Reliability assessment of the Biffl Scale for blunt traumatic cerebrovascular injury as detected on computer tomography angiography

OBJECTIVE Blunt traumatic cerebrovascular injury (TCVI) represents structural injury to a vessel due to high-energy trauma. The Biffl Scale is a widely accepted grading scheme for these injuries that was developed using digital subtraction angiography. In recent years, screening CT angiography (CTA) has been used to identify patients with TCVI. The reliability of this scale, with injuries assessed using CTA, has not yet been determined. METHODS Seven independent raters, including 2 neurosurgeons, 2 neuroradiologists, 2 neurosurgical residents, and 1 neurosurgical vascular fellow, independently reviewed each presenting CTA of the neck performed in 40 patients with confirmed TCVI and assigned a Biffl grade. Ten images were repeated to assess intrarater reliability, for a total of 50 CTAs. Fleiss' multirater kappa (kappa) and interclass correlation were calculated as a measure of interrater reliability. Weighted Cohen's kappa was used to assess intrarater reliability. RESULTS Fleiss' multirater kappa was 0.65 (95% CI 0.61-0.69), indicating substantial agreement as to the Biffl grade assignment among the 7 raters. Interclass correlation was 0.82, demonstrating excellent agreement among the raters. Intrarater reliability was perfect (weighted Cohen's kappa = 1) in 2 raters, and near perfect (weighted Cohen's kappa > 0.8) in the remaining 5 raters. CONCLUSIONS Grading of TCVI with CTA using the Biffl Scale is reliable.