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

Results

A total of 3793 patients were identified from the Networked Online Processing of Acute Pain Information database as having had hip arthroplasty, knee arthroplasty, and spine fusion surgery between April 1, 2015 and June 30, 2017. Of these patients, 155 (4.1%) patients were identified as cannabinoid users. Among the cannabinoid users, 34 (21.9%) were on nabilone on prescription and the rest were on other cannabinoid preparations (inhaled marijuana and cannabis oils) for medical or recreational purposes. Univariable analysis revealed that compared to noncannabinoid users, cannabinoid users were more likely to be younger and male. They were also more likely to be on opioids preoperatively, undergo spine surgery, and less likely to receive perioperative regional analgesia. The characteristics of the patients included in this study are summarized in Table 1.

After propensity score matching was performed, a total of 310 patients were included in the final analysis—155 patients in the cannabinoid cohort and a matched noncannabinoid cohort of 155 patients (Figure). The characteristics of the patients included in the propensity-matched cohorts are summarized in Table 1. The 2 cohorts were appropriately matched for the baseline variables likely to be potential confounders. Distribution of data was nonnormal for all continuous variables. The primary outcome of the study was pain score on movement in the early postoperative period. The median numerical rating score at rest in the early postoperative period was 5.0 (25th and 75th percentiles: 3.0, 6.1) and 3.0 (2.0, 5.5) in the cannabinoid cohort and noncannabinoid cohort, respectively. The distributions of numerical rating scores at rest were found to be significantly different between the 2 groups using the Wilcoxon signed-rank test with a P value of .01. The median numerical rating score with movement was 8.0 (6.0, 9.0) and 7.0 (3.5, 8.5), respectively, in the cannabinoid and noncannabinoid cohorts. The distributions of numerical rating scores on movement were also found to be significantly different using the Wilcoxon signed-rank test with a P value of .003. However, there was no difference in median opioid consumption (measured in oral morphine equivalents in milligram) in the first 24 postoperative hours among the 2 cohorts (Table 2).

Figure.

Flow chart for the study. APS indicates Acute Pain Service.

We compared analgesia-related adverse effects of pruritus, nausea and vomiting, impact on sleep and physical activity, sedation, delirium, patient satisfaction with analgesia, and duration of Acute Pain Service follow-up in the 2 cohorts. There was a higher incidence of sleep impairment in the cannabinoid cohort as compared to the noncannabinoid cohort (72.1% and 58%, respectively; P = .040). There were no differences in the other pain- and analgesia-related variables (Table 2).

Sensitivity analysis to explore the impact of type of surgery on analgesic outcomes was performed by analyzing pain scores and analgesia-related adverse effects for cohorts of patients who underwent major joint (hip and knee) and spine surgery. Cannabinoid users in the spine surgery cohort had higher median numerical rating scores for pain during movement as compared to those not on cannabinoids (8.00 [6.25, 10.00] and 6.00 [3.00, 9.00], respectively; P = .013), while patients who had hip or knee surgery who were not on cannabinoids had higher median numerical rating scores for pain at rest (4.75 [2.75, 6.00] and 3.00 [1.00, 5.75], respectively; P = .027) (Table 3). Further, cannabinoid users who had hip or knee surgery had a higher requirement for opioids in the early postoperative period as compared to noncannabinoid users (45.00 mg [30.00, 172.13 mg] and 40.00 [20.00, 99.00], respectively; P = .009). However, there were no differences in analgesia-related adverse effects between cannabinoid and noncannabinoid users in the 2 orthopedic surgery cohorts (Table 3). Sensitivity analysis for intensity of pain found the incidence of moderate-to-severe pain at rest and with movement to be significantly higher in the cannabinoid cohort than in the noncannabinoid cohort. A higher number of patients in the cannabinoid group had moderate-to-severe pain at rest as compared to the noncannabinoid cohort (62.3% and 45.5% respectively; P = .004; odds ratio, 1.98; 95% CI, 1.25–3.14). Further, more patients in the cannabinoid group had moderate-to-severe pain with movement as compared to the noncannabinoid cohort (85.7% and 75.2% respectively; P = .021; odds ratio, 1.98; 95% CI, 1.10–3.37).

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....