Polymyalgia rheumatica primarily affects persons of northern European descent and has an annual incidence of about 50 per 100,000 adults older than 50 years. The condition is believed to be increasing in incidence but is rarely seen in Asians or blacks. A review by Östör and Hazleman stresses the need for accurate diagnosis and prompt treatment with adequate dosages of steroids to avoid serious complications or prolonged symptoms in persons with polymyalgia rheumatica.
The initial symptoms of symmetric bilateral aching and stiffness in the neck musculature and shoulder and pelvic girdles are usually insidious but can begin abruptly with an accompanying febrile illness. Symptoms are classically worse in the morning and following periods of inactivity. In addition, many patients report fever, weight loss, malaise, and depression. Physical examination appears paradoxical because patients have tenderness and limitation of active movement of involved areas but full range of passive movements.
The diagnosis depends on clinical features, exclusion of other conditions (especially fibromyalgia and polymyositis), elevated erythrocyte sedimentation rate (ESR), and prompt response to steroid therapy. Because polymyalgia rheumatica occurs in up to one half of patients with giant cell arteritis and because 30 percent of patients with polymyalgia have changes consistent with giant cell arteritis, finding one disease should trigger suspicion of the other. In particular, physicians should be alert for visual changes and the danger of blindness caused by temporal arteritis.
More than 90 percent of patients with polymyalgia rheumatica respond to systemic prednisolone therapy. Many patients report an 80 percent improvement in symptoms within 48 hours of initiating treatment. The optimal starting dosage is 15 to 20 mg of prednisolone per day. Lower dosages are associated with poor rates of response and higher rates of relapse. The initial dosage is maintained for one month and then, depending on clinical response, tapered by 2.5 mg per month to a dosage of 10 mg per day. Further reduction by 1 mg every four to six weeks is cautiously recommended until a maintenance dosage of 5 to 7.5 mg is reached or clinical symptoms limit further reduction.
Withdrawal of steroids can be attempted if the patient is symptom-free after six to 12 months and the ESR is normal. Withdrawal is achieved by reducing the steroid dosage by 1 mg every six to eight weeks. If the patient does not respond to steroids, the diagnosis should be reconsidered. In some cases, methotrexate therapy is indicated. All patients treated with long-term steroids should be monitored for complications, including osteoporosis, diabetes, dyslipidemia, and adrenal suppression.
The outcome of treatment cannot be predicted. Only 25 percent of patients have successfully discontinued steroids after two years. Most patients require three to six years of treatment. Relapse of disease is most frequent in the initial 18 months of steroid therapy.