van den Hoofdakker 2007.

Methods	Parallel randomised controlled trial.
Participants	Participants: parents of children between 4 and 12 years of age with ADHD who were referred to an outpatient mental health clinic by their GP. Sex: both mothers and fathers (no further information). Age of parents: not stated. Unit of allocation: individual family. Number randomised: 96 (48 intervention; 48 control). Number used in analysis: 94 (47 intervention; 47 control). Country & setting: Netherlands; single‐site; recruited from an outpatient setting; intervention delivered in an outpatient clinic. Inclusion criteria: DSM‐IV criteria for ADHD; IQ > 80; child aged between 4 and 12 years; both parents (if present) willing to participate in the parent program. Exclusion criteria: families who had already received intensive behavioural parent training the year before; problems with the child/or family that required immediate intervention (for example: crisis in the family). Ethnicity: 94.7% white, 2.1% African, 2.1% Asian, 1.1% unknown. Baseline characteristics: marital status: 73 (77.7%) two biological parents; 10 (10.6%) single parent; 11 (11.7%) one biological, one step‐parent; no statistically significant differences in child or family characteristics between two conditions, with the exception of tics (significantly higher frequency in the control group).
Interventions	Two conditions: Behavioural parent programme plus treatment as usual; treatment as usual control. Duration of intervention: 12 sessions over 5‐month period. Length of follow‐up: 6 months (intervention group only).
Outcomes	Stress (Parenting Stress Index).
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Information reported insufficient for a judgement to be made, but information from trial investigator (email from B van den Hoofdakker to CB on 24 Nov) states "the randomisation sequence of family id‐numbers was computer generated".
Allocation concealment (selection bias)	Low risk	Information reported insufficient for a judgement to be made, but information from trial investigator (email from B van den Hoofdakker to CB on 24 Nov) states ""an external researcher generated the allocation sequence and preserved the list of randomised family id‐numbers. This researcher did not work in the outpatient mental health clinic where the study was conducted, was not involved in assessment or treatment, and did not determine eligibility for the study or entry of patients".
Blinding (performance bias and detection bias) Participants	High risk	Review authors judge that it would not be possible to fully blind participants in this type of study, and found no indication of any specific additional measures taken to reduce the risk of bias that might result from differential behaviours by participants.
Blinding (performance bias and detection bias) Personnel	Unclear risk	Information reported insufficient for a judgement to be made. We requested clarification from the trial investigators, but no further information was available at the time this review was prepared.
Blinding (performance bias and detection bias) Outcome assessors	Unclear risk	Information reported insufficient for a judgement to be made. We requested clarification from the trial investigators, but no further information was available at the time this review was prepared.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data for 1/48 (2%) missing from the intervention condition (urgent problems requiring immediate treatment), and for 1/48 (2%) from the control condition. Overall attrition was 2% at post‐intervention. Investigators report that an additional 5 discontinued (for personal reasons or because immediate treatment was required) with the missing endpoint data replaced with LOCF values. Review authors considered the numbers of and reasons for missing data reasonably likely to be balanced across the treatment conditions.
Selective reporting (reporting bias)	Low risk	Review authors judge that the published report includes all expected outcomes, including those that were pre‐specified.
Other bias	Low risk	Investigators report: a) there were no statistically significant differences between conditions at baseline on demographic or outcome measures with the exception of the presence of tics (a comorbid condition) which had a significantly higher frequency in the control group (P=.006). b) investigators carried out repeated‐measures ANOVAs to examine for interaction effects between time, treatment, and medication status and parenting stress. Results (F(2,91) = 0.010, P=.990) indicate that medication status at study entry did not affect treatment effects. c) there were no statistical differences (Chi2 tests) in the proportion of children who were taking medication between the two conditions at baseline and at post‐treatment. The study appeared free of other sources of bias.