Objectives We assessed leucocytosis and evaluated its prognostic value in isolated paediatric traumatic brain injury (TBI).

Design Retrospective analysis.

Subjects 106 consecutive paediatric patients with isolated TBI admitted between June 2008 and June 2016.

Methods Initial blood leucocyte count (WCC), Glasgow Coma Score (GCS), computed tomographic (CT) findings, duration of hospital stay, and Paediatric Cerebral Performance Category Scale (PCPCS) scores were analysed.

Results Mean age was 4.2 years. For patients with GCS 3–8, 9–13 and 14–15, WCC was 20, 15.9 and 10.7 × 109/L respectively. Differences in WCC were significant between the different GCS groups (p<0.01). Length of hospital stay, extent of midline shift on CT and poor 6 month PCPCS rating were each significantly correlated with WCC (p<0.05). Multivariate regression analysis revealed a cut-off WCC of 16.1 × 109/L, above which GCS, CT findings, length of hospital stay and PCPCS were less favourable. Application of the International Mission on Prognosis and Analysis of randomized Controlled Trials in TBI (IMPACT) adult TBI prediction model to our paediatric cohort, using area under the operating curve (AUROC) and coefficient analyses, demonstrated increased accuracy with incorporation of WCC as a risk factor.

Conclusions High initial leucocytosis (>16.1×109/L) is predictive for poor GCS, severe CT findings, lengthy hospital stay and poor PCPCS in isolated paediatric TBI. Incorporating WCC into TBI prediction models may increase the accuracy of prognostication.