NCT01624675.

Study characteristics
Methods	8‐week parallel trial of risperidone versus placebo
Participants	Inclusion criteria: 5‐17 years of age diagnosis of autism CGI‐S score of ≥ 4 and an ABC‐I score of ≥ 18 mental age > 18 months participants must have parent or caregiver willing and able to observe and rate their behaviour weigh ≥ 15 kg at time of screening Exclusion criteria: patients with current or previous psychotic disorders, or "endocrine, metabolic, cardiac, hepatic, renal, or pulmonary disorder, or hypertension" "Patients with known hypersensitivity to risperidone or paliperidone" Location/setting: 18 study centres in Japan Mean IQ: not reported Mean age: not reported Gender: not reported Sample size 39: risperidone (21); placebo (18) Reasons for dropouts/withdrawals: no dropouts reported Baseline ABC‐I or other BoC scale: ABC‐I risperidone 28.2 (6.36); placebo 27.5 (5.26) Concomitant medications: not reported Previous medications: not reported
Interventions	Intervention (risperidone) for 8 weeks: participants weighing < 20 kg received risperidone 0.25 mg/day up to day 4. On day 4, dose was titrated in increments of 0.25 mg/day (up to a daily dose of 1.0 mg) at the regular study visit thereafter until week 8. Participants weighing ≥ 20 kg received risperidone 0.5 mg/day up to day 4. On day 4, dose was titrated in increments of 0.5 mg/day (up to a daily dose of 2.5 mg) at the regular visit thereafter until week 8. The maximum daily dose for participants weighing ≥ 45 kg was 3.0 mg. Comparator (placebo) for 8 weeks: matching placebo
Outcomes	Primary outcomes: ABC‐I (Aman 1985) AEs Secondary outcomes: none reported Timing of outcome assessments: unclear
Notes	Study start date: June 2012 Study end date: October 2015 Funding: details not provided Conflicts of interest: details not provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Details not provided
Allocation concealment (selection bias)	Unclear risk	Details not provided
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information beyond double‐blinded
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information beyond double‐blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data available for all participants
Selective reporting (reporting bias)	Low risk	All outcomes reported
Other bias	Low risk	Outcomes matched those on clinical trials registry