[1] Univ Edinburgh, Western Gen Hosp, Dept Clin Neurosci, Div Clin Neurosci, Edinburgh EH4 2XU, Midlothian, Scotland
[2] Ulleval Hosp, Dept Internal Med, Oslo, Norway
[3] Univ Edinburgh, Div Community Hlth Sci, Sect Publ Hlth Sci, Edinburgh, Midlothian, Scotland
[4] Royal Melbourne Hosp, Dept Neurol, Melbourne, Vic, Australia
[5] Univ Southampton, Southampton Gen Hosp, Dept Geriatr Med, Southampton, Hants, England
[6] HealthEcon, Basel, Switzerland