Abstract
This study aimed to assess the effect of a single infusion of intravenous (IV) ketamine on suicidal ideation in patients with treatment-resistant depression (TRD). Patients with TRD were randomized in a double-blind fashion to a single infusion of IV ketamine or IV midazolam placebo. Suicidal ideation was measured using the Montgomery-Asberg Depression Rating Scale (MADRS) suicide item at 3, 5, 7, 14 and 30 days post infusion. Clinically significant suicidal ideation was defined as a MADRS suicide item score ≥2. Forty patients who received IV ketamine and 16 who received IV midazolam had suicide item scores of ≥2 at baseline (IV ketamine group mean 2.90±0.74; IV midazolam group 2.69±0.70). The mean suicide scores of these groups differed significantly from each other on day 30; the IV ketamine group had a lower mean score than controls (2.03±1.59 vs. 3.00±1.41, t-test p = 0.049; Hedges' g 0.71). Among patients with a suicide score of ≥2 at baseline and <2 at day 3, the two groups did not differ significantly on mean scores changes at days 3, 5, 7, 14 or 30. Recurrence of suicidal ideation was extensive in both treatment groups. A single infusion of IV ketamine may reduce suicidal ideation in TRD out to 30 days post infusion, but early anti-suicidal effects appear to diminish rapidly. This post-hoc analysis was not powered to compare different doses of ketamine. A single infusion of IV ketamine might have a role as an adjunct to standard treatments in patients with TRD and suicidal ideation. Trial registration: NCT01920555.