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Clinical Trial
. 2025 Oct 1;143(4):851-861.
doi: 10.1097/ALN.0000000000005655. Epub 2025 Jul 15.

Gabapentin for Pain Management after Major Surgery: A Placebo-controlled, Double-blinded, Randomized Clinical Trial (the GAP Study)

Sarah Baos  1 , Mandy Lui  1 , Terrie Walker-Smith  1 , Maria Pufulete  2 , David Messenger  3 , Reyad Abbadi  3 , Tim Batchelor  3 , Gianluca Casali  3 , Mark Edwards  4 , Nick Goddard  5 , Mohammed Abu Hilal  6 , Aiman Alzetani  6 , Marius Vaida  7 , Petr Martinovsky  8 , Palinikumar Saravanan  8 , Tim Cook  9 , Rajiv Malhotra  10 , Anna Simpson  11 , Ross Little  10 , Sarah Wordsworth  12 , Elizabeth Stokes  12 , Jingjing Jiang  12 , Barnaby Reeves  1 , Lucy Culliford  1 , Laura Collett  1 , Rachel Maishman  1 , Nilesh Chauhan  11 , Liz McCullagh  13 , Holly McKeon  1 , Samantha Abbs  1 , Jenny Lamb  1 , Anna Gilbert  1 , Chloe Hughes  1 , David Wynick  14 , Gianni Angelini  15 , Mike Grocott  16 , Ben Gibbison  17 , Chris A Rogers  1 ; GAP Investigators
Affiliations
Clinical Trial

Gabapentin for Pain Management after Major Surgery: A Placebo-controlled, Double-blinded, Randomized Clinical Trial (the GAP Study)

Sarah Baos et al. Anesthesiology. .

Abstract

Background: Gabapentin is an anticonvulsant medication with approval for use in neuropathic pain and epileptic disorders. It is frequently added to multimodal analgesic regimens during and after surgery to reduce opioid use while controlling pain effectively. There is little evidence to show its effectiveness in major surgery.

Methods: In this multicenter, double-blinded randomized controlled trial, adults undergoing major cardiac, thoracic, or abdominal surgery were randomized to receive either gabapentin (600 mg before surgery, 300 mg twice daily for 2 days after surgery) or placebo. The primary outcome was length of hospital stay. Secondary outcomes included acute and chronic pain, total opioid use, adverse health events, and health-related quality of life. Patients were followed up daily in-hospital until discharge and then at 4 weeks and 4 months after surgery.

Results: A total of 1,196 participants were randomized (500 underwent cardiac, 346 thoracic, and 350 abdominal surgery); 596 were allocated to placebo, and 600 were allocated to gabapentin. Median length of hospital stay was similar in the two groups (gabapentin, 5.94 [interquartile range (IQR), 4.08 to 8.04] days; placebo, 6.15 [IQR, 4.22 to 8.97] days; hazard ratio, 1.07; 95% CI, 0.95 to 1.20; P = 0.26). Overall, 384 participants experienced one or more serious adverse events (gabapentin, 189 of 596 [31.7%]; placebo, 195 of 599 [32.6%]), with some variation across surgical specialties.

Conclusions: Among patients undergoing major cardiac, thoracic, and abdominal surgery, adding gabapentin to multimodal analgesic regimes did not alter the length of hospital stay or the number of serious adverse events.

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Conflict of interest statement

Dr. Batchelor has received speaker fees/advisory board fees from JnJ, Medtronic, and Bristol Myers Squibb. Dr. Edwards has received an honorariam for a lecture from Edwards Lifesciences. Dr. Grocott declares the following conflicts of interest: Edwards Lifesciences (consultancy/medical advisory board). Dr. Casali left employment at the institution at which the study was being conducted during the trial; he is now employed by JnJ Med Tech. The other authors declare no competing interests.

The article processing charge was funded by the United Kingdom National Institute of Health and Care Research.

Figures

None
Graphical abstract
Fig. 1.
Fig. 1.
Participant flow through the trial.
Fig. 2.
Fig. 2.
Primary outcome was the time from surgery to discharge from hospital. (A) Time to discharge by treatment group and surgical specialty. (B to D) show hazard ratios with 95% CI for time to discharge for the gabapentin group versus the placebo group by subgroup. (B) Open and minimally invasive surgery. (C) Male and female recipients. (D) Surgery before and after the COVID-19 pandemic.
Fig. 3.
Fig. 3.
Opioid consumption after surgery to discharge and during follow-up. (A to C) Geometric mean ratios with 95% CI for opioid consumption in the first 5 days after surgery for the gabapentin group versus the placebo group by surgical specialty. (A) Cardiac. (B) Thoracic. (C) Abdominal. (D) Opioid consumption during follow-up in the different specialties. GMR, geometric mean ratio.
See this image and copyright information in PMC

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