Introduction
The inflammatory bowel diseases (IBDs), which include Crohn’s disease and ulcerative colitis, are life-long and life-limiting diseases of the gastrointestinal tract, which are increasing across the world, likely to reach a prevalence of 1% within this decade. All age groups are affected and patients live with chronic symptoms affecting both the gastrointestinal tract and extraintestinal manifestations. Unpredictability of disease course and outcomes has been one of the hallmarks of these diseases, and this contributes significantly to disease burden and its impact on quality of life. For example, in an individual patient at diagnosis, the long-term disease trajectory remains unpredictable (ie, whether the disease will follow an indolent or a more aggressive disease course). It is not known exactly why patients have different phenotypes of disease—with or without extraintestinal manifestations—nor when and why relapses of intestinal inflammation or progression of disease will occur. It is unpredictable which therapy will yield the best response for an individual patient and whether disease-related complications such as colorectal cancer will occur. Such unpredictability is associated with challenges for patients, physically and psychologically, and also challenges for management strategies by clinicians.