Eosinophilia-myalgia syndrome. Natural history in a population-based cohort

To determine the natural history of eosinophilia-myalgia syndrome, we followed up all patients with eosinophilia-myalgia syndrome reported to the Oregon Health Division, Portland, during the recent epidemic caused by contaminated tryptophan.

Patients were interviewed by telephone from 1 to 5 months after illness onset and again at least 12 months after onset. Symptoms (type, onset, and duration), overall disability, treatment, and tryptophan lot and dose were assessed for each patient.

Information was obtained for 55 (96%) of 57 case-patients: 53 patients completed interviews and two patients had died. For the 53 patients who were interviewed, symptoms with onset more commonly during the first 3 months of illness included severe myalgias, fatigue, generalized weakness, edema, and rash. Symptoms with later onset included paresthesias, muscle cramps, extremity weakness, and alopecia. At 12 months, 41 patients (77%) continued to report fatigue, 36 (68%) weakness, and 34 (64%) myalgias; 26 patients (49%) had difficulty climbing stairs, 23 (43%) had difficulty getting up from a chair, and 15 (28%) had difficulty holding a cup. Higher doses of tryptophan were correlated with more severe disability, both initially (rs = .33) and at follow-up (rs = .42). Although most patients reported improvement in symptoms at 12 months, only 14 (26%) patients reported that they were able to perform all normal daily activities.

Most patients with eosinophilia-myalgia syndrome in this population-based cohort are still symptomatic 1 year after onset, primarily with the complaints reported early in the illness. The association between degree of disability and daily tryptophan dose suggests that ingestion of varying amounts of contaminant may be responsible, in part, for the severity of symptoms experienced by individual patients.