Problems in the Diagnostic Evaluation

Polymyalgia rheumatica (PMR) is a rather common disorder in older age groups (prevalence 0.1%). After rheumatoid arthritis (RA) it is, however, not the second most common inflammatory rheumatic disorder—axial spondylarthritis, for example, is clearly more common (1). The epidemiological problem of ascertainment is indeed essential. A safe diagnosis is not trivial in a disorder for which no confirmatory test currently exists. The suggested use of classification criteria requires a correct individual diagnosis before (2).

The clinical problems of diagnosing PMR is based on the following:

In suspected PMR, the differential diagnosis of vasculitis is always important. Giant cell arteriitis is of particular importance in this setting because the patient’s eyesight is at risk. Unfortunately, patients often present to rheumatologists too late. If treatment with high-dose glucocorticoids is not initiated in time, vision loss is often irreversible. Duplex sonography of the temporal artery has now been standard already for a while, but magnetic resonance imaging can also be helpful (3).

Therapeutically, the situation is initially rather simple because administration of 15 mg prednisolone usually works rapidly. However, PMR is not the only disorder that improves with glucocorticoids (GC). Patients treated with GC without a proper diagnosis often present later as an emergency asking the important question of which disease they have. If giant cell arteritis (GCA), a connective tissue disease or polyangiitis have been overlooked, the consequences may be fatal. In the further course of the disease RA or GCA may develop—even if GC have initially been administered. The interleukin-6 receptor antagonist tocilizumab has already been licensed for GCA.

According to the current guideline, these often geriatric patients with PMR should be investigated for osteoporosis at the very start of treatment, because the fracture risk under treatment with GC is rather high and osteoprotective therapies are readily available.