Análisis comparativo de las frecuencias de ciertos defectos congénitos y su evolución secular en 11 comunidades autónomas

Abstract

Background and objective Knowledge of the frequency of the distinct congenital defects over time in the various Autonomous Communities in Spain is important, not only to quantify the scope of the problem and to plan the necessary resources, but also to have surveillance systems and analyze the impact of the diverse health interventions. The aim of this study was to analyze the comparative frequencies of 6 types of congenital defect in the 11 Autonomous Communities participating in the Epidemiological Network on Rare Disease Research (REpIER). Subjects and methods We analyzed data from the Spanish Collaborative Study of Congenital Malformations (ECEMC) corresponding to the 11 Autonomous Communities participating in REpIER (Andalusia, Aragon, the Canary Islands, Cantabria, Castilla-La Mancha, Catalonia, the Autonomous Community of Madrid, the Autonomous Community of Valencia, Extremadura, La Rioja, and the Principality of Asturias) from 1980 to 2003. The ECEMC is a clinical-epidemiological research program on the causes of congenital defects, structured as a permanent registration system with a case-control design. The program is hospital-based. The defects studied were anencephaly, spina bifida, cleft lip with or without cleft palate, cleft palate only, limb reduction defects, and Down syndrome in infants born to mothers aged 34 years or older. To analyze the time trends in each Autonomous Community, the lineal trend test (chi-square with 1 degree of freedom) and chi-square with k-2 degrees of freedom to detect deviations from linearity were used. Results The time trend of the frequencies was not the same for all the defects studied or for all the Autonomous Communities. The highest concordance between the 11 Autonomous Communities analyzed was observed in the decreasing secular trend for Down syndrome in infants born to mothers aged 34 years or older, which was statistically significant in 8 Autonomous Communities. The frequency of anencephaly significantly decreased in 6 Autonomous Communities, and in a further 2 no cases were registered. The frequency of spina bifida significantly decreased in 6 Autonomous Communities. The secular distribution of the frequencies of the other 3 types of malformations studied showed no significant trends in most of the regions. Conclusions Since pregnancy terminations after prenatal detection of anomalies became legal in Spain, the frequency of prenatally diagnosable birth defects has clearly decreased. This decrease has not been equal in all the regions. Differences were found in the time the decreases began and in their intensity, which may reveal, among other factors, differences in health care.