Rationalising neurosurgical head injury referrals: development and validation of the Liverpool Head Injury Tomography Score (Liverpool HITS) for mild TBI

Introduction: A radiological scoring system to define a 'surgically significant' mild Traumatic Brain Injury (TBI) could stratify neurosurgical referrals, and improve communication between referral centres and neurosurgical units, as most referrals are not accepted.

Materials and methods: A computed tomography (CT) scoring system based on radiological injuries sustained in a TBI was developed and validated. All neurosurgical referrals to a major tertiary neurosurgery centre in England, UK with a mild TBI (GCS 13-15) during the period of 1st January to 30th October 2017 were scored retrospectively and stratified according to their mean score, and if they were accepted for transfer to the neurosurgical centre. A total of 1248 patients were identified during the study period, with 1144 being included in the final analysis.

Results: Of the referrals to the neurosurgical centre, 17% (n = 195) were accepted for transfer and 83% (n = 946) were not accepted. The scoring system was 99% sensitive and 51.9% specific for determining a surgically significant TBI. Diagnostic power of the model was fair with an area under the curve of 0.79 (95% CI 0.76 to 0.82). The score identified 495 (52.2%) patients in ten months of referrals that could have been successfully managed locally without neurosurgical referral if the scoring system was correctly used at the time of injury.

Conclusions: The Liverpool Head Injury Tomography Score (HITS) score is a CT-based scoring system that can be used to define a surgically significant mild TBI. The scoring system has high sensitivity and could be incorporated into local, regional and national head injury guidance.