Why is colchicine added to the treatment of acute pericarditis?

Why Colchicine is Given with Pericarditis

Colchicine is added to NSAIDs as first-line therapy for acute pericarditis because it reduces recurrence rates by 50-60% by blocking IL-1β activation and preventing the immune-mediated inflammatory cascade that characterizes recurrent pericarditis. 1

Mechanism of Action

Colchicine works by blocking IL-1β activation, which prevents the chronic immune activation and inflammatory cascade that drives recurrent pericarditis. 1 This sustained anti-inflammatory effect over 3-6 months of treatment addresses the underlying immune dysregulation, not just the acute symptoms. 1

Evidence for Efficacy

The combination of colchicine with NSAIDs reduces recurrence rates from 15-30% down to approximately 10-18% at 18 months. 2, 1, 3 This translates to a number needed to treat (NNT) of 4-5 patients to prevent one recurrence. 3, 4

Key Clinical Outcomes:

• Recurrence prevention: Colchicine reduces the hazard ratio for recurrence to 0.37-0.40 (60% relative risk reduction) in both acute and recurrent pericarditis. 4
• Symptom relief: Greater symptom resolution at 72 hours compared to NSAIDs alone (88% vs 63%). 3, 4
• Hospitalization: 71% reduction in pericarditis-associated rehospitalization. 5

Treatment Algorithm

First-Line Therapy (Combination Required):

• NSAIDs: Aspirin 750-1000 mg every 8 hours OR ibuprofen 600 mg every 8 hours for 1-2 weeks with gastroprotection 2
• PLUS Colchicine: Weight-adjusted dosing
  • 0.5 mg once daily if <70 kg 2
  • 0.5 mg twice daily if ≥70 kg 2
  • Duration: 3 months (inadequate duration increases recurrence risk) 2, 1

Why Combination Therapy Works:

NSAIDs address acute symptomatic inflammation while colchicine prevents the underlying immune dysregulation that leads to recurrences. 1 Using NSAIDs alone leaves patients vulnerable to the 15-30% recurrence rate, which increases to 50% after the first recurrence. 2

Critical Caveat: Corticosteroids Blunt Colchicine's Effect

Corticosteroids are NOT recommended as first-line therapy because they increase recurrence risk and may attenuate colchicine's protective effects. 2, 6, 3

• Corticosteroid use is an independent risk factor for recurrence (OR 4.30). 3
• One study showed that adding colchicine to prednisone resulted in a 40.5% recurrence rate versus 18.2% with NSAIDs plus colchicine. 7
• Corticosteroids should only be used when NSAIDs/colchicine are contraindicated or have failed, and only after excluding infectious causes. 2, 6

Safety Profile

Adverse effects are predominantly gastrointestinal (abdominal pain, diarrhea), occurring in approximately 8-9% of patients. 3, 4 While more patients stop colchicine due to side effects compared to controls (RR 1.87), serious adverse effects are rare when proper precautions are followed. 4, 8

Contraindications and Dose Adjustments:

• Severe renal impairment (CrCl <30 mL/min): Start at 0.3 mg once daily 2
• Dialysis patients: Maximum 0.3 mg twice weekly 2
• Moderate renal impairment (CrCl 30-50 mL/min): Standard dose with close monitoring 2

Common Pitfalls to Avoid

• Inadequate treatment duration: Using colchicine for less than 3 months increases recurrence risk. 2
• Using corticosteroids first-line: This promotes chronicity and recurrence. 2, 3
• Premature tapering: Only taper when symptoms are absent AND CRP is normalized. 2
• Treating isolated effusions without inflammation: Colchicine is only indicated when systemic inflammation (elevated CRP) is present. 2