Questions on a Randomized Clinical Trial of Stellate Ganglion Block for Patients With Posttraumatic Stress Disorder—Reply

Olmsted et al thank Dr Stein for his interest in their study, "Effect of Stellate Ganglion Block Treatment on Posttraumatic Stress Disorder Symptoms: A Randomized Clinical Trial." Regarding the question about why the study enrolled fewer patients than were indicated in their ClinicalTrials.gov registration: enrollment failed to meet estimates used for the study design in the trial's first months. An interim sample size reestimation pooling all participants and conducted when the first 82 participants had 8-week data was conducted by analysts blinded to treatment regimen. The observed SD in the Clinician-Administered PTSD Scale for the DSM-5 (CAPS-5) score at 8 weeks was lower (12.4) than that used in the initial sample size estimate (25).