Ketamine as a rapid-acting agent for suicidal ideation: A meta-analysis.

The current systematic review and meta-analysis aimed at exploring acute effects of intravenous (IV) ketamine, an antagonist of N-methyl-D-aspartate (NMDA), in subjects with current suicidal ideation. We included clinical trials testing a single IV dose of ketamine and assessing changes in suicidal ideation within 4h after treatment. Meta-analyses based on random-effects models, were carried out generating pooled standardized mean differences (SMDs) between endpoint and baseline scores. Heterogeneity among studies was estimated using the I2 index. We searched main Electronic Databases, identifying five studies that met our inclusion criteria. The trials included 99 subjects treated with IV ketamine bolus or infusion. Data showed a large (SMD=-0.92; 95%CI: -1.40 to -0.44; p<0.001) and consistent (I2=21.6%) decrease of suicidal ideation, with effects comparable between IV bolus and infusion ketamine. Additional analyses confirmed the efficacy of ketamine across different time points. However, relevant, emerging evidence should be considered as 'very low' so far. Randomized, controlled and adequately powered trials are needed.