EAL

NGHC: Prevention of Chronic Disease (2013)

Citation:

Foster GD, Sherman S, Borradaile KE, Grundy KM, Vander Veur SS, Nachmani J, Karpyn A, Kumanyika S, Shults J. A policy-based school intervention to prevent overweight and obesity. Pediatrics. 2008, 121: e794-802.

PubMed ID: 18381508

Study Design:

Randomized Controlled Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

POSITIVE: See Quality Criteria Checklist below.

Research Purpose:

To examine the effects of a multi-component, School Nutrition Policy Initiative on the prevention of overweight and obesity among children in grades four to six over a two-year period.

Inclusion Criteria:

Inclusion of schools:
- Located in the School District of Philadelphia
- Enrolled students in kindergarten through eighth grade
- 50% or more of students eligible for free or reduced-price school meals
- Full service or heat-and-serve food service
Inclusion of children: Enrolled in the fourth through sixth grade in one of the schools selected for the study.

Exclusion Criteria:

Exclusion of schools:
- Not located in School District of Philadelphia
- Less than 50% of students eligible for free or reduced price meals
- Not a school enrolling students in kindergarten though eighth grade
- Not using full service or heat-and-serve food systems
Exclusion of children:
- Not enrolled in one of the schools selected for the study
- Not in the fourth, fifth or sixth grade at the start of the study

Description of Study Protocol:

Recruitment

27 kindergarten through eighth-grade schools in the School District of Philadelphia with 50% or more of students eligible for or receiving reduced-price meals were identified
Five clusters of four to seven schools matched on school size and type of food service were created
Schools from each cluster were approached until two schools from each cluster agreed to participate
Recruitment was stopped after 10 schools agreed to participate
Within schools, children in fourth to sixth grades and their parents were asked to consent.

Design

Schools were randomized to intervention or control within cluster (two schools per cluster participating)
School Nutrition Policy Initiative implemented in the intervention schools. Components consisted of:
- School self-assessment
- Nutrition education (staff training and classroom instruction)
- School nutrition policy
- Social marketing
- Parent and family outreach
Intervention lasted two years
Outcome measures were assessed at baseline and after two years; intermediate measures were also assessed after one year.

Dietary Intake/Dietary Assessment Methodology

Measured using the Youth/Adolescent Questionnaire; a validated self-administered food-frequency questionnaire (FFQ).

Intervention

School Nutrition Policy Initiative:

Self-assessment: Nutrition advisory groups (teachers, staff, parents) formed within each school to assess the school environment using the CDC School Health Index. After completing healthy eating and physical activity ratings, action plans for change were created.
Nutrition education: All school staff were offered 10 hours per year of training in nutrition education. Curricula, supporting materials and additional information aimed at integrating classroom lessons, cafeteria promotions and parent outreach were provided. A goal of 50 hours of nutrition education per student per year was set. Nutrition teaching was integrated into classroom subjects.
Nutrition policy: All foods served in schools changed to meet standards based on the Dietary Guidelines for Americans. Standards included all beverages limited to 100% juice, water and low-fat milk; snacks must contain less than 7g fat, 2g saturated fat, 360mg sodium and 15g sugar per serving; soda, chips and other items not meeting guidelines removed from vending machines and a la carte menus.
Social marketing: Raffle tickets and prizes given to students to increase school meal participation and consumption of healthy snacks and beverages
Family outreach: School association meetings, parent-teacher meetings and weekly nutrition workshops were utilized to encourage parents and children to purchase healthy snacks, increase time spent in activity, decrease sedentary time and eat more fruits and vegetables. Unhealthy foods were discouraged from fundraisers and classroom celebrations.

Statistical Analysis

Generalized estimating equations
Paired T-tests
Intent to treat analyses; multiple imputation method, baseline carried forward and last value carried forward.

Data Collection Summary:

Timing of Measurements

Baseline: All outcomes
Year One Weight and height
Year Two: All outcomes.

Dependent Variables

Weight status (underweight, normal weight, overweight, obese) was determined from BMI-z scores and percentiles derived from CDC growth charts using weight and height measured by trained staff
Dietary intake (total energy and fat consumption and number of fruit and vegetable servings eaten) was measured using the validated Youth/Adolescent FFQ
Physical activity and sedentary behavior (TV viewing and total inactivity) measured using the validated Youth/Adolescent Activity Questionnaire. Total inactivity quantified by combining the scores for the eight sedentary behaviors assessed by the questionnaire.
Body image assessed using the Eating Disorders Inventory-Two.

Independent Variables

School Nutrition Policy Intervention.

Control Variables

Race/ethnicity
Gender
Age
Intra-class correlations
School-matching (using indicator variable)
Prevalence of overweight and obesity at baseline.

Description of Actual Data Sample:

Initial N: 1,349
- Intervention: N=749 (412 females, 337 males)
- Control: N=600 (313 females, 287 males)
Attrition (final N): 844 (gender distribution not specified)
- Intervention: N=479
- Control: N=365
- Attrition rates did not differ between groups
Age (at baseline; mean±SD):
- Intervention: 11±1 years
- Control: 11±1 years
Ethnicity:

	Control	Intervention	P-value
Race (N)			<0.001
Black	281	332
Asian	166	128
Hispanic	35	168
Other	33	41
White	85	80

*Significant difference in race between groups.

