What is the initial treatment for polymyositis or polymyalgia rheumatica?

Initial Treatment for Polymyalgia Rheumatica and Polymyositis

For polymyalgia rheumatica (PMR), glucocorticoids at a dose of 12.5-25 mg prednisone equivalent daily are the initial treatment of choice, while polymyositis typically requires higher doses of 60 mg/day prednisone. 1, 2

Polymyalgia Rheumatica (PMR) Treatment

Initial Glucocorticoid Therapy

• Starting dose: 12.5-25 mg prednisone equivalent daily 1
  • Higher initial doses within this range for patients with high risk of relapse and low risk of adverse events
  • Lower initial doses for patients with comorbidities (diabetes, osteoporosis, glaucoma)
  • Doses ≤7.5 mg/day are discouraged and doses >30 mg/day are strongly discouraged 1
• Administration: Single daily dose rather than divided doses 1
• Alternative option: Intramuscular methylprednisolone (120 mg injection every 3 weeks) can be considered as an alternative to oral glucocorticoids 1

Tapering Schedule

1. Initial tapering: Reduce dose to 10 mg/day within 4-8 weeks
2. Maintenance tapering: Once remission is achieved, taper by 1 mg every 4 weeks (or by 1.25 mg using alternate day schedules) until discontinuation 1
3. Relapse management: If relapse occurs, increase to pre-relapse dose and decrease gradually (within 4-8 weeks) to the dose at which relapse occurred 1

Glucocorticoid-Sparing Agents

• Methotrexate: Consider early introduction (7.5-10 mg/week) in addition to glucocorticoids for:
  • Patients at high risk for relapse or prolonged therapy
  • Patients with risk factors for glucocorticoid-related adverse events
  • Patients experiencing relapse or glucocorticoid-related adverse events 1, 3
• Anti-IL-6 agents: Tocilizumab and sarilumab have shown efficacy in reducing relapses and glucocorticoid burden in recent studies 3
• Not recommended: TNFα blocking agents are strongly discouraged 1

Monitoring and Follow-up

• Follow-up visits every 4-8 weeks in the first year, every 8-12 weeks in the second year 1
• Monitor for:
  • Disease activity (symptoms, inflammatory markers)
  • Glucocorticoid-related side effects
  • Comorbidities and risk factors for relapse 1

Polymyositis Treatment

Initial Therapy

• Starting dose: Prednisone 60 mg/day 2
• Severe cases: Consider IV methylprednisolone pulse therapy 1
• Tapering: Based on clinical response, taper slowly to prevent recurrence 2

Additional Therapies

• For severe or refractory cases:
  • Consider immunosuppressants (methotrexate, azathioprine)
  • IVIG may be indicated in some cases
  • Plasmapheresis for cases with poor response to glucocorticoids or life-threatening situations 1

Important Considerations

Diagnostic Confirmation

• Ensure correct diagnosis before initiating treatment:
  • PMR: Bilateral shoulder pain, morning stiffness ≥30 minutes, elevated inflammatory markers, age >50 years 4, 5
  • Polymyositis: Proximal muscle weakness, elevated muscle enzymes (CK), abnormal EMG/MRI 1

Treatment Pitfalls to Avoid

• Underdosing: Starting with doses <12.5 mg for PMR may lead to inadequate symptom control
• Overdosing: Starting with doses >30 mg for PMR increases risk of adverse effects without additional benefit
• Rapid tapering: Tapering faster than recommended (>1 mg/month below 10 mg/day) increases relapse risk 1, 6
• Inadequate monitoring: Failure to regularly assess disease activity and glucocorticoid-related adverse effects
• Delayed use of steroid-sparing agents: Consider early introduction in high-risk patients 1

Special Populations

• Elderly patients: Carefully monitor for glucocorticoid side effects
• Patients with comorbidities: Consider lower initial doses and earlier introduction of steroid-sparing agents
• Patients with atypical presentation: Consider specialist referral, particularly for cases with peripheral inflammatory arthritis, systemic symptoms, or low inflammatory markers 1

By following these evidence-based recommendations, clinicians can effectively manage both PMR and polymyositis while minimizing disease activity and treatment-related complications.