Increase Font Size Decrease Font Size View as PDF Print
Citation:

He M, Beynon C, Sangster Bouck M, St. Onge R, Stewart S, Khoshaba L, Horbul BA, Chircoski B. Impact evaluation of the Northern Fruit and Vegetable Pilot Programme: A cluster-randomised controlled trial. Public Health Nutr. 2009 Nov; 12(11): 2,199-2,208. Epub 2009 May 28.


PubMed ID: 19476675
Study Design:
Cluster Randomized Trial
Class:
A - Click here for explanation of classification scheme.
NEUTRAL: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

To assess the effect of the Northern Fruit and Vegetable Pilot Programme (NFVPP) on psychosocial variables regarding fruit and vegetable behaviors and fruit and vegetable consumption patterns. Furthermore, this study addressed whether the combination of distributing free fruit and vegetables with enhanced nutrition education would result in a greater impact on children's fruit and vegetable consumption than distributing free fruit and vegetables alone.

Inclusion Criteria:

Elementary schools (junior kindergarten to grade eight) from four school boards in the Porcupine region.

Exclusion Criteria:

Schools that did not have grades five to eight (N=6) were excluded from evaluation.

Description of Study Protocol:

Recruitment

  • Elementary schools from four school boards in the Porcupine region were invited to participate voluntarily
  • All 32 schools agreed to participate, but six of these did not include grades five to eight, and were therefore excluded.

Design

Cluster randomized controlled trial:

  • Eligible schools were randomly allocated using SPSS for Windows statistical software into three groups:
    • Intervention I:  Free Fruit and Vegetable Snacks (FFVS) and Enhanced Nutrition Education (ENE) (nine schools)
    • Intervention II:  FFVS alone (nine schools)
    • Control:  no intervention (eight schools)
  • Although the intervention was offered to all students in the school, data were collected only from students in grades five to eight 
  • Although no mention was made of theory used to develop intervention, Social Cognitive Theory was mentioned in the discussion section, with a focus on reciprocal determinism and the reciprocal influence of behavior, personal factors, and the environment.

Blinding Used

Researchers were unable to prevent study subjects from knowing what intervention strategies they were receiving because the community knew the components of the intervention.

Intervention 

  • FFVS:
    • Canadian schools do not have a federally assisted meal program like the National School Lunch Program in the United States, and there are no cafeterias in Ontario elementary schools
    • The FFVS offered either one fruit or one vegetable serving three times per week to every student in junior kindergarten to grade eight in all intervention schools
    • FFVS menu was structured on a three-week rotation, with a total of nine items
  • ENE (entitled "Paint Your Plate! Create a Masterpiece: Vegetables and Fruit Action Guide for Schools"):
    • Comprehensive curriculum-based resource for teachers to incorporate into the classroom
    • Activities were to be used at the school and community level to promote fruit and vegetables and included various activities for each grade
    • Schools were encouraged to use the resource kit's nutritional education materials for morning announcements and school newsletters.

Statistical Analysis

  • Quantitative data were analyzed using SPSS
  • Intent-to-treat analysis principle was followed
  • GLM univariate procedure used to determine intervention effects
  • Cluster effects were accounted for in the analyses
  • Chi-square test was used to compare, by group, students' responses to each of the psychosocial and behavioral questions at baseline and endpoint.

 

Data Collection Summary:

Timing of Measurements

Baseline and at the end of the intervention (21 weeks).

Dependent Variables

  • Difference in children's fruit and vegetable consumption:
    • Measured with pre-coded 24-hour fruit and vegetable recall questionnaire asking about fruit and vegetable intake:
      • Morning before school
      • At school
      • Afternoon after school
      • At dinner
      • Evening after dinner
    • Amounts were indicated in terms of number of pieces, slices or glasses, with standards for each defined
    • Salad and vegetable soup consumption only assessed for lunch and later
    • Cooked vegetables consumption only assessed for three after-school intervals
  • Changes in children's consumption were measured using an instrument adapted from the Pro-Children Questionnaire:
    • Fruit and vegetable awareness, knowledge and preferences
    • Willingness and self-efficacy to increase fruit and vegetable consumption
  • Both instruments were previously validated and shown to be sensitive and reliable for measuring intervention effects
  • Surveys were administered on Wednesdays, Thursdays and Fridays during the data collection period in order to obtain a weekday 24-hour dietary recall that coincided with the Tuesday, Wednesday and Thursday FFVS distribution days (although schools may have deviated from these set distribution dates due to bad weather).

Independent Variables

Treatment condition (Intervention I, Intervention II, Control).

Control Variables

  • Baseline measures
  • Age
  • Gender
  • School clustering effect
  • School location (urban vs. rural)
  • Presence of existing fruit and vegetable programs at baseline (yes or no).
Description of Actual Data Sample:

Initial N

  • Intervention I: 492, 43% boys
  • Intervention II: 603, 47.7% boys
  • Control: 491, 44.2% boys.

Attrition (Final N)

  • Intervention I: 400 (81%)
  • Intervention II: 470 (78%)
  • Control: 407 (83%).

Age (means ± standard deviation, in years)

  • Intervention I: 11.5±1.2
  • Intervention II: 11.8±1.3
  • Control: 11.6±1.2
  • Total: 11.6±1.2.

