Efficacy of single and repeated ketamine administration for suicidal ideation in adults with psychiatric disorders: A meta-analysis

Previous studies have demonstrated rapid-onset anti-suicidal ideation effects of ketamine. This study aimed to compare the efficacy and duration of anti-suicidal thoughts following single- and repeated-dose ketamine administration.

We retrieved published studies on ketamine for suicidal ideation (SI) from PubMed, OVID (MEDLINE), Web of Science, and Embase, spanning from inception to May 1, 2024. Standardized mean differences (SMD) in the SI scores were calculated for continuous outcomes.

This study included 49 independent clinical trials involving 3982 participants. After a single ketamine administration, a significant reduction in SI was observed at 4 h (SMD = -0.607, 95 % confidence interval (CI) = [-0.797, -0.418], I² = 40.69 %), with peak effects observed at 24 h (SMD = -0.955, 95 % CI = [-1.229, -0.682], I² = 63.66 %) and effects persisted for one month (SMD = -0.948, 95 % CI = [-1.611, -0.285], I² = 74.32 %). Similar anti-suicidal effects were observed at the treatment endpoint (SMD = -1.228, 95 % CI = [-1.506, -0.950], I² = 94.56 %) and during a follow-up period of greater than or equal to 1 month (SMD = -1.012, 95 % CI = [-1.695, -0.330], I² = 80.44 %) with multiple doses of ketamine administration.

Single ketamine treatment may have a significant and lasting (up to 1 month) beneficial effect on SI. There was no statistical difference in the efficacy and duration of anti-suicidal thoughts between single and serial ketamine administration.