placebo response rate
The percentage of patients in the placebo group who show clinically meaningful improvement during a trial.
Full Definition
Placebo response rate refers to the proportion of patients receiving placebo treatment who demonstrate clinically significant improvement in their condition during a clinical trial. In psychiatric research, placebo response rates are typically high, often ranging from 20-40% in depression studies and even higher in anxiety disorders. This phenomenon poses significant challenges for demonstrating drug efficacy and is attributed to factors including the therapeutic effect of clinical attention, natural disease fluctuation, regression to the mean, and actual placebo effects. Understanding and managing placebo response is crucial for trial design, sample size calculations, and interpreting study results in psychiatric research.
Usage
Usage note: Express as a percentage and distinguish from overall response rate or active treatment response rate.
In Context
- "The unusually high placebo response rate of 45% made it difficult to demonstrate drug efficacy." — trial results discussion
- "Study design modifications were implemented to reduce the anticipated placebo response rate." — protocol amendment rationale