Open Access Highly Accessed Study protocol

Screen-time Weight-loss Intervention Targeting Children at Home (SWITCH): A randomized controlled trial study protocol

Ralph Maddison1*, Cliona Ni Mhurchu1, Louise Foley1, Leonard Epstein2, Yannan Jiang1, Midi Tsai1, Ofa Dewes3 and Ihirangi Heke4

Author Affiliations

1 Clinical Trials Research Unit, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

2 Department of Pediatrics, University at Buffalo, G56 Farber Hall, South Campus, Buffalo, NY 14260-0001, USA

3 Pacific Health, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand

4 School of Physical Education, University of Otago, PO Box 56, Dunedin 9054, New Zealand

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BMC Public Health 2011, 11:524  doi:10.1186/1471-2458-11-524

Published: 30 June 2011



Approximately one third of New Zealand children and young people are overweight or obese. A similar proportion (33%) do not meet recommendations for physical activity, and 70% do not meet recommendations for screen time. Increased time being sedentary is positively associated with being overweight. There are few family-based interventions aimed at reducing sedentary behavior in children. The aim of this trial is to determine the effects of a 24 week home-based, family oriented intervention to reduce sedentary screen time on children's body composition, sedentary behavior, physical activity, and diet.


The study design is a pragmatic two-arm parallel randomized controlled trial. Two hundred and seventy overweight children aged 9-12 years and primary caregivers are being recruited. Participants are randomized to intervention (family-based screen time intervention) or control (no change). At the end of the study, the control group is offered the intervention content. Data collection is undertaken at baseline and 24 weeks. The primary trial outcome is child body mass index (BMI) and standardized body mass index (zBMI). Secondary outcomes are change from baseline to 24 weeks in child percentage body fat; waist circumference; self-reported average daily time spent in physical and sedentary activities; dietary intake; and enjoyment of physical activity and sedentary behavior. Secondary outcomes for the primary caregiver include change in BMI and self-reported physical activity.


This study provides an excellent example of a theory-based, pragmatic, community-based trial targeting sedentary behavior in overweight children. The study has been specifically designed to allow for estimation of the consistency of effects on body composition for Māori (indigenous), Pacific and non-Māori/non-Pacific ethnic groups. If effective, this intervention is imminently scalable and could be integrated within existing weight management programs.

Trial Registration