Different symptomatic improvement pattern revealed by factor analysis between placebo response and response to Esketamine in treatment resistant depression.

AIMS: The aim of this study is to determine whether there is difference in the change in each symptom of depression and in symptomatic improvement pattern between placebo and antidepressant responses. METHODS: Using data from a randomized, double-blind (DB), placebo-controlled trial of esketamine (ESK) in patients with treatment-resistant depression (TRD), we conducted exploratory analyses. To determine differences in the change in each depressive symptom on the MADRS subscale between placebo and antidepressant responses, a two-way factorial analysis was conducted using the amount of change on Day 2 and 28 of treatment. In addition, exploratory and confirmatory factor analyses were conducted on the MADRS subtotal variables on Day 2 and 28 of treatment to determine symptomatic improvement pattern between placebo response and antidepressant responses. RESULTS: We found that as well as MADRS total score, each subscale of MADRS score did not significantly differ between esketamine and placebo at Day 2 and 28. On the other hand, factor analysis revealed that the factor structure of the response was different between esketamine and placebo at the 2nd day. There was no difference in the factor structure between esketamine and placebo in response on Day 28 of treatment. CONCLUSION: Factor analysis revealed different patterns of symptom improvement in the early phase of the intervention between esketamine and placebo. This finding suggests that a data driven approach may provide detailed efficacy information in clinical trials for antidepressants. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02918318. Registered: 28 September 2016.