Classification of traumatic brain injury: past, present, and future.

Disease classification is central to the practice of medicine; it systematizes clinical knowledge and experience. Classification is essential for diagnosis and effective treatment of human disease. Progress in classifying traumatic brain injury (TBI) for targeted treatment has lagged behind other diseases such as cancer, and has contributed to a lack of progress in the field. Today TBI is most frequently classified as mild, moderate, or severe using the Glasgow Coma Scale (GCS). However, the GCS is symptoms-based and does not allow for targeting of specific pathology. Here we review general schemas for disease classification and how they have evolved over time. We discuss the characteristics of an ideal classification system and the unique challenges inherent to achieving such a system for TBI. Current means of classifying TBI are reviewed, as are the strengths and limitations of these approaches. Generating the data required to modernize TBI classification and to perhaps facilitate a targeted, precision medicine approach to its management will require a highly collaborative international effort. Fortunately these efforts are underway and will benefit from the lessons and tools that have come from other areas of medicine that have already found success with this approach.