Diabetes Care, Vol 20, Issue 5 767-772, Copyright © 1997 by American Diabetes Association
Bacille Calmette-Guerin vaccination and incidence of IDDM in Montreal, Canada
ME Parent, J Siemiatycki, R Menzies, L Fritschi and E Colle
Epidemiology and Biostatistics Unit, Institut Armand-Frappier, Universite du Quebec, Laval, Canada. marie-elise_parent@iaf.uquebec.ca
OBJECTIVE: To describe the association between Bacille Calmette-Guerin
(BCG) vaccination and IDDM development in two different case-control series
(A and B) in Montreal. RESEARCH DESIGN AND METHODS: Case-control series A
comprised 93 IDDM cases and 2,903 control subjects who participated in a
community-based tuberculin reactivity survey and who belonged to the same
birth cohorts and areas of residence as the IDDM cases, Case-control series
B comprised 249 IDDM cases and 431 age- and sex-matched friends and
neighborhood control subjects. RESULTS: In series A, the BCG vaccination
prevalence among cases and control subjects was 21.5% (95% CI 13.2-29.8%)
and 22.3% (95% CI 20.8-23.8%), respectively. The odds ratio (OR) for IDDM
associated with BCG vaccination was 1.09 (95% CI 0.62-1.91), after
adjusting for the birth cohorts and areas of residence. The vaccination
prevalence in series B was 17.7% (95% CI 13.0-22.4%) among cases and 15.1%
(95% CI 11.7-18.5%) among control subjects. The OR for IDDM due to BCG
vaccination was 1.26 (95% CI 0.79-2.02), taking into account the matched
sets. Only one case (3.3%) from series B who had been vaccinated at birth
was diagnosed by age 5, compared with 52 cases (24.5%) who had not been
vaccinated (P < 0.01). CONCLUSIONS: The lower proportion of
birth-vaccinated IDDM cases diagnosed at a very young age, compared with
nonvaccinated cases, possibly reflects a temporary boost of the immune
functions after vaccination. However, as a whole, results from these
analyses fail to support a protective role of BCG vaccination against
juvenile-onset IDDM.