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An impact evaluation of a child nutritional program on the prevalence of overweight and obesity in Mexico
Last registered on May 10, 2019

Pre-Trial

Trial Information
General Information
Title
An impact evaluation of a child nutritional program on the prevalence of overweight and obesity in Mexico
RCT ID
AEARCTR-0002244
Initial registration date
August 22, 2017
Last updated
May 10, 2019 4:35 PM EDT
Location(s)
Region
Primary Investigator
Affiliation
Inter-American Development Bank
Other Primary Investigator(s)
PI Affiliation
Inter-American Development Bank
PI Affiliation
Secretaria de Salud
PI Affiliation
Inter-American Development Bank
PI Affiliation
Inter-American Development Bank
PI Affiliation
Inter-American Development Bank
Additional Trial Information
Status
In development
Start date
2017-08-01
End date
2019-05-31
Secondary IDs
Abstract
The prevalence of overweight and obesity in Mexican public schools affects one third of the students in primary education. The students are surrounded by a plentiful supply of foods with high contents of energy, fats and sugars. Survey data show that the conventional intervention of providing nutritional information to food consumers fails to reach most of the population. The latest official survey of health conditions, ENSANUT 2016, revealed that 76.3% of adults nationwide do not know or did not respond to the question of how many daily calories are recommended for them, while only 40.6% read the nutritional labels of the foods they eat. To remedy this situation, the Mexican government has designed a school-based intervention (Salud en tu Escuela) with the aim of reducing the prevalence of overweight and obesity in primary schools. The intervention is composed of three main components:
(1) Baseline measurement of height, weight and BMI of children, with information sent to parents.
(2) Physical activation by promoting extra-curricular sport practices,
(3) A school-based campaign to raise awareness of appropriate food consumption behavior among students, parents and teachers.
The program pilot is set to be rolled out in the school period of 2017/2018 with a randomized controlled trial in 13 participating federal entities. We randomized 1,560 schools to three groups. First, 520 schools to a treatment group (with interventions 1, 2 and 3); second, 520 schools to a control group (with intervention 1 only) and third, 520 schools to a "pure" control group (with no interventions).
The objective of this impact evaluation is to identify the causal effects of the program on knowledge, food habits, and body mass index (BMI) of school children in public primary schools in Mexico. Baseline data have been collected from before the intervention in August 2017 and follow-up observations were collected at the end of the school year in May 2018.
External Link(s)
Registration Citation
Citation
Cuellar, Christian et al. 2019. "An impact evaluation of a child nutritional program on the prevalence of overweight and obesity in Mexico ." AEA RCT Registry. May 10. https://doi.org/10.1257/rct.2244-4.0.
Former Citation
Cuellar, Christian et al. 2019. "An impact evaluation of a child nutritional program on the prevalence of overweight and obesity in Mexico ." AEA RCT Registry. May 10. https://www.socialscienceregistry.org/trials/2244/history/46261.
Sponsors & Partners

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Experimental Details
Interventions
Intervention(s)
The intervention is composed of six different components described as follows:
* Component 1: Children's anthropometric measurements and visual tests, and information sent to parents
- The objective is to identify the cases of overweight, obesity and visual sharpness in school children from the first, fifth and sixth grades.
- A crew of health practitioners and students will carry out anthropometric measurements and visual tests to those pupils whose parents have given informed consent. An educational session on oral hygiene will take place and a questionnaire on healthy behavior will be administered.

* Component 2: Installation and maintenance of water fountains
- The objective is to provide an adequate infrastructure that facilitates an increase in the consumption of water among children in treated schools.
- A public agency will set up and maintain water fountains in selected schools. The food authority, the sanitary authority in Mexico, will visit the schools to examine the quality of the water provided by the fountains.
* Component 3: Enforcement of the food and drink administration guidelines
- The objective is to enforce the guidelines in terms of food and drink administration in schools, specifically in school cafeterias and vendors.
- A public agency in coordination with the food authority will supervise the menus and advise the food providers in the preparation and administration of health food and drinks.

* Component 4: Physical activation
- The objective is to promote physical activity, moderate and vigorous, during physical education classes.
- Physical education teachers will teach classes using a technique that involves six physical activation stations painted on the school’s patio . Similarly, physical activity will be promoted during the daily recess or break.

* Component 5: Behavioral change strategy
- The objective is to promote healthy habits among pupils through the training of teachers and principals.
- Ludic materials will be provided to teach healthy eating habits focused on three areas: water consumption, bringing healthy snacks from home and the selection of healthy food and drinks.

* Component 6: Teacher and parental training
- The objective is to provide information to parents (or guardians) and teachers to reinforce the incorporation of the behavioral change strategy and health components into the curriculum.
- Face to face and online strategies will be designed to inform parents and teachers about promoting the healthy habits proposed by the behavioral change strategy.
Intervention Start Date
2017-09-01
Intervention End Date
2019-04-30
Primary Outcomes
Primary Outcomes (end points)
Body mass index (BMI), Prevalence of overweight, normalized knowledge index.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
I. Selection of treated units
In the school year 2017/2018 the Mexican Federal Government is set to launch the program “Salud en tu Escuela” (“Health at Your School”) to promote a physical activation strategy and training on nutritional practices at 520 primary schools in the States of Campeche, Ciudad de Mexico, Durango, Jalisco, Michoacán, Morelos, Nuevo Leon, Puebla, Queretaro, San Luis Potosi, Tlaxcala, Sonora and Yucatan.
II. Clusters and stratification
At the state level, the participating schools (clusters) were selected from the two sanitary jurisdictions with the lowest murder rates. The stratification of the experiment consisted of the selection of 40 schools at the state level, divided into 20 rural and 20 urban schools within each state. Eligible schools were randomly ordered in each stratum, the first 20 were selected to complete 520.
II. Selection of control units
Previous steps were replicated to select two different control schools: 520 schools with baseline and follow-up monitoring and another 520 schools with only follow-up monitoring. Finally, four schools were selected in each stratum as substitutes for potential dropouts.
III. Cluster size
All participating schools in treated and control groups totalize nearly 400,000 pupils. Within each school, all students are monitored with data collection with an average (standard deviation) of 281 (156) pupils.
IV. Timing
The experiment will start in August 2017 with and end in May 2018.
Experimental Design Details
Randomization Method
Computer randomization
Randomization Unit
School
Was the treatment clustered?
Yes
Experiment Characteristics
Sample size: planned number of clusters
1560 schools
Sample size: planned number of observations
400,000 students
Sample size (or number of clusters) by treatment arms
520 treated schools; 520 control schools with baseline and follow-up data collection; 520 control schools with follow-up data collection only.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Change of 0.19 in average BMI, Change of 2 percentage points in overweight, Change of 0.05 in a normalized knowledge index.
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
CEI / Instituto Nacional de Salud Pública
IRB Approval Date
2018-04-03
IRB Approval Number
N/A
Analysis Plan

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Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
No
Is data collection complete?
Data Publication
Data Publication
Is public data available?
No
Program Files
Program Files
Reports and Papers
Preliminary Reports
Relevant Papers