Weeding Out the Problem: The Impact of Preoperative Cannabinoid Use on Pain in the Perioperative Period

Christopher W. Liu, BSc, MBBS, MMED; Anuj Bhatia, MBBS, MD, FRCA, FRCPC, FIPP, FFPMRCA, EDRA; Arlene Buzon-Tan, RN, MN, NP; Susan Walker, RN, MN, NP; Dharini Ilangomaran, BSc; Jamal Kara, BSc, PG, Diploma; Lakshmikumar Venkatraghavan, MBBS, MD, FRCA, FRCPC; Atul J. Prabhu, MBBS, FRCA, FRCPC

Disclosures

Anesth Analg. 2019;129(3):874-881. 

In This Article

Abstract and Introduction

Abstract

Background: The recreational and medical use of cannabinoids has been increasing. While most studies and reviews have focused on the role of cannabinoids in the management of acute pain, no study has examined the postoperative outcomes of surgical candidates who are on cannabinoids preoperatively. This retrospective cohort study examined the impact of preoperative cannabinoid use on postoperative pain scores and pain-related outcomes in patients undergoing major orthopedic surgery.

Methods: Outcomes of patients who had major orthopedic surgery at our hospital between April 1, 2015 and June 30, 2017 were reviewed. Data were obtained from Networked Online Processing of Acute Pain Information, a locally developed database for our Acute Pain Service. Propensity score matching was used to balance baselines variables including age, sex, type of surgery, history of depression or anxiety, and perioperative use of regional anesthesia between patients who reported use of cannabinoids and those not on this substance. Intensity of pain with movement in the early postoperative period (defined as up to 36 hours after surgery) was the primary outcome of this study. The secondary outcomes (all in early postoperative period) were pain at rest, opioid consumption, incidence of pruritus, nausea and vomiting, sedation, delirium, constipation, impairment of sleep and physical activity, patient satisfaction with analgesia, and the length of Acute Pain Service follow-up.

Results: A total of 3793 patients were included in the study. Of these, 155 patients were identified as being on cannabinoids for recreational or medical indications in the preoperative period. After propensity score matching, we compared data from 155 patients who were on cannabinoids and 155 patients who were not on cannabinoids. Patients who were on preoperative cannabinoids had higher pain numerical rating score (median [25th, 75th percentiles]) at rest (5.0 [3.0, 6.1] vs 3.0 [2.0, 5.5], P = .010) and with movement (8.0 [6.0, 9.0] vs 7.0 [3.5, 8.5], P = .003), and a higher incidence of moderate-to-severe pain at rest (62.3% vs 45.5%, respectively, P = .004; odds ratio, 1.98; 95% CI, 1.25–3.14) and with movement (85.7% vs 75.2% respectively, P = .021; odds ratio, 1.98; 95% CI, 1.10–3.57) in the early postoperative period compared to patients who were not on cannabinoids. There was also a higher incidence of sleep interruption in the early postoperative period for patients who used cannabinoids.

Conclusions: This retrospective study with propensity-matched cohorts showed that cannabinoid use was associated with higher pain scores and a poorer quality of sleep in the early postoperative period in patients undergoing major orthopedic surgery.

Introduction

Social acceptance for the use of cannabinoids (marijuana) is at an all-time high in North America. In the United States, 8 states and the District of Colombia have decriminalized the use of recreational marijuana.[1] Twenty-nine states and the District of Colombia have also passed laws that allow the use of marijuana for medical purposes, and an additional 17 states have permitted medical access to low-tetrahydrocannabinol/high-cannabidiol products.[2] In Canada, legal provisions allowing access to medical marijuana were introduced in 2001,[3] and recreational use of marijuana is now legal with the passing of the Cannabis Control Act.[4] In a recent survey, it was noted that more than 80% of a cohort of preoperative patients in the United States believed that cannabinoid products would be effective for the management of postoperative pain, they would use cannabinoids if these were prescribed by their health care team,[5] and 1 in 10 adult users of cannabis use it for medical purposes.[6]

This pattern of accelerating use of cannabinoids is reflected in several recent studies and systematic reviews of cannabinoids that address the analgesic potential of synthetic and natural cannabinoids in treatment of chronic pain.[7,8] With regards to the acute pain (perioperative or trauma related) literature, there have been at least 7 small randomized controlled trials during the past 35 years that have evaluated the impact of cannabinoid use as an intervention on acute pain.[9–15] Of these, 6 did not show an analgesic impact,[9–14] and, in the only positive study,[15] it was difficult to make a definitive conclusion about the effects of cannabinoids due to minimal reporting of the strategies used for randomization, allocation concealment, and blinding. Two recent systematic reviews have identified the lacunae in the quality of randomized controlled trials on cannabinoids in the acute pain context, and the authors concluded that cannabinoids should not be used for the management of acute pain.[16,17]

It is now well recognized that chronic opioid use leads to tolerance and or opioid-induced hyperalgesia, resulting in poorer postoperative pain control and higher postoperative opioid requirements. Given the role of cannabinoid receptors in the pain pathways,[18] it is surprising that similar studies have not been performed to look at the impact of preoperative cannabinoid use on the postoperative pain experience. The paucity of data to guide the perioperative management of marijuana users spurred us to perform a retrospective cohort study with the objective of examining the impact of recreational or medical cannabinoid use on early postoperative pain outcomes in patients undergoing major orthopedic surgery. Intensity of pain with movement in the early postoperative period (defined as up to 36 hours after surgery) was the primary outcome of this study. Intensity of pain at rest, opioid requirements, physical activity, quality of sleep, patient satisfaction, adverse effects, and the length of Acute Pain Service follow-up were the secondary outcomes.

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