[1] Univ Edinburgh, Sch Med, Edinburgh, Midlothian, Scotland
[2] Virginia Commonwealth Univ, Med Coll Virginia, Sch Med, Dept Neurosurg, Richmond, VA 23298 USA
[3] Erasmus MC, Ctr Med Decis Making, Dept Publ Hlth, Rotterdam, Netherlands
[4] Erasmus MC, Dept Neurosurg, Rotterdam, Netherlands