What is the treatment algorithm for managing Inflammatory Bowel Disease (IBD)?

IBD Treatment Algorithm

Manage IBD using a disease-specific, severity-stratified approach: start with aminosalicylates for mild ulcerative colitis, corticosteroids for moderate-severe disease, and escalate to immunomodulators (azathioprine/mercaptopurine) or biologics (infliximab) for steroid-dependent or refractory disease, while Crohn's disease requires site- and pattern-based treatment with earlier consideration of immunosuppression and biologics.

Ulcerative Colitis Management

Mild to Moderate Distal UC

• First-line therapy combines topical mesalazine 1g daily with oral mesalazine 2-4g daily for optimal efficacy 1
• Topical corticosteroids serve as second-line for patients intolerant of topical mesalazine 1
• Combination therapy (topical + oral) is superior to either agent alone 1

Moderate Disease Not Responding to Mesalazine

• Escalate to oral prednisolone 40mg daily when combination mesalazine therapy fails 1
• Taper prednisolone gradually over 8 weeks based on response 1
• Continue topical agents as adjunctive therapy 1

Severe UC (Truelove and Witts Criteria)

• Admit for intravenous corticosteroids immediately—do not delay for stool cultures 1
• Manage jointly with gastroenterologist and colorectal surgeon from admission 1, 2
• Monitor vital signs four times daily, daily stool charts, and labs (FBC, CRP, electrolytes, albumin) every 24-48 hours 1
• Obtain daily abdominal radiographs if colonic dilatation >5.5cm detected 1
• Provide IV fluid/electrolyte replacement, transfuse to maintain hemoglobin >10g/dL 1
• Administer subcutaneous heparin for thromboembolism prophylaxis 1, 2
• Assess response by day 3; consider rescue therapy with infliximab or ciclosporin for non-responders 2
• Inform patients of 25-30% colectomy risk 1

Maintenance Therapy for UC

• Lifelong aminosalicylate maintenance (mesalazine ≥2g daily) is recommended for all patients, especially those with left-sided or extensive disease 1, 2
• Azathioprine 1.5-2.5mg/kg/day or mercaptopurine 0.75-1.5mg/kg/day for steroid-dependent patients 1, 2
• Maintenance therapy reduces colorectal cancer risk 1, 2

Crohn's Disease Management

Active Mild Ileocolonic CD

• High-dose mesalazine 4g daily may suffice as initial therapy 1, 2
• Consider nutritional therapy, antibiotics, or corticosteroids based on patient preference and disease characteristics 1

Moderate to Severe CD

• Corticosteroids for induction of remission 2
• Budesonide for ileal/right-sided colonic disease with lower systemic effects 1
• Do not use corticosteroids for maintenance—they are ineffective and cause steroid dependency 1

Steroid-Dependent or Refractory CD

• Azathioprine 1.5-2.5mg/kg/day or mercaptopurine 0.75-1.5mg/kg/day as second-line immunomodulation 1
• Methotrexate 25mg IM weekly for 16 weeks, then 15mg weekly for chronic active disease or azathioprine intolerance 1
• Add folic acid 5mg weekly (3 days after methotrexate) to reduce side effects 1

Biologic Therapy Indications

• Infliximab 5mg/kg at weeks 0,2, and 6 reserved for moderate-severe CD refractory to steroids, mesalazine, and immunomodulators where surgery is inappropriate 1, 2
• Maintenance dosing: 5-10mg/kg every 8 weeks for responders 1
• Use as part of comprehensive strategy including immunomodulation and surgical consultation 1

Perianal/Fistulating CD

• First-line: Metronidazole 400mg TDS and/or ciprofloxacin 500mg BD for simple perianal fistulae 1
• MRI and examination under anesthesia to define anatomy 1
• Azathioprine/mercaptopurine for simple fistulae after excluding distal obstruction and abscess 1
• Infliximab (three infusions at 0,2,6 weeks) for refractory fistulae combined with immunomodulation and surgical drainage 1
• Seton drainage, fistulectomy, or advancement flaps for persistent/complex fistulae 1

Maintenance of Remission in CD

• All smokers must stop—most important factor in maintaining remission 1
• Mesalazine has limited benefit, ineffective at <2g/day or after steroid-induced remission 1
• Azathioprine/mercaptopurine effective but reserved as second-line due to toxicity 1
• Methotrexate 15-25mg IM weekly for patients who responded to IM methotrexate induction 1

Surgical Management

UC Surgery Indications

• Disease not responding to intensive medical therapy 1
• Dysplasia or carcinoma 1
• Subtotal colectomy with long rectal stump is procedure of choice for acute fulminant disease 1, 2
• Counsel regarding ileo-anal pouch for elective surgery 1

CD Surgery Principles

• Operate only for symptomatic disease, not asymptomatic radiologic findings 1
• Resections limited to macroscopic disease only—be conservative 1, 2
• Avoid primary anastomosis in presence of sepsis and malnutrition 1
• Consider stricture dilatation or strictureplasty for diffuse small bowel disease 1

Common Pitfalls to Avoid

• Do not overprescribe mesalazine for Crohn's disease—limited efficacy compared to UC 3
• Never use steroids for perianal CD, in presence of sepsis, or for maintenance therapy 3
• Do not delay azathioprine/mercaptopurine introduction or underdose (use full 1.5-2.5mg/kg) 3
• Avoid introducing anti-TNF therapy too late in disease progression, but also avoid use with sepsis or fibrostenotic strictures 3
• Do not delay corticosteroids in severe UC while awaiting stool cultures 1

Emerging Treatment Paradigms

While traditional step-up therapy remains standard, accelerated step-up or top-down approaches with early immunosuppressants/biologics show superiority in selected high-risk patients recently diagnosed with IBD 4, 5. Treatment targets have shifted from symptom-based clinical remission to objective parameters like endoscopic healing due to discrepancies between symptoms and inflammatory activity 4. However, the choice between approaches should be based on prognostic factors, disease phenotype, and current disease status rather than applied universally 5.