The incidence of Guillain-Barre syndrome in Ontario and Quebec, 1983-1989, using hospital-service databases.

Abstract

Background. Guillain-Barre syndrome (GBS) is of public health interest in Canada, as well as the rest of North America, for two main reasons. It is occasionally a vaccine-associated adverse event and is also a differential diagnosis of poliomyelitis. Objectives. (1) To ascertain the incidence of GBS in the Canadian provinces of Ontario and Quebec for the years 1983-1989, inclusive. (2) To demonstrate the feasibility of measuring the incidence of GBS through internal record linkage of Canadian hospital-service data. Results. 1,302 and 1,031 records representing GBS incident admissions in Ontario and Quebec, respectively, were identified through the record-linkage procedure. The mean annual GBS incidence after age-and-sex-standardization to the 1986 Canadian census population was 2.02 per 100,000 person-years in Ontario and 2.30 in Quebec. The incidence was higher in older age-strata in both provinces (70-80 years), and was higher in males (M:F = 1.1). Reviews of charts of incident admissions of GBS cases reveal that 26.2%-32.6% of Ontario cases and 21.0%-24.0% of Quebec cases may be false positive diagnoses. No possible false negative cases were identified through chart review. Cross linkage of records belonging to the other province with records from the other dataset revealed 0.5% false negative misclassification of Ontario incident admissions and 1.8% for Quebec. Mortality figures obtained from CMDB were in both provinces less than those obtained in the hospital service data, indicating that it is unlikely a significant number of GBS cases die before reaching hospital. Conclusions. (1) It is possible to internally link records in the HMRI and Med-Echo databases into personal histories (cases) of a condition. (2) The high percentage of false positive misclassifications discovered on examination of incident admissions raises concern about the validity of HMRI and Med-Echo data for epidemiological purposes. (Abstract shortened by UMI.)