of + 12.6%) and CI (change of +8.2%) < Ctl  (change of +29.7%) (P<0.001 between Il and Ctl)
  • Girls: II (change of +9.0%) < Ctl (change of 20.0%) (P<0.05); CI (change of +18.0%) not different from Ctl.


  • Baseline: Boys averaged 26g fat from milk and 22 to 28g fat from butter per day; girls averaged 20g fat from milk and 14 to 19g fat from butter per day 
  • Mean amount fat from milk and butter: II (change of -8g in boys [-17%], - 16g in girls [-46%]) < Ctl (change of +3g in boys, -5g in girls) (P<0.001); NS difference between CI and Ctl
  • Although NS, mothers reported use of vegetable oil and low sodium salt at home increased among all three groups
  • Approximately half of mothers reported reduced fat consumption at home
  • Butter on bread: Decreased in all three groups; NS difference?
  • Extra salted butter or margarine: Decreased in II (P=?)
  • Use less salt at home: Increased in II? (P=?)

Physiological Measures

  • Total serum cholesterol: NS difference among boys; among girls II < Ctl (P<0.01) and CI < Ctl (P<0.05)
  • Systolic blood pressure: NS difference among boys or girls; slight difference (ANOVA P<0.01) between groups in girls disappeared after adjusting for changes in sexual development, height and weight
  • Diastolic blood pressure – II and CI > Ctl among boys (ANOVA P<0.01), but difference disappeared after adjusting for changes in sexual development, height and weight; NS difference among girls.
  • Urinary sodium: NS differences

Health Knowledge, Attitudes, Emotional Problems

  • Health knowledge score: NS differences among boys; among girls II (but not CI) > Ctl (P<0.05) [breakdown of subscores showed that this positive net change among II school girls was due to better performance in questions concerning cholesterol and blood pressure)
  • Health attitude score: Reduced in all groups (indicating a less positive health attitude); worse among II boys, but significance of difference not provided
  • Psychosomatic symptoms scale: NS differences among girls; among boys II (but not CI) < Ctl (P<0.01); when adjustment made for initial differences between groups, differences disappeared.


Author Conclusion:
  • This educational program was relatively effective in preventing smoking increase among children of the critical age
  • The nutritional program was more effective among girls than boys. Among girls the dietary changes were also related in respective changes of serum cholesterol levels. These effects were obtained by a broad-ranged intervention which taught practical skills and influences the social and physical environment, but did not emphasize increase in detailed health knowledge. The results also indicate that the program hardly had any major harmful emotional effects.
  • We consider the North Karelian Youth Project as a promising pilot study to test the hypothesis that health-related behaviors can be influence in adolescence by a comprehensive educational program
  • Obviously, we need further studies to confirm our experience as well as studies dealing with different age groups, those designed to test the value of different educational strategies and careful measurement of intervening variables, and those with much longer follow-up to assess the long-term implications of such activities.
Funding Source:
Government: NPHI (Finland), Finnish National Board of Health and Board of Education
Reviewer Comments:


  • Large sample size and good subject retention
  • Long duration
  • Multiple intervention components
  • Measures to ensure comparability between baseline and post-test measures (e.g., same measurer, same month of year)


  • Slight variations in N for different assessments not explained; not always clear when adjusted for baseline differences
  • Significance of other comparisons not always clear
  • Unclear intensity of intervention (e.g., how frequently lessons taught, degree of change in school food service), especially in CI group, no blinding of anthropometric measurements
  • Intervening variables measured only to limited extent (e.g., no assessment of physical activity and other critical dietary components such as energy, vegetables, fiber, sugar)
  • Unclear validation of diet-related questionnaire
  • Difficult to say whether two matched schools and "reference" schools represent the rest of North Korelia and county in Eastern Finland.

Other Comments:

Details on intervention described in greater detail in Puska et al. The North Karelia Project. A community-based intervention study on CVD risk factors among 13- to 15-year-old children: Study design and preliminary findings.  Prev Med 1981;10:133-48.


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? N/A
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? ???
  2.3. Were health, demographics, and other characteristics of subjects described? No
  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? ???
  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? 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? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  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? 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? No
  7.1. Were primary and secondary endpoints described and relevant to the question? No
  7.2. Were nutrition measures appropriate to question and outcomes of concern? ???
  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? No
  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)? 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