T. Waldhoer et al., LONG-TERM PATTERNS IN SEASONALITY OF INSULIN-DEPENDENT DIABETES-MELLITUS DIAGNOSIS IN AUSTRIAN CHILDREN, Journal of clinical epidemiology, 50(2), 1997, pp. 159-165
The analysis of the seasonal pattern of incidence of childhood insulin
-dependent diabetes mellitus in Austria was carried out among cases wh
ere the child was under the age of 15 when diagnosed between 1979 and
1993. The cases are registered in the nationwide population-based Aust
rian insulin-dependent diabetes mellitus registry. Seasonal variation
was compared between boys and girls and between three 5-year age group
s. We also tested whether the seasonal pattern changed over the 15-yea
r observation period. We found a significant seasonal variation among
boys aged 10-14 and girls aged 5-14, while in the 0-4 years age group
no seasonal pattern could be demonstrated. Two peaks in incidence were
identified during a calendar year (February-March and September-Octob
er) for girls aged 5-14. For boys aged 10-14, a yearly cycle was found
with a peak in January and October. An extension of the Poisson regre
ssion model for testing seasonality by Jones et al. was developed to a
llow for estimation of a time-dependent amplitude of the seasonal comp
onent. The annual incidence rate increased by 36% during the observati
on period, but no significant change in seasonal pattern could be demo
nstrated. Copyright (C) 1997 Elsevier Science Inc.