Polymyalgia Rheumatica

Definition/diagnostic criteria Polymyalgia rheumatica (PMR) is defined as a clinical syndrome marked by pain and stiffness in the neck, shoulders and hips, typically seen in individuals over 50 years old. The British Society of Rheumatology (BSR) guidelines emphasise the diagnostic importance of bilateral aching lasting at least two weeks, morning stiffness persisting more than 45 minutes, raised inflammatory markers such as erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), and the absence of other diseases that could explain the symptoms.

Epidemiology PMR is more common in individuals of Northern European descent and affects women more than men. The condition is most prevalent in those aged 70-80 years and has an estimated incidence of 1 in 1,000 among the UK population over 50 years old annually. It is the leading inflammatory rheumatic disease in older adults in the UK.

Diagnosis
Clinical features: The clinical presentation includes sudden-onset bilateral pain and stiffness in the shoulder and hip girdles, which is most pronounced in the mornings or after periods of inactivity. The presence of systemic symptoms like fever and weight loss may also be observed.

Investigations: Alongside clinical evaluation, laboratory tests showing elevated ESR or CRP levels support the diagnosis. Imaging, particularly ultrasound, may demonstrate characteristic abnormalities, such as bursitis or tenosynovitis associated with PMR, although is not usually required

Response to steroids: A rapid and dramatic response to low-dose corticosteroids is often considered a hallmark of PMR and can be diagnostically supportive. However, while a good response to steroids may be suggestive, it is not definitive for PMR diagnosis since other inflammatory conditions can also respond to corticosteroids.

Association with temporal arteritis: PMR is closely associated with giant cell arteritis (GCA), also known as temporal arteritis, a vasculitis of large and medium-sized arteries. Approximately 10-20% of patients with PMR may develop GCA. Conversely, 40-60% of patients with GCA may exhibit features of PMR. Symptoms such as new headaches, jaw claudication and visual symptoms in a patient with PMR should prompt immediate investigation for GCA, given the risk of vision loss.

Treatment Initial treatment typically involves low-dose corticosteroids, such as prednisolone, starting at 15 mg daily. The response is usually rapid, and dosages are adjusted based on symptom control and the patient’s response. The minimum effective dose for the shortest possible duration is used to manage symptoms and minimise side-effects. Calcium and vitamin D supplementation, along with bone protection strategies, are recommended due to the increased risk of osteoporosis associated with long-term steroid use.

Prognosis The prognosis for PMR is generally favourable with steroid treatment. While symptoms often improve within days of starting treatment, the disease may relapse, and some patients require long-term therapy. Regular monitoring and adjustments of therapy are important to manage the condition and minimise side-effects.