Assessment of the integrity of study blindness in a pediatric clinical trial of risperidone

Benedetto Vitiello, Mark Davies, L. Eugene Arnold, Christopher J. McDougle, Michael Aman, James T. McCracken, Lawrence Scahill, Elaine Tierney, David J. Posey, Naomi B. Swiezy, Kathleen Koenig

Research output: Contribution to journalArticle

6 Scopus citations


Objective: Controlled clinical trials in pediatric psychopharmacology rely on blinded parents and clinical evaluators for outcome data, but little is known about the success of the masking procedures. The blindness of clinical evaluators and parents was examined in a clinical trial of risperidone in autism. Methods: Clinical evaluators and parents were asked to guess individual treatment assignments at the end of an 8-week placebo-controlled trial of risperidone in children (aged 5-17 years) with autism. Clinical evaluators did not have access to adverse event data. Results: The rates of correctly guessing individual treatment assignment (risperidone or placebo) were significantly greater than chance for both clinical evaluators and parents (P < 0.001). Clinical evaluators associated improvement with attribution to risperidone, and lack of improvement with attribution to placebo, in both the risperidone and placebo treatment arms. Parents associated improvement with attribution to risperidone only in the placebo treatment arm. Parents reported that adverse events influenced their guesses, but presence of adverse events was not associated with correctness of guess. Conclusion: Improvement was associated with attribution to active treatment regardless of actual treatment assignment, and adverse events did not appear to be a threat to study blindness.

Original languageEnglish (US)
Pages (from-to)565-569
Number of pages5
JournalJournal of Clinical Psychopharmacology
Issue number6
StatePublished - Dec 2005

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Pharmacology (medical)

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    Vitiello, B., Davies, M., Arnold, L. E., McDougle, C. J., Aman, M., McCracken, J. T., Scahill, L., Tierney, E., Posey, D. J., Swiezy, N. B., & Koenig, K. (2005). Assessment of the integrity of study blindness in a pediatric clinical trial of risperidone. Journal of Clinical Psychopharmacology, 25(6), 565-569.