What is the recommended treatment for perianal Crohn's disease?

Treatment of Perianal Crohn's Disease

Infliximab is strongly recommended as first-line therapy for complex perianal fistulizing Crohn's disease, with an induction regimen of 5 mg/kg at weeks 0,2, and 6, followed by maintenance dosing every 8 weeks. 1

Initial Management Algorithm

1. Drainage of perianal sepsis/abscesses

   • Surgical drainage of any perianal abscesses must be performed before initiating biologic therapy
   • Seton placement may be required for complex fistulae
   • Medical therapy should be started promptly after adequate surgical drainage 1

2. First-line medical therapy

   • Infliximab 5 mg/kg IV at weeks 0,2, and 6 for induction, then every 8 weeks for maintenance 1
   • Complete response rate: 46% vs 12.9% with placebo (RR: 3.57; 95% CI: 1.38–9.25) 1
   • Maintenance efficacy: 34.4% at week 54 vs 19.2% with placebo (RR: 1.79; 95% CI: 1.10–2.92) 1
   • Higher serum trough infliximab levels (>10 μg/kg) are associated with better outcomes 1

3. Adjunctive therapy

   • Antibiotics (metronidazole 750-1500 mg/day or ciprofloxacin 1000 mg/day) for up to 3-4 months 1
   • Not effective as monotherapy but useful for managing sepsis and as adjunctive therapy 1, 2

Management of Inadequate Response or Intolerance to Infliximab

1. Alternative biologics

   • Adalimumab as second-line therapy (weak recommendation, very low-quality evidence) 1
     • Induction: 160 mg at week 0,80 mg at week 2, then 40 mg every other week 3
     • Efficacy: RR 2.57 (95% CI: 1.13-5.84) for fistula healing at 56 weeks 1

2. For refractory disease

   • Ustekinumab may be considered for patients who have failed anti-TNF therapy 2
   • Vedolizumab may be considered, though evidence is limited 2

Special Considerations

1. Monitoring response

   • Clinical response (reduction in draining fistulae) should be assessed at weeks 10-14 after starting infliximab 4
   • Complete radiological healing occurs in only a minority of patients (11%) despite clinical improvement 5

2. Duration of therapy

   • Longer maintenance therapy appears more beneficial given the high relapse rate of perianal fistulizing disease 6
   • Consider maintenance therapy for at least 12 months in responders 4, 6

3. Surgical considerations

   • Avoid excision of Crohn's disease skin tags due to high rate of postoperative complications 1
   • Hemorrhoidectomy is usually contraindicated due to poor wound healing and risk of complications 1
   • Anal fissures in Crohn's disease are usually painless and heal spontaneously in >80% of patients 1

4. Safety precautions

   • Screen for tuberculosis before initiating infliximab therapy 1, 7
   • Monitor for infusion reactions, infections, and other adverse events 7
   • Consider combination therapy with immunomodulators to reduce immunogenicity, though evidence specifically for fistula healing is insufficient 1, 2

The evidence strongly supports infliximab as the most effective therapy for perianal fistulizing Crohn's disease, with the most robust clinical trial data demonstrating both induction and maintenance of fistula closure. Early intervention with appropriate surgical drainage followed by prompt initiation of infliximab offers the best chance for improved outcomes and quality of life in these patients.