What are the most common comorbidities associated with Crohn disease?

Common Comorbidities in Crohn's Disease

Crohn's disease is associated with a wide spectrum of comorbidities affecting approximately 46% of patients, with extraintestinal manifestations occurring in 25-36% of cases, alongside metabolic complications like gallstones and kidney stones, and increased risks of thromboembolic disease, osteoporosis, and certain malignancies. 1, 2, 3

Extraintestinal Manifestations (Colitis-Related)

These complications are immunologically mediated, wax and wane with bowel inflammation, and occur more frequently when the colon is involved (42% vs 23% in small bowel-only disease) 3:

Musculoskeletal Manifestations (Most Common)

• Peripheral arthropathy affects 22-23% of patients, representing the most frequent extraintestinal manifestation 2, 3
• Ankylosing spondylitis occurs in a subset of patients and may precede or persist independent of bowel disease activity 1, 4
• These manifestations are significantly more frequent in patients with colonic involvement 2

Dermatologic Manifestations

• Erythema nodosum affects 13-15% of patients and typically parallels bowel disease activity 4, 2, 3
• Pyoderma gangrenosum occurs in 4% of cases, may persist after bowel disease subsides, and requires aggressive treatment 4, 3
• Psoriasis shows increased association with Crohn's disease 1

Ophthalmologic Manifestations

• Iritis/uveitis affects approximately 4% of patients and may precede bowel symptoms or persist independently 1, 4, 3
• Screening for eye disease is appropriate to prevent complications 4

Metabolic and Gastrointestinal Complications

These relate to small bowel pathophysiology and persist even without active inflammation 3:

Hepatobiliary Disease

• Cholelithiasis occurs in 11% of patients, significantly more common in males and those over 40 years of age 2, 3
• Primary sclerosing cholangitis is associated with Crohn's disease, though less common than in ulcerative colitis 1
• Liver disease affects approximately 5% of patients 3

Renal Complications

• Nephrolithiasis affects 8-9% of patients, particularly those over 40 and those with small bowel resection or ileostomy 2, 3
• Non-calculous hydronephrosis and hydroureter can occur 3

Malabsorption

• Malabsorption is virtually confined to small bowel disease, affecting 10% of these patients 3

Thromboembolic Disease

• Deep venous thrombosis and pulmonary embolism risk is increased 3-fold compared to the general population 1
• Thromboembolic illness affects approximately 3% of patients and is significantly linked to female gender 2

Skeletal Complications

• Fracture risk is increased by 30-40% due to chronic inflammation, corticosteroid use, and malabsorption 1
• Osteoporosis affects approximately 3% of patients, and screening is appropriate to prevent complications 4, 3

Pulmonary Manifestations

While less common than in ulcerative colitis, Crohn's disease can cause respiratory complications 5:

• Chronic bronchiolitis with nonnecrotizing granulomatous inflammation has been documented 5
• Cough may be a presenting symptom in some patients 5
• Pulmonary manifestations can develop even after colectomy 5

Malignancy Risk

• Small bowel cancer risk is dramatically elevated (21-27 times higher) than the general population 1
• Colorectal cancer risk is modestly increased (1.4-1.9 times higher) in patients with Crohn's colitis 1
• Lymphoma risk is slightly increased irrespective of medication use 1

Perianal Disease

• Perianal fistulas, abscesses, and involvement occur in 15-33% of patients, representing a distinct disease phenotype 5, 6

Psychological and Functional Impact

• High incidence of psychological morbidity including depression and anxiety affects both children and adults 7, 8, 4
• Pain and depression are associated with inflammatory bowel disease and require specific management 4
• Approximately 15% of patients may be unable to work after 5-10 years of disease 8

Key Clinical Pitfalls

Multiple extraintestinal manifestations occur simultaneously in one-third of affected patients, so identifying one should prompt screening for others 3. The pattern of complications differs by disease location: colonic disease predisposes to immunologic manifestations (joints, skin, eyes), while small bowel disease predisposes to metabolic complications (gallstones, kidney stones, malabsorption) 3. Some severe manifestations like pyoderma gangrenosum and axial arthropathy may precede bowel symptoms or persist after bowel disease is controlled, requiring independent management 4.