Polymyalgia Rheumatica

Lab Workup

• Lab tests alone are not diagnostic of PMR
• ESR and CRP elevated 
  • Normal inflammatory markers should raise concern for an alternate diagnosis (like rotator cuff tendinopathy, hip osteoarthritis, fibromyalgia, etc.)

Imaging

Imaging is not indicated to establish a diagnosis of PMR.  However, it may be useful to evaluate for mimics of PMR.

• X-rays: may be normal or show OA changes
• MRI/ultrasound: non-specific, may show subacromial bursitis and/or trochanteric bursitis

Response to Steroids

• Significant improvement with prednisone 20 mg/d
• With systemic steroids on board, if symptoms are worsening after 3-7 days or persistent after 7 days, this essentially excludes the diagnosis

• Other rheumatic diseases
  • Giant cell arterits
  • Rheumatoid arthritis
  • Myositis
  • Fibromyalgia
• Malignancy
• Infection
  • Infectious arthropathy (TB, bacteria)
  • Endocarditis
• Endocrinopathies:
  • Hypothyroidism
  • Diabetes associated myalgia, arthralgia
• Drug toxicities
  • Statins
• Osteoarthritis/mechanical musculoskeletal disease (with normal ESR/CRP):
  • Rotator cuff tendinopathy
  • Osteoarthritis of hips or shoulders
  • Cervical radiculopathy/stenosis

• Prompt response to prednisone (15-20 mg/d) is highly characteristic of PMR
  • Symptom reduction should be evident ~72 hours, usually within 24 hours
• Initial dose of prednisone
  • Start at 10-20 mg/d
  • Taper by 2.5 mg every month
  • When able to get to 10 mg/d: taper dose by 1 mg every month until off
  • Ending with an every other day dosing before coming completely off of steroids can help decrease symptoms of relative adrenal insufficiency
• Second line therapy: sarilumab
  • Used if patient unable to wean or tolerate steroids; refer to rheumatology
  • If sarilumab needed for refractory/recurrent PMR, when sarilumab is started, start prednisone at 15 mg/d with decrease of 1 mg every week until off (~14 week taper)

Flares

• Best identified by symptoms, ESR/CRP usually elevated
  • An increase in ESR/CRP without symptoms is not a flare
  • CRP can be falsely low with use of IL6 pathway antagonists like sarilumab
  • If no symptoms but the inflammatory markers are persistently elevated or rise, screen for symptoms of GCA or signs of GCA-like thoracic aneurysm
  • If CRP rises back up with constitutional symptoms, keep infection on differential diagnosis
• Escalate prednisone back to previous dose for flare
• 75% of patients able to taper off steroids in 2 years

Monitor for Giant Cell Arteritis (GCA)

• 15% of patients with PMR can get GCA
• GCA symptoms:
  • Unilateral headache
  • Jaw claudication
  • Scalp tenderness
  • Vision loss

Monitor for Toxicities of Systemic Steroids

• Very important to screen for osteoporosis with DEXA scans
• Monitor for signs of steroid-induced diabetes (serum glucose, A1C, etc.)
• Infections can occur even at lower doses of steroids, but PJP ppx at these doses without parenchymal disease usually not warranted

• Alternative diagnosis should be strongly considered if no symptom relief with ≥10-20 mg/d of prednisone.
• Flares often occur if prednisone is tapered too rapidly.
• Every visit, inquire about giant cell arteritis (GCA) symptoms (vision loss, recurrent headaches, scalp tenderness, jaw claudication).
  • If GCA suspected, patient should be started on high dose prednisone (1 mg/kg/d or more).
  • Temporal artery biopsy is gold standard for GCA diagnosis – prednisone should not be delayed for biopsy.