Effect of Gabapentin on Post-Operative Pain in Minimally Invasive Sacrocolpopexy

Enhanced recovery after surgery (ERAS) has been synonymous with increasing non-opioid multimodal therapies and decreasing opioid therapies after surgery to improve perioperative care. Gabapentin has been standardized as part of routine adjuvant post-operative enhanced recovery protocols after other surgical specialties surgeries. Limited data is known about the specifics of routine adjuvant post-operative gabapentin in the realm of urogynecology. Sacrocolpopexy has been noted as a highly effective prolapse surgical treatment, especially with apical and multicompartment prolapse. In 2006, approximately 73% of all sacrocolpopexy across the nation are completed through a minimally invasive approach. The role of gabapentin as part of a postoperative pain protocol following minimally invasive sacrocolpopexy (MISC) has yet to be determined.

This will be a randomized controlled pilot trial to determine the effect of a standard postoperative pain protocol with scheduled gabapentin versus placebo in decreasing post-operative pain scores. An institutional review board approach will be obtained and the trial will be registered at Clinicaltrials.gov and the protocol adhered to CONSORT guidelines.

Recruitment will start in October 2022 until completion of pilot study enrollment numbers at OU Health - a single academic center. If patients meet inclusion criteria (see below), willing participants will sign a written consent on their preoperative visit.

Researchers will be recruiting 20 patients per study arm: standard ERAS protocol post-operative care with placebo vs study group given standard ERAS protocol with scheduled postoperative gabapentin for the first two weeks following surgery.

Randomization will be computer generated, using a 1:1 allocation and variable block sizes of 2 and 4. Randomization and packing with opaque bags will be performed by our institution's investigation drug pharmacy. Consents will be signed by trained research assistant(s) and randomization should be maintained throughout the duration of enrollment. Patients will receive their medications concealed within an opaque bag given by the surgical team.

The primary outcome is pain during normal activity and rest via a standardized telephone prompt using the validated surgical pain scale (SPS) on POD 3-5 and 7-10. The SPS uses a numeric range from 0 to 10 with 0 representing no pain and 10 representing the worst pain imaginable. Pain scale will be assessed and opioid consumption will be measured at POD 14-16 during their routine follow up. Patients will be asked the number remaining opiate medications left at their follow up visit.

The secondary outcomes include adverse events, characterized using the National Institute of Health Common Terminology of Criteria for Adverse Events version 5.0. Researchers also plan to collect sociodemographic data: age, parity, race, past medical, and past surgical history. Data from routinely administered validated PFDI-20 and PFIQ-7 forms will also be obtained. Surgical data including concomitant procedures, intra- and perioperative complications, estimated blood loss, length of stay, and whether or not the patient discharges home with a catheter will be noted.

Standard post-operative pain control consists of continuous acetaminophen and/or NSAIDs and as needed oral opiates (oxycodone 5-10mg) for moderate to severe pain. If the patient randomizes to the study group, they will receive 14 days of gabapentin starting on postoperative day (POD) 1. Researchers will utilize a dosing pattern that was previously used in the Wu et al. randomized control trial as it was made in consultation with a geriatric pharmacist. Dosing will include administration of gabapentin 300mg nightly for 3 nights and then be increased to 300mg twice a day for an additional 11 days - a total of 25 tablets. Funding for the study and placebo medications for this study will be provided by an internal grant by the Department of Obstetrics and Gynecology.

Patients will be asked to complete a validated Surgical Pain Scale (SPS) pre-operatively to assess baseline pain. All vaginal and abdominal incisions will be infiltrated with local anesthetic prior to incision for both groups. Both groups will be given a standard senna (8.6mg) with docusate (50mg) daily post-operative bowel regimen as previously published by Patel et al. a.

Eligibility Criteria:
Inclusion Criteria:

• Patients have a diagnosis of uterovaginal prolapse, vaginal vault prolapse, or pelvic organ prolapse (based on International Classification of Diseases \[ICD\]).

Exclusion Criteria:

* Concurrent sphincter or fistula repair, urethral diverticulectomy or mesh excision
* Current gabapentin or pregabalin use
* Oxygen dependency
* Renal failure or glomerular filtration rate of \< 30mL/min
* Daily narcotic usage \>2 months - this is to allow us to capture an opiate-naïve patient population to better assess the impact of adjuvant gabapentin