Preoperative cannabinoid use in patients undergoing major orthopedic surgery may be associated with greater postoperative pain intensity, higher incidence of moderate to severe pain, and poorer sleep, according to a study published in Anesthesia & Analgesia.
With marijuana use increasing medically and recreationally, the likelihood that patients may have consumed cannabinoids prior to surgery is greater than ever. Because no studies have examined the impact of preoperative cannabinoid use on perioperative pain outcomes, investigators sought to describe the effects of consuming cannabinoids before major orthopedic surgery on pain and related outcomes in the early (first 36 hours) postsurgical period.
A retrospective cohort study examined data for the 2015 to 2017 period from the Networked Online Processing of Acute Pain Information database (n=3793 orthopedic patients). In this cohort, 155 patients (4.1%; mean age, 57 years; 56% men) were identified as preoperative medical or recreational cannabinoid users. These patients were propensity score matched on multiple demographic and clinical variables to 155 participants (mean age, 55 years; 52% men) who did not consume cannabinoids before surgery.
The primary outcome was early postoperative pain intensity with movement, as assessed using a 0 to 10 numeric rating scale (NRS). Secondary outcomes included early postoperative NRS pain scores at rest, impairments in sleep and physical activity, opioid consumption, and incidence of adverse effects.
Patients who consumed cannabinoids had higher early postoperative median pain scores compared with those who did not, both with movement (8.0 vs 7.0, respectively; P =.003) and at rest (5.0 vs 3.0, respectively; P =.010), as well as greater incidences of moderate to severe pain with movement (85.7% vs 75.2%, respectively; P =.021; odds ratio [OR], 1.98; 95% CI, 1.10-3.57) and at rest (62.3% vs 45.5%, respectively; P =.004; OR, 1.98; 95% CI, 1.25-3.14). Cannabinoid users vs non-users also reported more difficulty sleeping (P =.040). All other outcomes were similar between groups, without significant differences.
Study limitations include the use of self-reporting methods vs validated screens, potential unknown confounders inherent to observational research, the short follow-up period, and the relatively low cannabinoid usage rate.
“Patients who are on preoperative cannabinoids should be regarded as being at higher risk for poorly controlled postoperative pain, and more aggressive analgesic strategies may be indicated for this cohort,” noted the authors. They recommended that future research involve prospective randomized controlled trials examining possible mechanisms behind their findings.
Liu CW, Bhatia A, Buzon-Tan A, et al. Weeding out the problem: the impact of preoperative cannabinoid use on pain in the perioperative period. Anesth Analg. 2019;129(3):874-881.