Ketamine in electroconvulsive therapy for depressive disorder: A systematic review and meta-analysis.

Electroconvulsive therapy (ECT) is one of the most effective treatments for depressive disorder. Sub-anesthetic dose of ketamine exerts a rapid and robust antidepressive effect. However, it is still unclear whether ketamine usage in ECT is efficacious as an antidepressant. We aimed to conduct a systematic review and meta-analysis on the effects of ketamine in ECT among patients with depressive disorder. MEDLINE, EMBASE, the CENTRAL and PsycINFO for randomized controlled trials were searched to assess the effects of ketamine used in ECT until 31 Mar 2018 (PROSPERO: CRD42018081024). Sixteen studies including 928 patients were enrolled. At the end of ECT, no significant standardized mean difference (SMD) was observed in favor of the ketamine group. Depressive scores were lower in the ketamine group after 1st ECT and 3rd to 6th ECTs. The depressive scores were lower after 2nd, 3rd, 4th and 6th ECTs when the ketamine was used as an add-on anesthetic, while the depressive scores were lower after 1st ECT when ketamine alone was used. Ketamine in ECT showed no better response and remission rate, while increased adverse events, especially related to cardiovascular and psychiatric systems, during the whole ECT course. In conclusion, although ketamine used in ECT cannot reduce the depressive symptoms at the end of treatment, it could accelerate the antidepressive effect in depressive patients receiving ECT, especially in those who used ketamine as an add-on anesthetic. However, ketamine cautiously needs to be administered in ECT due to the possibility of increased risk of side effects.