Two-center analysis of cannabis on venous thromboembolism risk after traumatic injury: A matched analysis

Background: Conflicting evidence exists evaluating associations between cannabis (THC) and post-traumatic DVT. Methods: Retrospective analysis (2014–2023) of patients ≥15yrs from two Level I trauma centers with robust VTE surveillance and prophylaxis protocols. Multivariable hierarchical regression assessed the association between THC and DVT risk. THC ​+ ​patients were direct matched to other drug use categories on VTE risk markers and hospital length of stay. Results: Of 7365 patients, 3719 were drug-, 575 were THC ​+ ​only, 2583 were other drug+, and 488 were TCH+/other drug+. DVT rates by exposure group did not differ. TCH ​+ ​only patients had higher GCS scores, shorter hospital length of stay, and the lowest pelvic fracture and mortality rates. A total of 458 drug-, 453 other drug+, and 232 THC+/other drug ​+ ​patients were matched to 458, 453, and 232 THC ​+ ​only patients. There were no differences in DVT event rates in any paired sub-cohort set. Additionally, iteratively adjusted paired models did not show an association between THC and DVT. Conclusions: THC does not appear to be associated with increased DVT risk in patients with strict trauma chemoprophylaxis. Toxicology testing is useful for identifying substance abuse intervention opportunities, but not for DVT risk stratification in THC ​+ ​patients.