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[Prevalence of selected congenital anomalies in the Czech Republic: congenital anomalies of the central nervous system and gastrointestinal tract].

OBJECTIVE
Analysis of the prevalence of selected congenital anomalies in the Czech Republic in 1994-2009.


DESIGN
Retrospective epidemiological analysis of the postnatal and overall (including prenatally diagnosed cases) prevalence of congenital anomalies from the database of the National Registry of Congenital Anomalies of the Czech Republic.


MATERIAL AND METHODS
Data from the National Registry of Congenital Anomalies (NRCA) maintained by the Institute of Health Information and Statistics of the Czech Republic (IHIS CR) were used. The analysis was carried out for the entire Czech Republic, based on the data from 1994 to 2009. Additional data on prenatally diagnosed anomalies were obtained from medical genetics centres and laboratories in the Czech Republic. This study analyzed the postnatal and overall (including prenatally diagnosed cases) prevalence of congenital anomalies. More detailed analysis was carried out for the following diagnoses: anencephaly, spina bifida, encephalocoele, congenital hydrocephalus, omphalocoele, gastroschisis, oesophageal atresia and stenosis, anorectal anomalies, and diaphragmatic hernia. Prevalence trends were analysed using Poisson regression.


RESULTS
In 2009, a total of 118 348 live births were recorded in the Czech Republic, 60 368 boys and 57 980 girls. Of this total, 4 653, i.e. 2 745 boys and 1 908 girls, were diagnosed with congenital anomalies. In 2007-2009, the total of life births with congenital anomalies ranged between 4.6 and 4.8 thousand per year. The respective ranges in this three-year period were in the order of 2.7 and 2.8 thousand per year for boys and 1.9 thousand per year for girls. The prevalence of postnatally diagnosed anencephaly was minimal, as most cases were diagnosed prenatally, and the data did not vary significantly. The prevalence of postnatally diagnosed cases remained at the same level. The effectiveness of the prenatal diagnosis of spina bifida increased and thus the prevalence of postnatally diagnosed cases decreased. The prevalence of prenatally diagnosed encephalocoele increased and that of postnatally diagnosed cases varied between years, with no clear trend. The prevalence of omphalocoele varied for both prenatally and postnatally diagnosed cases; nevertheless, the effectiveness of prenatal diagnosis of this defect increases. The prevalence of gastroschisis remained unchanged, but the number of live births with this diagnosis showed a non-significant upward trend. If the trend reflects the real situation, it could be a result of a changed approach to prenatal diagnosis due to advances in corrective surgery of this defect. The prevalence of live births with congenital hydrocephalus showed a downward trend in the second half of the period 1994-2009 thanks to the improved diagnosis. The prevalence rates of live births with congenital esophageal and anorectal anomalies were slightly increasing. The prevalence of congenital diaphragmatic hernia varied between years but the overall prevalence appeared to be slightly increasing.


CONCLUSION
The prevalence of some congenital anomalies (spina bifida, omphalocoele, and congenital hydrocephalus) showed a downward trend over the study period 1994-2009, mainly as a result of effective prenatal diagnosis. The prevalence of other congenital anomalies such as anencephaly or encephalocoele remained unchanged in live births. As for anencephaly, postnatally diagnosed cases were rare as the prenatal diagnosis was close to 100 %. The trend in encephalocoele is explained by the low incidence of this diagnosis in the population. The third group of postnatally diagnosed congenital anomalies such as gastroschisis or esophageal and anorectal anomalies were on the rise. As for gastroschisis, the reason was the changed approach to prenatal diagnosis due to good prognosis of this operable defect. The prevalence of congenital esophageal and anorectal anomalies varied between years, with a slowly increasing trend, similarly to diaphragmatic hernia.