Esketamine at induction lowered postoperative mood scores, but the paper will not say by how much

Design

Prospective, randomised, placebo-controlled trial, 1:1 allocation

Population

Adults undergoing elective laparoscopic radical resection for colorectal cancer

Primary outcome

Hospital Anxiety and Depression Scale score on postoperative day 1

Effect

HADS-A and HADS-D both lower on days 1 and 3, with lower 24-hour interleukin-6 and higher satisfaction (all P < 0.05); no effect sizes reported

Adults having elective laparoscopic radical resection for colorectal cancer were randomised 1:1 to conventional general anaesthesia with patient-controlled intravenous analgesia, or to the same plus esketamine: 0.5 mg/kg at induction and 1 mg/kg added to the analgesia pump. The primary outcome was the Hospital Anxiety and Depression Scale on postoperative day 1, with scores at days 3 and 7, sleep quality, level of consciousness, complications, length of stay, 24-hour inflammatory markers and satisfaction as secondary outcomes.

The esketamine group had lower HADS anxiety and HADS depression scores on days 1 and 3, lower 24-hour interleukin-6, and higher satisfaction, all reported at P below 0.05. The day 7 scores are not reported as differing, which suggests the effect is an early one.

What is missing matters as much as what is there. The report gives significance without effect sizes, and does not state how many patients were randomised. A HADS difference can be statistically significant and clinically trivial - the scale runs 0 to 21 per subscale and a change of 1.5 points is usually taken as the smallest that patients notice. Without the numbers a psychiatrist cannot tell whether this is a meaningful reduction in perioperative distress or a measurable one. Treat it as a signal worth following rather than a reason to ask anaesthetic colleagues to change a protocol.

• Perioperative esketamine is an anaesthetic decision; the psychiatric relevance is what it does to early mood scores
• Ask for the actual HADS values when a surgical team reports an improvement, not just the P value
• The effect appears confined to days 1 and 3, so it does not speak to persistent postoperative depression
• Interleukin-6 is a mechanistic marker here, not a patient outcome
• No safety signal is reported, but dissociative and haemodynamic effects remain the usual considerations with ketamine analogues

Why it matters

The question is no longer whether ketamine analogues affect mood quickly, but whether a perioperative dose is worth building into a pathway.

Don't overread it

Significance is reported without effect sizes or a sample size, so the clinical size of the benefit is unknown.

The statistics, in plain English

'All P < 0.05' is the least informative way to report a psychometric outcome. A P value tells you the difference is unlikely to be chance; it says nothing about whether the difference is large enough for a patient to feel. With the HADS this distinction is sharp, because the scale is sensitive enough that small group differences reach significance routinely. The absence of a stated sample size compounds the problem: in a small trial a significant result implies a large effect, in a large one it may imply a negligible one, and the reader cannot tell which situation this is.

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