DISCRIMINATING PLACEBO AND DRUG IN GENERALIZED ANXIETY DISORDER (GAD)TRIALS - SINGLE VS MULTIPLE CLINICAL RATERS

A multisite, double-blind, placebo-controlled study was made of 177 pa tients with the diagnosis of generalized anxiety disorder. After a 1-w eek placebo lead-in, they were randomized to 4 weeks of treatment by p lacebo or one of two doses of a novel, nonsedating compound that had d emonstrated reduction of fear-avoidance behavior in animals. Efficacy was not demonstrated at a significant level. A further analysis of 142 patients who completed the treatment was undertaken to test the hypot hesis that efficacy might be demonstrated by the single-rater procedur e (SRP), which eliminates interrater error variance. The 86 patients w ho were examined by the same clinical rater for all six visits were co mpared with the 62 patients who had the multiple-rater procedure (MRP) , ratings by two or more clinicians sequentially over the six visits. A two-way analysis of variance showed significantly greater discrimina tion of placebo and drug for the MRP group. The results provided no su pport for the frequent preference for the SRP. The MRP may include les s psychotherapeutic interaction with the patient and less researcher b ias in ratings.