Ketamine eased "psychological pain" for up to 4 days in suicidal inpatients

The question

Does intravenous ketamine reduce “psychological pain” - the unbearable inner distress often described before suicidal thoughts - more than a placebo infusion in hospitalized patients at risk of suicide?

What they did

Researchers re-analyzed data from KETIS, a six-week randomized, double-blind, placebo-controlled trial in suicidal psychiatric inpatients. Participants received two 40-minute intravenous infusions given 24 hours apart: either ketamine at 0.5 mg/kg or salt-water placebo, on top of their usual care and medication. Psychological and physical pain were rated by patients themselves on a visual scale at the start, repeatedly over the first 96 hours, and again at weeks 2, 4 and 6. Statistical models compared how pain changed over time in the two groups.

What they found

Seventy-three people were randomized to ketamine and 83 to placebo. Psychological pain fell in both groups, but scores were lower with ketamine across the first 96 hours, with the biggest gaps at 40 minutes, 2 hours, 4 hours and 24 hours (all p < 0.001). There was no difference between groups at weeks 2, 4 or 6. The early advantage held after accounting for depressive symptoms and hopelessness, and appeared larger in the subgroup with bipolar disorder. No reliable baseline characteristics predicted who responded.

The fine print

This was a secondary analysis, so the psychological pain outcome was not the trial’s original main question and the findings should be treated as exploratory. The outcome was a single self-rated scale, the groups were modest in size, and the bipolar subgroup finding comes from a smaller slice of the sample. The difference disappeared after the first few days, and the abstract does not report effect sizes, actual scores or side effects. This summary is based on the abstract alone.

What it means

In hospitalized patients with suicidal thoughts, two ketamine infusions were linked to a short-lived drop in self-reported inner distress compared with placebo, lasting hours to a few days rather than weeks.

Evidence grade: Low. This is a secondary analysis of a randomized placebo-controlled trial, using a self-rated single-scale outcome that was not the original trial’s main target.

This summary is based on the study’s published abstract.