The association between stage of treatment-resistant depression and clinical utility of ketamine/esketamine: A systematic review.
Journal of affective disorders December 1, 2022 Anastasia Levinta, Shakila Meshkat, Roger S McIntyre et al.
Ketamine rapidly reduces depressive symptoms in people with treatment-resistant depression, but its effectiveness may diminish as the number of prior failed treatments increases. A systematic review of 18 randomized controlled trials found that ketamine and esketamine worked at both lower and higher stages of treatment resistance, yet effect sizes and duration of benefits were greater in studies involving patients with fewer prior antidepressant failures. Variability in how studies defined treatment resistance and measured outcomes prevented clear comparisons of efficacy across different resistance stages. The authors conclude that while ketamine remains broadly effective, more failed treatment trials may reduce its efficacy, and participant-level data are needed to clarify the relationship between resistance level and response.