[1] Silkeborg Reg Hosp, Silkeborg, Denmark
[2] Aarhus Univ, Dept Clin Med, Aarhus, Denmark
[3] Aalborg Univ, Danish Ctr Clin Hlth Serv Res, Dept Clin Med, Aalborg, Denmark
[4] Univ Copenhagen, Sect Biostat, Copenhagen, Denmark
[5] Univ Liverpool, Liverpool Ctr Cardiovasc Sci, Liverpool, England
[6] Liverpool Chest & Heart Hosp, Liverpool, England
[7] Aalborg Univ, Dept Clin Med, Aalborg, Denmark
[8] Boston Univ, Boston Med Ctr, Sch Med, Dept Med, Framingham, MA USA
[9] Boston Univ, Dept Epidemiol, Sch Publ Hlth, Framingham, MA USA