17. The impact of preoperative cannabis on outcomes following cervical spinal fusion: a propensity score-matched analysis

Abstract

BACKGROUND CONTEXT Cannabis is the most commonly used illicit drug in the United States with 4 million Americans meeting clinical criteria for cannabis dependence or abuse in 2015. With recent state-level legalization efforts and changing public perception, its use is expected to grow. Considering these changes and the reported medicinally beneficial effects, studies evaluating cannabis use and its impact on outcomes following cervical fusion (CF) are quite limited; further detailed study is warranted. PURPOSE This study sought to identify if adverse outcomes, such as complications, readmissions, and revisions, are comparable between cannabis users and noncannabis users undergoing CF. We compared 90-day complication and readmission rates and 2-year revision rates between baseline cannabis users and nonusers following CF. STUDY DESIGN/SETTING Retrospective cohort study of a prospectively collected database. PATIENT SAMPLE All patients who underwent CF between January 2009 and September 2013 in the New York Statewide Planning and Research Cooperative System (SPARCS) were identified. Patients were included if they had ≤90-day follow-up for complications and readmissions, or ≥2-year follow-up for revisions. Patients with a preoperative ICD-9-CM diagnosis of cannabis abuse (Cannabis) or dependence were identified. Patients were excluded for systemic disease, osteomyelitis, cancer, trauma, or concomitant substance or polysubstance abuse/dependence. OUTCOME MEASURES Demographic information, fusion approach, fusion levels, complications, readmissions, and revisions. METHODS All patients aged ≥18y who underwent CF from 2009-13 were identified via the SPARCS database and included if they had ≤90D follow-up for complications and readmissions or 2Y follow-up for revisions. Pts with preoperative cannabis abuse/dependence identified (Cannabis). Pts were excluded for systemic disease, osteomyelitis, cancer, trauma, or concomitant substance or polysubstance abuse/dependence. Following patient selection in the SPARCS database, Cannabis patients were 1:1 propensity score-matched by age, gender, race, Deyo score, fusion levels and approach, and tobacco use to nonusers (Non-Cannabis). These groups were compared for hospital-related parameters, rates of 90-day complications and readmissions, and 2-year revisions. Multivariate binary stepwise logistic regression models identified independent predictors of these outcomes. RESULTS A total of 432 pts (n=216 each) were identified, with comparable age, sex, Deyo scores, tobacco use rates, and distribution of anterior or posterior approach (all p>0.05). Cannabis patients were more frequently African American (27.8% vs 12.0%), primarily utilized Medicaid (29.6% vs 12.5%), and incurred longer lengths of stay (3.0 vs 1.9 days), all p≤0.001. Both cohorts experienced comparable rates of 90-day medical, surgical and overall complications (5.6% vs 3.7%) and 2-year revisions (4.3% vs 2.8%), p≤0.430. Cannabis users experienced higher 90-day readmission rates (11.6% vs 6.0%, p=0.042). Cannabis use was an independent predictive factor of 90-day readmission (OR=2.0, 95%CI, 1.0-4.1, p=0.049), but did not predict any 90-day complications or 2-year revisions (all p>0.05). CONCLUSIONS Baseline cannabis dependence/abuse was associated with increased 90-day readmission odds following CF. Further investigation of the physiologic impact of cannabis on musculoskeletal patients may identify what measurable or overlooked patient factors contribute to this association. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.