Pelham 1989.

Study characteristics
Methods	Cross‐over trial with 2 interventions: MPH placebo Phases No clear method description: "The procedure was double‐blind placebo‐controlled in which each child received, in random order with condition varied daily, placebo twice/d and 0.3 mg MPH/kg twice/d." ‐ "5 to 9 days of data were gathered"
Participants	Number of participants screened: not stated Number of participants included: 24 (12 boys, 12 girls) Number followed up: not stated Number of withdrawals: not stated Diagnosis of ADHD: DSM‐III (combined (not stated), hyperactive‐impulsive (19/24), inattentive (2/24)) Age: mean not reported (range: boys 5 years 6 months‐11 years; girls 5 years 8 months‐11 years 3 months) IQ: boys 100.8 (SD 14.23), girls 104.0 (SD 16.52) MPH‐naive: not stated Ethnicity: not stated Country: USA Setting: outpatient clinic (summer treatment programme) Comorbidity: attention deficit disorder (1/24), CD (5/24), ODD (15/24), learning disability (6/25) Comedication: yes; other doses of stimulants reported but not on trial days Other sociodemographics: none   Inclusion criteria None stated Exclusion criteria Children with an intellectual disability and those who had gross neurological disorders were not included in the trial
Interventions	Participants were randomly assigned to 1 of 2 possible drug condition orders of 0.3 mg/kg methylphenidate and placebo. "Each child received, in random order with condition varied daily, placebo twice a day and 0.3 mg MPH/kg twice a day." Mean MPH dosage: boys 9.8 mg (range 5.3‐16.9), girls 9.5 mg (range 5.2‐13.1) Administration schedule: twice daily at breakfast and at lunchtime Duration of each medication condition: not stated Washout before trial initiation: not stated Medication‐free period between interventions: no Titration period: none Treatment compliance: not stated
Outcomes	ADHD symptoms Abbreviated CTRS: 1‐3 times per condition Revised Behaviour Problem Checklist: counsellor‐rated, 1‐3 times per condition IOWA CTRS (IOWA CTRS) General behaviour Daily frequencies (following rules, non‐compliance, positive peer behaviours, conduct problems, negative verbalisations, numbers of time‐outs per day): daily Time‐out: daily Classroom measures, teacher recorded: daily Daily report card Observed peer interaction using modification of RECESS code: daily
Notes	Sample calculation: no Ethics approval: not stated Comment from trial authors Trial involved only 12 boys and 12 girls; 1 dose of MPH in the context of a highly structured summer programme: results must be considered preliminary Key conclusions of trial authors Results revealed equivalent and beneficial effects of MPH for both boys and girls MPH therefore would appear to be a treatment that is as useful for girls with ADD as for boys with ADD Comments from review authors Data reported from this trial cannot be considered robust No information on ethics committee approval, on randomisation, on primary endpoint (multiple endpoints), on sample size calculation, on safety, etc. Concomitant behavioural treatment was provided, but no details are given in the Methods section Exclusion of MPH non‐responders/children who have previously experienced AEs while taking MPH before randomisation: not stated Any withdrawals due to AEs: not stated Funding source: not declared Email correspondence with trial authors: October 2014. We received no supplemental information/data from trial authors. We asked authors whether this article was part of the Johnston 1988 trial but received no response, so we extracted the data as from 2 separate studies
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Each child received, in random order with condition varied daily, placebo and MPH
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Active medication and placebo were disguised in gelatin capsules and were pre‐packaged in individual, dated envelopes
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not stated Selection bias (e.g. titration after randomisation → exclusion): unclear
Selective reporting (reporting bias)	Unclear risk	No protocol found