Blood biomarker outliers and clinical events during intensive care in patients with traumatic brain injury

Abstract

<p><em>Introduction: </em>Monitoring and timely clinical assessment are fundamental to treating patients with traumatic brain injury (TBI) in the intensive care unit (ICU). Proactive, individualised treatment is unavailable with the current methods.<br><em>Research question: </em>How do outlying blood biomarker levels associate with clinical events or outcome in TBI?<br><em>Materials and methods: </em>Glial fibrillary acidic protein (GFAP), neurofilament light (NfL), interleukin-10 (IL-10) and total tau (t-tau) were analysed from blood plasma samples of 70 ICU-treated patients, aged ≥18, with a clinical diagnosis of TBI and an indication for a head CT scan. The blood samples were collected on arrival and on days 1, 2, 3 and 7. The biomarkers were screened for outliers and biomarker values outside Q1-1.5 × interquartile range (IQR) or Q3+1.5 × IQR on any day post-injury were considered outliers. The outlier group was compared with the non-outlier group targeting clinically significant aspects such as high intracranial pressure, seizures/status epilepticus, or mortality/poor outcome. The Glasgow Outcome Scale Extended (GOSE) was evaluated between 6 and 12 months after the injury.<br><em>Results: </em>Difference was found in epileptic activity (n = 7 vs n = 0) and the number of performed decompressive hemicraniectomies (n = 6 vs n = 0) between the outlier and the non-outlier groups, p = 0.015 and < 0.0001, respectively. Patients in the outlier group were also more likely to have a poor outcome (GOSE 1-3) than patients in the non-outlier group, p = 0.011.<br><em>Discussion and conclusion: </em>Biomarker outliers seem to associate with clinical events and poor outcome in ICU-treated patients with TBI, possibly due to greater severity of TBI.<br></p>