[1] UiT Arctic Univ Norway, Fac Hlth Sci, Dept Hlth & Care Sci, POB 6050, N-9037 Tromso, Norway
[2] Univ Hosp North Norway, Dept Cardiol, Tromso, Norway
[3] Univ Oulu, Res Unit Hlth Sci & Technol, Oulu, Finland
[4] Oulu Univ Hosp, Univ Oulu, Med Res Ctr Oulu, Oulu, Finland
[5] Lovisenberg Diaconal Univ Coll, Lovisenberggt 15b, N-0456 Oslo, Norway
[6] Univ Hosp North Norway, Dept Anaesthesiol & Surg, Tromso, Norway
[7] Univ Oulu, Fac Med, Res Unit Nursing Sci & Hlth Management, POB 5000, FI-90014 Oulu, Finland