Paper 3: EUROCAT data quality indicators for population-based registries of congenital anomalies

The European Surveillance of Congenital Anomalies (EUROCAT) network of population-based congenital anomaly registries is an important source of epidemiologic information on congenital anomalies in Europe covering live births, fetal deaths from 20 weeks gestation, and terminations of pregnancy for fetal anomaly. EUROCAT's policy is to strive for high-quality data, while ensuring consistency and transparency across all member registries. A set of 30 data quality indicators (DQIs) was developed to assess five key elements of data quality: completeness of case ascertainment, accuracy of diagnosis, completeness of information on EUROCAT variables, timeliness of data transmission, and availability of population denominator information. This article describes each of the individual DQIs and presents the output for each registry as well as the EUROCAT (unweighted) average, for 29 full member registries for 2004-2008. This information is also available on the EUROCAT website for previous years. The EUROCAT DQIs allow registries to evaluate their performance in relation to other registries and allows appropriate interpretations to be made of the data collected. The DQIs provide direction for improving data collection and ascertainment, and they allow annual assessment for monitoring continuous improvement. The DQI are constantly reviewed and refined to best document registry procedures and processes regarding data collection, to ensure appropriateness of DQI, and to ensure transparency so that the data collected can make a substantial and useful contribution to epidemiologic research on congenital anomalies.     

Impact of prenatal diagnosis on livebirth prevalence of children with congenital anomalies

The objectives of this study were to describe the impact of prenatal diagnosis on the birth prevalence of congenital anomalies over 21 years (1979-1999) in a well defined population in northeastern France (13,500 births per year). The material for this study came from the analysis of data from multiple sources on births and terminations of pregnancy after prenatal diagnosis of congenital anomalies in 279,642 consecutive pregnancies of known outcome. The study period was divided into three subgroups 1979-1988, 1989-1993 and 1994-1999. Between 1979-1988, 1989-1993 and 1994-1999, prenatal detection of congenital anomalies increased, respectively, from 12.0% to 25.5% and to 31.7%. Termination of pregnancy (TOP) increased in the same proportions during the three time periods. However, the increase of TOP was much higher for chromosomal anomalies than for nonchromosomal congenital anomalies. The birth prevalence of Down's syndrome fell by 80% from 1979-1988 to 1994-1999. Sensitivity of prenatal detection of congenital anomalies and TOPs were lower for isolated cases (only one malformation present in the fetus) than for multiple malformations in the same fetus. Sensitivity varied with the type of malformations: it was high for neural tube defect (79.7%) and urinary anomalies (50.7%) and low for congenital heart defects (16.4%). In conclusion, the introduction of routine prenatal diagnosis has resulted in a significant fall in the birth prevalence of children with congenital anomalies. However, this fall varied with the types of congenital anomalies.     

Evaluation of the General Practice Research Database congenital heart defects prevalence: comparison to United Kingdom national systems

BACKGROUND: As part of an effort to validate the General Practice Research Database (GPRD) for future studies of medication use in pregnancy, this study examined whether the rates of all, and specific types of, congenital heart defects obtained from the GPRD are similar to those obtained from UK national systems. METHODS: The prevalence rates of heart defects for 2001-2003 were determined from the GPRD and compared with both the National Congenital Anomaly System (NCAS) and the European Concerted Action of Congenital Anomalies and Twins (EUROCAT). Rate ratios (RRs) and 95% CIs were calculated comparing the prevalence of all congenital heart defects as well as specific types of heart defects in the three data sources. In addition, the effect of the child's age on the frequency of heart defects in the GPRD was determined. RESULTS: The prevalence of heart defects in the GPRD was more than twice as high as in the NCAS and slightly higher than in the EUROCAT. All differences were statistically significant. The prevalence of specific heart defects varied across the GPRD, NCAS, and EUROCAT. The measured prevalence of congenital heart defects in the GPRD was higher if calculated including children up to age 6. CONCLUSIONS: The comparisons of the GPRD prevalence rates to national prevalence estimates demonstrate that the GPRD can serve as a more complete source of background prevalence for the most commonly occurring congenital heart defects, which is essential to properly assess possible associations between maternal exposures and congenital heart defects.     

Heterogeneity of neural tube defects in Europe: the significance of site of defect and presence of other major anomalies in relation to geographic differences in prevalence.

