Treatment of Autoimmune Pancreatitis
The initial standard treatment for autoimmune pancreatitis (AIP) is oral prednisolone at a dose of 0.6 mg/kg/day for 2-4 weeks, followed by gradual tapering over 2-3 months to a maintenance dose of 2.5-5 mg/day. 1, 2
Initial Assessment and Treatment Approach
Indications for Treatment
- Symptomatic disease, including:
Pre-treatment Considerations
- Manage obstructive jaundice with biliary drainage before starting steroids
- Control blood glucose levels in patients with diabetes mellitus
- Rule out pancreatic malignancy (critical differential diagnosis) 1, 2, 3
Treatment Protocol
Induction Therapy
- Initial dose: Oral prednisolone 0.6 mg/kg/day (approximately 30-40 mg/day)
- Duration: Maintain initial dose for 2-4 weeks
- Monitoring: Assess clinical symptoms, liver enzymes, IgG/IgG4 levels, and imaging findings (US, CT, MRCP, ERCP)
Tapering Schedule
- Reduce dose by 5 mg every 1-2 weeks
- Taper to maintenance dose over 2-3 months
- Target maintenance dose: 2.5-5 mg/day 1, 2, 4
Maintenance Therapy
- Continue low-dose prednisolone (2.5-5 mg/day)
- Duration: Typically planned for up to 3 years in cases showing radiological and serological improvement
- Maintenance therapy significantly reduces relapse rates (23% with maintenance vs. 34% without, p=0.048) 1, 2, 4
Management of Relapse
Relapse Patterns
- 56% of relapses occur within 1 year of starting treatment
- 92% of relapses occur within 3 years 4
Treatment of Relapse
- Re-administration or dose increase of steroids is effective in 97% of relapsed cases
- Consider immunomodulatory drugs for steroid-resistant cases 1, 4
Alternative Therapies for Refractory or Relapsing Disease
- Immunomodulators: Azathioprine for maintenance of remission
- Biologics:
- Rituximab for induction and maintenance in relapsing AIP type 1
- Anti-TNF therapy for AIP type 2 relapses or steroid dependence 5
Predictors of Relapse
- Proximal bile duct stenosis
- Elevated serum IgG4 levels 3
Long-term Considerations
Monitoring
- Regular assessment of pancreatic exocrine and endocrine function
- Surveillance for associated malignancies
- Follow-up imaging to detect early relapse 1, 2
Prognosis
- Short-term prognosis is generally good with steroid therapy (98% remission rate)
- Long-term outcomes are less clear due to concerns about relapse, pancreatic dysfunction, and potential associated malignancies 1, 2
Special Considerations
- AIP type 1 is considered a pancreatic manifestation of IgG4-related disease and may involve multiple organs
- AIP type 2 is pancreas-specific and not related to IgG4
- Both types respond well to steroid therapy 5
The high efficacy of steroid therapy (98% remission rate vs. 74% without steroids, p<0.001) makes it the cornerstone of AIP treatment, with the treatment protocol outlined above representing the current standard of care based on extensive clinical experience in Japan and internationally 1, 2, 4.