1. Department of Health and Social Research, Bergen University College, PO Box 7030, N-5020 Bergen, Norway 10.1177/1352458506071210
2. Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway
3. Department of Surgery, Section of Urology, Haukeland University Hospital
4. Multiple Sclerosis National Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway