Pelham 1993a.

Study characteristics
Methods	Cross‐over trial with 2 interventions: MPH 0.3 mg/kg and 0.6 mg/kg placebo Phases: 3
Participants	Number of participants screened: not stated Number of participants included: 31. Number of participants followed up: 31 (all boys) Number of withdrawals: 0 Diagnosis of ADHD: DSM‐III‐R (therefore no subtype) Age: mean 98.8 months (approximately 8.2 years; range 5.42‐9.92) IQ: mean 110.7 (range not stated) MPH‐naive: not stated Ethnicity: white (93.5%), African American (6.5%) Country: USA Setting: hospital (Summer Treatment Program) Comorbidity: ODD (32%), CD (48%) Comedication: not stated Other sociodemographics: none Inclusion criteria Boys with ADHD attending a Psychiatric Institute and Clinic Summer Treatment Program Exclusion criteria None described
Interventions	Participants were randomly assigned to 1 of 3 possible drug condition orders of 0.3 mg/kg and 0.6 mg/kg MPH and placebo Mean MPH dosage (SD): low 8.1 mg (range 5‐15); high 16.0 mg (range 10‐22.5) Administration schedule: twice/d morning and midday; conditions were changed daily over 6 weeks Duration of each medication condition: 2 weeks overall (individual treatment condition 1 day) Washout before trial initiation: not described Titration period: none Treatment compliance: not reported
Outcomes	ADHD symptoms Teachers rated inattention/overactivity daily with the IOWA CTRS
Notes	Sample calculation: no Ethics approval: not stated Key conclusion of trial authors Relatively small incremental value was gained by the higher dose of medication or by the addition of behaviour modification compared with the effects of the low dose of MPH Inclusion of MPH responders only/exclusion of MPH non‐responders/children who have previously experienced AEs while taking MPH before randomisation: no Any withdrawals due to AEs: no Funding source: not declared Email correspondence with trial author: June 2014. Emailed trial author to ask for additional information but have received no response
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Referred to as a randomised trial but sequence generation not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Capsules were identically packaged
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Referred to as double‐blind but not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	Appears to be 100% follow‐up Selection bias (e.g. titration after randomisation → exclusion): no
Selective reporting (reporting bias)	Unclear risk	Protocol not identified