Intravenous versus oral acetaminophen for pain and quality of recovery after ambulatory spine surgery: a randomized controlled trial

INTRODUCTION: As ambulatory spine surgery increases, efficient recovery and discharge become essential. Multimodal analgesia is superior to opioids alone. Acetaminophen is a central component of multimodal protocols and both intravenous and oral forms are used. While some advantages for intravenous acetaminophen have been touted, prospective studies with patient-centered outcomes are lacking in ambulatory spine surgery. A substantial cost difference exists. We hypothesized that intravenous acetaminophen would be associated with fewer opioids and better recovery. METHODS: Patients undergoing ambulatory spine surgery were randomized to preoperative oral placebo and intraoperative intravenous acetaminophen or preoperative oral acetaminophen. All patients received general anesthesia and multimodal analgesia. The primary outcome was 24-hour opioid use in intravenous morphine milligram equivalents (MMEs), beginning with arrival to the postanesthesia care unit (PACU). Secondary outcomes included pain, Quality of Recovery (QoR)-15 scores, postoperative nausea and vomiting, recovery time, and correlations between pain catastrophizing, QoR-15, and pain. RESULTS: A total of 82 patients were included in final analyses. Demographics were similar between groups. For the primary outcome, the median 24-hour MMEs did not differ between groups (12.6 (4.0, 27.1) vs 12.0 (4.0, 29.5) mg, p=0.893). Postoperative pain ratings, PACU MMEs, QoR-15 scores, and recovery time showed no differences. Spearman's correlation showed a moderate negative correlation between postoperative opioid use and QoR-15. CONCLUSION: Intravenous acetaminophen was not superior to the oral form in ambulatory spine surgery patients. This does not support routine use of the more expensive intravenous form to improve recovery and accelerate discharge. TRIAL REGISTRATION NUMBER: NCT04574778.