Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden; Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden. Electronic address: asa.hallqvist-everhov@ki.se. Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden. Division of Surgery, Department of Clinical and Experimental Medicine, Faulty of Health Sciences, Linköping University and Department of Surgery, County Council of Östergötland Linköping, Sweden. Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; Center for Digestive Disease, Division of Coloproctology, Karolinska University Hospital, Stockholm, Sweden. Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden. Department Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Department of Pediatrics, Örebro University Hospital, Örebro University, Örebro, Sweden; Division of Epidemiology and Public Health, School of Medicine, University of Nottingham, Nottingham, UK; Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York. Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden; Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden; Department of Pediatric Gastroenterology and Nutrition, Sachs' Children and Youth Hospital, Stockholm, Sweden.