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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 Рa type of arteritis which is usually described as causing face and scalp pain Рand 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

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

Prognosis

  • Relapse is common but usually responds well to restarting steroids
  • 15% of patients will develop giant cell arteritis
  • PMR is not associated with an increased risk of mortality

References

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