Blindness of Clinical Evaluators, Parents, and Children in a Placebo-Controlled Trial of Fluvoxamine

Abstract

Few of the increasing number of pediatric clinical trials of selective serotonin reuptake inhibitors (SSRIs) in children have been evaluated for level of blindness of investigators, children, and parents. The success of the masking procedures used in a double-blind, pediatric trial of fluvoxamine in children was examined. Clinical evaluators, parents, and children were asked to guess individual treatment assignment at the end of an 8-week, placebo-controlled trial of fluvoxamine conducted in 128 outpatients (6-17 years of age) with anxiety disorders. The relationship between treatment attribution and improvement status or presence of adverse events was examined. The rate of correct guesses was significantly greater than chance among clinical evaluators (78%), parents (81%), and children (67%) (for all, p < 0.001). Attribution to fluvoxamine was associated with presence of clinical improvement, and attribution to placebo with lack of improvement (p < 0.001) in both the fluvoxamine and placebo group. There was no association between presence of adverse events and direction of the guess. Accuracy of the guess did not improve with time. The tendency to attribute improvement to active treatment and lack of improvement to placebo was consistent across investigators, parents, and children and was applied regardless of actual treatment received by the patient. Adverse events did not influence treatment attribution.