Diagnosis of Polymyalgia Rheumatica
Diagnose PMR based on age ≥50 years, bilateral shoulder pain with morning stiffness, elevated inflammatory markers (ESR and/or CRP), and exclusion of mimicking conditions, followed by confirmation with dramatic response to glucocorticoids within 2 weeks. 1, 2
Clinical Diagnostic Criteria
Essential Features
- Age ≥50 years at symptom onset 1, 3
- Bilateral shoulder pain with severe morning stiffness lasting >1 month 1, 3
- Neck and/or pelvic girdle involvement may be present but is not mandatory 2, 3
- Functional impairment from pain and stiffness 4
Laboratory Markers
- Elevated ESR and/or CRP in >90% of cases 4, 5
- ESR >40 mm/1st hour is typical and associated with higher relapse risk 1, 6
- Normal inflammatory markers represent an atypical presentation requiring specialist referral 1, 2
Important caveat: ESR is preferred over CRP for long-term monitoring and predicting relapse risk, as high ESR (>40 mm/1st hour) independently predicts need for prolonged therapy 6
Mandatory Exclusion Testing
Rheumatologic Conditions
- Rheumatoid factor and/or anti-CCP antibodies to exclude elderly-onset rheumatoid arthritis (EORA), which is the most common PMR mimic 1, 2, 7
- Complete peripheral joint examination to identify inflammatory arthritis 2
Other Mimicking Conditions
- Thyroid function tests to exclude thyroid disorders 1
- Serum protein electrophoresis to exclude myeloma 1
- Consider ANCA testing if vasculitis suspected 1
- Chest radiograph at physician discretion to exclude malignancy 1
Critical pitfall: Malignancies and seronegative symmetrical polyarthritis are common PMR mimics. Patients with solid malignancies show poor response to low-dose prednisone, while those with hematologic malignancies may have atypical continuous aching rather than movement-related pain 7
Imaging for Diagnostic Support
Ultrasound Findings
- Bilateral subdeltoid bursitis detected in 69% of PMR patients 4
- Ultrasound improves diagnostic accuracy when clinical features are present 4
When to Use Imaging
Diagnostic Confirmation Through Treatment Response
Dramatic clinical improvement within 2 weeks of starting glucocorticoids at 12.5-25 mg prednisone equivalent daily confirms the diagnosis 1, 2, 3
- Almost complete response expected within 4 weeks 1
- Lack of response within 2 weeks should prompt dose increase to 25 mg or reconsideration of diagnosis 1
Atypical Presentations Requiring Specialist Referral
Refer immediately if any of the following are present 1, 2:
- Age <60 years 1, 2
- Peripheral inflammatory arthritis 1, 2
- Systemic symptoms (fever, weight loss) 1, 2
- Low or normal inflammatory markers 1, 2
- Poor response to appropriate glucocorticoid therapy 1
Assessment of Comorbidities Before Treatment
Document the following risk factors for glucocorticoid-related adverse events 1:
- Hypertension, diabetes, glucose intolerance 1, 2
- Cardiovascular disease, dyslipidemia 1, 2
- Osteoporosis (particularly recent fractures) 1, 2
- Cataract or glaucoma risk factors 1, 2
- Peptic ulcer disease 1, 2
- Chronic or recurrent infections 1
- Concomitant NSAID use 1
Female sex is associated with higher risk of glucocorticoid side effects and higher relapse rates 1, 2
Initial Treatment Algorithm
Starting Dose Selection
Use 12.5-25 mg prednisone equivalent daily as initial therapy 1, 2
Choose higher dose (20-25 mg) when:
- High ESR (>40 mm/1st hour) 1, 6
- Peripheral inflammatory arthritis present 1, 2
- Female sex 1, 2
- Low risk of adverse events 1
Choose lower dose (12.5-15 mg) when:
- Diabetes, osteoporosis, or glaucoma present 1
- Multiple risk factors for glucocorticoid side effects 1
- Elderly with frailty 1
Strongly avoid initial doses ≤7.5 mg/day (ineffective) or >30 mg/day (excessive toxicity risk) 1
Monitoring Schedule
- Every 4-8 weeks during first year 1, 2
- Every 8-12 weeks during second year 1
- As indicated for relapses or during tapering 1
Document at each visit: disease activity, inflammatory markers, glucocorticoid-related side effects, and relapse risk factors 1