Abstract
Objectives:
The purpose of this study was to evaluate the efficacy of gabapentin and its effect on narcotic use in an outpatient sports medicine practice by comparing patients before and after initiating the routine use of gabapentin as part of a standardized post-operative pain medication regimen. We hypothesized that adding gabapentin to a multimodal post-operative pain regimen would decrease the number of requested pain medication refills and have no detrimental effect on Visual Analogue Scale and Single Assessment Numerical Evaluation scores at early post-operative visits.
Methods:
This study was designed as a retrospective cohort study of prospectively collected data and was approved by our institutional review board. All surgical patients <90 years of age undergoing outpatient orthopedic surgery at the senior author’s orthopaedic sports medicine practice were included over a 6-month period. All patients had a standard perioperative pain regimen consisting of 200 mg celecoxib, 1000 mg acetaminophen, and 75 mg pregabalin pre-op and hydrocodone/acetaminophen 5 mg/325 mg (28 pills, 1-2 tablets every 4 hours prn) and ketorolac 10 mg (every 6 hours for 20 doses) post-op. The study group also had gabapentin 300 mg TID for 7 days post-op. Intra-operative medications and regional anesthesia were at the discretion of the anesthesiologist. Patients were allowed 1 narcotic refill post-operatively and only in the first 3 weeks.
Patients were excluded from the study if their postoperative pain medication regimen deviated from the standardized protocol. This included any patient admitted to the hospital postoperatively as they were cared for by the internal medicine team upon admission. Patients were also excluded if they did not receive the standard perioperative pain medication regimen for various reasons such as medical comorbidities precluding the use of certain medications, medication allergies, patient preference regarding prescribed medications or prescribing oversight on the part of the orthopedic surgical team. Additionally, patients under workers compensation claims were excluded.
The primary outcome was difference in percentage of patients who requested a narcotic refill within 3 weeks post-op. Two and 6-week VAS and SANE scores, and baseline health and demographic data were collected. The closest dates to the 2- and 6-week time points were used when collecting VAS and SANE scores. Any patients that did not have a 2-week VAS or SANE score were excluded; however, patients that had a 2-week VAS and SANE score but not a respective score at 6-weeks were still included.
A difference of 20% was considered clinically significant. Prehoc power analysis using a power of 80% (β level = .20, α level = .05) revealed a minimum of 70 per group (n = 140) would be necessary to properly evaluate the primary hypothesis. A sample size of 200 (100 per group) was selected to generate greater study power for the primary outcome. Secondary outcomes included SANE and VAS scores. Tertiary outcomes were demographic differences, surgical intervention, location of surgery, anesthesia, admission to hospital after surgery, complications requiring repeat visit to the operating room, ED visit, re-admit to hospital.
T- tests were run on continuous variables, Chi-Square or Fisher’s Exact Test were run on dichotomous variables, and Mann-Whitney U test was run on all other categorical variables. Statistical significance was set at P < .05 for all tests. All analyses were performed using SPSS 29.0 (IBM, Armonk, New York).
Results:
234 patients were assessed for participation in the study: 121 patients in the pre-gabapentin cohort and 113 patients in the post-gabapentin cohort. From these cohorts, 33 total patients were excluded. A total of 201 patients were included in the final analysis. There were 101 patients in the pre-gabapentin cohort and 100 patients in the post-gabapentin cohort (Figure 1).
Notably, there were some baseline differences between the 2 groups. BMI was slightly lower in the pre-gabapentin cohort (28.0 vs 30.1; p = .014). There was higher tobacco and illicit drug use pre-op in the pre-gabapentin cohort [tobacco use: 18.8% vs 5.0% (p = .003); illicit drug use: 16.8% vs 5.0% (p = .007)] (Table 1).
Fifteen total patients were seen in the ED following surgery (pre-gabapentin: n = 7; post-gabapentin: n = 8; p = .773). Only 6 patients were seen in the ED for a concern directly related to their surgery: post-op pain, drainage from surgical incision site, surgical wound dehiscence, and swelling at site of surgery (pre-gabapentin: n = 4; post-gabapentin: n = 2; p = .231). No patient had a recorded complication related to taking gabapentin.
Patients who received gabapentin requested fewer narcotic refills [pre-gabapentin: n = 23 (22.8%); post-gabapentin: n = 9 (9.0%); p = .006]. There were no significant differences between VAS and 2-week SANE scores. Six-week SANE scores were lower in the post-gabapentin cohort (mean difference = 6.4; p = .027), though, less than the established MCID for SANE scores (Table 2).
Additionally, we found that smokers requested more narcotic refills (p = .005) (Table 3). This may indicate challenges in controlling tobacco user’s pain or some other cause of a greater demand from smokers for opioids post-operatively.
Conclusions:
The present study found that the addition of gabapentin to a postoperative pain regimen reduced the use of narcotics after sports medicine surgeries and provided equivalent pain control. This study adds to the growing body of literature on the usefulness of multimodal pain regimens in orthopedic surgery. Further prospective randomized trials in orthopaedic sports medicine are needed to further delineate the benefit derived from using gabapentin as part of a multimodal regimen for postoperative pain control.
