Probability of Developing Crohn's Disease

Crohn's disease, a type of inflammatory bowel disease (IBD), affects approximately 780,000 Americans (about 0.3% of the population). Incidence has been increasing over recent decades, particularly in previously low-prevalence regions. It most commonly appears between ages 15 and 35, though it can develop at any age.

Crohn's can affect any part of the gastrointestinal tract (from mouth to anus) but most commonly involves the end of the small intestine (ileum) and the beginning of the colon. Risk factors include family history (having a first-degree relative increases risk 5-20 fold), Ashkenazi Jewish ancestry, smoking (uniquely, smoking increases Crohn's risk while it appears to decrease ulcerative colitis risk), use of NSAIDs and antibiotics, and living in urban or northern areas.

Treatment aims to induce and maintain remission through anti-inflammatory drugs (aminosalicylates, corticosteroids), immunosuppressants (azathioprine, methotrexate), and biologic therapies (infliximab, adalimumab, vedolizumab, ustekinumab). About 50% of patients require surgery within 20 years of diagnosis, though biologics have reduced surgical rates. Complications include strictures, fistulas, abscesses, malnutrition, and an increased risk of colorectal cancer.