1. Department of Medicine; Division of Gastroenterology; Örebro University Hospital; Örebro Sweden
2. School of Health and Medical Sciences; Örebro University; Örebro Sweden
3. Clinical Epidemiology and Biostatistics; Örebro University Hospital; Örebro Sweden
4. The Clinical Epidemiology Unit; Karolinska University Hospital; Karolinska Institutet; Stockholm Sweden