What are the diagnostic criteria and treatment options for a patient over 50 with polyartralgia rheumatica, presenting with joint pain and stiffness, particularly in the shoulders, hips, and knees?

Diagnosing Polymyalgia Rheumatica

Polymyalgia rheumatica (PMR) is diagnosed clinically in patients over 50 years old presenting with bilateral shoulder and/or hip girdle pain, morning stiffness lasting >30-60 minutes, and elevated inflammatory markers (ESR/CRP), after systematically excluding septic arthritis, malignancy, and giant cell arteritis. 1, 2

Clinical Diagnostic Criteria

The diagnosis is primarily clinical and requires:

• Age >50 years - this is an absolute requirement 2, 3
• Bilateral shoulder pain with or without pelvic girdle involvement, developing over weeks 2, 4
• Morning stiffness lasting >30-60 minutes to 1 hour, improving with activity 5, 3
• Elevated inflammatory markers (ESR and CRP) in >90% of cases, though a small proportion may have normal values 2, 4
• Dramatic response to glucocorticoids within 24-48 hours - failure to respond should prompt reconsideration of the diagnosis 6, 7

Essential Diagnostic Workup

Initial laboratory evaluation must include:

• ESR and CRP - elevated in >90% of cases 2, 3
• Creatine kinase (CK) - must be normal to differentiate from myositis 5
• Rheumatoid factor (RF) and anti-CCP - should be negative 5
• Complete blood count - may show anemia of chronic disease 2
• Thyroid function tests - to exclude thyroid disease as a mimic 4

Imaging studies to support diagnosis:

• Ultrasound of shoulders - bilateral subdeltoid bursitis is present in 69% of PMR patients and significantly improves diagnostic accuracy 2, 7
• X-rays of affected joints - to exclude other pathology when diagnosis is uncertain 5
• MRI - may show mild shoulder joint effusion and bursitis 5

Critical Differential Diagnoses to Exclude First

You must systematically rule out these high-priority conditions:

1. Giant cell arteritis (GCA) - present in up to 20% of PMR patients 4

   • Ask specifically about new headache, jaw claudication, and visual disturbances at every visit 4
   • If any GCA symptoms present, initiate high-dose glucocorticoids (40-60 mg prednisone daily) immediately and arrange urgent temporal artery biopsy 2

2. Septic arthritis - requires urgent arthrocentesis if suspected 1

3. Malignancy - PMR may be the first manifestation of cancer 7, 4

   • Age-appropriate cancer screening is mandatory 4

4. Rheumatoid arthritis - look for small joint involvement, positive RF/anti-CCP, and symmetric polyarthritis 7, 4

5. Myositis - distinguished by true muscle weakness (not just pain), elevated CK, and abnormal EMG 5

6. Infection - consider in patients with fever and failure to respond to glucocorticoids 7

Common Diagnostic Pitfalls

Avoid these errors:

• Overdiagnosis - many conditions mimic PMR including bilateral shoulder capsulitis, osteoarthritis, Parkinsonism, and depression 4
• Missing GCA - failure to ask about headache, jaw claudication, and visual symptoms at every visit can lead to preventable blindness 4
• Assuming normal inflammatory markers exclude PMR - a small proportion of patients have normal ESR/CRP 4
• Not checking CK levels - this is essential to differentiate PMR from myositis, which can be life-threatening if myocarditis is present 5

Treatment Approach

Initial glucocorticoid therapy:

• Prednisone 12.5-25 mg daily is the standard starting dose for PMR 2
• Expect dramatic improvement within 24-48 hours - lack of response should prompt diagnostic reconsideration 6, 7
• Taper slowly over months to minimize relapse risk 2, 7

Adjunctive therapy:

• Methotrexate reduces cumulative glucocorticoid dose by 20-44% and relapses by 36-54% in patients requiring prolonged therapy or at risk for glucocorticoid-related adverse effects 2, 8
• Tocilizumab or secukinumab are promising alternatives for refractory cases 8

Monitoring Strategy

Serial assessments every 4-6 weeks should include:

• ESR and CRP to monitor disease activity 1
• Screening for GCA symptoms at every visit 4
• Assessment of glucocorticoid side effects including bone density, glucose, blood pressure 8
• Functional assessment particularly upper extremity function and activities of daily living 8

Refer to rheumatology if:

• Diagnostic uncertainty persists 1
• Failure to respond to appropriate glucocorticoid doses within 48-72 hours 7
• Glucocorticoid dependency develops requiring prolonged therapy 2, 7
• Any suspicion of GCA 4