This study is a prospective observational, multi-center study of subjects enrolled in the Brain Oxygen Optimization in Severe Traumatic Brain Injury-Phase 3 (BOOST-3) trial. BOOST-3 is a multicenter, randomized, blinded-endpoint, comparative effectiveness study of goal-directed critical care based upon monitoring of brain tissue oxygen and intracranial pressure versus monitoring of intracranial pressure alone in patients with severe traumatic brain injury.~The investigators will obtain an initial set of biospecimens (serum, plasma, cerebrospinal fluid (CSF), DNA and RNA) shortly after randomization into BOOST-3 and within 24 hours of injury. Subsequent biospecimens will be obtained every 8 hours for the first 24 hours post-enrollment. This will allow the characterization of acute changes in biomarker levels. On study days 2 through 5, biospecimens will be obtained twice a day to allow characterization of sub-acute changes in biomarker levels, without overburdening study teams or taking too much blood from individual subjects. On study days 7 and 14 and at 6-months post-enrollment, one set of biospecimen will be obtained, preferably in the morning. Biospecimens collected at each time point will consist of 6 ml of whole blood for serum extraction, 6 ml of whole blood for plasma extraction, 2.5 ml of whole blood for RNA extraction (a total of 14.5 ml [one tablespoon] of blood) and 5 ml of cerebrospinal fluid (CSF).~BioBOOST will utilize data collected in the BOOST-3 trial. This data includes: demographic data and clinical data such as injury characteristics, vital signs, head CT findings, laboratory data and data on physiologic parameters such as intracranial pressure (ICP), partial pressure of brain tissue oxygen (PbtO2), mean arterial pressure (MAP), and cerebral perfusion pressure (CPP), among others.~BioBOOST will also utilize outcome assessment data collected from BOOST-3 participants at 6 months after injury (180 Days ± 30 days). Trained study personnel who are blinded to the treatment arm will administer the outcome assessments, which will include the measures listed below. The battery includes measures of functional status (GOSE), cognition, and emotional health. The 6-month follow-up interview will be done in person whenever possible. It may be done by telephone or video conference with participants where an in-person interview is not possible.
BioBOOST is a multicenter, observational study of the effect of derangements in brain physiologic parameters on brain injury biomarker levels in patients with severe traumatic brain injury.