inflammatory bowel disease
Definition (NEJM 2020;383:2652)
- Ulcerative colitis (UC): inflammation of the colonic mucosa; contiguous, starting at ↣ rectum
- Crohn’s disease (CD): transmural inflammation anywhere along GI tract, skip lesions
Epidemiology & pathophysiology (Lancet 2016;387:156 & 2017;390:2769)
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Age of onset 15-30 y; bimodal w/ 2nd peak at ↣ 50-70 y; 1:1 M:F in N America
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Genetic predisposition (↑ Caucasian/Jewish) + environmental risk factors (smoking ↑ risk for CD, defective mucosal barrier) → T cell dysregulation → inflammation
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TABLE 326-7 extraintestinal manifestations of inflammatory bowel disease
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different clinical, endoscopic, and radiographic features of UC and CD
| ULCERATIVE COLITIS | CROHN’S DISEASE | |
|---|---|---|
| Age of onset | Second to fourth decades and seventh to ninth decades | Second to fourth decades and seventh to ninth decades |
| Female-to-male ratio | 0.51–1.58 | 0.34–1.65 |
| Smoking | May prevent disease (odds ratio 0.58) | May cause disease (odds ratio 1.76) |
| Oral contraceptives | No increased risk | Hazard ratio 2.82 |
| Appendectomy | Protective (risk reduction 13–26%) | Not protective |
| Monozygotic twins | 6–18% concordance | 38–58% concordance |
| Dizygotic twins | 0–2% concordance | 4% concordance |
- Infections in the first year of life: 1.6 and 3 times the risk of developing IBD by age 10 and 20 years
- Ethnicity : Jewish > non-Jewish white > black > Latinx (西班牙人)> Asian
Abbreviation: IBD, inflammatory bowel disease.