Polymyalgia Rheumatica - PMR

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Contents

Introduction
Epidemiology
Aetiology
Presentation
Pathophysiology
Diagnosis
Investigations
Differentials
Prognosis
References
Related Articles

Introduction

Polymyalgia rheumatica (PMR) is a common inflammatory condition which causes bilateral pain, typically worse in the morning and associated with morning stiffness, in the shoulder, neck and pelvic girdle. It is rarely seen before the age of 50 with increasing prevalence as age advances.

It responds well to treatment with corticosteroids, and is usually managed in primary care.

It is associated with giant cell arteritis – a type of arteritis which is usually described as causing face and scalp pain – and is also often known as temporal arteritis. Some consider that they are different manifestations of the same disease.

This classification is not yet definitively proven, however the two conditions are closely related – and up to 50% of individuals with giant cell arteritis will develop polymyalgia rheumatica, and 10-15% of those with polymyalgia with later develop giant cell arteritis.

Epidemiology

Presents exclusively in those over 50
- Mean age of onset is 73
Increasing incidence as age increases
Annual incidence between 1-10 people per 10,000
F:M ratio 3 :1
- Female lifetime risk – 2.5%
- Male lifetime risk – 1.7%
Approximately 2-3x more common than Giant Cell Arteritis

Aetiology

Aetiology is essentially unknown
Thought to involve a combination of environmental and genetic risk factors
Some families appear to have clusters of cases
More common at northern latitudes – most common in Scandinavia, less common in mediterranean and least common in asian populations
Seasonal variation – most commonly presents in summer

Presentation

Morning pain and stiffness – most common in the shoulders and pelvic girdle
- Morning stiffness typically lasts more than 30 minutes
- Pain may also occurs in the thighs, lower back and upper arms
- Hands, feet and ankles are usually spared at first (the opposite of rheumatoid arthritis, where these joints are usually the worst affected) – but as the condition progresses can be involved in up to 50% of patients
Bilateral
Particularly difficult activities include:
- Standing from seated position
- Getting up out of bed
- Raising arms to brush the hair / wash the hair or face
Often sudden onset
Examination findings are often normal
- Not usually any joint swelling
- There may be some restricted range of movement in more severe cases
Systemic Signs
- Occur in 40% of patients
- Fevers
- Depression
- Fatigue
- Anorxiea
- Weight loss
- Most commonly seen as a “flu-like illness” during the first 2 weeks of the illness

Pathophysiology

Morning stiffness caused by synovitis – in particular inflammation of the axtraaritcular synovial structures

Diagnosis

Guidelines exist to assist with diagnosis. Some widely used guidelines in both the UK and Australia are those from the British rheumatological society:

Core Criteria – all are required

Bilateral shoulder or pelvic girdle pain
Morning stiffness >45 minutes
Age >50 years
Duration of symptoms >2 weeks
Evidence of inflammation (raised CRP or ESR)*
- *Not necessarily required if other features are strongly suggestive. Are usually, but not always positive.

Also be wary of coexisting giant cell arteritis. If there is any headache, visual disturbance or jaw claudication then consider GCA is also present and start steroids immediately and consider urgent referral to ophthalmology +/- rheumatology. Diagnosis can be confirmed with temporal artery biopsy (although this can be difficult to arrange).

Investigations

Could include:

FBC
U&E
LFTs
TFTs – to exclude thyroid disease
CK
Rh factor (+/- CCP and ANA)
Inflammatory markers – CRP / ESR – can help to confirm the diagnosis

Differentials

Malignancy
- e.g. lymphoma, leukaemia, myeloma, ca lung or ca prostate
Other rheumatoid conditions
- Rheumatoid arthritis
- Ankylosing spondylitis
- Psoriatic arthritis
- SLE
- Scleroderma
- Dermatomyositis
Fibromyalgia
Hypothyroidism or other metabolic disturbances
Drug induced – most commonly statin induced myopathy

Management

Unlike GCA, immediate treatment with steroids is not necessary (although is often appropriate)
Steroids are the mainstay of treatment – usually low dose, which tapers over the following months
- 15mg daily for 3 weeks
- 12.5mg daily for 3 weeks
- 10mg daily for 4-6 weeks
- Reduced by 1mg daily every 4-8 weeks subsequently
Be aware that long term steroids increase the risk of osteoporosis (and lots of other things!)
- Always start vitamin D and calcium when starting steroids for PMR
- Consider the use of bisphosphonates in higher risk patients
- Consider DEXA scan in lower risk patients to assess individual risk
Symptoms should improve quickly – there should be a noticeable improvement within one week
- If there isn’t – consider an alternative diagnosis, and / or referral to rheumatology
Educate the patient about the risk of GCA and the symptoms – if they experience any of this they need to start urgent higher doses of steroids. Always ask about these symptoms at FU appointments
- Consider repeat inflammatory markers to check the effectiveness of treatment – in most cases, inflammatory markers have returned to normal within 4 weeks.
- A patient information sheet including information on GCA is available from Arthritis Australia
Most patients require treatment between 1-3 years
- A typical maintenance dose is 1mg – 2.5mg daily
- A small number of patients require ongoing treatment beyond 3 years
NSAIDs have NOT been shown to improve outcomes, and have been shown to increase adverse events – as such they are NOT recommended for the treatment of PMR
Steroid sparing drugs – such as methotrexate or anti-TNF agents are occasionally used – but evidence is poor
Consider physiotherapy in patients shoes mobility and function is affected