In the period 1980-1987, neural tube defects were two to three times more prevalent in populations covered by EUROCAT registries in the United Kingdom and Ireland (UKI) than in Continental Europe and Malta (CEM). 1864 NTD cases in a total population of 580,000 births in UKI and 455 cases in a population of 380,000 births in CEM were analysed to find if there were differences in the ratio of prevalence rates between UKI and CEM according to site of the defect and association with non-central nervous system (CNS) anomalies. The prevalence rate ratio was high for anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida, and low for encephalocele, lower spina bifida, and anencephaly without other neural tube defects. There was a greater female excess for anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida than for other defects in both geographic areas. There was a female excess for encephalocele in UKI but a male excess in CEM. Certain sites (anencephaly with accompanying spina bifida, iniencephaly, and encephalocele) were more likely to have accompanying non-CNS anomalies. The prevalence rate ratio of multiply malformed NTD was in general lower than for isolated NTD but showed the same pattern by site. The prevalence rate ratio was high for multiply malformed anencephaly with accompanying spina bifida, iniencephaly, and upper spina bifida. The sex ratio was similar between isolated and multiply malformed cases when site of the defect is taken into account. It is concluded that the geographic prevalence pattern and sex ratio differ according to site of NTD but do not differ substantially according to whether NTD is isolated or associated with non-CNS anomalies.     

Sex differences in the prevalence of congenital anomalies: a population-based study

BACKGROUND: Limited data is available concerning the sex distribution of various congenital anomaly subtypes. This study investigated sex differences in the prevalence of congenital anomalies, overall and by subtype, using high quality population‐based data from the North of England. METHODS: Information on congenital anomalies occurring among singleton pregnancies during 1985–2003 were extracted from the Northern Congenital Abnormality Survey (NorCAS). Anomalies were categorized by groups, subtypes, and syndromes according to the European Surveillance of Congenital Anomalies guidelines. Relative risks (RRs) comparing the prevalences in males to that in females were calculated for a range of congenital anomaly subtypes. RESULTS: A total of 12,795 eligible cases of congenital anomaly were identified during the study period, including 7019 (54.9%) males and 5776 (45.1%) females. Overall, male fetuses were significantly more prevalent in pregnancies affected by a congenital anomaly than female fetuses (RR, male vs. female = 1.15; 95% confidence interval [CI], 1.11–1.19), but there was significant heterogeneity between subtypes (p < 0.001). Forty‐four of 110 (40%) unique subtypes were at least 40% more prevalent in males than females, with affected subtypes occurring across all major anomaly groups. Thirteen of 110 (12%) unique subtypes were at least 40% more prevalent in females than males, but the female‐biased RR of a neural tube defect was less pronounced than previously reported (RR = 0.84; 95% CI, 0.73–0.95). CONCLUSION:This study adds to the growing evidence of sex‐specific differences in the prevalence of a wide range of congenital anomaly subtypes. Birth Defects Research (Part A), 2011. © 2011 Wiley‐Liss, Inc.     

Congenital malformations in offspring of Vietnamese women in California, 1985-97

BACKGROUND: Little is known about reproductive outcome risks for Vietnamese women delivering infants and fetuses in the U.S. METHODS: Using data from a large population-based registry, we explored risks of selected congenital malformation phenotypes in offspring of Vietnamese women in California. Data were derived from the California Birth Defects Monitoring Program, a population-based active surveillance system for collecting information on infants and fetuses with congenital malformations using multiple source ascertainment. Approximately 3.4 million births (liveborn and stillborn) occurred during the ascertainment period, 1985-97. Information on maternal race/ethnic background was obtained from California birth certificate and fetal death files. Vietnamese women delivered 45,453 births and 1,257,853 births were delivered to non-Hispanic white women. RESULTS: The overall prevalence of structural congenital malformations was 1.92 among Vietnamese and 2.63 among non-Hispanic whites per 100 births and fetal deaths. Grouping by 20 3-digit malformation codes of the International Classification of Diseases-Ninth Revision revealed relative risks of 0.8 or less for spina bifida, eye, upper alimentary, genital, urinary, musculoskeletal, "other" limb, and "other" musculoskeletal anomalies, and relative risks of 1.3 or more for anencephaly and chromosomal anomalies. Grouping by the more specific 4-digit malformation codes revealed 50, among 178, malformation groupings with associated relative risks of >or=1.3 or 相似文献   

Maternal diabetes and congenital anomalies in South Australia 1986-2000: a population-based cohort study

