What are the characteristics of Polymyalgia Rheumatica (PMR)?

Characteristics of Polymyalgia Rheumatica (PMR)

Polymyalgia rheumatica is characterized by bilateral pain and stiffness in the shoulder girdle, neck, and pelvic girdle, affecting people over 60 years of age, with elevated inflammatory markers and rapid response to low-dose glucocorticoids.

Clinical Presentation

• Age: Typically affects individuals over 60 years old 1, 2
• Symptom onset: Relatively rapid onset of symptoms 1
• Core symptoms:
  • Bilateral pain and stiffness in the shoulder girdle (most common) 3, 1, 2
  • Pain and stiffness in the neck 1, 2
  • Pain and stiffness in the hip/pelvic girdle 1, 2
  • Prolonged morning stiffness 1, 2
  • Proximal muscle pain without true weakness 2

Laboratory Findings

• Inflammatory markers: Elevated erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) 3, 1

• Required laboratory evaluation:

  • Complete blood count
  • ESR and CRP
  • Rheumatoid factor
  • Anti-cyclic citrullinated peptide antibodies
  • Basic biochemistry 3, 1

• Additional tests to consider based on clinical presentation:

  • Urinalysis
  • Glucose
  • Liver function tests
  • Bone profile
  • Protein electrophoresis
  • Thyroid-stimulating hormone
  • Creatine kinase
  • Vitamin D
  • Antinuclear antibodies
  • Antineutrophil cytoplasmic antibodies 1

Diagnostic Confirmation

• Glucocorticoid response: Significant improvement within 24-72 hours of starting low-dose glucocorticoids (15-20 mg/day prednisone) is considered confirmatory 1
• No single diagnostic test exists; diagnosis is primarily clinical 4

Differential Diagnosis

PMR must be distinguished from conditions that can mimic it, including:

• Rheumatoid arthritis (especially elderly-onset)
• Spondyloarthritis
• Inflammatory myopathies
• Malignancies
• Chronic infections
• Endocrine diseases (particularly hypothyroidism)
• Fibromyalgia
• Polymyositis 3, 1

Association with Giant Cell Arteritis

• PMR can coexist with giant cell arteritis (GCA) 5, 6
• Both conditions may share pathophysiological mechanisms 5
• Patients should be monitored for symptoms of GCA including headache, jaw claudication, and visual disturbances 6

Risk Factors for Relapse/Prolonged Therapy

• Female sex 3
• High ESR (>40 mm/1st hour) 3
• Peripheral inflammatory arthritis 3

Management Considerations

• First-line treatment: Glucocorticoids at 12.5-25 mg prednisone equivalent daily 3, 1
• Initial dose considerations:
  • Higher dose (within range) for patients with high relapse risk and low adverse event risk
  • Lower dose for patients with comorbidities (diabetes, osteoporosis, glaucoma) 3, 1
• Tapering: Reduce to 10 mg/day within 4-8 weeks, then taper gradually 3, 1
• Steroid-sparing agents: Consider methotrexate in patients with high relapse risk or glucocorticoid-related adverse events 1, 7

Monitoring

• Follow-up visits every 4-8 weeks in the first year
• Every 8-12 weeks in the second year
• More frequently during relapses or tapering periods 3, 1
• Monitor for:
  • Clinical response
  • Inflammatory markers
  • Glucocorticoid-related side effects
  • Comorbidities 1

Common Pitfalls

• Avoid initial glucocorticoid doses ≤7.5 mg/day (conditionally discouraged)
• Avoid initial glucocorticoid doses >30 mg/day (strongly discouraged)
• Failure to exclude mimicking conditions
• Inadequate monitoring for glucocorticoid-related complications 3, 1
• Failure to consider giant cell arteritis as a comorbid condition 5, 6

PMR is the second most common inflammatory rheumatic disease in people over 50 years of age (after rheumatoid arthritis) and requires careful diagnosis and management to minimize both disease burden and treatment-related complications 7.