Polymyalgia rheumatica
Epidemiology
- Sex: ♀ > ♂ (3:1)
- Age of onset: >70 years (rarely seen in patients < 50 years)
Tip
Women of advanced age are particularly prone to the disease.
Etiology
Association with giant cell arteritis (GCA): Approx. 10% of individuals with polymyalgia rheumatica also have GCA.
Pathophysiology
Clinical features
- Systemic symptoms
- Constitutional symptoms: fever, weight loss, night sweats
- Fatigue and malaise
- Musculoskeletal symptoms: primarily affects shoulders, neck, and pelvic girdle
- New onset, symmetric pain that is worse at night
- Morning stiffness (> 45 min)
- Muscular atrophy and weakness: not directly caused by PMR but resulting from reduced activity due to pain and stiffness
Diagnostics
- ↑ ESR, specifically > 50 mm/h
- ↑ CRP
- Normochromic anemia
- Normal creatine kinase, negative rheumatoid factors, and no autoantibodies
| Feature | PMR | RA |
|---|---|---|
| Age | 60 to 80 years | 30 to 50 years |
| Female predominance | 2 to 3 times as likely | 2 times as likely |
| Morning stiffness | always | always |
| Onset of symptoms | days to few weeks | weeks to months |
| Predominant joints | shoulders, hips | small joints of hands, feet |
| Extra-articular feature | giant-cell arteritis | subcutaneous nodules |
| Joint swelling | unusual | always |
| Elevated ESR, CRP | 80% to 90% | 70% to 80% |
| Positive RF, anti-CCP | not present | 50% to 70% |
| Response to low-dose steroid | rapid, very good | equivocal after a few weeks |