title: Epidemiology of childhood IDDM in Northern Ireland 1989-1994: low incidence in areas with highest population density and most household crowding. Northern Ireland Diabetes Study Group.
abstract: During the period 1989-1994, 462 cases of insulin-dependent diabetes mellitus were registered among children from Northern Ireland aged under 15 years. The estimated completeness of the register was 98.8% (95% confidence interval (CI) 97.7%, 99.9%). A standardised rate of 19.6 (95% CI 17.8, 21.4) per 100 000 person years was obtained, placing Northern Ireland near the top of the range of published incidence in the United Kingdom, with a rate close to that reported for Scotland. In an analysis based on 217 postcode sectors, areas with a high population density and the most material deprivation were observed to have the lowest incidence rates. After inclusion of population density in a Poisson regression analysis, the component of deprivation which was found to be most significant was household crowding. Relative to children living in areas of low population density, there was a reduced risk for children in medium (relative incidence 0.85 (95% confidence limits CI 0.67, 1.09)) and high (0.62 (95% CI 0.48,0.80)) population density areas. Similarly, relative to children living in areas with low levels of household crowding, there was a reduced risk for children in medium (relative incidence 0.73 (95% CI 0.58,0.93)) and high (0.67 (95% CI 0.53, 0.83)) levels of household crowding. Tests for space-time clustering at diagnosis and at birth were negative. A possible explanation for the differences in incidence rate observed in this study is that exposure to infections very early in childhood is a protective factor. Later infections may act as either initiators or promoters of diabetes, but the absence of space-time clustering suggests that no single specific infectious agent is responsible.
authors.affiliation: Department of Epidemiology and Public Health, Queen's University of Belfast, Northern Ireland, UK.
authors.forename: C C
authors.initials: CC
authors.lastname: Patterson
authors.forename: D J
authors.initials: DJ
authors.lastname: Carson
authors.forename: D R
authors.initials: DR
authors.lastname: Hadden
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D016001:Confidence Intervals; D003710:Demography; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D006798:Housing; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D009660:Northern Ireland / Q000453:epidemiology; D011156:Population Density; D012042:Registries; D012727:Sex Characteristics; D012737:Sex Factors; D012959:Socioeconomic Factors