Wilkison 1995.

Study characteristics
Methods	Double‐blind, placebo‐controlled, cross‐over trial with 2 interventions: MPH Placebo Phases: 2
Participants	Number of participants screened: not stated Number of participants included: 16 Number of participants followed up: 16 implied (16 boys, 0 girls) Number of withdrawals: not stated Diagnosis of ADHD: DSM‐III‐R (subtype not stated) Age: mean 10.2 years (range 8‐13) IQ: mean 112.6 MPH‐naive: 0% Ethnicity: not stated Country: USA Setting: outpatient clinic Comorbidity: no Comedication: not stated Other sociodemographics: none Inclusion criteria Boys 8‐13 years of age ADHD Recruited from an outpatient clinic at a large metropolitan children’s hospital in the USA Conners' Hyperactivity Index score 1.5 SD above the norm on parent ratings ≥ 6 months of treatment with MPH Confirmed DSM‐III‐R diagnosis History of > 6 months of MPH treatment Exclusion criteria No physical or psychiatric diagnosis other than ADHD Evidence of learning disability "Each parent and prescribing physician reported that the subject responded positively to MPH"
Interventions	Participants were randomly assigned to 1 of 2 possible drug condition orders of MPH (normal dose) and placebo Mean MPH dosage: 0.030 mg/kg (range 0.08 to 1.10 mg/kg/d) Administration schedule: not stated Duration of each medication condition: 36 h Washout before trial initiation: not stated Titration period: not stated Treatment compliance: not stated
Outcomes	General behaviour Behaviour problems ‐ CBCL, parent ratings. Data not reported
Notes	Sample calculation: not described Ethics approval: not described Key conclusion of trial authors Stimulant effects on child’s motivation to perform a task may compensate for deficits in other areas Comment from review authors All participants had been treated previously with MPH for longer than 6 months; each parent and physician reported good response Exclusion of MPH non‐responders/children who have previously experienced AEs while taking MPH before randomisation: yes, only participants who responded positively to MPH included Any withdrawals due to AEs: unclear Funding source: a University of Utah Biomedical Sciences Research Grant and a grant from the University Research Committee Email correspondence with trial authors: May 2014. We obtained supplemental information from trial authors (Magnusson 2014c [pers comm])
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	From correspondence: "generated by pharmacist" (Magnusson 2014c [pers comm])
Allocation concealment (selection bias)	Low risk	From correspondence: "recruiter had no involvement in and was blinded to allocation sequence" (Magnusson 2014c [pers comm])
Blinding of participants and personnel (performance bias) All outcomes	Low risk	From correspondence: "pharmacist instructed parents (via instructions on pill bottle) regarding which pills should be administered and at what time" (Magnusson 2014c [pers comm])
Blinding of outcome assessment (detection bias) All outcomes	Low risk	See above
Incomplete outcome data (attrition bias) All outcomes	Low risk	From correspondence: "approximately 2% of skin conductance and heart rate data were affected by participant movement and were replaced with interpolated values Physiological data were lost for 2 participants with ADHD and for 2 participants without ADHD. For 3 of the remaining 28 participants, 1 of the 4 repeated measurements of interbeat intervals was replaced with the mean of the participant's diagnostic group because his ECG recordings were inadequate" (Magnusson 2014c [pers comm]) Selection bias (e.g. titration after randomisation → exclusion): no
Selective reporting (reporting bias)	Low risk	No indication of reporting bias