[1] Hvidovre Univ Hosp, Dept Day Surg, Kettegaards Alle 30, DK-2650 Hvidovre, Denmark
[2] Univ Copenhagen, Ctr Head & Orthoped, Rigshosp, Blegdamsvej 9, DK-2100 Copenhagen O, Denmark
[3] Aarhus Univ, Dept Sci Nursing, Dept Publ Hlth, Campus Emdrup Tuborgvej 164, DK-2400 Copenhagen NV, Denmark