Anthropometrics

  • School characteristics were similar across the three groups, except that Intervention I schools had more pre-existing fruit and vegetable programs. This was considered a confounder and controlled for in all analyses to determine intervention effect. Students' profiles were similar across the three groups.
  • Baseline fruit and vegetable intake were not significantly different among the three groups.

Location

Ontario, Canada.

Summary of Results:

Key Findings

  • Fruit and vegetable intake (primary outcome):
    • Intervention I and II groups had higher total fruit and vegetable intake than the Control group, although the differences were not statistically significant (mean difference 0.6 and 0.5 serving per day, respectively)
    • Intervention I students consumed statistically more fruit and vegetables at school than students in the Control group (mean difference 0.49 serving per day, P<0.05)
    • Intervention II students consumed more fruit and vegetables at school than students in the Control group, but the difference was not statistically significant (mean difference 0.42 serving per day, P>0.05)
    • The difference in fruit and vegetable intake at school between Intervention I and Intervention II was not statistically significant (mean difference 0.07 serving per day)
  • Psychosocial and behavioral scales (secondary outcomes):
    • At endpoint, there were no statistically significant differences among the three groups for all scores, adjusting for baseline measures, age and gender as covariates and school clustering effect and presence of existing fruit and vegetable programs as random factors
    • Comparing responses at baseline and endpoint:
      • Students' preferences for certain fruit and vegetables shifted significantly from "never tried it" towards "like it" in Intervention I (for cauliflower) and Intervention II (for rutabaga, cauliflower, leeks, peach cup and apple sauce) groups
      • The Control group also showed statistically significant changes in their preferences for peach cups and cauliflower; but the shifts were bi-directional (i.e., some "never tried" responses shifted to "like it" and some to "dislike it")
      • Intervention II students showed significantly unfavorable changes in self-efficacy, intention and peer influence related to vegetable consumption
        • Proportion of students in Intervention II who "agreed" that "I want to eat vegetables" decreased from 74% at baseline to 70% at endpoint (Χ2 = 8.3, P<0.05)
        • At baseline 83% of students felt that "If I decided to eat vegetables, I can do it," decreasing to 76% at endpoint (Χ2 = 9.7, P<0.05). The proportion of students who perceived that "my best friend(s) eat vegetables," decreased from 55% at baseline to 46% at endpoint (Χ2 = 9.5, P<0.05).

 

Variables
Intervention I (N=378)
Intervention II (N=441)
Control (N=393)
Like (%)
Never Tried (%)
Dislike (%)
P
Like (%)
Never Tried (%)
Dislike (%)
P
Like (%)
Never Tried (%)
Dislike (%)
P
Rutabaga       >0.05       <0.01       >0.05
  Baseline
15
62
24
 
12
71
17
 
22
57
21
 
Endpoint
21
55
23
 
15
68
18
 
21
59
21
 
Cauliflower
 
 
 
<0.05
 
 
 
<0.01
 
 
 
<0.01
  Baseline
54
17
29
 
57
17
26
 
59
16
25
 
Endpoint
63
7
29
 
70
6
24
 
62
9
29
 
Leeks
 
 
 
>0.05
 
 
 
<0.05
 
 
 
>0.05
  Baseline
21
58
21
 
17
65
18
 
32
45
24
 
Endpoint
28
51
21
 
22
60
18
 
26
47
27
 
Peach Cups
 
 
 
>0.05
 
 
 
<0.01
 
 
 
<0.01
  Baseline
71
6
23
 
70
8
22
 
73
10
17
 
Endpoint
78
3
19
 
75
4
20
 
75
4
20
 
Applesauce
 
 
 
>0.05
 
 
 
<0.05
 
 
 
>0.05
  Baseline
60
10
30
 
58
9
33
 
61
13
26
 
Endpoint
67
5
28
 
65
7
28
 
61
9
31
 

 

Author Conclusion:
  • The NFVPP resulted in positive changes in elementary school-aged children's fruit and vegetable consumption at school and favorable preference changes for certain fruit and vegetables; however, observed differences in children's preferences must be interpreted with caution because it cannot be determined whether they were a result of receiving the NFVPP or other events such as history, maturation and testing. 
  • It is speculated that Intervention I's ENE component may have prevented the adverse changes seen in self-efficacy, intention and peer influence pertaining to vegetable consumption among those students receiving only the FFVS. Furthermore, although no statistical differences were detected between the intervention arms, the combined strategy, but not the FFVS-alone strategy, resulted in significant increases in children's fruit and vegetable consumption at school. These findings imply that the combined strategy worked better than the single strategy, despite the fact that the ENE component was not implemented fully.
Reviewer Comments:
  • Statistical analysis could have included a time x condition interaction rather than comparing these effects separately; however, the authors cite as a limitation the limited capacity for analyzing categorical data with commonly used statistical software
  • Other limitations reported by the authors:
    • Students received poor quality vegetables
    • ENE component was not implemented fully
    • The European 24-hour recall questionnaire was not pre-tested with the sample of Ontario children; the questionnaire was relatively complicated to complete, which may have resulted in a substantial proportion of missing and invalid values
    • Missing and invalid values decreased the sample size and compromising statistical power
  • Although the number of students who participated in surveys was reported at both time points and an explanation of excluding outliers and missing data was given, the authors did not describe the characteristics of these missing students and it was unclear if these students differed from those included at baseline or if they differed between treatment groups.

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?
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 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?
No
  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?
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.)
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?
???
  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?
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?
No
  8.7. If negative findings, was a power calculation reported to address type 2 error?
Yes
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).