Initial severity and efficacy of risperidone in autism: Results from the RUPP trial

Area of Science:

• Psychopharmacology
• Neurodevelopmental Disorders
• Clinical Trials

Background:

• Risperidone is a common treatment for irritability in autism spectrum disorder (ASD).
• The efficacy of risperidone across varying baseline symptom severity in ASD is not well-established.
• This study investigates how initial symptom severity influences risperidone's effectiveness in treating ASD.

Purpose of the Study:

• To examine the influence of baseline severity on the efficacy of risperidone in treating autism spectrum disorder (ASD).
• To determine if risperidone's effectiveness varies based on the initial severity of ASD symptoms.

Main Methods:

• Analysis of data from a multisite, randomized, double-blind trial (NCT00005014) involving participants aged 5-17 with ASD.
• Comparison of risperidone (n=49) versus placebo (n=52) using the Aberrant Behavior Checklist (ABC) for irritability and lethargy.
• Statistical examination using mixed-effects models to assess the relationship between baseline severity and treatment response.

Main Results:

• Significant interactions between risperidone treatment and baseline severity were found for parent-reported irritability and lethargy (P<0.01).
• Greater treatment effects of risperidone over placebo were observed in participants with moderate to very severe baseline symptoms.
• Initial severity scores above 30 strongly influenced symptom change, with large effect sizes (ES=1.9 for irritability, ES=0.9 for lethargy) and low numbers needed to treat (NNT=2 for irritability, NNT=5 for lethargy).

Conclusions:

• Risperidone may offer significant benefits for irritability and lethargy in children with moderate to severe autism spectrum disorder (ASD).
• Baseline symptom severity is a crucial factor in predicting treatment response to risperidone for specific ASD-related symptoms.