What is the appropriate management of moderate to severe active Crohn's disease?

Management of Moderate to Severe Active Crohn's Disease

For moderate to severe active Crohn's disease, initiate biologic therapy (infliximab, adalimumab, ustekinumab, risankizumab, mirikizumab, or guselkumab) or upadacitinib as first-line treatment, avoiding the traditional step-up approach with corticosteroids or immunomodulators. 1, 2

First-Line Treatment Selection

The 2025 AGA guidelines represent a paradigm shift by strongly recommending advanced therapies over conventional treatments. The AGA recommends using infliximab, adalimumab, ustekinumab, risankizumab, mirikizumab, guselkumab, or upadacitinib over no treatment (strong recommendation, moderate to high certainty evidence) 2. Vedolizumab and certolizumab pegol receive conditional recommendations due to lower comparative efficacy 2.

Efficacy Hierarchy

When selecting among advanced therapies in biologic-naïve patients, the AGA suggests using HIGHER efficacy medications (infliximab, adalimumab, vedolizumab, ustekinumab, risankizumab, mirikizumab, guselkumab) rather than LOWER efficacy medications (certolizumab pegol, upadacitinib) 2. This recommendation is based on network meta-analysis comparing induction of clinical remission rates.

Key efficacy considerations:

• TNF antagonists (infliximab, adalimumab) remain highly effective first-line options with the most robust long-term data 3, 1
• IL-23 antagonists (risankizumab, mirikizumab, guselkumab) show comparable or superior efficacy, particularly valuable after TNF failure 2
• Biosimilars of infliximab, adalimumab, and ustekinumab are equivalent to originators 2

What NOT to Use

Strongly avoid these approaches:

• 5-ASA/sulfasalazine: The AGA strongly recommends AGAINST their use for induction or maintenance (strong recommendation, moderate certainty) 1. They are ineffective and delay appropriate therapy.

• Corticosteroids for maintenance: While corticosteroids may induce remission (conditional recommendation), the AGA strongly recommends AGAINST using them for maintenance (strong recommendation, moderate certainty) 1

• Thiopurine monotherapy for induction: The AGA suggests AGAINST thiopurine monotherapy to induce remission (conditional recommendation, low-quality evidence) 3, 1

• Oral methotrexate: The AGA suggests AGAINST oral methotrexate (conditional recommendation, very low certainty) 1

Combination Therapy Strategy

For biologic-naïve patients starting TNF antagonists, combine with an immunomodulator (thiopurine or methotrexate) rather than using monotherapy 1. Specifically:

• Infliximab + thiopurine: Conditional recommendation over infliximab monotherapy (very low certainty evidence) 1
• Infliximab + methotrexate: Based on indirect evidence, may be more effective than monotherapy 1
• Adalimumab + thiopurine or methotrexate: Based on indirect evidence, combination may be superior 1

Important caveat: For non-TNF biologics (ustekinumab, vedolizumab, IL-23 antagonists), there is NO recommendation for or against combination therapy—this is a knowledge gap 1. Use monotherapy for these agents.

Early Biologic Introduction

The AGA suggests early introduction of biologics with or without immunomodulators rather than delaying until after failure of mesalamine and/or corticosteroids (conditional recommendation, low certainty) 1. This "top-down" approach is particularly important for patients with:

• Risk factors for poor prognosis
• Extensive disease
• Deep ulcerations
• Perianal involvement
• Young age at diagnosis

The Canadian guidelines specifically recommend anti-TNF therapy as first-line in patients with moderate to severe disease AND poor prognostic factors (strong recommendation, moderate-quality evidence) 3.

Treatment Monitoring and Optimization

Evaluate for symptomatic response between 8-12 weeks after starting anti-TNF therapy to determine need for modification (strong recommendation, very low-quality evidence) 3. For severe disease, evaluate IV methylprednisolone response within 1 week 3.

If suboptimal response occurs:

• Consider dose intensification (conditional recommendation) 3
• Use therapeutic drug monitoring to guide optimization 3
• Extended induction regimens (up to 16 weeks) or dose escalation may benefit patients with severe disease 2

Higher maintenance doses of risankizumab, guselkumab, and upadacitinib should be preferred in patients with:

• High burden of inflammation
• More severe disease
• Previous TNF antagonist failure 2

Special Consideration: JAK Inhibitors

Critical FDA restriction: Upadacitinib should be used in patients with prior failure or intolerance to TNF antagonists, not as first-line in biologic-naïve patients 2. This is based on safety concerns identified in post-marketing surveillance.

Perianal Fistulizing Disease

If perianal fistulas are present:

• Infliximab is the preferred agent (strong recommendation, moderate certainty) 1
• Adalimumab, ustekinumab, or vedolizumab are alternatives (conditional recommendation, low certainty) 1
• Combine biologics with antibiotics rather than biologic alone (strong recommendation, moderate certainty) 1
• Do NOT use antibiotics alone without biologics (conditional recommendation against) 1

Practical Algorithm

1. Confirm moderate-severe active Crohn's disease (CDAI 220-450 or equivalent clinical/endoscopic severity)

2. Assess for perianal fistulas → If present, prioritize infliximab + antibiotics

3. Check for contraindications to specific drug classes (active infections, malignancy history, cardiovascular risk for JAK inhibitors)

4. Select first-line biologic:

   • Biologic-naïve: Choose from higher efficacy group (infliximab, adalimumab, ustekinumab, risankizumab, mirikizumab, guselkumab)
   • If choosing TNF antagonist: Add thiopurine or methotrexate
   • If choosing non-TNF biologic: Use monotherapy

5. Avoid: 5-ASA, oral corticosteroids beyond brief induction, thiopurine monotherapy, oral methotrexate

6. Reassess at 8-12 weeks → If inadequate response, optimize dosing or switch agents

7. Continue effective therapy for maintenance—do not withdraw biologics in remission

Common Pitfalls to Avoid

• Do not delay biologics waiting for conventional therapy failure—this worsens outcomes
• Do not use corticosteroids for maintenance—they are ineffective and harmful long-term
• Do not start 5-ASA—it provides false reassurance while disease progresses
• Do not use upadacitinib first-line in biologic-naïve patients due to FDA restrictions
• Do not combine immunomodulators with non-TNF biologics outside clinical trials—no evidence of benefit