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Citation:

Reinaerts E, Crutzen R, Candel M, De Vries NK, De Nooijer J. Increasing fruit and vegetable intake among children: Comparing long-term effects of a free distribution and a multi-component program. Health Educ Res. 2008; 23 (6): 987-996.


PubMed ID: 18550582
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
NEUTRAL: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

The aim of this study was to evaluate and compare the effectiveness of two primary school-based interventions on children's fruit and vegetable (F&V) consumption over the long term (two years after the start of the interventions).

Inclusion Criteria:

Children and one of their parents (to complete the questionnaire).

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

  • Six schools in The Netherlands were recruited to receive one of two interventions. These schools were paired, on ethnic composition because the proportion of foreign students can differ substantially among primary schools.
  • Of each pair, one school was randomly assigned to the distribution condition (N=690 children) and one to the multi-component condition (N=648) resulting in two intervention groups each consisting of three schools
  • Six control schools (N=1,168) were identified and matched to the intervention schools based on ethnicity and school size.

Design

Group randomized controlled trial.

Intervention

  • Two intervention groups:
    • Distribution condition (N=690 children
    • Multi-component condition (N=648).
  • Control group.

Statistical Analysis 

  • Chi-square tests for proportions and used to compare baseline characteristics between study groups
  • Separate analyses were performed for each of the outcome measures [24-hour FJV (times per day), fruit (portions per day), vegetable snack (times per day) vegetables (gram per day) was used in the analysis model, where the three levels were the time of the follow-up measurement (Level 1), pupil (Level 2) and school (Level 3)
  • In all analyses, dummy variables for the distribution and the multi-component intervention group as main independent variables were included, and the model adjusted for the effects of child’s age, ethnicity and baseline value of the outcome measure. Furthermore, all analyses included interactions between time and the dummy indicating the distribution group and between time and the dummy indicating the multi-component group.
  • Attrition between baseline and the second follow-up (June 2006) was studied by means of multi-level logistic regression analysis with attrition as the dependent variable and child’s age, sex and ethnicity, child’s F&V consumption at baseline and the intervention factor as predictors
  • Long-term effectiveness of the interventions was analyzed using random coefficient analyses.
Data Collection Summary:

Timing of Measurements

Baseline measurements were conducted in October 2004, while the first follow-up was conducted in June 2005 and the second in June 2006.

Dependent Variables

  • Fruits and vegetable consumption
  • The pre-structured 24-hour food recall assessed the number of times children consumed food (including fruit or vegetables) the previous day.

Independent Variables 

  • Two intervention groups:
    • Distribution condition (N=690 children)
    • Multi-component condition (N=648).
  • Control group.

Control Variables

  • Child's age
  • Ethnicity
  • Baseline value of the outcome measure.
Description of Actual Data Sample:

Initial N

  • In October 2004, a total of 1,739 parents filled out the questionnaire for their child
    • Matched to intervention schools and allocated to control group (N=6 schools; ±1,168 children)
    • Allocated to distribution program (N=3 schools; ±690 children)
    • Allocated to multi-component program (N=3 schools; ±648 children).

Attrition (Final N)

  • Of these parents, a total of 940 (54%) also filled out the second one in June 2005 and 436 (25%) filled out all three measurements
  • June 2005: Total response at follow-up I (N=1,229 parents)
  • June 2006: Total response at follow-up II (N=814 parents).

Age

The mean age of the children was eight years (standard deviation=2.2 years).

Ethnicity 

  • 47% (N=206) were boys
  • 82% (N=357) were of Dutch origin.

Anthropometrics

  • Exploratory analyses showed that children in the control group were 0.7 years (P<0.05) older than the children in the multi-component group and that the distribution of ethnicity among the three groups differed significantly (control vs. multi-component vs. distribution: 38 vs. 14 vs. 48% non-native; P<0.001)
  • Children in the distribution group consumed more vegetable snacks at baseline than children in the control group (P<0.05).

Location

The Netherlands.

Summary of Results:

Key Findings

  • Multilevel logistic analyses of dropout at first and second follow-up (combined) did reveal some selective dropout. Parents of non-native children (OR=1.67; 95% CI =1.16-2.38) dropped out significantly more often (19% native vs. 32% non-native).
  • Children of parents who dropped out consumed 0.1 portion less fruit per day (OR=0.69; 95% CI =0.69-0.93) at baseline compared with the children whose parents filled out all three surveys
  • A significant intervention effect of the distribution program compared with the control group (P<0.05) was found on all outcome measures. This means that the distribution program was able to increase all outcome measures and that this effect sustained after the intervention was terminated.
  • At second follow-up, children who received the distribution program had increased their consumption with a net effect of 0.13 times FJV on the day prior to data collection (d=0.09), they consumed 0.09 more portions of fruit per day (d=0.15) and 0.07 times more a vegetable snack compared with the control group (d=0.29)
  • A serving of fruit weights on average; 80g, so the consumption of fruit was increased with ; 7.2g day 1. Furthermore, the uncorrected data showed that children from the distribution group consumed 3.25g more vegetables during dinner (d=0.14).
  • The multi-component program showed significant effects over time in increasing children’s 24-hour FJV (P<0.05) and fruit consumption (P<0.05) compared with the control group. At second follow-up, they had increased
  • No effects were found for vegetable snack intake and vegetable intake during dinner. The interventions showed similar effects in increasing 24-hour FJV and fruit consumption but that the distribution program also increased vegetable snack intake (P<0.05) and vegetable intake during dinner (P<0.01).
  • Vegetable consumption during dinner was increased by the distribution program, but we only found this effect
  • On the short term (Follow-up I). Vegetable consumption during dinner was increased by the distribution program, but we only found this effect on the short term (Follow-up I)
  • For fruit consumption, the significant time by intervention interaction revealed that the effect of both programs decreased over time. However, separate analyses for the first and the second follow-up showed that the effects remained significant at both measurements.

 

Author Conclusion:

Despite the limitations of our study, we carefully conclude that both a free distribution program and a multi-component program can increase children's fruit consumption over time. The distribution program also increased children's vegetable consumption over time, and it is therefore considered as the preferred intervention of the two. In view of these results reported, implementation of a distribution scheme on a larger scale should be investigated.

 

Reviewer Comments:

Significant differences between groups at baseline. Authors note the following limitations:

  • Although schools were randomly assigned to the intervention conditions, the control schools were matched to the intervention schools based on school size and ethnicity
  • Use of self-reports from parents.

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?
???
  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?
???
3. Were study groups comparable?
No
  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?
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?
N/A
  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?
???
  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?
???
  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?
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
 
 

Copyright American Dietetic Association (ADA).