A Cochrane review included 16 studies with a total of 911 children under 18 years. Twenty-five established standardised outcome measures were reported to assess core features of autism spectrum disorders (ASD), communication, behaviour, visio-spatial skills, affect and adverse events. One standardised measure of global impression was also used. No more than four studies used any one outcome measure similarly. Outcomes were reported between three and six weeks. Meta-analysis of data was not possible but there is now consistency of findings, with RCTs of the efficacy of secretin in autism not showing improvements for core features of ASD.
Comment: The quality of evidence is downgraded by study limitations (unclear allocation concealment and blinding) and by inconsistency (unexplained variability in results).