Sample Size Planning for Psychiatric Clinical Trials
*Anastasia Ivanova, University of North Carolina at Chapel Hill 

Keywords: SPCD, Phase 2, Dose-finding

The sequential parallel comparison design (SPCD) is a two-stage design recommended for trials with possibly high placebo response. Drug-placebo comparison is followed by placebo non-responders being re-randomized between drug and placebo. Such two-stage strategy might be beneficial when combined with dose selection in a Phase 2 trial. Data obtained in such a study can guide the sponsor as to what study design to use in a pivotal trial, parallel design, placebo lead-in or a two-stage approach such as the SPCD. We give recommendations on how to design such a study, analyze the data and compute required sample size.