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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
The effectiveness of an intervention promoting water consumption among primary school students: A cluster-randomized controlled trial
Scientific title
A cluster-randomized controlled to compare the efficacy between receiving a social-network implemented intervention and none of the intervention on water and sugar-sweetened beverages consumption in primary school students
Secondary ID [1] 285468 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
water and sugar-sweetened beverages consumption 293242 0
overweight/ obesity 293340 0
Condition category
Condition code
Diet and Nutrition 293511 293511 0 0
Public Health 293606 293606 0 0
Health promotion/education

Study type
Description of intervention(s) / exposure
Selection procedure: Along with the baseline questionnaire, the children in the experimental schools completed peer nominations questions (whom they “respected”, “wanted to be like”, “looked up to”, “went to for advice”, and regarded as “good leaders”) to identify the most influential children in their classroom. Fifteen percent of boys and 15% of girls with the most nominations over all questions were invited for to be trained as peer motivators.

Training: The training was delivered by the experimenter in groups of max. 12 children in a one 90-minute session during school hours. The aim of the training was to give the most influential children the knowledge and skills to promote water consumption within their social networks. The objectives of the training were: (1) to emphasize the benefits of water, (2) to encourage peer motivators to consume more water, and (3) to teach peer motivators skills to promote water consumption within their social network. The children were taught skills to promote water consumption by discussing possible ways through which they can encourage their peers to drink more water.

follow-up sessions: The peer motivators were asked to promote water consumption within their social networks during eight weeks. The experimenters offered support at two school-based follow-up sessions (one and four weeks after the training). The purpose of the follow-up visits was to (1) offer the peer motivators visible support and resolve any problems they experienced in their role and (2) refresh the information that was discussed in the training.
Intervention code [1] 290398 0
Comparator / control treatment
The control condition schools received none of the intervention.
Control group

Primary outcome [1] 293326 0
self-reported water consumption (i.e., average amount of glasses on a day)
Timepoint [1] 293326 0
baseline and 9 weeks
Primary outcome [2] 293327 0
self-reported sugar-sweetened beverages consumption (i.e., average amount of glasses on a normal day). The question was asked separately for fruit juice, soda, and energy drinks.
Timepoint [2] 293327 0
baseline and 9 weeks
Secondary outcome [1] 310798 0
behavioral intentions: participants were asked to indicate on a 4-point scale how likely they were to drink more water.
Timepoint [1] 310798 0
baseline and 9 weeks

Key inclusion criteria
girls and boys in grade 7 and 8 of the Dutch school system (9 - 13 yrs)
Schools without any water stimulation programs
Parents that provided passive consent for their children Children that were willing and able to provide written consent
Minimum age
9 Years
Maximum age
13 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
schools with water stimulation programs

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
After receiving consent from the headmasters of the schools, the schools were randomly assigned to either the experimental or the control condition by an independent researcher.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation was done using a computerised sequence generation
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
A two-way repeated measures design including one between-group factor (condition: experimental vs. control) and one repeated measure (time: baseline vs. post-intervention) to assess the effect of the intervention.

Power analyses using G*Power indicated that n= 98 for each condition is expected to be sufficient to detect significant (alpha = .05, one-tailed) small effects (d= .25) of
conditions (power = .8).

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 6401 0
State/province [1] 6401 0

Funding & Sponsors
Funding source category [1] 290070 0
Name [1] 290070 0
Radboud University Nijmegen
Address [1] 290070 0
Comeniuslaan 4, 6525 HP Nijmegen
Postbus 9102, 6500 HC Nijmegen
Country [1] 290070 0
Primary sponsor type
Radboud University Nijmegen
Comeniuslaan 4, 6525 HP Nijmegen
Postbus 9102, 6500 HC Nijmegen
Secondary sponsor category [1] 288762 0
Name [1] 288762 0
Address [1] 288762 0
Country [1] 288762 0

Ethics approval
Ethics application status
Ethics committee name [1] 291774 0
Ethics Committee of Radboud University Nijmegen
Ethics committee address [1] 291774 0
Montessorilaan 3
6525 HR Nijmegen
Ethics committee country [1] 291774 0
Date submitted for ethics approval [1] 291774 0
Approval date [1] 291774 0
Ethics approval number [1] 291774 0

Brief summary
Overweight and obesity are among the most common public health problems in Western society. One major contributor of obesity in children is the consumption of sugar sweetened beverages. A possible solution to the obesity epidemic is to replace children’s consumption of sugar sweetened beverages with water. With use of the diffusion of innovation theory, the proposed program targeted primary school students aged 9-13 years and aimed to increase water consumption among these students. The program consisted of training opinion leaders to acts as peer supporters during informal interactions and encourage their peers to drink more water. The primary goal of this project was to develop and assess the effectiveness of the program in primary schools in the Netherlands.
Trial website
Trial related presentations / publications
Not applicable
Public notes

Principal investigator
Name 51978 0
Miss Crystal Smit
Address 51978 0
Communication Science
Radboud University Nijmegen
P.O. Box 9104, 6500 HE Nijmegen, The Netherlands
Country 51978 0
Phone 51978 0
+(31)(0)24 361 572345
Fax 51978 0
Email 51978 0
Contact person for public queries
Name 51979 0
Miss Crystal Smit
Address 51979 0
Communication Science
Radboud University Nijmegen
P.O. Box 9104, 6500 HE Nijmegen, The Netherlands
Country 51979 0
Phone 51979 0
+(31)(0)24 361 572345
Fax 51979 0
Email 51979 0
Contact person for scientific queries
Name 51980 0
Miss Crystal Smit
Address 51980 0
Communication Science
Radboud University Nijmegen
P.O. Box 9104, 6500 HE Nijmegen, The Netherlands
Country 51980 0
Phone 51980 0
+(31)(0)24 361 572345
Fax 51980 0
Email 51980 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary