Polymyalgia Rheumatica and Giant Cell Arteritis
Epidemiology
PMR and GCA are tends ends of the same spectrum.
- GCA: prevalence 200 per 100,000 over the age of 50. 40% also have PMR. There is a 3:1 female to male ratio.
- PMR: prevalence 700 per 100,000 over the age of 50. 10-30% develop GCA.
PMR doesn't occur in those under 50. It is the most common inflammatory disease of the elderly and the most common reason for long term glucocorticoid use in the elderly.
Clinical Features
PMR
It has an acute to sub-acute onset. Typical features are pain and stiffness in the shoulder and pelvic girdle. Fatigue and early morning stiffness are prominent but other systemic symptoms are usually absent. Peripheral synovitis occurs in 12-77%, and tenosynovitis in 10-14%. There may be pitting oedema.
All patients that present with PMR should be assessed for GCA.
GCA
- Headache: an abrupt onset new headache, however in 2/3 the headache can be gradual.
- Scalp tenderness occurs in ~60%
- Jaw claudication in ~60%
- PMR symptoms in ~40%
- Visual loss (1 or both eyes) in ~15-20%
- Fever occurs in ~15-50%
- Fatigue and weight loss.
- Arm claudication occurs in ~15%.
- Tenosynovitis.
- Upper respiratory symptoms occur in ~10%.
The visual loss is due to anterior ischaemic optic neuropathy, which is a painless complete loss of vision. It is due to involvement of the posterior ciliary artery. If left untreated, the remaining good eye is generally affected within 1-2 weeks.
Investigations
PMR
All patients should have FBC, ESR or CRP, UEC, LFTs, CK, TSH, Calcium, and RF. ESR is <40 in up to 22% of cases.
A dipstick urinalysis should be done.
In the presence of atypical features test for anti-CCP, myeloma screen, ANA, and obtain a CXR.
GCA
The ESR is usually >50. An ESR of < 30 has a -LR of 0.02. A normal ESR doesn't exclude the diagnosis however; this finding is associated with less jaw claudication but not milder disease. There is also an elevated CRP. On FBC there is a normochromic normocytic anaemia, reactive thrombocytosis, but a normal WCC. On urinalysis ~30% have haematuria. Raised AST and ALP occurs in ~25-35%.
Cranial duplex ultrasound can be used to look for stenosis, occlusions, and the halo sign. The sensitivity is 81%, specificity of 98%, PPV of 97%, and NPV of 88%.
Temporal artery biopsy has a specificity of 100%, sensitivity of 53%, PPV of 100%, and NPV of 47%.
Diagnostic Criteria
PMR
| Required Criteria | ||
|---|---|---|
| ||
| Criteria | Algorithm w/o US | Algorithm w US |
| Morning stiffness duration >45 minutes | 2 | 2 |
| Hip pain or limited range of motion | 1 | 1 |
| Negative RF or Anti-CCP | 2 | 2 |
| Absence of other joint involvement | 1 | 1 |
| โฅ 1 shoulder with subdeltoid bursitis and/or biceps tenosynovitis and/or glenohumeral synovitis (either posterior or axillary)
AND โฅ 1 hip with synovitis and/or trochanteric bursitis |
NA | 1 |
| Both shoulders with subdeltoid bursitis, biceps tenosynovitis or glenohumeral synovitis | NA | 1 |
| A score of โฅ 4 has a 68% sensitivity, and 78% specificity.
A score of โฅ 5 has a 66% sensitivity and 81% specificity | ||
GCA
Need 3 out of 5 of:
- Age of onset โฅ50years
- New headache
- Temporal artery tenderness or decreased pulsation
- ESR >50mm or raised CRP
- Abnormal arterial biopsy
Sensitivity 93.5%, specificity 91.2%
Differential Diagnosis
- Malignancy
- Infection
- Inflammatory rheumatic disease
- Drug-induced myalgia
- Hypothyroidism
- Hyperparathyroidism
- Regional musculoskeletal disease
- Neurological disease.
- Chronic pain syndromes
- Herpes zoster
- Migraine
- Intracranial pathology
- Referred cervical pain
- Sinus disease
- Temporo-mandibular joint pain
- Referred dental pain
- Referred ear pain
- Primary systemic vasculitis
Management
PMR
The suggested regimen of prednisone is 15mg daily for three weeks, 12.5mg daily for 3 weeks, 10mg daily for 4 weeks, then reduce by 1mg every 4-8 weeks.
If symptoms recur then titrate up by one or two steps. If the patient is asymptomatic for one month on 1mg of prednisone then stop. Most patients need 18-36 months of treatment.
Refer for Rheumatological opinion if
- Age <60
- Chronic onset >2 months
- Reduced shoulder movement
- Prominent systemic features
- Features of other rheumatic disease
- Normal or alternatively very high inflammatory markers
- Incomplete or non-responsive to prednisone
- Inability to reduce prednisone
- Prolonged use of prednisone >2 years.\
All patients should be advised to maintain adequate calcium intake in their diet and take vitamin D supplements. Bone protection should be considered in everyone. Intraocular pressure may rise in some individuals. Consider the development of diabetes.
GCA
Prednisone is started as soon as the diagnosis is suspected. The suggested regimen is 1mg/kg which is usually 40-60mg for ~4 weeks, then reduction by 10mg every 2 weeks to 20mg, then 2.5mg every 2-4 weeks to 10mg, then 1mg every 1-2 months.
If symptoms recur then titrate up by one or two steps. If the patient is asymptomatic for one month on 1mg of prednisone then stop. Most patients need 2-3 years of treatment, but some need lifelong treatment.
If there are visual symptoms the minimum dose needed to save the vision is 60-80mg. Steroids should not be delayed while waiting for investigations. The patient should be referred to hospital.
Relapse is common and occurs if the prednisone is tapered too fast, however 30-50% have spontaneous exacerbations regardless of the prednisone regimen, and this occurs along with a rise in CRP and ESR.
