Early chemoprophylaxis is associated with decreased venous thromboembolism risk without concomitant increase in intraspinal hematoma expansion after traumatic spinal cord injury

BACKGROUND After traumatic spinal cord injury (SCI), there is increased risk of venous thromboembolism (VTE), but chemoprophylaxis (PPX) may cause expansion of intraspinal hematoma (ISH). METHODS Single-center retrospective study of adult trauma patients from 2012 to 2015 with SCI. Exclusion criteria: VTE diagnosis, death, or discharge within 48 hours. Patients were dichotomized based on early (≤48 hours) heparinoid and/or aspirin PPX. Intraspinal hematoma expansion was diagnosed intraoperatively or by follow-up radiology. We used multivariable Cox proportional hazards to estimate the effect of PPX on risk of VTE and ISH expansion controlling for age, injury severity score (ISS), complete SCI, and mechanism as static covariates and operative spine procedure as a time-varying covariate. RESULTS Five hundred one patients with SCI were dichotomized into early PPX (n = 260 [52%]) and no early PPX (n = 241 [48%]). Early PPX patients were less likely blunt injured (91% vs 97%) and had fewer operative spine interventions (65% vs 80%), but age (median, 43 vs 49 years), ISS (median 24 vs 21), admission ISH (47% vs 44%), and VTE (5% vs 9%) were similar. Cox analysis found that early heparinoids was associated with reduced VTE (hazard ratio [HR], 0.37; 95% confidence interval [CI], 0.16–0.84) and reduced pulmonary embolism (PE) (HR, 0.20; 95% CI, 0.06–0.69). The estimated number needed to treat with heparinoids was 10 to prevent one VTE and 13 to prevent one PE at 30 days. Early aspirin was not associated with reduced VTE or PE. Seven patients (1%) had ISH expansion, of which four were on PPX at the time of expansion. Using heparinoid and aspirin as time-varying covariates, neither heparinoids (HR, 1.90; 95% CI, 0.32–11.41) nor aspirin (HR, 3.67; 95% CI, 0.64–20.88) was associated with ISH expansion. CONCLUSION Early heparinoid therapy was associated with decreased VTE and PE risk in SCI patients without concomitant increase in ISH expansion. LEVEL OF EVIDENCE Therapeutic, level IV.