What is the epidemiology of polymyalgia rheumatica?

From the Guidelines

Polymyalgia rheumatica (PMR) is a condition that primarily affects older adults, with a peak incidence in individuals aged 70-80 years, and its epidemiology is characterized by a higher prevalence in Northern European populations, particularly those of Scandinavian descent. The condition is rare before age 50, with incidence increasing steadily with advancing age [ 1 ]. Women are affected approximately twice as often as men, and the estimated annual incidence ranges from 20 to 50 cases per 100,000 persons over age 50, making it one of the most common inflammatory rheumatic diseases in older adults [ 1 ].

Key Epidemiological Features

• The condition shows geographic and ethnic variations, with higher prevalence in Northern European populations, particularly those of Scandinavian descent, and lower rates in Mediterranean and non-Caucasian populations [ 1 ].
• PMR often shows seasonal variations with peaks in winter months, suggesting potential environmental triggers.
• There is a strong association with giant cell arteritis, with approximately 15-30% of PMR patients developing this condition [ 1 ].
• Genetic factors appear to play a role, with associations to certain HLA haplotypes.

Clinical Course and Treatment

• The disease typically follows a self-limiting course lasting 1-5 years, though some patients experience a more chronic course requiring longer treatment [ 1 ].
• Early recognition is important as prompt treatment with low-dose corticosteroids (typically prednisone 12.5-25mg daily initially) usually results in dramatic symptom improvement within days [ 1 ].
• The use of intramuscular methylprednisolone and methotrexate may be effective as glucocorticoid sparing agents, and female sex, high erythrocyte sedimentation rate (ESR), and peripheral arthritis are potential risk factors for a worse prognosis [ 1 ].

From the Research

Epidemiology of Polymyalgia Rheumatica

• The incidence of polymyalgia rheumatica (PMR) varies geographically, with a higher frequency in the northern hemisphere, ranging from 12.7/100,000 in Italy to 112.6/100,000 in Norway 2.
• The average annual incidence of PMR increases with age, from 19.8 per 100,000 in persons 50 to 59 years of age, to a maximum of 112.2 per 100,000 in persons 70 to 79 years of age 3.
• PMR is more common in women, with a female-to-male ratio of 2-3:1 4.
• The disease is characterized by pain and morning stiffness in the shoulder and pelvic girdle, and may be associated with giant cell arteritis (GCA) 4, 5.

Risk Factors and Associations

• Risk factors for PMR/GCA include infections, smoking, sun exposure, and nulliparity 2.
• The incidence of PMR and GCA has increased in recent years, which may be related to greater awareness of the disease or real epidemiological changes 2.
• PMR may appear as a side effect of cancer treatment with checkpoint inhibitors 4.

Diagnosis and Treatment

• Diagnosis of PMR relies mainly on symptoms and signs combined with laboratory markers of inflammation, and imaging modalities such as ultrasound, magnetic resonance imaging, and positron emission tomography with computed tomography may be helpful in the diagnostic workup 4, 6.
• Glucocorticoid (GC) therapy is effective in PMR, with most patients responding promptly to 15-25 mg prednisolone per day 4, 6.
• Treatment with GCs is indispensable, and the duration of treatment varies, often exceeding 1 year 5.
• Methotrexate may be considered as an adjunct to GCs in patients with PMR or GCA who are at high risk of relapse 6.