What factors increase the risk of developing Crohn's disease in a patient with a family history, smoking habit, and history of appendectomy?

Risk Factors for Crohn's Disease

Family history and cigarette smoking are the most significant risk factors for developing Crohn's disease, while appendectomy may actually be protective against inflammatory bowel disease. 1

Analysis of Risk Factors

Family History

• First-degree relatives of patients with Crohn's disease have a significantly increased risk of developing the disease
• The risk is greatest in first-degree relatives with an incidence rate ratio (IRR) of 4.08 (95% CI: 3.81-4.38) 1
• Risk extends to second-degree relatives (IRR: 1.85; 95% CI: 1.60-2.13) and third-degree relatives (IRR: 1.51; 95% CI: 1.07-2.12) 1
• Having a brother with Crohn's disease significantly increases this patient's risk

Cigarette Smoking

• Current smoking is a well-established risk factor for Crohn's disease 1
• Smokers have approximately 2-3 times higher risk of developing Crohn's disease compared to non-smokers 2
• In patients with familial predisposition, smoking appears to be an important environmental trigger (OR 2.28, CI 1.5-3.48) 3
• Smoking not only increases disease risk but also worsens disease course and increases relapse rates 4

Appendectomy

• Contrary to increasing risk, appendectomy (especially for proven appendicitis) before adulthood is actually protective against ulcerative colitis 1
• The protective effect of appendectomy is additional to that of smoking for ulcerative colitis 1
• For Crohn's disease specifically, appendectomy does not appear to increase risk and may have a neutral effect 1

Gender

• Male gender alone is not consistently identified as an independent risk factor for Crohn's disease 1
• The lifetime risks of colorectal cancer (which can be a complication of long-standing Crohn's disease) are similar between men and women 1

Risk Stratification

When evaluating this patient's risk profile:

1. Highest risk factor: Family history of Crohn's disease in a first-degree relative (brother)
2. Significant risk factor: Current smoking status (5-year history)
3. Neutral/potentially protective factor: History of appendectomy

Clinical Implications

For this patient with multiple risk factors:

• Consider earlier and more frequent screening for Crohn's disease
• Smoking cessation counseling is essential as it would reduce both the risk of developing Crohn's disease and improve outcomes if the disease develops
• Monitor for early symptoms including abdominal pain, diarrhea, weight loss, and fatigue

Common Pitfalls to Avoid

• Don't dismiss family history in a first-degree relative as this represents the strongest risk factor
• Don't assume appendectomy increases risk - evidence suggests it may be protective for ulcerative colitis and neutral for Crohn's disease
• Don't overlook modifiable risk factors like smoking, which this patient could address to reduce risk

In summary, this patient should be informed that his family history and smoking status significantly increase his risk for developing Crohn's disease, while his history of appendectomy is not a risk factor.