Hanisch 2010.

Methods	Cluster randomised controlled trial.
Participants	Participants: parents of children aged between 3 and 6 years, who were attending kindergartens. Sex: both mothers and fathers (no further information). Age of parents: not stated. Unit of allocation: kindergarten. Number randomised: 58 kindergartens randomised (32 intervention; 26 control); 155 participants randomised (91 intervention group, 64 control). Number used in analysis: 54 kindergartens (31 intervention; 23 control); 121 families (75 intervention; 46 control). Country & setting: Germany; multi‐site (n=54); recruited from community settings; intervention delivered in the community. Inclusion criteria: families with children aged 3‐6 years; children with externalising behavioural problems indicated by scores above the 85th percentile for scores on a screening instrument derived from the Child Behaviour Checklist. Exclusion criteria: not stated. Ethnicity: not stated. Baseline characteristics: mean CBCL scores: 43.14 (SD 20.99) and 39.72 (SD 19.35); mean mother‐assessed symptoms: 0.11 (SD 0.84) and ‐0.14 (SD 0.75).
Interventions	Two conditions: Prevention Programme for Externalising Problem behaviour (behavioural parenting programme); no‐treatment control. Duration of intervention: 10 weeks. Length of follow‐up: 8 weeks.
Outcomes	Depressive symptoms (Depressive Anxiety Stress Scale). Anxiety symptoms (Depressive Anxiety Stress Scale). Stress (Depressive Anxiety Stress Scale).
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Trial investigators report "each of the kindergartens was randomly assigned to either the intervention group of the control group so that any one teacher was not simultaneously teaching children in both groups" (page 98). Information reported insufficient for a judgement to be made. The trial investigator (e‐mail from C Hanisch to CB. on 19 Nov 2010) confirmed that states that lots corresponding to participating kindergartens were drawn manually.
Allocation concealment (selection bias)	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) 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	High risk	‘Research assistants were blind to treatment group membership’ (page 99). However: ‘the blindness of the research assistants to the family’s group membership could not be fully guaranteed as a few families gave away their group membership during the home visit’ (page 107).
Blinding (performance bias and detection bias) Outcome assessors	High risk	Trial investigators report "research assistants were blind to treatment group membership’ (page 99). However, "the blindness of the research assistants to the family’s group membership could not be fully guaranteed as a few families gave away their group membership during the home visit" (page 107).
Incomplete outcome data (attrition bias) All outcomes	Low risk	16/91 (18%) missing from experimental group (families declined to participate), and 18/64 (28%) missing from control group (families declined to participate). Trial investigators report "the pre‐test composite scores for families that dropped out of the study between the pre‐ and post‐tests did not differ from those that remained in the study. However, mothers who dropped out after the pre‐test assessment had a lower level of education than those who remained in the study (P<.001)" (page 103).
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	The study appeared free of other forms of bias. "There were no significant differences between these groups for children’s age and gender, or symptom severity on the CBCL total, PCL, ADHD, or PCL ODD. Mothers and fathers of both groups reported similar levels of school education and vocational training". However, ". . . children in the intervention group were rated as more severely impaired than children in the control group" (page 103).