Intraoperative ketamine was not linked to less long-term opioid dispensing after lumbar spine surgery

Design

Propensity-matched retrospective cohort study, electronic health record network, 2010 to 2024

Population

53,639 opioid-naive adults and 2,031 adults with opioid use disorder after lumbar spine surgery

Primary outcome

Outpatient opioid prescriptions at 48 hours, 6 weeks, 3, 6 and 12 months

Effect

Opioid-naive: RR 1.23 (95% CI 1.22 to 1.25) at 48 hours; no meaningful difference at 3 to 12 months

This retrospective study used a large US electronic health record network to compare patients who received intraoperative ketamine during lumbar spine surgery with propensity-matched patients who did not. After matching there were 53,639 opioid-naive patients and 2,031 with opioid use disorder.

In opioid-naive patients, ketamine exposure was linked to more outpatient opioid prescribing at 48 hours (RR 1.23, 95% CI 1.22 to 1.25) and 6 weeks (RR 1.14, 95% CI 1.10 to 1.18), and no meaningful difference at 3, 6 or 12 months. In patients with opioid use disorder, higher prescribing was seen only up to 48 hours. Opioid-related adverse events and new opioid use disorder were similar or more frequent with ketamine.

The authors stress that this is population-level database evidence. It cannot show whether particular doses or protocols help, and ketamine may have been used preferentially in patients expected to have more pain.

• Do not expect a single intraoperative ketamine dose to reduce long-term opioid use after spine surgery.
• Plan opioid-sparing pathways around the whole perioperative course, not one drug.
• Review discharge opioid prescriptions explicitly for patients who received ketamine.
• Consider ketamine for its other roles, such as acute analgesia, on separate evidence.
• Treat these findings as associations, since ketamine use was not randomised.

Why it matters

A widely used opioid-sparing adjunct showed no population-level signal on the outcome that matters most to patients.

Don't overread it

Retrospective and observational; it does not exclude benefit from particular ketamine doses or infusions.

The statistics, in plain English

A risk ratio of 1.23 with a very narrow interval reflects the huge sample, not a large effect: it means about 23% more prescribing at 48 hours in relative terms. In a database study, patients given ketamine may differ in ways matching cannot capture, a problem called confounding by indication.

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