Treatment Assignment Guesses by Study Participants in a Double-Blind Dose Escalation Clinical Trial of Saw Palmetto

Abstract

Objectives: This report assesses participant perception of treatment assignment in a randomized, double-blind, placebo-controlled trial of saw palmetto for the treatment of benign prostatic hyperplasia (BCM). Design: Participants randomized to receive saw palmetto were instructed to take one 320 mg gelcap daily for the first 24 weeks, two 320 mg gelcaps daily for the second 24 weeks, and three 320 mg gelcaps daily for the third 24 weeks. Study participants assigned to placebo were instructed to take the same number of matching placebo gelcaps in each time period. At 24, 48, and 72 weeks postrandomization, the American Urological Association Symptom Index (AUA-SI) was administered and participants were asked to guess their treatment assignment. Settings: The study was conducted at 11 clinical centers in North America. Participants: Study participants were men, 45 years and older, with moderate to low severe BPH symptoms, randomized to saw palmetto (N = 151) or placebo (N = 155). Outcome measures: Treatment arms were compared with respect to the distribution of participant guesses of treatment assignment. Results: For participants assigned to saw palmetto, 22.5%, 24.7%, and 29.8% correctly thought they were taking saw palmetto, and 37.3%, 40.0%, and 44.4% incorrectly thought they were on placebo at 24, 48, and 72 weeks, respectively. For placebo participants, 21.8%, 27.4%, and 25.2% incorrectly thought they were on saw palmetto, and 41.6%, 39.9%, and 42.6% correctly thought they were on placebo at 24, 48, and 72 weeks, respectively. The treatment arms did not vary with respect to the distributions of participants who guessed they were on saw palmetto ( p = 0.823) or placebo ( p = 0.893). Participants who experienced an improvement in AUA-SI were 2.16 times more likely to think they were on saw palmetto. Conclusions: Blinding of treatment assignment was successful in this study. Improvement in BPH-related symptoms was associated with the perception that participants were taking saw palmetto.