Vigilancia epidemiológica de anomalías congénitas en España: Análisis de los datos del registro del ECEMC en el período 1980-2008

Abstract

The Spanish Collaborative Study of Congenital Malformations (ECEMC) is a programme for research on congenital anomalies. It was created in 1976 by Prof. Martínez-Frías, as a hospital-based, case-control registry of newborn infants in Spain. Since its foundation, it has surveyed a total population of more than 2.6 million births, and studied more than 39,900 consecutive infants with congenital anomalies. According to the most recent data, the coverage of the registry reaches 21.55% of total births in Spain. The global frequency of infants with congenital defects has significantly decreased along the time, from 2.22% in the base period (1980-1985), to 1.03% in 2008. This significant decrease is mainly attributable to the impact of prenatal diagnosis and further interruption of some affected pregnancies, which is legal in Spain since 1985. Such a decrease has been observed in most of the Spanish Autonomic Regions (see Fig. 1) and participating hospitals, being statistically significant in many of them. The only Autonomic Region in which an increase was detected is Extremadura, where the base frequency was quite low due to a small coverage of births, in a period during which the most complicated pregnancies, and infants with serious birth defects, had to be referred to other regions (a situation that has changed since the basal period). From the periodic analysis of the frequency of a group of 33 defects selected due to their relatively high base frequency or morbidity/ mortality that they bear, only the heart/great vessels defects, and unilateral renal agenesis, have increased along the time, possibly as a result of increasing facilities for their diagnosis. The temporal-spatial analyses mostly detected decreases in the frequency of many of the defects studied in several Spanish Autonomic Regions. However, there were also some increases. Specifically, in the frequency of anophthalmia/microphthalmia in the Región de Murcia, cleft palate in Aragón, oesophageal atresia/stenosis in Galicia, and anal-rectal atresia/stenosis in Canarias. Regarding anophthalmia/ microphthalmia in the Región de Murcia, after excluding one case with a chromosomal abnormality and another one with familial Waardenburg syndrome, the increase lost its statistical significance, and apparently there was not any common denominator among the other cases registered, apart from the area of birth. With respect to the increase of oesophageal atresia/stenosis in Galicia, this was due to the birth of 4 cases in 2008, without any known common characteristic from which a causal relationship could be inferred. This defect will be subject to a special surveillance during the next months. Concerning the increase of cleft palate in Aragón, there was not any sign of a common cause restricted to this geographical area either. The last increase was based on the birth of 3 clinically different cases with anal atresia in Canarias, and no causal agent could be specifically linked to this area. From this report, it is clear the crucial role of the ECEMC system in the epidemiological surveillance of congenital anomalies in Spain, given its long experience since 1976, its huge database, the network of hospitals established, and the close and dynamic collaboration between its participants. This has enabled not only to calculate the birth frequency of congenital defects in Spain on a consecutive series on non-selected newborn infants, in a live and active system, but also to study their evolution along the time, and their geographical distribution, as well as their clinical diagnosis.