[1] Aarhus Univ, Hosp Skejby, Dept Cardiol, DK-8200 Aarhus N, Denmark
[2] Aarhus Univ Hosp, Dept Clin Epidemiol, Aarhus, Denmark
[3] Univ Leeds, Ctr Epidemiol & Biostat, Leeds, W Yorkshire, England
[4] York Teaching Hosp NHS Fdn Trust, Dept Cardiol, York, N Yorkshire, England
[5] Wake Forest Sch Med, Dept Epidemiol & Prevent, Winston Salem, NC USA