The study also found that the prevalence of cannabis dependence or abuse recorded among surgical patients increased significantly over the last decade.
For the study, Li Ka Shing, MD, St. Michael’s Hospital, Toronto, Ontario, and colleagues analysed the records of over 4 million adults aged 18 to 65 years in the United States from 2006 to 2015 undergoing 1 of 11 common elective procedures, including total knee or hip replacement, coronary artery bypass graft surgery, gallbladder removal, caesarean section, hysterectomy, and hernia repair.
The principal exposure was an active cannabis use disorder, as defined by ICD-9-CM diagnostic codes for cannabis dependence and cannabis abuse.
The primary outcome was a composite endpoint of in-hospital postoperative MI, stroke, sepsis, deep vein thrombosis, pulmonary embolism, acute kidney injury requiring dialysis, respiratory failure, and in-hospital mortality.
There was no statistically significant difference between patients with (400 of 13,603 [2.9%]) and without (415 of 13,603 [3.1%]) a reported active cannabis use disorder with regard to the composite perioperative outcome.
However, the adjusted odds of postoperative MI was 1.88 (95% confidence interval [CI], 1.31-2.69; P< .001) times higher for patients with a reported active cannabis use disorder (89 of 13,603 [0.7%]) compared with those without (46 of 13,603 [0.3%]) an active cannabis use disorder (unadjusted odds ratio = 2.88; 95% CI, 2.34-3.55; P< .001).
“While cannabis is often purported as being safe or benign, we don’t fully understand the health implications of this drug, particularly in heavy users,” said co-author Karim Ladha, MD, St. Michael’s Hospital. “The results of this study make it clear that we need to pay more attention to cannabis users undergoing surgery.”