How do you differentiate and treat Polymyalgia Rheumatica (PMR) versus gout?

Differentiating and Treating Polymyalgia Rheumatica (PMR) vs Gout

Glucocorticoids are the cornerstone treatment for PMR (12.5-25 mg prednisone daily), while gout requires NSAIDs, colchicine, or urate-lowering therapy depending on whether it's acute or chronic management. 1, 2

Diagnostic Differentiation

Clinical Presentation

PMR Characteristics:

• Age: Typically affects people >60 years old 2
• Key Symptoms:
  • Bilateral shoulder girdle pain and stiffness
  • Neck pain and stiffness
  • Hip/pelvic girdle pain and stiffness
  • Prolonged morning stiffness (>45 minutes)
  • Proximal muscle pain without true weakness 2
• Laboratory Findings:
  • Elevated ESR and/or CRP (>90% of cases)
  • Normal rheumatoid factor and anti-CCP antibodies 2
• Diagnostic Confirmation: Rapid response to low-dose glucocorticoids (15-20 mg/day) within 24-72 hours 2

Gout Characteristics:

• Key Symptoms:
  • Acute, severe joint pain (often first MTP joint)
  • Erythema, warmth, and swelling of affected joint
  • Self-limiting episodes lasting days to weeks
  • Asymmetric joint involvement
  • Tophi in chronic cases
• Laboratory Findings:
  • Elevated serum uric acid levels
  • Joint aspiration showing negatively birefringent monosodium urate crystals (gold standard)
  • Elevated inflammatory markers during acute attacks

Key Differentiating Features

1. Joint Distribution: PMR affects shoulder and hip girdles bilaterally; gout typically affects lower extremity joints asymmetrically
2. Age Group: Both affect older adults, but PMR rarely occurs <50 years
3. Response to Treatment: PMR shows dramatic response to low-dose glucocorticoids; gout responds to NSAIDs, colchicine
4. Laboratory: Both have elevated inflammatory markers, but gout has hyperuricemia and crystal identification
5. Disease Course: PMR is chronic; gout typically presents as intermittent acute attacks

Treatment Approaches

PMR Treatment Algorithm

1. Initial Therapy:

   • Glucocorticoids: 12.5-25 mg prednisone equivalent daily 1
     • Higher initial dose (within range) for patients with high relapse risk and low adverse event risk
     • Lower dose for patients with comorbidities (diabetes, osteoporosis, glaucoma)
     • Strongly discouraged: initial doses >30 mg/day
     • Conditionally discouraged: initial doses ≤7.5 mg/day 1, 2

2. Dose Tapering:

   • Initial tapering: Reduce to 10 mg/day within 4-8 weeks
   • Once stable: Taper by 1 mg every 4 weeks (or by 1.25 mg using alternate day schedules)
   • For relapse: Increase to pre-relapse dose and decrease gradually within 4-8 weeks 1

3. Alternative Administration:

   • Single daily dose preferred over divided doses
   • Intramuscular methylprednisolone (120 mg every 3 weeks) may be considered as alternative to oral therapy 1

4. Steroid-Sparing Agents:

   • Consider methotrexate for patients with:
     • High relapse risk
     • Glucocorticoid-related adverse events
     • Prolonged therapy requirements 2, 3

5. Monitoring:

   • Every 4-8 weeks in first year
   • Every 8-12 weeks in second year
   • Monitor for GCA symptoms (headache, jaw claudication, visual disturbances)
   • Assess steroid-related side effects and comorbidities 1, 2

Gout Treatment Algorithm

1. Acute Attack Management:

   • NSAIDs at full anti-inflammatory doses
   • Colchicine (1.2 mg followed by 0.6 mg one hour later, then 0.6 mg daily)
   • Glucocorticoids (prednisone 30-40 mg daily with taper over 7-10 days)
   • Joint rest, ice application

2. Chronic Management:

   • Urate-lowering therapy (allopurinol or febuxostat)
   • Target serum uric acid <6 mg/dL
   • Lifestyle modifications (weight loss, limiting alcohol and purine-rich foods)
   • Adequate hydration

Special Considerations

PMR and Giant Cell Arteritis (GCA) Overlap

• PMR and GCA are closely interrelated conditions 1
• Monitor all PMR patients for GCA symptoms (headache, jaw claudication, visual disturbances)
• GCA requires immediate treatment (medical emergency) due to risk of sight loss 1
• Higher glucocorticoid doses (40-60 mg prednisone) are required for GCA

PMR and Gout Coexistence

• Contrary to previous assumptions, gout is associated with >2-fold higher risk of incident PMR in older adults 4
• Mean duration of gout before PMR diagnosis: 2.2 years 4
• When both conditions coexist, treatment should address both pathologies

Treatment Compliance Considerations

• Medication adherence varies significantly between treatment regimens
• Compliance with prednisolone for PMR (88%) is higher than compliance with colchicine for gout (44%) 5
• Factors affecting compliance include dosing frequency, medication class, and patient characteristics 5

Pitfalls and Caveats

1. Misdiagnosis Risk: Elderly-onset rheumatoid arthritis is frequently misdiagnosed as PMR 6

2. Incomplete Response: If PMR symptoms don't respond dramatically to glucocorticoids within 72 hours, reconsider diagnosis

3. Glucocorticoid Side Effects: Monitor for and manage steroid-related complications, particularly in elderly patients with comorbidities

4. Relapse Management: Up to 60% of PMR patients experience relapse during glucocorticoid tapering 1

5. Gout Mimics: Septic arthritis, pseudogout, and reactive arthritis can present similarly to gout

By understanding the distinct clinical presentations and treatment approaches for PMR and gout, clinicians can accurately differentiate between these conditions and implement appropriate management strategies to improve patient outcomes.