Independent and combined associations of cannabis and nicotine use with postoperative outcomes after cervical and lumbar interbody fusion: a retrospective cohort study.

Background Context: Cannabis use has increased substantially in the United States and is commonly perceived to improve pain control and reduce opioid requirements. However, its perioperative impact in spine surgery remains unclear, particularly when isolated from nicotine use. Purpose: To evaluate the independent and combined associations of cannabis and nicotine use with postoperative outcomes following cervical and lumbar interbody fusion. Study Design/Setting: Retrospective cohort study using the TriNetX Research Network, a federated national database of deidentified electronic health records from over 200 US healthcare organizations. Patient Sample: A total of 144,488 adult patients undergoing primary anterior cervical discectomy and fusion or lumbar interbody fusion procedures between 2015 and 2022. Outcome Measures: Neurological complications, surgical complications (including infection and pseudoarthrosis), medical complications, pain and functional outcomes, psychiatric outcomes, opioid-related outcomes, and healthcare utilization through 2 years postoperatively. Methods: Substance use exposures were defined using ICD-10 codes within 2 years preoperatively and categorized as nonusers, nicotine-only users, cannabis-only users, or concurrent cannabis and nicotine users. Cannabis exposure was identified using cannabis-related disorder codes or cannabis poisoning, and therefore reflects clinically documented problematic use rather than recreational cannabis behaviors. Multivariable logistic regression models adjusted for demographics, comorbidities, spine region, and surgical approach were used to estimate adjusted odds ratios (aORs) for outcomes. Pairwise intergroup comparisons and subgroup analyses by region and surgical approach were performed. Results: Among 144,488 patients, 108,962 were nonusers (75.4%), 33,309 nicotine-only users (23.1%), 540 cannabis-only users (0.4%), and 1,677 concurrent users (1.2%). Cannabis-only use was associated with higher odds of radiculopathy, cauda equina syndrome, chronic pain, myocardial infarction, acute respiratory failure, acute kidney injury, depression, opioid use disorder, and increased rehospitalization and emergency department utilization. Nicotineonly and concurrent use demonstrated broadly elevated risk across neurologic, surgical, medical, psychiatric, and utilization outcomes, including higher rates of infection, pseudoarthrosis, and opioid-related complications. Across most domains, concurrent users exhibited the highest adjusted odds. Venous thromboembolism was not significantly associated with any exposure group. Findings were generally consistent across cervical and lumbar procedures, with stronger associations observed following anterior approaches. Conclusions: Cannabis-related diagnoses were associated with higher odds of multiple adverse postoperative outcomes following spine fusion, particularly for pain, psychiatric, opioid-related, and healthcare utilization endpoints. Rather than demonstrating an opioid-sparing effect, documented cannabis-related diagnoses appear to identify a subgroup of patients with increased perioperative vulnerability, especially when combined with nicotine use. These findings support routine preoperative screening, risk stratification, and targeted counseling regarding cannabis and nicotine use before elective spine fusion.