What is polymyalgia rheumatica?

Polymyalgia Rheumatica: Clinical Overview

Polymyalgia rheumatica (PMR) is a chronic inflammatory disease affecting adults over 50 years of age, characterized by bilateral proximal muscle pain and morning stiffness in the shoulders, neck, and pelvic girdle, accompanied by elevated inflammatory markers. 1, 2

Clinical Presentation

PMR presents with a distinctive pattern of symptoms that typically develops in older adults:

• Bilateral proximal pain and stiffness affecting the shoulder girdle, neck, and pelvic region, with morning stiffness being a hallmark feature 3, 4
• Age requirement: Patients are typically over 50 years old, with 80% presenting in their 60s or 70s, though 6.8% may present younger than 50 5
• Functional impairment is common, with patients experiencing difficulty performing daily activities due to pain and stiffness 6
• Peripheral joint involvement occurs in approximately 36% of patients, most commonly affecting the wrists and knees as monarthritis or oligoarthritis 5
• Systemic inflammatory response is intense and characteristic of the condition 7

Pathophysiology

PMR is an inflammatory disease of the connective vascular tissue, though the exact etiology remains unknown 3, 5. The condition can occur independently or in association with giant cell arteritis (GCA), which complicates approximately 7% of cases based on available data 5.

Diagnostic Approach

The diagnosis of PMR is primarily clinical, supported by laboratory evidence of inflammation and systematic exclusion of mimicking conditions. 6

Essential Laboratory Workup

The European League Against Rheumatism/American College of Rheumatology guidelines mandate the following baseline assessments before initiating therapy 1, 6:

• Inflammatory markers: ESR and/or CRP (typically markedly elevated, with mean maximum CRP around 8.18 mg/dl) 5, 6
• Autoantibody testing: Rheumatoid factor and/or anti-CCP antibodies to exclude rheumatoid arthritis 1, 6
• Complete blood count: To assess for anemia of inflammation and exclude other causes 6
• Metabolic panel: Glucose, creatinine, and liver function tests to establish baseline before glucocorticoid therapy 6
• Bone profile: Calcium and alkaline phosphatase to assess bone health prior to steroid exposure 6
• Urinalysis: To exclude inflammatory or infectious conditions 6

Additional Testing When Indicated

• Protein electrophoresis, TSH, creatine kinase, and vitamin D should be considered as part of the initial workup 1, 6
• ANA and ANCA testing when other autoimmune conditions are suspected based on clinical presentation 1, 6
• Tuberculosis screening when immunosuppressive therapy is being considered 6
• Chest radiography to exclude malignancy or other pulmonary conditions 6

Diagnostic Pitfalls and Mimicking Conditions

The clinical evaluation must systematically exclude several categories of mimicking conditions 1:

• Inflammatory conditions: Giant cell arteritis (which can coexist), rheumatoid arthritis, and other inflammatory arthritides 1, 2
• Non-inflammatory conditions: Bilateral shoulder capsulitis, rotator cuff tendinitis, and other soft tissue disorders 2
• Endocrine disorders: Thyroid dysfunction that can present with similar symptoms 1
• Infectious causes: Particularly in patients being considered for immunosuppression 1
• Malignancy: Which can mimic PMR symptoms 1
• Drug-induced syndromes: Particularly immune checkpoint inhibitor-induced PMR-like syndromes in cancer patients 2

A critical diagnostic consideration is that progression from PMR to rheumatoid arthritis can occur, typically within 1-5 years of initial diagnosis, necessitating ongoing vigilance for evolving peripheral joint involvement. 5

Atypical Presentations Requiring Specialist Referral

The American College of Rheumatology recommends specialist consultation for 2:

• Peripheral inflammatory arthritis beyond the typical oligoarticular pattern 2
• Systemic symptoms beyond typical PMR presentation 2
• Low or normal inflammatory markers despite typical symptoms 2
• Age less than 60 years 2

Treatment Strategy

Initial therapy consists of glucocorticoids at 12.5-25 mg prednisone equivalent daily, with higher doses within this range reserved for patients at high relapse risk and low adverse event risk. 2

Glucocorticoid Management

• Starting dose: 12.5-25 mg prednisone daily, with the median maximum dose used being approximately 0.195 mg/kg body weight daily 2, 5
• Expected response: Rapid clinical improvement should occur within days to weeks; lack of response should prompt reconsideration of the diagnosis 1
• Tapering strategy: Gradual reduction guided by clinical response and inflammatory markers 1

Steroid-Sparing Agents

Methotrexate at 7.5-10 mg/week should be considered early in patients at high risk of relapse, those with prolonged therapy anticipated, or those with comorbidities where glucocorticoid-related adverse events are more likely. 1

Specific scenarios warranting MTX consideration include 1:

• Female patients (who have higher relapse rates) 8, 2
• High initial ESR (>40 mm/hour), which predicts increased relapse risk 8, 2
• Peripheral inflammatory arthritis at presentation 1
• Comorbidities that may be exacerbated by glucocorticoid therapy (diabetes, osteoporosis, hypertension) 1

Agents to Avoid

TNF-α blocking agents are strongly contraindicated in PMR due to lack of efficacy evidence, considerable potential harm, and high resource utilization. 1

Chinese herbal preparations (Yanghe and Biqi capsules) are strongly contraindicated due to lack of FDA/EMA approval, unclear generalizability, and potential for unforeseeable adverse effects. 1

Monitoring and Follow-Up

Surveillance Schedule

The European League Against Rheumatism/American College of Rheumatology recommend structured follow-up 8, 2:

• First year: Every 4-8 weeks 2
• Second year: Every 8-12 weeks 8
• During flares: Increase frequency back to every 4-8 weeks until remission is re-established 8

Monitoring During Flares

When relapse occurs, repeat the following assessments 8:

• ESR and/or CRP: To confirm inflammatory activity 8
• Complete blood count: To assess anemia of inflammation 8
• Glucose: To monitor for steroid-induced hyperglycemia during dose escalation 8
• Creatinine and liver function tests: To ensure safe continuation of therapy 8
• Bone profile: To assess for steroid-induced bone loss 8
• Rheumatoid factor and/or anti-CCP: If atypical features develop, such as new peripheral joint involvement 8
• Creatine kinase: If true muscle weakness develops, to exclude steroid myopathy or inflammatory myositis 8

Comorbidity Assessment and Management

Prior to initiating therapy, assess and document 1, 2:

• Hypertension, diabetes, glucose intolerance, and cardiovascular disease 2
• Dyslipidemia and peptic ulcer disease 2
• Osteoporosis (particularly recent fractures) 1
• Cataracts or risk factors for glaucoma 1
• Chronic or recurrent infections 1

Prognostic Factors

Female sex, high baseline ESR (>40 mm/hour), and peripheral inflammatory arthritis at presentation are the strongest predictors of relapse and prolonged therapy requirement. 8, 2

Disease recurrence is estimated to occur in approximately 50% of patients during glucocorticoid tapering, highlighting the chronic relapsing nature of PMR 7.

Non-Pharmacological Management

An individualized exercise program should be implemented to maintain muscle mass and function and reduce fall risk, particularly important in older adults on long-term glucocorticoids. 1