Introduction

Crohn's disease (CD) progression is marked by the occurrence of stricturing complications or intestinal and perianal penetrating complications, typically requiring surgery.1 ,2 We previously reported three factors at the time of diagnosis that increased the chance of disabling disease during the 5 years following: (1) age <40 years old, (2) presence of perianal lesions and (3) the requirement for steroids to control the first flare.3 However, as the median age of diagnosis is 27 years, the course of CD may last more than 50 years in the Western world, where the life expectancy of patients exceeds 70 years. Therefore, identifying predictive criteria throughout such a long period remains challenging. We believe the assessment of CD severity should not be skewed by only taking into account occasional disease events.4 For example, one patient may be operated on once and then experience a long period of quiescent disease. CD manifestations are often quite active during the early few years before subsequently resolving and becoming more stable.5 One may consider a CD complication as an acute phenomenon without recurrence,6 and, in the absence of significant sequelae, such an event should therefore not be regarded as a marker of severe disease. Notably, most therapeutic strategies aim to avoid short-term complications; however, CD is a chronic disease requiring lifelong monitoring. Very little is known about the long-term evolution of CD. Therefore, the aim of our study was to identify predictable factors associated with a mild-to-moderate, long-term CD course; for this purpose, we prospectively analysed a large cohort of patients with CD over 15-year period.