Gabapentin for pain management following major surgery: a placebo controlled, double blind, randomized clinical trial (The GAP Study).

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 (600mg before surgery, 300mg 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 1196 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 (IQR 4.08-8.04) days, placebo 6.15 (IQR 4.22 - 8.97) days; hazard ratio 1.07, 95%CI 0.95-1.20, p=0.26). Overall, 384 participants experienced one or more serious adverse events (gabapentin 189/596, 31.7%; placebo 195/599, 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.