Zeiner 1999.

Study characteristics
Methods	Cross‐over trial with 2 interventions: MPH Placebo Phases: 7 weeks (3 weeks of medication, 1 week washout, 3 weeks of placebo) Zeiner 1995 (in Zeiner 1999): "extended treatment (mean duration 634 ± 130 days)"
Participants	Number of participants screened: 46 Number of participants included: 38 Number of participants followed up: 36 (36 boys, 0 girls) Number of withdrawals: 2 Diagnosis of ADHD: DSM‐III‐R or DSM‐IV (combined type (> 75%), hyperactive‐impulsive and inattentive types not stated) Age: mean 8.7 years (range 7‐11) IQ: mean 102 (range 79‐139) MPH‐naive: 100% Ethnicity: not stated Country: Norway Setting: outpatient clinic Comorbidity: ODD (23; 64%) Comedication: not stated Other sociodemographics: none Inclusion criteria Male Between 7 and 12 years of age Fulfilled diagnostic criteria for ADHD IQ ≥ 70 Exclusion criteria Pervasive developmental disorder Psychosis or mood disorder Any acute or chronic medical or neurological disease Used stimulants or any other psychotropic drug
Interventions	Participants were randomly assigned to 1 of 2 possible drug condition orders of MPH (0.5 mg/kg) and placebo. 31 children received a morning dose of 10 mg or 15 mg (and 5 young boys received 7.5 mg) Mean MPH dosage: not stated; "0.55 mg/kg to 0.56 mg/kg daily across the entire duration of the extended treatment period" (Zeiner 1995 in Zeiner 1999) Administration schedule: capsules were given in 2 doses (at 8 am and 11.30 am) Duration of each medication condition: 3 weeks Washout before trial initiation: not relevant MPH‐naive: all Medication‐free period between interventions: 1 week Titration period: none Treatment compliance: no information
Outcomes	ADHD symptoms Parent Account of Childhood Symptoms, at home CTRS, in classroom Assessments of the child were made during the last week of each trial period Non‐serious AEs Height, weight, heart rate, SBP, DBP
Notes	Sample calculation: no Ethics approval: no information Comment from trial authors This study has obvious limitations. Sample size was limited, and heterogeneity was noted with regard to behavioural characteristics and test performance. This heterogeneity may conceal associations found in subgroups of children with ADHD. Boys between 7 and 11 years of age were chosen. They represent the majority of children admitted with hyperactivity and inattention, but boys of other age groups may show a different clinical picture Key conclusions of trial authors Response to MPH was examined in 36 boys, 7‐11 years of age, with ADHD in a double‐blind, placebo‐controlled trial of cross‐over design Hyperactivity and conduct problems were significantly reduced during MPH treatment Stimulant medication was associated with improvement on tests of sustained attention, working memory and motor steadiness When individual changes were studied, it was found that 83% showed significant improvement in their hyperactivity at home or at school, and for 60%, levels of hyperactive behaviour were within the normal range High levels of hyperactivity at school at a relatively low age was a significant predictor of normalisation of hyperactivity in ≥ 1 setting. However, these predictors could classify correctly only 71% of children In clinical practice, a trial with stimulants is indicated for children with ADHD who show symptoms that are sufficiently severe to cause impairment at home and at school Comments from review authors Generation of allocation sequence is unclear No sample size calculation was performed Number of screened patients is unclear In Zeiner 1995 (in Zeiner 1999), this was written: "no sociodemographic information" Exclusion of MPH non‐responders/children who have previously experienced AEs while taking MPH before randomisation: no Any withdrawals due to AEs: no Funding: the Norwegian Medical Research Council, the Norwegian Public Health Association and the Legacy of Haldis and Josef Andresen Email correspondence with trial authors: May‐June 2014. We emailed Dr. Zeiner on 05 May 2014 and 02 June 2014 but never received a reply
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Children were randomly allocated to receive MPH first or placebo first
Allocation concealment (selection bias)	Unclear risk	No information
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"A randomized crossover, double‐blind design with methylphenidate and placebo". Placebo and MPH capsules that were used were identical, to ensure blindness to the drug condition
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"All raters were blind to the drug condition"
Incomplete outcome data (attrition bias) All outcomes	High risk	"The report from a teacher during one of the periods was missing for one child. Owing to technical problems or unwillingness to participate data were missing on some of the test measures [which measured side effects] for a few children" (Zeiner 1995 in Zeiner 1999) Selection bias: yes; only responders from the 7‐week trial were included in the extended‐treatment MPH group
Selective reporting (reporting bias)	Low risk	No selective outcome reporting