Short 2004.

Methods	Single‐center, randomized, double‐blind, placebo‐controlled, cross‐over trial Country: United States Number of study sites: 1 Statistical methods: per protocol
Participants	Sample size: 34* children/adolescents with an ADHD diagnosis according to DSM‐IV criteria Dropouts: NR Psychiatric comorbid conditions: NR Age range: 3 years to 5.9 years Mean age (SD): 5.3 (NR) years Sex: 24 (85%) males ADHD subtype: 5 (17%) inattentive; 23 (83%) hyperactive ‐ impulsive or combined
Interventions	Two conditions (28 children/adolescents participated in one of two conditions)*: Amphetamine: Mixed amphetamine salts (short acting), 5 mg/day, once daily Mixed amphetamine salts (short acting), 10 mg/day, once daily Mixed amphetamine salts (short acting), 15 mg/day, once daily Placebo Methylphenidate: Methylphenidate, 5 mg/day, twice a day Methylphenidate, 10 mg/day, twice a day Methylphenidate, 15 mg/day, twice a day Placebo Amphetamine or methylphenidate determined by a physician Duration: 28 days (4 x 7‐day treatment periods)
Outcomes	Relevant outcomes: ADHD core symptom severity, assessed with Conners' Parent Rating Scale‐short form and Conners' Teacher Rating Scale‐short form** Adverse events
Notes	ClinicalTrial.gov identifier: not available Authors' affiliations: university Study funding: public funds *Clinical characteristics only presented on children/adolescents included in analysis (n = 28) **The authors did not separate the two active interventions (amphetamine and methylphenidate) in their analysis. We contacted the authors on three occasions to obtain the data on amphetamines only, but we received no response, and therefore outcomes could not be included in the meta‐analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of sequence generation not described
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not sufficiently described
Incomplete outcome data (attrition bias) All outcomes	High risk	Reasons for attrition not described. In addition, six participants were dropped from the analysis, and their last data point was not carried forward
Selective reporting (reporting bias)	Unclear risk	Study protocol not available and the possibility of reporting bias could not be assessed
Other bias	Low risk	Study appears to be free of other biases
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Intervention and placebo described as identical
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessors blinded to order of trial interventions