A large trial found ketamine was not inferior to ECT for treatment-resistant depression. That leaves a practical question for anyone facing the choice: is there anything that suggests one might suit you better?
Researchers went back into that trial's data to look. They examined whether particular characteristics measured before treatment — depression severity, thinking and memory scores, a history of attempted suicide, and whether someone was an inpatient or outpatient — were linked to doing better on one treatment than the other.
The purpose was explicitly to support shared decision-making: helping a person and their clinician choose together, rather than the choice being made purely on availability or habit.
It is worth being clear that this was a secondary analysis, meaning these questions were not the ones the trial was originally designed to answer. Findings from this kind of analysis are a guide for further research and for conversations, not a rule.
Still, the direction is encouraging. The question is shifting from "is there anything left to try" to "which of these suits this particular person". If you are at that point in your own treatment, it is a fair thing to ask your psychiatrist directly.