1 University Neurosurgical Centre Holland, Leiden University Medical Centre, Haaglanden Medical Centre, and Haga Teaching Hospital, Leiden and The Hague, 2333 ZA Leiden, Netherlands. Electronic address: essen@lumc.nl.
2 Centre for Medical Decision Sciences, Department of Public Health, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, Netherlands.
3 Department of Biomedical Data Sciences, Leiden University Medical Centre, Leiden, Netherlands.
4 University Neurosurgical Centre Holland, Leiden University Medical Centre, Haaglanden Medical Centre, and Haga Teaching Hospital, Leiden and The Hague, 2333 ZA Leiden, Netherlands.
5 Department of Neurosurgery, Antwerp University Hospital, Edegem, and University of Antwerp, Belgium.