Other relevant demographics:

	Control	Intervention	P-value
Fruit and vegetable intake (N per day)	5.6±4.2	5.3±3.9	0.16
Total energy intake (kJ per day)	13,979±8,171	14,030±8,113	0.91
Total fat intake (g per day)	118±72	119±71	0.86
Activity (hours per week)	26.2±19.3	25.9±19.8	0.77
Inactivity (hours per week)	108.8±44.5	113.9±50.1	0.14
TV viewing (hours per weekday)	2.8±1.5	2.9±1.6	0.49
TV viewing (hours per weekend)	3.3±1.6	3.3±1.6	0.75
Body dissatisfaction score	9.2±7.8	9.0±7.6	0.74

Mean±SD; No between group differences at baseline for outcome variables.

Anthropometrics:

	Control	Intervention	P-value
Weight status (N)			0.08
Underweight	18	10
Normal weight	352	420
Overweight	99	129
Obese	131	190
BMI (mean±SD, kg/m²)	20.7±5.0	21.0±5.1	0.33
BMI z-score (mean±SD)	0.65±1.1	0.71±1.1	0.35

No between group differences at baseline for anthropometric variables.

Location: Philadelphia, PA.

Summary of Results:

Prevalence, Incidence and Remission of Overweight and Obesity During Two-year Intervention

	Total Sample, N	Baseline, N (%)	Follow-up, N (%)	Unadjusted Change (%)	Adjusted Odds (95% CI)	P-value
Overweight
Prevalence
Control	365	57 (16)	73 (20)	4.11	1.00
Intervention	479	78 (16)	70 (15)	-1.67	0.65 (0.47 to 0.79)	<0.001
Incidence
Control	208		31 (15)	14.9	1.00
Intervention	268		20 (7)	7.5	0.67 (0.47 to 0.96)	0.03
Remission
Control	144		11 (8)	-7.6	1.00
Intervention	206		22 (11)	-10.7	1.34 (0.71 to 2.54)	0.37
Obese
Prevalence
Control	365	86 (24)	91 (25)	1.4	1.00	0.48
Intervention	479	128 (27)	134 (28)	1.2	1.09 (0.85 to 1.40)
Incidence
Control	266		17 (6)	6.4	1.00	0.99
Intervention	346		20 (6)	5.8	1.00 (0.66 to 1.52)
Remission
Control	86		12 (14)	-13.9	1.00	0.54
Intervention	128		14 (11)	-10.9	0.84 (0.48 to 1.46)

Unadjusted change is the change in the proportion of students between baseline and follow-up. Odds ratios (OR) adjusted for race, gender, age and an indicator of the randomization pair.

Adjusted odds were approximately 33% lower for the incidence of overweight, and approximately 35% lower for the prevalence of overweight in the intervention group, but not different for remission of overweight between groups
Adjusted odds for the incidence, prevalence and remission of obesity were not different between groups
Adjusted odds were approximately 15% lower (OR: 0.85; 95% CI: 0.74 to 0.99), P<0.05) for the incidence of overweight or obesity (weight status combined), and approximately 32% higher (OR: 1.32; 95% CI: 1.09 to 1.60, P<0.01) for the remission of overweight or obesity in the intervention group, but adjusted odds for the prevalence of overweight or obesity was not different between groups (P=0.07)
Younger children were less likely to be obese (OR: 0.73; 95% CI: 0.56 to 0.94, P<0.05), to become obese (OR: 0.73; 95% CI: 0.54 to 0.99, P<0.05), and to remit (OR: 1.46; 95% CI: 1.07 to 1.99, P<0.05) after two years
Change in BMI (2.1 vs. 2.0, P=0.71) and BMI z-score (0.1 vs. 0.1, P=0.80) was not different between groups.

Other Findings

Education:
- Intervention group teachers and staff received 10.4±2.9 hours of study-related training during year one and 8.4±2.2 hours during year two
- Intervention group students received 48.0±27.1 hours of nutrition education during year one and 44.0±18.3 hours during year two
Dietary intake and activity (control vs. intervention):
- Decreases in consumption of energy (-2,764 vs. -3,745mJ per day, P=0.12), fat (-26 vs. 34g per day, P=0.12) and fruits and vegetables (-1.0 vs. -1.1 servings per day, P=0.82) were not different between groups
- Decrease in self-reported physical activity was not different between groups (-4.6 vs. -3.8 hours per week, P=0.40)
- Total inactivity increased 3.5 hours per week in controls but decreased 10.8 hours per in the intervention group, and was 4% lower in the intervention group (OR: 0.96; 95% CI: 0.94 to 0.99, P<0.05) at follow-up
- Total weekday TV time increased 0.2 hours per day in controls but decreased 0.03 hours per day in the intervention group, and was 5% lower in the intervention group (OR: 0.95; 95% CI: 0.93 to 0.98, P<0.05) at follow-up.

Author Conclusion:

The data suggest that a multi-component school-based intervention can be effective in curbing the development of overweight among children in grades four to six in urban public schools with a high proportion of children eligible for free and reduced-price school meals.

Reviewer Comments:

Authors do not separate final sample size by gender
Authors do not note between group differences for reasons of attrition
Limitations: Self-reported measures of dietary intake and physical activity used.

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?		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?	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?		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?	???
	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?		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?	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)?	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?	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