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Citation:

Vandongen R, Jenner DA, Thompson C, Taggart AC, Spickett EE, Burke V, Beilin LJ, Milligan RA, and Dunbar DL. A controlled evaluation of a fitness and nutrition intervention program on cardiovascular health in 10- to 12-year-old children. Prev Med. 1995; 24: 9-22.


PubMed ID: 7740021
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
POSITIVE: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

To examine the effectiveness and practicality of a one-school-year intervention aimed at improving cardiovascular health according to the goals and priorities established by the Australian National Health Targets and Implementation Committee.

Inclusion Criteria:
  • 10- to 12-year-olds in Western Australia
  • Parental consent.
Exclusion Criteria:

Not discussed.

Description of Study Protocol:

Recruitment

School selection and recruitment was not discussed; student recruitment was completed by inviting all children enrolled in year six at the start of the 1990 school year. A letter was sent to their parents explaining the project and seeking consent.

Design

Randomized controlled trial with six groups:

  • Physical fitness
  • Physical fitness and school nutrition
  • School nutrition
  • School nutrition and home nutrition
  • Home nutrition
  • Control.

Dietary Intake/Dietary Assessment Methodology

Two weekday food records were completed by the students:

  • A dietitian trained students on describing and estimating quantities of foods
  • Students were given sets of measuring cups and spoons
  • On the day following the two-day collection, the dietitian returned to the school to collect and individually check each record
  • Records were coded using NUTTAB 89.

Intervention

  • The intervention was a school-based nutrition and physical fitness program developed by a team of researchers, classroom teachers and specialists in healthy and physical education. The nutrition program consisted of 10 one-hour lessons aimed to improve knowledge, attitudes and eating habits. The program was designed to increase consumption of fruit, vegetables, whole grain bread and cereals and decrease consumption of fatty, sugary and salty foods relative to other foods. 
  • Teachers received a program guide and teaching resources when they attended a half-day in-service training. Messaging was delivered with comics and targeted children and their parents (to help with homework, assist with preparing healthy recipes). Children completed homework sheets for their school and were rewarded. 
  • The fitness education program included six 30-minute lessons aimed at giving children a rationale for exercise and activity programs. A range of fitness activities were offered, increasing intensity and duration throughout the program. Teachers were given resource packages (daily lessons for one year, strategies for effective teaching, ways to monitor exercise intensity and test fitness) at two half-day in-service training sessions. Fitness classes were to be carried out for 15 minutes every school day throughout the year.

Statistical Analysis

  • Data were analyzed separately for boys and girls
  • Regression models were used for comparison of results at follow-up with responses in the control group:
    • There were significant between-group differences in some baseline variables, so all follow-up measurements were adjusted for baseline values
    • Differences in responses between boys and girls in different treatment groups were included in the regression model by adding an interaction term (group membership by sex).
Data Collection Summary:

Timing of Measurements

  • Baseline: First term of the school year (February to April)
  • Follow-up (post-intervention): Fourth term (October to December).

Dependent Variables

  • Dietary intake: See description for food records under Dietary Assessment; intake of fats, sugar and protein were expressed as percentage of energy intake
  • Physical fitness: Assessed with a 1.6km run and the Leger shuttle run
  • Body composition: Height and weight to calculate body mass index (BMI), triceps and subscapular skinfold measurements to calculate percentage body fat
  • Blood pressure: Systolic, diastolic using Dinamap 1846 SX/P; non-fasting; four readings were averaged after resting for five minutes 
  • Blood cholesterol: Finger prick; Reflotron dry-chemistry system for estimating cholesterol concentration; non-fasting.

Independent Variables

Randomization group.

