Informe anual del ECEMC sobre vigilancia epidemiológica de anomalías congénitas en España: Datos del período 1980-2010 / Annual Report of epidemiological surveillance of congenital anomalies in Spain: Data of the period 1980-2010

Resumen

The Spanish Collaborative Study of Congenital Malformations (ECEMC) annually undertakes the preparation and updating of the report of epidemiological surveillance of congenital anomalies in Spain. ECEMC is a research programme for congenital anomalies, based on an ongoing registry of births in Spain, which is hospital-based and has a case-control design. It has surveyed about 2.8 million births (Table 1), and gathered data on 41,800 consecutive infants with congenital anomalies and a similar number of healthy controls. Present coverage of the registry is 19.8% of total births in Spain (Table 2). The basal frequency of infants with congenital defects in our country is 2.22% (registered in 1980-1985), and it fell up to 1.07% in 2010, mainly as a result of the impact of elective termination of pregnancy after the detection of foetal anomalies (ETOPFA). TOPFA has been legal in Spain since the end of the year 1985. Such a statistically significant decrease of the global frequency can be observed (Table 3) in many of the participating hospitals and most Spanish Autonomic Regions (see Fig. 1). Some increases in six hospitals were studied in detail. The only Autonomic Region in which an increase was detected is Extremadura, but this finding is probably due to methodological reasons in the first years, and referrals of high-risk pregnancies to other regions in those years, with considerable further changes that allow a better detection and reporting of cases in this region. The corrected global frequency by hospital and Autonomic Region, taking ETOPFA into account, was also analysed. The evolution of the frequency of a selected group of 33 defects with a relatively high base frequency and/or bearing a high morbidity/mortality was studied (Table 4). Most of them diminished along the time, the only increases being observed for heart/great vessels defects and unilateral renal agenesis, possibly as a result of better diagnostic procedures. Down syndrome is the defect for which a more marked decrease was measured (Graphs-1). A group of 18 defects were selected for the temporal-spatial analyses of the frequency, and also many statistically significant decreases were observed in most Spanish Autonomic Regions (Tables 5-10). The only increase was detected for anencephaly in the Balearic Islands, based on two births, and no clue on a local cause was obtained. Geographical heterogeneity could be detected in 2010 for anencephaly, spina bifida, anal/rectal atresia/stenosis, and hypospadias. For anencephaly, heterogeneity was attributable to the previously mentioned relatively high frequency registered in the Balearic Islands. For spina bifida, it was due to a high frequency observed in La Rioja, but based on the birth of just one case. For anal/rectal atresia/stenosis it was due to the high frequency registered in the quite distant regions of the Balearic Islands and La Rioja, and no common factor was identified as a possible cause. In all these cases it is noticeable that in regions where a small number of births is surveyed, the birth of just one case can bring the frequency to unusually high levels, and this can generate some geographical heterogeneity. For hypospadias, it was due to the low frequency observed in 2010 in the Comunidad Valenciana, and the relatively high frequency registered in Andalucia; all cases were balanic and isolated, and the higher frequency was observed in three hospitals in the provinces of Córdoba, Jaén and Malaga. All these findings will be subject to close scrutiny until the next surveillance report. Due to the importance of immigration in Spain in the last years, the ethnic origin of cases and foreign extraction of their parents were also analysed. The percentage of foreign parents has significantly increased with time, and was higher among the cases than among the controls (Graph 4). All ethnic groups had a higher risk for congenital anomalies than the native white group (Graph 6) and, except the oriental group, have increased with time (Graph 5). A reflection is included as a final comment, regarding the need of research on causes of birth defects, as expressed by Olshan et al. [Am J Med Genet A. 2011;155:1794–1797]: ‘For future generations, it is essential that we identify causes so that effective public health and clinical prevention programs can be established’. ECEMC, and other programmes worldwide, collaborate with that aim. For that purpose, ECEMC has a considerable background and experience of more than 35 years, as well as enough flexibility to adapt itself to new challenges, working for the prevention of birth defects.