title: A systematic review and meta-analysis of randomized, double-blind, placebo-controlled trials of ketamine in the rapid treatment of major depressive episodes.
abstract: BACKGROUND
  There is growing interest in glutamatergic agents in depression, particularly ketamine, a glutamate N-methyl-d-aspartate (NMDA) receptor antagonist. We aimed to assess the efficacy of ketamine in major depressive episodes.
  
  
  METHODS
  We searched EMBASE, PsycINFO, CENTRAL, and Medline from 1962 to January 2014 to identify double-blind, randomized controlled trials with allocation concealment evaluating ketamine in major depressive episodes. Clinical remission, response and depressive symptoms were extracted by two independent raters. The primary outcome measure was clinical remission at 24 h, 3 days and 7 days post-treatment. Analyses employed a random-effects model.
  
  
  RESULTS
  Data were synthesized from seven RCTs employing an intravenous infusion and one RCT employing intranasal ketamine, representing 73 subjects in parallel arms and 110 subjects in cross-over designs [n = 34 with bipolar disorder (BD), n = 149 with major depressive disorder (MDD)]. Ketamine was associated with higher rates of clinical remission relative to comparator (saline or midazolam) at 24 h [OR 7.06, number needed to treat (NNT) = 5], 3 days (OR 3.86, NNT = 6), and 7 days (OR 4.00, NNT = 6), as well as higher rates of clinical response at 24 h (OR 9.10, NNT = 3), 3 days (OR 6.77, NNT = 3), and 7 days (OR 4.87, NNT = 4). A standardized mean difference of 0.90 in favor of ketamine was observed at 24 h based on depression rating scale scores, with group comparisons revealing greater efficacy in unipolar depression compared to bipolar depression (1.07 v. 0.68). Ketamine was associated with transient psychotomimetic effects, but no persistent psychosis or affective switches.
  
  
  CONCLUSIONS
  Our meta-analysis suggests that single administrations ketamine are efficacious in the rapid treatment of unipolar and bipolar depression. Additional research is required to determine optimal dosing schedules, route, treatment schedules, and the potential efficacy of other glutamatergic agents.
authors.affiliation: Department of Psychiatry,University of British Columbia,Vancouver, BC,Canada.
authors.forename: A
authors.initials: A
authors.lastname: McGirr
authors.affiliation: Neuromodulation Research Clinic,Douglas Mental Health University Institute and McGill University,Montréal, Québec,Canada.
authors.forename: M T
authors.initials: MT
authors.lastname: Berlim
authors.affiliation: Department of Psychiatry,University of Minnesota,Minneapolis, MN,USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Bond
authors.affiliation: Depressive Disorders Program, Douglas Mental Health University Institute and McGill University,Montréal, Québec,Canada.
authors.forename: M P
authors.initials: MP
authors.lastname: Fleck
authors.affiliation: Department of Psychiatry,University of British Columbia,Vancouver, BC,Canada.
authors.forename: L N
authors.initials: LN
authors.lastname: Yatham
authors.affiliation: Department of Psychiatry,University of British Columbia,Vancouver, BC,Canada.
authors.forename: R W
authors.initials: RW
authors.lastname: Lam
mesh_terms: D003865:Major Depressive Disorder / Q000188:drug therapy*; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D016032:Randomized Controlled Trials as Topic
chemical_list: D018691:Excitatory Amino Acid Antagonists; D007649:Ketamine
keywords: RCT