The Impact of Isolated Preoperative Cannabis Use on Outcomes Following Cervical Spinal Fusion: A Propensity Score-Matched Analysis.

Background: Cannabis is the most commonly used recreational drug in the USA. Studies evaluating cannabis use and its impact on outcomes following cervical spinal fusion (CF) are limited. This study sought to assess the impact of isolated (exclusive) cannabis use on postoperative outcomes following CF by analyzing outcomes like complications, readmissions, and revisions. Methods: The New York Statewide Planning and Research Cooperative System (SPARCS) was queried for patients who underwent CF between January 2009 and September 2013. Inclusion criteria were age ≥18 years and either a minimum 90-day (for complications and readmissions) or 2-year (for revisions) follow-up surveillance. Patients with systemic disease, osteomyelitis, cancer, trauma, and concomitant substance or polysubstance abuse/dependence were excluded. Patients with a preoperative International Classification of Diseases, 9th Edition, Clinical Modification (ICD-9-CM) diagnosis of isolated cannabis abuse (Cannabis) or dependence were identified. The primary outcome measures were 90-day complications, 90-day readmissions, and two-year revisions following CF. Cannabis patients were 1:1 propensity score-matched by age, gender, race, Deyo score, surgical approach, and tobacco use to non-cannabis users and compared for outcomes. Multivariate binary stepwise logistic regression models identified independent predictors of outcomes. Results: 432 patients (n=216 each) with comparable age, sex, Deyo scores, tobacco use, and distribution of anterior or posterior surgical approaches were identified (all p>0.05). Cannabis patients were predominantly Black (27.8% vs. 12.0%), primarily utilized Medicaid (29.6% vs. 12.5%), and had longer LOS (3.0 vs. 1.9 days), all p≤0.001. Both cohorts experienced comparable rates of 90-day medical and surgical, as well as overall complications (5.6% vs. 3.7%) and two-year revisions (4.2% vs. 2.8%, p=0.430), but isolated cannabis patients had higher 90-day readmission rates (11.6% vs. 6.0%, p=0.042). Isolated cannabis use independently predicted 90-day readmission (Odds Ratio=2.0), but did not predict any 90-day complications or two year revisions (all p>0.05). Conclusion: Isolated baseline cannabis dependence/abuse was associated with increased risk of 90-day readmission following CF. Further investigation of the physiologic impact of cannabis on musculoskeletal patients may elucidate significant contributory factors.