What are the necessary steps to take before starting biologicals in a patient with Crohn's disease?

Pre-Biologic Checklist for Crohn's Disease

Before initiating biologic therapy in a patient with Crohn's disease, you must complete infectious disease screening (tuberculosis, hepatitis B/C, HIV), verify vaccination status, assess disease phenotype and risk factors, and ensure appropriate patient counseling about risks and benefits.

Mandatory Infectious Disease Screening

Tuberculosis Screening

• Perform tuberculin skin test (TST) or interferon-gamma release assay (IGRA) plus chest X-ray in all patients before starting biologics 1
• If TST is positive (≥5mm induration in immunosuppressed patients), obtain chest X-ray and infectious disease consultation 1
• Initiate latent TB treatment before starting biologics if indicated, typically with 9 months of isoniazid or 3 months of rifampin plus isoniazid 1

Viral Hepatitis Screening

• Check hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), and hepatitis B surface antibody (anti-HBs) 1
• Screen for hepatitis C antibody with reflex HCV RNA if positive 1
• Screening rates for hepatitis B remain suboptimal (only 36-49% in recent years), representing a critical gap that must be addressed 1
• If HBsAg positive, consult hepatology and initiate antiviral prophylaxis before biologics 1

HIV Screening

• Perform HIV antibody/antigen testing as part of comprehensive infectious screening 1

Vaccination Status Assessment

• Verify and update all vaccinations before starting immunosuppressive therapy, as live vaccines are contraindicated once biologics begin 1
• Ensure completion of pneumococcal, influenza, hepatitis A and B, and HPV vaccines where indicated 1
• Administer any needed live vaccines (MMR, varicella, zoster) at least 4 weeks before biologic initiation 1

Disease Phenotype and Risk Stratification

High-Risk Features Warranting Early Biologics

Identify patients with aggressive disease characteristics who benefit most from early biologic introduction 2:

• Complex disease behavior: Stricturing (B2) or penetrating (B3) disease at presentation 2, 3
• Perianal fistulizing disease: Associated with more aggressive course and higher treatment intensity needs 2, 3
• Young age at diagnosis: Patients under 40 years tend toward more aggressive progression 2, 3
• Steroid dependency: Need for corticosteroids to control the index flare indicates severe disease activity 2, 3
• Extensive small bowel disease: Jejunal involvement or extensive disease distribution increases complication risk 2, 3

Disease Location Considerations

• Document Montreal classification (L1-L4) to guide treatment decisions 2
• Patients with jejunal or extensive small bowel disease should be considered for early biologics due to poorer prognosis 2
• Colonic disease with rectal involvement carries up to 92% risk of perianal complications 3

Laboratory and Clinical Assessment

Baseline Laboratory Testing

• Complete blood count with differential 1
• Comprehensive metabolic panel including liver function tests 1
• C-reactive protein and fecal calprotectin to establish baseline inflammatory markers 2
• Thiopurine methyltransferase (TPMT) activity if considering combination therapy with azathioprine 2

Comorbidity Assessment

• Document all comorbid conditions carefully, as comorbidity significantly increases serious infection risk (hazard ratio 3.94) 1
• Exercise particular caution when prescribing biologics in patients with multiple comorbidities 1

Patient Counseling and Shared Decision-Making

Risk-Benefit Discussion

• Discuss infection risks: Opportunistic infections occur in 9% of patients (3.4/100 patient-years), and serious infections in 4% (1.6/100 patient-years) 1
• Address concerns about immunogenicity, which can lead to loss of response 4
• Explain the 20-40% primary failure rate with current biologics 4
• Discuss potential for neoplasia promotion with long-term immunosuppression 4

Treatment Goals and Expectations

• Establish clear treatment targets: clinical remission, endoscopic healing, and prevention of complications 2
• Discuss the importance of scheduled maintenance therapy versus episodic treatment 5
• Consider patient factors including stage of life, work absence, and treatment preferences 2

Biologic Selection Considerations

First-Line Biologic Options

Anti-TNF therapy (infliximab, adalimumab), vedolizumab, and ustekinumab can all be considered as first-line biologics 2:

• Infliximab with azathioprine combination shows highest efficacy for induction in biologic-naive patients (OR 7.49) 6
• Adalimumab monotherapy is highly effective (OR 3.01) and preferred if combination therapy is not feasible 6
• Vedolizumab may be preferred in patients with concurrent eczema due to gut-selective mechanism 7
• Ustekinumab is optimal for patients with eczema or other extraintestinal manifestations where TNF antagonists may worsen skin disease 7

Special Populations

• For patients with concurrent eczema, avoid TNF antagonists as they paradoxically induce or worsen eczematous eruptions in 10-25% of IBD patients 7
• In post-surgical settings with high-risk features, initiate biologics within 90 days of surgery 2

Documentation Requirements

• Record all screening test results in the medical record 1
• Document discussion of risks, benefits, and alternatives 2
• Obtain informed consent specifically addressing infection risks and monitoring requirements 1
• Establish baseline disease activity scores (CDAI or similar) for future comparison 5

Common Pitfalls to Avoid

• Do not skip hepatitis B screening: This remains the most common screening gap despite increasing awareness 1
• Do not delay TB treatment if indicated: Complete latent TB therapy before starting biologics to prevent reactivation 1
• Do not use biologics as episodic therapy: Scheduled maintenance dosing is superior to on-demand treatment 5
• Do not overlook comorbidities: These significantly increase serious infection risk and require heightened vigilance 1
• Do not start live vaccines after biologic initiation: Complete all needed live vaccines at least 4 weeks before starting therapy 1