“A guy ought to be very careful in making predictions, especially about the future.” [Yogi Berra (1925–), professional baseball player and manager]

The Holy Grail of Crohn’s disease—aside from finding the elusive cause and cure—is understanding its “natural history”; that is, how it develops, presents, evolves, and responds to different therapies. A principal objective of this level of understanding would be the ability to predict the course of disease in any given individual or group of individuals. This aim has been the focus of clinical studies of inflammatory bowel disease for nearly four decades.

One of the earliest attempts to find clinical markers to predict outcomes was made by the late FT de Dombal in Leeds, who proposed a rise in serum β-globulin as an early warning sign of impending flare of ulcerative colitis.¹ Later efforts to develop laboratory predictors of Crohn’s disease flares included studies by Brignola et al in Bologna.² A sharper focus on clinical predictors, as distinct from pure laboratory indices, was introduced by JP Wright in Cape Town.³ All of these studies were as well intentioned as, but not much more successful than, the search for the historical Holy Grail had been over the previous millennium.⁴

Meanwhile, a less sophisticated but …