Abstract: Study Goal: Analysis of the prevalence rates of selected diagnoses of congenital anomalies in the Czech Republic in 1994-2009.
Study Type: Retrospective epidemiological analysis of postnatal and total (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. Data on congenital anomalies in general and selected types of congenital anomalies were analyzed for the entire Czech Republic from 1994-2009. Additional data on prenatally diagnosed anomalies were obtained from medical genetics centres in the Czech Republic thanks to voluntary cooperation. This study analyzed postnatal and overall prevalence of congenital anomalies, with the latter including results of positive prenatal diagnosis. More detailed analysis was carried out for the following diagnoses: cystic kidney disease, renal agenesis/hypoplasia, tetralogy of Fallot, large vessel transposition, left heart hypoplasia, aortic coarctation, Down syndrome, Edward syndrome, and Patau syndrome.
Results: Cystic kidney disease showed a significant increase in 1999 and 2000, mainly due to postnatally diagnosed cases. This can be explained, on the one hand, by the modification made to the reporting of congenital anomalies in the Czech Republic and, on the other hand, by an earlier and more complete detection of postnatal cases. Since 2000, there has been a significant increase in reported cystic kidney disease as a result of postnatal kidney screening. In 1994-1999, the prevalence rates of this diagnosis ranged from 1.7 to 3.1 per 10,000 live births. Similar trend is seen in the prevalence of renal agenesis/hypoplasia. In the monitored period, prenatally diagnosed cases showed a slight increase while postnatally diagnosed cases showed a considerable rise. In 1994-1999, the prevalence rates of renal agenesis/hypoplasia ranged between 1.7 and 3.0 per 10,000 live births and in 2000-2009, between 3.9 and 7.7 per 10,000 live births. A major contributor to the upward trend is more frequent detection of unilateral renal agenesis/hypoplasia. The prevalence of tetralogy of Fallot remains nearly unchanged, with prenatally diagnosed cases accounting for more than 20% since 2000. The mean postnatal prevalence rate was 3.20 per 10,000 live births and the overall prevalence rate was 3.54 per 10,000 live births. A similar prevalence trend is seen in large vessel transposition. The mean postnatal prevalence rate was 3.01 per 10,000 live births and the mean overall prevalence rate was 3.38 per 10,000 live births. The proportion of prenatally diagnosed left heart hypoplasia showed a slow upward trend, reaching more than 75% in 2006. The mean postnatal prevalence rate was 1.44 per 10,000 live births and the mean overall prevalence rate was 2.86 per 10,000 live births. Aortic coarctation was diagnosed prenatally most often in 2003 (15.25%), with a mean of 7.5% for the whole period analyzed. Despite the prenatal diagnostic outcomes, the postnatal prevalence rates of left heart hypoplasia did not substantially vary in 1994-2009. The mean postnatal prevalence rate was 4.87 per 10,000 live births and the mean overall prevalence rate was 5.26 per 10,000 live births. The prevalence rates of prenatally diagnosed Down syndrome were continuously increasing from 4.79 to 17.73 per 10,000 live births and conversely, the postnatal prevalence rates were continuously decreasing from 7.79 to 3.31 per 10,000 live births. Increase in the overall prevalence rates can be explained mainly by the demographic situation in the Czech Republic in recent years: the average age at first birth and the first birth rate for women aged over 35 years were on the rise. The rate of prenatally diagnosed Down syndrome doubled from 40% to 80%. Similarly, the prevalence rate of prenatally diagnosed Edwards syndrome was on the rise while that of postnatally diagnosed cases was declining. The rate of prenatally diagnosed cases rose from 63% to 96% over the last two years. The mean prevalence rate of postnatally diagnosed cases was 0.72 per 10,000 live births and the mean overall prevalence rate was 3.78 per 10,000 live births. Similarly, the rate of prenatally diagnosed Patau syndrome increased from 30% in 1997 to 100% in 2009 and the rate of postnatally diagnosed cases was declining. The mean prevalence rate of postnatally diagnosed cases was 0.40 per 10,000 live births and the mean overall prevalence rate was 1.38 per 10,000 live births.
Conclusion: The overall prevalence rates of the monitored diagnoses from the group of congenital kidney disease (cystic kidney disease and renal agenesis/hypoplasia) were on the rise in the monitored -period mainly due to advances in imaging technologies (ultrasonography) and their use in both prenatal and postnatal diagnosis. Increase in postnatally diagnosed cases can be attributed primarily to the reporting of less severe cases (cystic kidney disease) or unilateral anomalies (renal agenesis and hypoplasia). As for the monitored congenital heart defects, advances in ultrasonographic imaging diagnosis played a considerable role in the increase of cases. The overall prevalence rate show a slow upward trend, but there is a significant decline in postnatally diagnosed cases due to prenatal diagnosis of a severe anomaly, left heart hypoplasia. As for congenital chromosomal aberrations, several interconnected factors influenced the final rate. Firstly, the proportion of prenatally diagnosed cases increases due to quantitative and qualitative improvements of the screening tests. They resulted in greater efficiency of prenatal diagnosis and, at the same time, in less need for invasive prenatal diagnostic procedures. Another factor is increase in average age at first birth and in the first birth rate for women aged over 35 years resulting in higher overall prevalence rates of Down syndrome, Edwards syndrome, and Patau syndrome in the Czech Republic.
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