Owley 2001.

Study characteristics
Methods	Cross‐over trial of porcine secretin versus placebo
Participants	Inclusion criteria: met the criteria for ASD by both the ADI‐R and the ADOS Exclusion criteria: any history of allergy to porcine products significant medical illness (excluding autism) including nonfebrile seizures Location/setting: University of Chicago, University of California‐Irvine, University of Utah, USA Sample size: 56 in total (28 to secretin‐placebo, 28 to placebo‐secretin) Number of withdrawals/dropouts: none reported Gender: 48 boys, 8 girls Mean age: 6.7 years IQ: mental age ≥ 24 months Baseline ABC‐I or other BoC: ABC‐I placebo‐secretiin 10.1. secretin‐placebo 11.6 Concomitant medications: 14 participants were taking a total of 15 psychotropic medications (at stable doses) during the study, including SSRIs (3), atypical neuroleptics (3), α‐adrenergic agonist (1), and psychostimulants (8) History of previous medications: participants on stable doses of psychotropic medications were included but they were asked not to change the dosages of these medications for the duration of the trial.
Interventions	Intervention (secretin) for 4 weeks: secretin was administered at 2 CU/kg/day Comparator (placebo) for 4 weeks: placebo (infused saline) that was indistinguishable from the active treatment
Outcomes	Primary outcomes: irritability, measured using the ABC‐Irritability subscale (Aman 1985) Secondary outcomes: none reported Timing of outcome assessments: baseline and then at the end of weeks 2, 4, 6 and 8
Notes	Study start date: not reported Study end date: not reported Source of funding: "this work was supported in part by the University of California at Davis Medical Investigation of Neurodevelopmental Disorders Institute (WM, EHC, PAF). Additional support was provided by grants from the NIMH (R01 MH52223, K02 MH01389, EC), the Jean Young and Walden W. Shaw Foundation (BLL), and the Irving B. Harris Foundation (BLL). This work was conducted as part of the NICHD/NIDCD Collaborative Network on the Neurobiology and Genetics of Autism." Conflicts of interest: none disclosed
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Randomisation was done by the investigational pharmacy at each site". Unclear as to the method and whether the same method was used across all sites.
Allocation concealment (selection bias)	Unclear risk	Details not provided
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "All patients, their parents, all members of the assessment team were blind to drug assignments until all subjects at that site had completed the trial."
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Members of the assessment team were blind to drug assignments until all subjects at that site had completed the trial.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants were accounted for and where particular assessments were missed, the number of participants who were analysed were indicated in brackets ().
Selective reporting (reporting bias)	Low risk	All outcomes reported at cross‐over endpoints
Other bias	High risk	Only a single dose of secretin was used.