Polymyalgia Rheumatica (PMR)

Polymyalgia rheumatica (PMR) is a term first used in 1957¹ to describe an inflammatory condition which is characterised by severe bilateral pain and morning stiffness of the shoulder, neck and pelvic girdle.² There is some controversy as to whether or not PMR represents a form of giant cell arteritis (GCA), however the balance of evidence would appear to suggest that they are two distinct and relatively common diseases which often co-exist and which share many common features.³

• PMR is a common condition of older age. It is rare under the age of 50, but the incidence rises with age with a peak between the ages of 70-80.
• There is an increased incidence of the disorder at higher latitudes.
• Women are more frequently affected than men with a M:F ratio of approximately 3:1.

Aetiology

• The aetiology of PMR is as yet unknown, however family clusterings of the disease and an association with the HLA-DRBI*04 and *01 alleles, suggest that a genetic predisposition to environmental factors may play a part.⁴
• A viral or infectious cause has also been suspected due to the increased prevalence of antibodies to respiratory syncytial virus and adenovirus in PMR and the association between the increased incidence of the disorder and epidemics of Mycoplasma pneumoniae, Parvovirus B19 and Chlamydia pneumoniae.

PMR may present with a variety of signs and symptoms, however the most common presenting symptoms include bilateral, severe, persistent pain in the neck, shoulders and pelvic girdle. Other symptoms and signs may include:

• Pain on active and passive movement of joints ( shoulders 70-95%, hips and neck 50-70%)
• Morning stiffness
• Myositis
• Lethargy
• Loss of weight
• Depression
• Fever
• Joint effusions

± Asymmetric peripheral arthritis ( mainly knee and wrist)
± Carpal tunnel syndrome
± Oedema of hands, wrists, ankles and feet

The differential diagnosis will include many other conditions which may produce arthralgia including:

• Elderly onset rheumatoid arthritis (EORA)
• Systemic lupus erythematosus
• Polymyositis
• Spondyloarthropathy
• Bacterial endocarditis
• Myeloma
• Paraneoplastic syndromes
• Primary systemic amyloidosis

Investigations which will be useful in making a diagnosis of PMR include:

• ESR - raised to a level of at least 40 mm/hour, although up to 20% of patients may have a normal ESR at diagnosis.⁵
• C-reactive protein - more sensitive than ESR.
• IL-6 levels - usually raised, and a useful marker of disease activity.
• FBC - anaemia of chronic disease may be present.
• Anti-cyclic citrullinated peptide ( anti-CCP) - useful in differentiating patients with EORA and a polymyalgic onset of disease, antibodies present in EORA but not in PMR.
• MRI/scintigraphy/ultrasound examination of joints - may show proximal synovitis and/or bursitis.

Giant cell arteritis commonly co-exists with PMR and shares many features of the disease.

General Principles

• Document symptoms and level of any disability at diagnosis.
• Consider giant cell arteritis (GCA) in all people with polymyalgia rheumatica (PMR).
• Advise people with PMR to seek medical attention if they developed GCA or any new visual disturbances.
• Monitor response to treatment by assessing changes in clinical features and inflammatory markers.
• Manage any residual physical or psychosocial disability caused by the disease.
• Consider other possible diagnoses, particularly if symptoms are not responding to treatment.

Non-drug

Patients with PMR are frequently elderly and may have mobility problems and difficulty with many aspects of daily living. Many patients will benefit from referral to a physiotherapist and occupational therapist for assessment.

Drug therapy

• Prednisolone remains the drug of choice for treating PMR.
  • Treatment is generally initiated at a relatively high dose e.g. 10-20mg per day, and reduced as clinical improvement and improvement in inflammatory markers allows. Treatment usually lasts 18-24 months, but may need to be longer.
  • Patients may be able to come off treatment altogether but may require further courses of treatment for exacerbations.
  • A small number of patients will need to remain on long term low dose steroids.
• Bisphosphonates, or if they are not tolerated Calcium and vitamin D supplementation, should be given to all PMR patients who are receiving doses of Prednisolone (or equivalent)>5mg daily for >6 months.
• Several drugs have been proposed as steroid sparing agents in PMR. These include:
  • Deflazacort; clinical trials have yet to show if this is as effective as prednisolone. The potential benefit is fewer adverse effects, particularly on bone metabolism.⁶
  • Pulse treatment with intravenous methylprednisolone
  • Intramuscular methylprednisolone; although there is a lower cumulative dosage than would have been used with oral prednisolone, clinical advantages remain to be demonstrated.
  • Methotrexate; there are inconsistent results and few advantages in the small trials yet conducted.
  • Infliximab
  • Etanercept
  • Azathioprine

• PMR usually responds well to treatment with steroids resulting in remission in the majority of cases.
• Relapse may occur, usually within 2 years of stopping the steroids, but the condition remains steroid responsive.
• Morbidity and mortality may occur as a result of immunosuppression or steroid side effects, and patients should be regularly monitored whilst on steroids.