Preoperative Gabapentin Dosage Relationship to Length of Stay in Post-Anesthesia Care Unit in Patients Undergoing Pelvic and Breast Surgery

Abstract

Background: Gabapentin is routinely prescribed preoperatively to decrease postoperative pain intensity. It is included in the enhanced recovery after surgery (ERAS) recommendations. Objective: To analyze correlation of gabapentin dosage and post anesthesia care unit (PACU) length of stay (LOS) and cost. Study Design: A retrospective chart review of patients who underwent general anesthesia and received preoperative oral gabapentin from June 2017 to August 2017 for pelvic and breast procedures. The main outcome was correlation between PACU LOS and gabapentin dosage in the outpatients. Financial analysis was performed to assess the cost to the hospital associated with increased LOS. Results: Of the 636 patients, 405 patients received 300 mg and 231 patients received 100 mg gabapentin. Mean dosage per kg (mg/kg ± SD) was 3.12 ± 1.51 (range: 0.86 to 6.12). PACU LOS was 96 ± 77 (minutes ± SD) in patients receiving 100 mg and 120 ± 96 in patients receiving 300 mg capsule (p = 0.001). Linear regression analysis, failed to show a statistically significant correlation between per kg dosage and PACU LOS (p = 0.13). Using multiple regression analysis, we calculated the correlation coefficient to be +1.71 minutes per 1mg/kg gabapentin (95% CI: -3.75 to +7.10, p = 0.54) after adjusting for confounders. Adding 3 mg/kg to pre-op gabapentin dosage of all outpatients cost on average, an extra $9794 per month in this cohort. Conclusion: Every 1mg/kg increase in gabapentin dosage adds an estimated 7.1 minutes to PACU LOS. A 3 mg/kg increase in gabapentin adds estimated 22 additional minutes in PACU LOS. Unfortunately, increase LOS is associated with increased hospital costs.