Risk of venous thromboembolism after spinal cord injury: not all levels are the same.

BACKGROUND

Venous thromboembolism (VTE), a diagnosis that includes both deep vein thrombosis and pulmonary embolism, is a well-recognized complication following injury. Previous studies have identified multiple risk factors including spinal cord injury (SCI). We hypothesized that the level of SCI also influences the likelihood of VTE.

METHODS

The National Trauma Data Bank was queried to identify all patients with SCI admitted in 2007 and 2008. Rates of VTE, demographics, admitting comorbidities, in-hospital complications, level of SCI (divided by National Trauma Data Bank into five groups), associated injuries, and outcome variables were abstracted. Multiple regression was used to identify independent risk factors for VTE.

RESULTS

During the 2-year period, 18,302 patients were admitted with SCI. The overall rate of VTE was 4.3% but varied significantly depending on the level of SCI injury (χ(2), 44.8; p < 0.05). Patients with high cervical spine (C1-4) injury had a rate VTE of 3.4%, whereas patients with high thoracic spine (T1-6) injury had the highest rate of VTE at 6.3%. The lowest rate of VTE was in patients with lumbar injury (3.2%). There were no significant differences in the preexisting comorbidities or in-hospital complications among the five SCI groups with the exception of pneumonia. In a multiple logistic regression model, the level of SCI was an independent risk factor for VTE as was increasing age, increasing Injury Severity Score, male gender, traumatic brain injury, and chest trauma.

CONCLUSIONS

The rate of VTE differs with various SCI levels. Patients with high thoracic (T1-6) injury seem to be at the highest risk and patients with high cervical (C1-4) injury at one of the lowest. A higher index of suspicion for VTE should therefore be maintained in patients with a high thoracic SCI. Further studies are required to elucidate the underlying mechanisms.