The impact of body mass index on traumatic spinal cord injury characteristics

It is unknown whether body mass index (BMI) is associated with traumatic spinal cord injury (TSCI) characteristics. Understanding BMI's impact on TSCI would demonstrate how body mechanics can predispose to and alter TSCI.

A retrospective cohort study was conducted using the Spinal Cord Injury Model System Program. Patients with TSCI were grouped by BMI category. A multinomial logistic regression identified associations between BMI class (compared with healthy BMI) and TSCI characteristics (e.g., etiology, injury level, and severity).

Among the 10,316 patients included in this study, 2384 (mean age: 44.0 ± 18.1 years) were included in the regression. Healthy BMI was the most common category (n = 958). Underweight patients had lower odds of injury from medical/surgical complications (RRR = 0.06 [95% CI: 0.02, 0.18], p < 0.0001). Class III obesity had greater odds of TSCI due to gunshot/stabbings (RRR = 1.40 [95% CI: 0.76, 2.47], p = 0.30). Increasing BMI class was associated with a lower likelihood of vertebral injury. Underweight and Class III obesity were associated with a greater likelihood of injuries at C5-C8 (compared to C1-C4). Obesity was associated with a lower likelihood of injury to T1-S5. Underweight patients were more likely to have complete TSCI.

BMI was variably associated with TSCI characteristics. Higher BMI may protect against severe TSCI. Injury level showed a bimodal distribution, with extremes of the BMI spectrum sharing similarities. It appeared that BMI may alter how traumatic forces affect the spine and spinal cord.