Cook 1993.

Study characteristics
Methods	6‐week, double‐blind, single cross‐over, placebo‐controlled trial conducted on a group of 15 participants with ADD and a comparison group of 10 age‐matched participants who did not have ADD ADD group was randomly assigned to 1 of 2 experimental groups: MPH placebo
Participants	ADD group Number of participants screened: not stated Number of participants included: 15 (all boys) Number of participants followed up: 15 Number of withdrawals: 0 Diagnosis of ADHD: DSM‐III (100% met DSM‐III criteria for ADD with hyperactivity) Age: mean 104.5 months (approximately 8.7 years) (range 6‐10 years) IQ: mean 110.5 (SD 7.15) MPH‐naive: 100% Ethnicity: not stated Country: USA Setting: outpatient clinic Comorbidity: central auditory processing disorder (80%) Comedication: not stated Other sociodemographics: none Inclusion criteria Male 6‐10 years of age IQ > 85 Clinical diagnosis of ADD from paediatrician and met DSM‐III criteria for ADD on both Parent and Teacher Versions of the SNAP; scored ≥ 15 points on the Parent Version of the Abbreviated Conners' Rating Scale Exclusion criteria Seizures Cerebral palsy Learning disabilities Speech or language problems Vision or peripheral hearing problems Thought disorder Abnormal auditory brainstem‐evoked potentials Previous drug treatment for ADHD
Interventions	Participants were randomly assigned to 1 of 2 possible drug condition orders of MPH and placebo Mean MPH dosage: 0.30 mg/kg (0.057) Administration schedule: not stated Duration of each medication condition: 3 weeks Washout before trial initiation: not relevant, 100% treatment‐naive Medication‐free period between interventions: minimum of 48 h between the 2 interventions Titration period: dose was titrated up to a maximum (MPH tablets or placebo tablets) over the first 3 weeks of the experimental period Treatment compliance: not stated
Outcomes	ADHD symptoms SNAP: teacher‐ and parent‐rated, only items on the Inattention and Impulsivity subdomains, measured at the end of each treatment condition ADD/H Comprehensive Teacher Rating Scale: measured at the end of each treatment condition Abbreviated Conners' Rating Scale: parent‐rated, measured at the end of each treatment condition
Notes	Sample calculation: no information Ethics approval: yes Comment from trial authors Limitations: the conclusion should not be generalised to results obtained with measures other than the 3 behaviour rating scales. The sample is small. Stimulant treatment periods were brief, and results may not have been maintained at the same level if the trial had been conducted over a longer period Comment from review authors Read relevant parts of Dr. Cook's Ph.D. dissertation to get additional information about the trial Key conclusion of trial authors "The implications of these results are 3‐fold. First, sustained attention is a critical feature of performance on tests of central auditory processing disorder, and current diagnostic criteria for central auditory processing disorder make clinical separation of the 2 disorders problematic. Second, stimulants appear to be a useful treatment for symptoms of both ADD and central auditory processing disorder. Third, tests of central auditory processing disorder may provide a useful measure of ADD symptoms and response to stimulants" 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: supported by the Medical Center Rehabilitation Hospital Foundation and the School of Medicine, University North Dakota; the Veterans Hospital; the Dakota Clinic; and The Neuropsychiatric Institute, Fargo, North Dakota Email correspondence with trial authors: September 2013. Emailed trial author requesting additional information about the trial and data. Dr. Cook referred to his Ph.D. dissertation, which we managed to get.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were assigned to groups by a table of random numbers known only to the pharmacist
Allocation concealment (selection bias)	Low risk	Drugs were coded and administered by a pharmacist, and clinical titration of dosage was done by the participant’s paediatrician; neither practitioner was involved in data collection
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Physician, audiologist, teachers and parents involved in behaviour ratings and participants themselves were blinded to assigned treatment
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Physician, audiologist, teachers and parents involved in behaviour ratings and participants themselves were blinded to assigned treatment
Incomplete outcome data (attrition bias) All outcomes	Low risk	No incomplete outcome data Selection bias (e.g. titration after randomisation → exclusion): no
Selective reporting (reporting bias)	Low risk	No indication of selective reporting