Diagnosis, differential diagnosis and treatment of polymyalgia rheumatica

Abstract

Polymyalgia rheumatica (PMR) is a common disorder in the elderly population. The diagnosis is based upon recognition of a clinical syndrome, consisting of pain and stiffness in the shoulder and pelvic girdle, muscle tenderness of the upper and lower limbs and nonspecific somatic complaints. In addition, in most cases the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) concentration are highly elevated. Although PMR and giant cell arteritis (GCA) are commonly regarded as two clinical variations of the same disease, their clinical picture is quite different. Whilst in PMR the musculoskeletal symptoms predominate, the major features of GCA are arterial inflammation and its consequences, which suggests clinical and pathological discrepancies between the two syndromes and important differences with respect to morbidity and mortality. The prognosis of correctly diagnosed PMR is excellent. It is well known that corticosteroid therapy in PMR usually leads to rapid and dramatic improvement of patients' complaints and returns them to previous functional status. However, prolonged corticosteroid treatment, sometimes for several years, may be necessary to maintain clinical improvement. Despite all the knowledge about the beneficial effects of corticosteroid treatment, data concerning the optimal dosage regimen are lacking. Long-term corticosteroid use can be associated with various adverse events, of which induction of osteoporosis, diabetes mellitus and infection among the worst. A Corticosteroid Side Effect Questionnaire has been shown to dose-dependently detect adverse effects perceived by patients. The European League Against Rheumatism (EULAR) response criteria for PMR comprise a core set of markers for monitoring therapeutic responses in PMR, namely ESR or CRP, the visual analogue scale of patient's pain and physician's global assessment, as well as morning stiffness and the ability to elevate the upper limbs. The PMR-disease activity score has been developed on the basis of EULAR response criteria as a means of expressing disease activity as an absolute number. A score <7 indicates low disease activity, scores 7-17 suggest medium activity, and a score >17 is indicative of high disease activity. The PMR-disease activity score has been proven to be highly correlated with patient's global assessment, patient satisfaction and ESR. It provides an easily applicable and valid tool for disease activity monitoring in patients with PMR. Improved knowledge of disease activity processes, exact monitoring of disease activity and treatment responses, and increased risk-estimation of treatment schedules should ultimately improve the care of patients with PMR.