Birken 2012.

Study characteristics
Methods	Study design: RCT Intervention period: 10 min (brief intervention) Follow‐up period (post‐intervention): 1 year Differences in baseline characteristics: reported Reliable outcomes: reported Protection against contamination: study authors report potential for contamination Unit of allocation: individual Unit of analysis: individual
Participants	N (controls baseline) = 79 N (controls follow‐up) = 68 N (interventions baseline) = 81 N (interventions follow‐up) = 64 Setting (and number by study group): 1 community‐based, primary care paediatric group practice, with 3 physicians Recruitment: at child’s 3‐year health maintenance visit Geographic region: Toronto, Canada Percentage of eligible population enrolled: 91% (53% assessed for eligibility of those due for health visit) Mean age: intervention 3.12 ± 0.19; control 3.08 ± 0.12 Sex: intervention, 44% female; control, 49% female
Interventions	To determine if an intervention for preschool‐aged children in primary care is effective in reducing screen time, meals in front of the TV, and BMI Parents in the intervention group received a 10‐min behavioural counselling intervention by trained study personnel directly after the health maintenance visit, which included information on the health impact of screen time in children and provided strategies to decrease screen time. These strategies included suggestions such as removing the TV from the child’s bedroom, encouraging meals to be eaten without the TV on, and budgeting of the child’s screen time. Families were encouraged to try a 1‐ week TV turn off, in which children were encouraged to spend time without the TV and were provided with a calendar and stickers to reward the children for days without the TV. Contingency planning for time spent not watching TV was promoted. Activities for the child, during this session, included providing a story to parents about TV viewing (The Berenstain Bears and Too Much TV) and creating a list of non TV‐related activities. The intervention group also received a Canadian Pediatric Society handout titled 'Promoting Good Television Habits' Parents of children in both the intervention and control groups received standardised counselling from trained study personnel on safe media use, which included information on TV rating systems, internet safety, and limiting exposure to violent programming. They both received a previously published Canadian Pediatric Society parent handout titled “Managing Media in the Home.” PA intervention vs control
Outcomes	Outcome measures Primary outcome: screen time Secondary outcomes: zBMI, number of meals with TV, TV in bedroom Process evaluation: NR
Implementation‐related factors	Theoretical basis: concepts of goal setting, positive reinforcement, monitoring, and cognitive restructuring Resources for intervention implementation: NR Who delivered the intervention: reported PROGRESS categories assessed at baseline: child: gender; parent: education, occupation, race/ethnicity (country of origin) PROGRESS categories analysed at outcome: NR Outcomes relating to harms/unintended effects: NR Intervention included strategies to address diversity or disadvantage: NR Economic evaluation: NR
Notes	NCT00959309 Funding: supported in part by a Paediatric Consultants Research Grant, Hospital for Sick Children, Toronto. The Paediatric Outcomes Research Team is supported by a grant from the Hospital for Sick Children Foundation. The funding organisations were not involved in any of the following: design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript. The intervention group had a clinically significantly higher zBMI at baseline, compared with the control group (0.66 ± 1.18 vs 0.30 ± 0.83) adjusted in analysis Study authors estimate cost of implementing this intervention to all children: if implemented as an additional counselling service at the primary care visit, this intervention would be a significant cost. For example, if we calculate direct costs for physician counselling for all children in Ontario attending a primary care practice and use an existing fee code for smoking cessation counselling in Ontario, the cost would be > CAD 2 million annually.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation
Allocation concealment (selection bias)	Low risk	Sequentially numbered, opaque, identical, sealed envelopes
Blinding (performance bias and detection bias) All outcomes	Low risk	Assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	79% and 86% follow‐up in the intervention and control groups, respectively
Selective reporting (reporting bias)	Low risk	Trial registration document checked. All outcomes reported
Other bias	Unclear risk	Contamination possible