1. Division of Neurocritical Care, Department of Neurology University of North Carolina at Chapel Hill Chapel Hill North Carolina USA
2. Division of Brain Injury Outcomes, Department of Neurology Johns Hopkins University Baltimore Maryland USA
3. Neurovascular Surgery Program, Section of Neurosurgery, Department of Surgery University of Chicago Medicine and Biological Sciences Chicago Illinois USA
4. Department of Biostatistics, Bloomberg School of Public Health Johns Hopkins University Baltimore Maryland USA