1. Department of Anaesthesiology and Intensive Care Medicine; Institute of Surgical and Perioperative Sciences; Umeå University; Umeå; Sweden
2. Department of Medicine; Institute of Public Health and Clinical Medicine; Umeå University; Umeå; Sweden
3. Department of Neurosurgery; Institute of Pharmacology and Clinical Neurosciences; Umeå University; Umeå; Sweden
4. Department of Statistics; Umeå School of Business and Economics; Umeå University; Umeå; Sweden