[1] Stavanger Univ Hosp, Dept Surg, Postboks 8100, N-4068 Stavanger, Norway
[2] Stavanger Univ Hosp, Res Grp Nursing & Healthcare Sci, Postboks 8100, N-4068 Stavanger, Norway
[3] Univ Stavanger, Fac Hlth Sci, Kjell Arholms Hus, Postboks 8600, N-4036 Stavanger, Norway
[4] Stavanger Univ Hosp, Sect Biostatist, Dept Res, Postboks 8100, N-4068 Stavanger, Norway
[5] Stavanger Univ Hosp, Gen Practice & Care Coordinat Res Grp, Postboks 8100, N-4068 Stavanger, Norway