Hazell 2003.

Methods	A 6‐week, double‐blind, randomised, parallel study comparing clonidine vs placebo in methylphenidate‐treated children diagnosed with ADHD
Participants	Number of participants screened: not stated Number of participants included: 29 Number of participants followed up: 25 Number of withdrawals: 4 Diagnosis of ADHD: DSM‐IV (subtype: not stated) Age: mean 125.4 months (range: 6‐14 years old) IQ: > 70 Sex: 25 males, 4 females Methylphenidate‐naïve: none Ethnicity: white Country: Australia Comorbidity: borderline intellectual functioning: 12%, anxiety: 6%, pervasive developmental disorder: 1.5% Comedication: none Sociodemographics: not stated Inclusion criteria 6 to 14 years DSM‐IV diagnosis of ADHD and comorbid ODD or CD treated for a minimum of 3 months with either methylphenidate or dexamphetamine Attended psychiatric or paediatric clinics supervised by the authors T‐scores for attention problems and aggressive behaviour on the Child Behavior Checklist of ≥ 70, placing them in the 'clinically significant' range Exclusion criteria Obsessional symptoms, movement disorders, or psychosis Mental retardation (IQ < 70) History as determined by a physician of cardiac anomalies or other medical contraindications to the prescription of clonidine
Interventions	Mean methylphenidate dosage: 0.67 mg/kg/day Administration schedule: not stated Duration of intervention: 6 weeks Treatment compliance: not stated
Outcomes	Non‐serious adverse events: Parent and self‐report side effects checklists (Barkley) Pulse rate, and lying and standing blood pressure. Obtained at baseline and at weekly intervals for 6 weeks Height and weight assessed at baseline and at week 6
Notes	Sample calculation: yes Any withdrawals due to adverse events: no Ethics approval: approved by the Hunter Area Health Research Ethics Committee and the University of Newcastle Human Research Ethics Committee Funding/vested interests: supported by the Australian Rotary Health Research Fund Authors' affiliations: none declared Key conclusions of the study authors: the findings support the continued use of clonidine in combination with psychostimulant medication to reduce conduct symptoms associated with attention‐deficit/hyperactivity disorder. Treatment is well tolerated and unwanted effects are transient Exclusion of methylphenidate non‐responders/children who have previously experienced adverse events on methylphenidate: no. But patients had to have been treated with methylphenidate for a minimum of 3 months