The epidemiology of down syndrome in four counties in ireland 1981-1990
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Johnson, Z. Lillis, D.; Delany, V.; Hayes, C.; Dack, P. (1996). The epidemiology of down syndrome in four counties in ireland 1981-1990. Journal of Public Health 18 (1), 78-86
Background We conducted a descriptive epidemiological study oi Down syndrome (DS) in the four Irish counties (Dublin, Kildare, Wicklow and Galway) covered by EUROCAT registries of congenital malformations for the years 1981-1990. Methods EUROCAT registries, which cover defined populations, use multiple sources for case ascertainment Ali DS cases born between 1 January 1981 and 31 December 1990 to mothers resident in the lour counties were identified. Crude birth prevalence rates and maternal age-standardized rates (SPRs) were calculated for each county and for each year in the study period, The prevalence oi DS by maternal age grouped in five-year periods and the risk for each live-year group were also estimated. Results The crude birth prevalence for the :our counties was 18.5/10000 for all births and 18.3 for live births. There was a fall in the total number oi DS births over the decade, but less change in the crude birth prevalence owing to an increase in the proportion oi mothers aged 35 +. Galway had the highest crude birth prevalence of DS (23.5/10000) but the SPR was within average for the lour counties as a whole - 110.3, 95 per cent confidence interval (CI) 86.7-139. The risk oi having a DS child increased 70-fold from 1:1841 at age 15-19 to 1:26 at 45 years or older. Nearly half oi all DS cases (47.4 per cent) had at least one additional anomaly Conclusions The parts oi ireland covered by EUROCAT have a high birth prevalence oi DS births as compared with some other countries, but the maternal age-specific rates are not substantially different from those in large international studies.