[1] Aalborg Univ, Ctr Prehosp & Emergency Res, Dept Clin Med, Sondre Skovvej 15, DK-9000 Aalborg, Denmark
[2] Aarhus Univ, Res Unit Gen Practice, Aarhus, Denmark
[3] Aarhus Univ, Dept Publ Hlth, Res Unit Epidemiol, Aarhus, Denmark
[4] Univ Copenhagen, Emergency Med Serv, Copenhagen, Denmark