The future research path of traumatic brain injury

Abstract

Every year, more than 27 million new cases of traumatic brain injury (TBI) occur worldwide and, in the USA alone, over 1 million people sustain a TBI. However, despite substantial progress in understanding TBI over the past decade, barriers and challenges remain in relation to the most effective preventive, acute, rehabilitative, and long-term care strategies. It is, therefore, timely that the US National Academies of Sciences, Engineering, and Medicine (NASEM) have focused their attention on this public-health problem. On Feb 1, 2022, NASEM held a webinar to launch their report on Traumatic Brain Injury: A Roadmap for Accelerating Progress. The report, while US-focused, makes recommendations that have the potential to improve research and care for people with TBI globally. The NASEM report presents a consensus from clinical and research experts on a strategy to overcome barriers and knowledge gaps for advancement of TBI care in the USA. To develop an optimal system of care and research, the report recommends that biological, psychological, sociological, and ecological factors must inform all phases of patients’ care. Such aspects encompass disparities in socioeconomic determinants of health, including race, education and employment status, and geographic location. But, a key factor that can affect the care and outcomes of patients with TBI is how the injury is classified. Classification is a core concept that underpins our understanding of the mechanistic heterogeneity of TBI and, thus, optimal management and accurate prognostication. Currently, the Glasgow Coma Scale (GCS) is used by many clinicians to define TBI as mild (GCS sum score 13–15), moderate (GCS 9–12), or severe (GCS 3–8). However, the GCS was intended as “a practical method for bedside assessment of impairment of conscious level, the clinical hallmark of acute brain injury“. The use of mild, moderate, and severe categories in TBI might create bias in treatment, and could mean that the long-term care of patients is affected. For example, patients identified as having a mild TBI, according to the GCS, often report long-term disability or complaints that interfere with activities of daily living, such as headaches, fatigue, or anxiety. The NASEM report recommends development and dissemination of a classification system for TBI that incorporates not only the GCS score but also brain imaging and other prognostic biomarkers. A patient could be reclassified regularly during the treatment and recovery periods. An improved classification for TBI could also include conditions associated with the injury, such as subdural haematoma, skull fracture, or contusion. The Global Neurotrauma Outcomes Study has analysed epidemiological data for patients needing emergency neurosurgery after a TBI. In this study, countries were stratified according to their Human Development Index, and the investigators found that admission characteristics (eg, severity of TBI and mechanism of injury) and management received (eg, type of surgical procedure) varied across human development settings. For example, patients from countries in the low Human Development Index tier were often young and had a mild TBI with a depressed skull fracture due to an assault. The inclusion of conditions such as subdural haematoma, skull fracture, or contusion within a new TBI classification system might provide improved insight for a clinician managing a patient's care. The NASEM report also calls for further research efforts to address gaps in knowledge about prevention, care, and recovery. For international, collaborative, clinical studies, use of a consistent method to characterise TBI will help with appropriate recruitment of patients. In the past decade, several large projects have been initiated, including the landmark CENTER-TBI and TRACK-TBI studies. These projects have led to a wealth of findings on the characterisation of TBI, patients’ short and long-term outcomes, and diagnostic and prognostic biomarkers. While these projects are proving successful, improved classification is needed to apply their findings and facilitate advances in long-term care. The recommendations of the NASEM report also support those made by The Lancet Neurology Commission, Traumatic Brain Injury: Integrated Approaches to Improve Prevention, Clinical Care, and Research, launched in 2017, which called for improvement in the classification of TBI for optimum clinical management. An update to that Commission is in progress. A tremendous amount of work has been accomplished in the past decade, and more advances are within reach. The research path for TBI might seem long and winding, but if the recommendations of the NASEM report are implemented the path could become smoother.