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Trial registered on ANZCTR

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

Titles & IDs
Public title
Screen-time Weight-loss Intervention Targeting Children at Home
Scientific title
A randomised controlled trial to determine the effectiveness of a family-based intervention to decrease screen-based sedentary behaviours compared with usual care in New Zealand overweight children.
Secondary ID [1] 253439 0
Health Research Council 10-077
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Reducing screen-based sedentary behaviour 260988 0
Overweight and obesity 260989 0
Physical activity 260990 0
Condition category
Condition code
Public Health 259119 259119 0 0
Health promotion/education

Study type
Description of intervention(s) / exposure
The intervention is a family-based education programme aimed at reducing screen-based sedentary behaviours such as TV watching and video game console use. The intervention is grounded in behavioural economics theory (BET) and social cognitive theory (SCT). Trained culturally appropriate research assistants will deliver the intervention content to participant’s primary caregivers during a one hour face-to-face meeting, within two weeks of the baseline assessment. Meetings will be at the participant’s home and will involve providing the caregiver with skills and strategies to monitor and reduce use of screen-based sedentary activities.

The primary caregiver will be responsible for implementing the various strategies of the intervention.

Television monitoring devices (Time Machine) will be used as a tool to assist families to budget their TV watching time. The Time Machine controls the amount of time the television can be turned on and is used as a tool for parents to help budget TV watching time and can be used to set screen free times by preventing usage during certain time.

A research assistant will visit the participant’s home (face-to-face meeting) to connect the Time Machine to the two devices (television, video game console or computer) most commonly used by the child.

Tailored monthly newsletters will also be delivered to primary caregivers outlining additional strategies for reducing screen-based sedentary activities. A website for participants to access will also be provided to support the intervention content. The website includes the information included in the monthly newsletters as well as links to community-based activity programmes that may be of interest to the family.

The intervention duration is 20 weeks and parents/caregivers will be encouraged to implement the changes on a daily basis.
Intervention code [1] 257883 0
Intervention code [2] 257959 0
Comparator / control treatment
The control group will continue with their usual screen-based activities (usual care) and will not receive the behavioural intervention. Usual screen-based activities include their usual daily leisure time TV watching, computer and video game play.
Control group

Primary outcome [1] 261972 0
Change in child BMI (z-score, kg/m2) from baseline to 24 weeks
Timepoint [1] 261972 0
Baseline and 24 weeks
Secondary outcome [1] 268900 0
Change in parent's BMI (kg/m2)
Timepoint [1] 268900 0
Baseline and 24 weeks
Secondary outcome [2] 268901 0
Change in parent's physical activity (International Physical Activity Questionnaire)
Timepoint [2] 268901 0
Baseline and 24 weeks
Secondary outcome [3] 268902 0
Child daily minutes spent in all sedentary behaviour (self-report, MARCA)
Timepoint [3] 268902 0
Baseline and 24 weeks
Secondary outcome [4] 268903 0
Child daily minutes spent in physical activity (self-report, Multi Media Activity Recall Questinanire)
Timepoint [4] 268903 0
Baseline and 24 weeks
Secondary outcome [5] 268904 0
Child dietary intake (self-report, Food Frequency Questionnaire)
Timepoint [5] 268904 0
Baseline and 24 weeks

Key inclusion criteria
Child aged at least 9 years of age and less than 13 years
Live within the greater Auckland area
Uses electronic media (TV, computer, video games) greater than or equal to 15 hours per week in the primary household (according to primary caregiver report)
Overweight/obese according to Cole International cut-off criteria
Able to provide written informed assent/consent to participate in study
Speaks and understands English
Minimum age
9 Years
Maximum age
12 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Any medical condition that prevents/interferes with regular physical activity
Another child in the household has been recruited into the study
Lives in more than one household and spends an equal amount of time per week in each household

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Recruitment will be undertaken via advertising using community contacts, churches, maraes, public health organisations, and word of mouth.

Potential participants will either contact the research office to register their interest or will be contacted by the research team following direct contact. Interested and potentially eligible participants and their primary caregiver will be screened over the phone during a recruitment phone call. A baseline assessment will be scheduled for eligible participants and their caregiver within 4 weeks of the screening call at the participant’s home.

Following the baseline assessment a research assistant will enter the participant's details on the research database using electronic data capture systems using a secure study laptop computer. Once demographic details have been entered participants will be randomised using a central computer system. Allocation concealment will be maintained up until the point of randomisation using this method.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Eligible children will be randomised by computerised central randomisation using stratified blocked randomisation with variable block sizes (i.e., multiple of 2 arms) to maintain balance across important prognostic factors. Two stratification factors will be considered: sex (female and male) and preferred ethnicity (Maori, Pacific and non-Maori/non-Pacific). Allocation concealment up to the point of randomisation will be maintained.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint/s
Statistical methods / analysis

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] 3146 0
New Zealand
State/province [1] 3146 0

Funding & Sponsors
Funding source category [1] 258419 0
Government body
Name [1] 258419 0
Health Research Council
Country [1] 258419 0
New Zealand
Primary sponsor type
Ralph Maddison
Clinical Trials Research Unit
University of Auckland
Private Bag 92019, Auckland Mailing Centre
Auckland, 1142
New Zealand
Secondary sponsor category [1] 257570 0
Name [1] 257570 0
Address [1] 257570 0
Country [1] 257570 0

Ethics approval
Ethics application status
Ethics committee name [1] 260398 0
Lower South Regional Ethics Committee
Ethics committee address [1] 260398 0
PO Box 5849
Dunedin, 9058
Ethics committee country [1] 260398 0
New Zealand
Date submitted for ethics approval [1] 260398 0
Approval date [1] 260398 0
Ethics approval number [1] 260398 0

Brief summary
Despite epidemiological evidence supporting an association between TV watching and obesity, to date few interventions have been undertaken. There has been very little home-based research to date examining the effectiveness of interventions to decrease sedentary behaviours such as TV watching and video game computer use. The proposed trial will implement and evaluate the effectiveness of a family-based intervention to decrease screen-based sedentary behaviour and improve body composition among New Zealand families. Two hundred and seventy children aged 9-12 years and their primary caregivers will be allocated at random to receive a package of information, support and strategies aimed at reducing leisure time screen-based activities over a 24 week period or a control group (usual screen-based activities). Assessments at baseline and 24-weeks will compare BMI, body composition, physical activity, sedentray behaviours, and dietary habits. If effective, this approach has potential to be implemented as part of existing primary care approaches to reduce BMI in children.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 32108 0
Address 32108 0
Country 32108 0
Phone 32108 0
Fax 32108 0
Email 32108 0
Contact person for public queries
Name 15355 0
Colin Howe
Address 15355 0
Clinical Trials Research Unit
University of Auckland
Private Bag, 92019, Auckland Mailing Centre
Auckland, 1142
Country 15355 0
New Zealand
Phone 15355 0
0064 9 923 4765
Fax 15355 0
Email 15355 0
Contact person for scientific queries
Name 6283 0
Ralph Maddison
Address 6283 0
Clinical Trials Research Unit
University of Auckland
Private Bag, 92019, Auckland Mailing Centre
Auckland, 1142
Country 6283 0
New Zealand
Phone 6283 0
0064 9 3737 599 ext 84767
Fax 6283 0
Email 6283 0

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.