Description of Actual Data Sample:
  • Initial N: 1,240 children were invited and 1,147 (93%) entered the study
  • Attrition (final N):
    • 83% of children had dietary data
    • 88% fitness data
    • 96% blood pressure
    • 96% cholesterol
    • 92% anthropometry
  • Age: 10- to 12-year-olds
  • Anthropometrics:
    • Mean BMI for girls was 18.0kg/m2 and BMI for boys was 17.8kg/m2
    • 6.6% of boys and 4.3% of girls were above the 95th percentile for BMI (similiar to the general population in Australia)
  • Location: Australia.
Summary of Results:

 Main Findings

  • Fitness increased and diastolic blood pressure (61.6mmHg (CI: 60.6, 61.6) and  62.7mmHg (CI: 61.6, 63.9) for attenders and non-attenders, respectively) and triceps skinfolds decreased significantly for girls in the fitness groups. There were no differences in subscapular skinfolds, total percentage body fat or BMI relative to controls. 
  •  At baseline, sugar intake in 63% of boys and 66% of girls exceeded the 20% of daily energy intake set as a national dietary target. Almost 90% of all participants exceeded the 10% of energy guideline for saturated fat
    • Boys: There was a decrease in sugar intake different from controls in both fitness groups and the school and home nutrition group
    • Girls: No significant difference from controls in sugar intake with a pattern of a decrease in all groups except for the two home nutrition groups in which sugar intake tended to increase
    • There were no differences in dietary patterns or cholesterol for boys or girls in relation to their attendance at follow-up
      • Girls: Fat intake decreased in the two home nutrition groups and fiber intake increased in the school and home nutrition and fitness groups (3.1g, CI: 1.6, 4.6).
      • There was a significantly greater decrease in total fat intake in girls compared with boys in the school and home nutrition group (2.9g, CI: 1.5, 4.3) and in the home nutrition group (3.6, CI 2.1, 5.1). Saturated fat decreased more in girls than boys in the school and home nutrition group (1.6g, CI: 0.8, 2.4) and home nutrition group (1.6g, CI: 0.9, 2.3), but also in the fitness and school nutrition group (1.5g, CI: 0.8, 2.2).
    • Change in sugar intake correlated negatively with fat intake in both boys and girls
      • Boys: R=-0.5261, P<0.0001 for total fat and R=-0.3505, P<0.0001 for saturated fat
      • Girls: R=-0.5437, P<0.0001 for total fat and R=-0.3562, p<0.0001 for saturated fat
  • About 32% of boys and 34% of girls had blood cholesterol levels above the Australian National Heart Foundations' desirable level of 4.5mmol per L for children
    • Blood cholesterol increased significantly for the whole cohort after the intervention. Increases were greater for controls for girls in all intervention groups and for boys in the fitness group
    • Boys: cholesterol at follow-up was negatively related in regression to fiber intake (B=-0.007, SE=0.003, R2=0.61) after adjustment for baseline cholesterol
    • Girls, after adjustment, cholesterol at follow-up was related to percentage body fat (B=0.009, SE=0.003, R2=0.59).
Author Conclusion:
  • Teacher-implemented health packages are feasible with minimal training, but programs should differ between boys and girls. Fitness programs are more successful than nutrition education, particularly in girls. Clearer nutrition messages should prevent reciprocal changes in sugar and fat.
  • For girls, 3mmHg reduction of diastolic blood pressure, less obesity and increased fitness could translate into a substantial reduction in cardiovascular risk in adult life.
Reviewer Comments:
  • Strength: Randomized control trial study design
  • Weaknesses: No discussion of limitations.

Research Design and Implementation 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 nutrition or dietetics practice?
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?
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?
No
  3.3. Were concurrent controls used? (Concurrent preferred over historical controls.)
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 or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)
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%.)
No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for?
Yes
  4.4. Were reasons for withdrawals similar across groups?
No
  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?
Yes
  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?
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?
Yes
  6.6. Were extra or unplanned treatments described?
Yes
  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)?
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?
No
9. Are conclusions supported by results with biases and limitations taken into consideration?
No
  9.1. Is there a discussion of findings?
Yes
  9.2. Are biases and study limitations identified and discussed?
No
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