Ketamine for suicidal ideation in adults with psychiatric disorders: A systematic review and meta-analysis of treatment trials

A single infusion of ketamine may reduce suicidal thoughts in people with treatment-resistant depression within four hours, and the effect can last up to 72 hours. The analysis combined 15 randomized controlled trials with 572 participants, mostly with mood disorders. At four hours after infusion, suicidal ideation scores dropped significantly (standardized mean difference -0.51), and the reduction persisted through 72 hours (standardized mean difference -0.57 to -0.63 at different intervals) but not beyond. Results varied widely across studies, and evidence quality was moderate to low. There were almost no data on whether ketamine prevents actual suicide attempts or self-harm. Further trials are needed to confirm these findings and find ways to sustain the anti-suicidal effect.

Study at a glance

Abstract

OBJECTIVE: Ketamine may reduce suicidal ideation in treatment-resistant depression. But it is not known how quickly this occurs and how long it persists. We undertook a systematic review and meta-analysis to determine the short- and long-term effectiveness of ketamine for suicidality. METHOD: CENTRAL, EMBASE, Medline, and PsycINFO were searched until 12 December 2018. Randomised controlled trials of ketamine or esketamine reporting data on suicidal ideation, self-harm, attempted or completed suicide in adults diagnosed with any psychiatric disorder were included. Two reviewers independently extracted data, and certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation tool. Standardised mean difference was used for continuous outcomes. RESULTS: Twenty-five reports from 15 independent trials, with a total of 572 participants diagnosed with predominately affective disorders, were included. The evidence was rated moderate to low. In most trials, ketamine was administered at 0.5 mg/kg via a single intravenous infusion over a 30- to 45-minute period. Only a single trial of intranasal esketamine was identified. At 4 hours post-infusion, treatment with ketamine was associated with a significant reduction in suicidal ideation scores (standardised mean difference = -0.51, 95% confidence interval = [-1.00, -0.03]), which persisted until 72 hours post-infusion (time points between 12 and 24 hours: standardised mean difference = -0.63, 95% confidence interval = [-0.99, -0.26]; between 24 and 72 hours: standardised mean difference = -0.57, 95% confidence interval = [-0.99, -0.14]), but not thereafter. However, there was marked heterogeneity of results. In a single trial of esketamine, marginal effects on suicidal ideation were observed. In terms of actual suicidal behaviour, there were virtually no data on effects of ketamine or esketamine. CONCLUSION: A single infusion of ketamine may have a short-term (up to 72 hours) beneficial impact on suicidal thoughts. While confirmation of these results in further trials is needed, they suggest possible use of ketamine to treat acute suicidality. Means of sustaining any anti-suicidal effect need to be found.