Natural history of the eosinophilia-myalgia syndrome

To describe the natural history and disease progression of the eosinophilia-myalgia syndrome and to assess the therapeutic effects of orally administered steroids on the disorder as of October 1990.

Case-series analysis. A cohort of 45 patients with the eosinophilia-myalgia syndrome was followed prospectively by periodic telephone interviews and medical examinations for an average of 14 months after onset of illness.

Washington state.

The cases of 47 patients were reported to the Washington State Department of Health from 1 July to 12 December 1989. Two patients were unavailable for follow-up, and the remaining 45 completed the study.

Patients were predominantly non-Hispanic white women (87%) with an average age of 49 years. Symptoms typically progressed from early onset of myalgia and fatigue to later development of neurologic and scleroderma-like skin changes. Six (13%) patients recovered completely within 2 to 5 months of symptom onset. After 14 months of illness, over half of the patients who initially presented with myalgia, fatigue, or scleroderma-like skin changes remained symptomatic. The average severity of each major symptom was measured using interviews and patient self-reports and has improved subjectively by at least 40%. Statistical analyses showed no significant difference in long-term symptom duration or severity between patients treated and those not treated with prednisone.

The eosinophilia-myalgia syndrome is a long-term illness characterized by progressive improvement during the first 25 weeks after symptom onset, followed by a protracted phase of symptom resolution. We could not show a clear-cut benefit of prednisone in reducing the long-term severity or duration of the disease.