Analysis of Centers for Disease Control and Prevention criteria for the eosinophilia-myalgia syndrome in a geographically defined population.

OBJECTIVE: To test whether individuals can be identified in a geographically defined population who would meet criteria for the eosinophilia-myalgia syndrome (EMS) established by the US Centers for Disease Control and Prevention (CDC), i.e, (1) eosinophil count > 1 x 10(9)/l, (2) myalgia severe enough to limit usual activities of daily living, and (3) no evidence of infection or neoplasm that could explain the first 2 findings. METHODS: To discover the number of individuals who would meet CDC criteria, the population was exhaustively searched using methods adapted from active pharmacoepidemiologic surveillance. Medical consultants and primary care practitioners were questioned as many as 5 times in a search for patients with severe myalgia. A predetermined protocol was used to screen those patients who appeared to meet CDC criteria for EMS using active surveillance methods. The study population was limited to Québec and Ontario (combined population 18,980,000) with special attention to the period July 1, 1992, to June 30, 1993. RESULTS: The prevalence of severe incapacitating myalgia was 43 per 100,000 persons, including 19 individuals with eosinophilia > 1 x 10(9)/l, who met CDC criteria for EMS. None of these individuals were reported to have taken L-tryptophan (LT). CONCLUSION: The CDC criteria for EMS are met by individuals in the general population who have never been exposed to LT.

Continuing occurrence of eosinophilia myalgia syndrome in Canada.

Eosinophilia myalgia syndrome (EMS), was defined by the Centers for Disease Control (CDC) as eosinophilia > 1000 mm3 and incapacitating myalgia without infection or neoplasm. Studies suggested that use of L-tryptophan (L-T), was a risk factor. We conducted a pharmacoepidemiological survey in Canada where access to L-T is limited. Using the active surveillance method, a 100% sample of potentially involved specialists and a 15% sample of family physicians from Ontario and Quebec were surveyed regarding treatment of patients with severe myalgia within the past year. Follow-up amplified clinical and laboratory information. Overall response rates were 61.4%. Thirty-eight per cent of respondents reported at least one patient. Of 6423 patients assessed, 19 'definite' and 25 'possible' EMS cases were identified. Information from physicians did not suggest use of L-T in patients with definite or possible EMS. It was considered that the cases found an underestimate of the incidence of EMS. Its continuing occurrence in Canada brings causal interpretations of earlier studies into question.