Polymyalgia rheumatica

Polymyalgia rheumatica is a chronic, infl ammatory disorder of unknown cause that aff ects people over age 50 years.
Classic symptoms include pain and long-term morning stiff ness of the neck, shoulders, hips, upper arms, and thighs.
Although markers of infl ammation are often raised, no specifi c laboratory test exists for the disorder and the diagnosis
is based on clinical assessment. Provisional classifi cation criteria were published in April, 2012, by a collaborative
initiative of the European League Against Rheumatism and the American College of Rheumatology. Several other
disorders can mimic polymyalgia rheumatica. In particular, clinical manifestations can be diffi cult to diff erentiate
from other forms of infl ammatory arthritis such as spondyloarthritis and rheumatoid arthritis. Imaging studies such
as ultrasonography and MRI typically show a predominantly periarticular infl ammatory process. A subset of patients
has an associated infl ammatory vasculopathy aff ecting large arteries (giant cell arteritis). The standard treatment is
low-dose glucocorticoids, which provide symptomatic relief for most patients. However, disease relapses are common,
and treatment with glucocorticoids is associated with substantial morbidity. Improved understanding of disease
pathogenesis might allow for more targeted immunotherapy.
Introduction
Polymyalgia rheumatica is a chronic, infl ammatory
disorder of unknown cause. It is not typically seen in
people under age 50 years. Clinically, the disorder is
characterised by pain and long-term morning stiff ness
aff ecting the neck, shoulders, hips, upper arms, and
thighs. There are no specifi c diagnostic tests; diagnosis is
typically based on clinical presentation and evidence
of systemic infl ammation. Ultrasonography of the
shoulders and hips is a useful imaging modality in the
initial assessment and often shows fi ndings of bursitis,
tenosynovitis, or synovitis. The diff erential diagnosis is
broad and clinicians need to consider several disorders
that can mimic the disease. In particular, late-onset
spondyloarthritis and rheumatoid arthritis can present
with polymyalgic symptoms. A well known association
exists between polymyalgia rheumatica and giant cell
arteritis, a systemic, granulomatous vasculitis that aff ects
the aorta and its branches.
Epidemiology
711 000 people aged 50 years or older in the USA have
polymyalgia rheumatica, according to one estimate.1
From population-based incidence studies in Olmsted
County, MN, USA, the lifetime risk of developing the
disease has been estimated at 2·43% for women and
1·66% for men.2 Polymyalgia rheumatica occurs almost
exclusively in people older than age 50 years, and the
mean age of onset is about 73 years. In general, its
incidence increases with advancing age,3 and varies by
geographical region. Although polymyalgia rheumatica
occurs worldwide, the highest incidence is seen in
Scandinavian countries and in people of northern
European descent.4 For example, in the county of Aust-
Agder, Norway, the annual incidence is 112·6 per
100 000 people aged 50 years and older.5 In the UK,
Denmark, and Sweden, incidence ranges from 41·3 to
84 per 100 000 people in this age group.6 –9 In Olmsted
County, the annual incidence is estimated at 58·7 per
100 000 people in the same age group.3

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