REVIEW OF: Pan Y et al, Transl Psychiatry 2024;14(1):327
STUDY TYPE: Retrospective cohort study

Ketamine is one of the few medications in psychiatry that reduces suicidal ideation (SI). But how well does it work in the long run? This study used real-world data to see if ketamine’s effects on suicidality in recurrent major depressive disorder (MDD) last.

This US-based study looked at 514,988 patients with a new diagnosis of recurrent MDD who were prescribed antidepressant treatment. From this group, researchers identified 22,014 patients who received ketamine plus or minus other antidepressants. They matched them with an equal number of patients who had similar characteristics and were treated with other antidepressants, but not ketamine. Using electronic health records (EHRs), they tracked diagnoses of SI in the EHR at one week and then one, three, six, and nine months. The effect of ketamine on SI risk was assessed using hazard ratios (HRs).

Ketamine outperformed other antidepressants in both the short and long terms. In the first month, ketamine lowered the risk of SI by about 33% (HR = 0.67; 95% confidence interval [CI]: 0.59–0.77). Over nine months, the reduction was about 22% (HR = 0.78; 95% CI: 0.69–0.83). The benefit was especially strong for adults over 24 and White patients. The difference between ketamine and other treatments gradually narrowed from one to nine months but remained statistically significant.

CARLAT TAKE
This large but observational study finds that ketamine is associated with less mention of suicide in charts than other antidepressants. We don’t know if patients got the meds they were prescribed, how their depressions themselves fared, or if doctors documented ketamine-associated care differently. That said, these results are encouraging and favor ketamine when patients with recurrent MDD suffer from suicidality.