Hutchings 2007.

Methods	Design: Parallel randomised controlled trial Unit of randomisation: Parent‐child dyads Follow‐up: 6 months Study dates: 2002 to 2006
Participants	Participants: Socially disadvantaged parents (gender not reported) with children scoring above the clinical cut‐off on either the Eyberg Child Behaviour Inventory ‐ problem or intensity scale Mean age of parents: Not reported Mean age of child: Entire sample range 3 to 4 years (mean, SD: NR), intervention mean 46.2 (SD 4.2; range: NR) months, control 46.4 (SD 6.6; range: NR) months; 70 boys and 63 girls Ethnicity: Not reported Number randomised: 153 (intervention 104; control 49) Country & setting: UK (Wales); multi‐site; recruited from community settings; intervention delivered in the community Eligibility criteria: Families living within a designated Sure Start (socially disadvantaged, predominantly low‐income) area with a child aged three or four years scoring above the clinical cut‐off on either the problem or intensity scale of the Eyberg Child Behaviour Inventory
Interventions	Two conditions: Group‐based parent training (Incredible Years BASIC parenting programme); wait‐list control Duration of intervention: 12 weeks Therapist training: Trained leaders with supervision
Outcomes	Externalising problems: Eyberg Child Behaviour Inventory ‐ intensity, parent‐reported (problem and conduct subscale data not added) Externalising problems subscale ‐ hyperactivity/inattention: Strengths and Difficulties Questionnaire ‐ hyperactivity, parent‐reported (total child deviance and conduct subscale data not added) Secondary outcomes: Parent‐child interaction as measured by Dyadic Parent‐Child Interaction Coding System ‐ child deviance, observer‐reported Data for Conners Abbreviated Parent/Teacher Rating Scale, parent‐report and Kendall Self Control Rating Scale, parent‐rated were not added to the meta‐analyses Timing of outcomes: Outcomes reported for 6 months follow‐up Adverse events: None specified
Notes	We are grateful to the study authors for replying to our request for additional data Level of prevention: Secondary or tertiary Funding: The Health Foundation (UK) (ref: 1583/1566)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were block randomised by area using a random number generator, after stratification by gender and age
Allocation concealment (selection bias)	Low risk	One of the authors blindly allocated participants, further information from the study investigators confirmed this and states "...researchers kept blind as to allocation" (Hutchings 2007)
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants: It would not be possible to fully blind participants in this type of study (there is an obvious difference between receiving group training and waiting list. No indication of any specific additional measures taken to reduce the risk of bias that might result from differential behaviours by participants were found Personnel: The design of the study means personnel delivering the intervention would be aware which groups had been assigned to the different study conditions
Blinding of outcome assessment (detection bias) Independent observer reported outcomes	Low risk	Study investigators reported "researchers blind to allocation carried out the interviews and observations"
Blinding of outcome assessment (detection bias) Parent reported outcomes	High risk	Outcome assessments by parents were not blinded as parents were aware of the intervention condition
Incomplete outcome data (attrition bias) All outcomes	Low risk	18 out of 104 participants in the intervention group and 2 out of 49 left the study early; reasons for leaving early were reported. An intention‐to‐treat analysis was used
Selective reporting (reporting bias)	Low risk	The published report includes all expected outcomes, including those that were prespecified
Other bias	High risk	The principal investigator reports a conflict of interest which could potentially lead to pro‐intervention bias in the language of the paper: “Competing interests: JH is paid by Incredible Years for running occasional training courses in the delivery of the parent programme . . ." (p 7600)