BACKGROUND: This study examined the risk of congenital anomalies in infants born in South Australia to women with maternal diabetes in a population-based cohort study of births over a 15-year period, 1986-2000. Differences in the reporting, recording, and diagnosis of pre-existing diabetes mellitus, gestational diabetes mellitus, and impaired glucose tolerance make comparisons between studies difficult. In order to compare published research, details of research methods and analytic approaches are required to understand the potential confounding, bias, and effect modification that may occur. METHODS: Data on congenital anomalies from the South Australian Birth Defects Register were linked to birth data from the Pregnancy Outcome Statistics Unit of the South Australian Department of Health. This enabled information on congenital anomalies to be linked to pregnancy details, including diabetes status. RESULTS: Between 1986 and 2000, the prevalence of congenital anomalies in the infants of mothers with pre-existing diabetes mellitus, gestational diabetes mellitus, or impaired glucose tolerance was significantly higher than in the total population; relative risk = 2.01 (1.66-2.43) and 1.19 (1.08-1.31), respectively. This increased prevalence was not modified by adjustments for maternal age, ethnicity, or other demographic factors, nor did the rate change over the 15 years of the study period. CONCLUSIONS: The prevalence of congenital anomalies was found to be significantly higher in the infants of mothers with maternal diabetes. Larger population-based studies are needed to determine which anomalies are involved and how their occurrence can be reduced.     

Patterns of infant mortality caused by major congenital anomalies

BACKGROUND: We assessed the impact of recent advances in perinatal care on infant mortality due to congenital anomaly. METHODS: Analysis of trends in congenital anomaly-attributed infant mortality, using the 1981-1995 Statistics Canada's birth and death records, with a total of 2,878,826 live births, 21,883 infant deaths, and 6, 908 infant deaths due to congenital anomalies. RESULTS: Infant mortality due to major congenital anomaly decreased from 3.11 per 1, 000 live births in 1981 to 1.89 per 1,000 live births in 1995. Cause-specific infant mortality rates for anencephaly, spina bifida, other central nervous system anomalies, cardiovascular system anomalies, respiratory system anomalies, digestive system anomalies, certain musculoskeleton anomalies, urinary system anomalies, chromosomal anomalies, and multiple congenital anomalies were 0.20, 0.23, 0.27, 1.04, 0.24, 0.08, 0.22, 0.16, 0.22, and 0.13 per 1,000 live births, respectively, in 1981-1983, whereas corresponding rates were 0.07, 0.07, 0.18, 0.73, 0.25, 0.03, 0.12, 0.12, 0.26, and 0.06 per 1,000 live births, respectively, in 1993-1995. CONCLUSIONS: Recent Canadian data show that infant deaths caused by major congenital anomalies have decreased significantly, but reductions varied substantially according to specific forms of anomalies.     

A rare case of congenital heart disease with ambiguous genitalia

Birth defects have become the important cause of mortality and morbidity in the perinatal period. Congenital heart disease (CHD) is the most common birth defect which includes the varying forms of cardiac abnormalities and occurs with an incidence of 1 per 100 live births. In most of the cases, CHD is an isolated malformation, but about 33% have associated anomalies. Ambiguous genitalia are one such rare anomaly that is associated with CHD among other genital abnormalities. The possible causes for this association could be pseudohermaphroditism, which in turn, may be due to congenital adrenal hyperplasia. The government of any country should consider providing for its people a free prenatal diagnosis for susceptible disorders.     

Contribution of ultrasonographic examination to the prenatal detection of chromosomal abnormalities in 19 centres across Europe.

The objective of this study was to evaluate the prenatal detection of chromosomal abnormalities by fetal ultrasonographic examination in a large database provided by 19 Registries of Congenital Anomalies from 11 European countries. This study included 1738 cases of chromosomal abnormalities, liveborn, stillborn or termination of pregnancy regardless of maternal age from a population of 664,340 births during the period 1996 - 1998. The most frequent chromosomal anomalies were Down syndrome (n=1050), trisomy 18 (n=191), Turner syndrome (n=125), trisomy 13 (n=86), and triploidy (n=56). Fetal ultrasonographic examination resulted in the prenatal detection of 37.7% of the chromosomal abnormalities, thereby resulting in a reduction of 28.6% in their prevalence at birth due to terminations of pregnancy. The detection rate by ultrasound examination varied according to local policies of prenatal diagnosis : it was lower in countries where routine scan were not performed and higher in countries in which at least one routine anomaly scan during the second trimester of pregnancy was performed. The ultrasound detection varied according to the specific chromosomal anomaly and was lowest for Klinefelter syndrome (5.7%) and highest for triploidy (78.6%). For Down syndrome it was 26.4%. Termination of pregnancy was performed in 75.9% of the cases. Among the 655 cases detected by ultrasound, the most frequent ultrasound signs by category of chromosomal abnormalities were analysed. This study shows that ultrasound screening is an important tool in the prenatal detection of chromosomal abnormalities in Europe, leading to a significant reduction in the prevalence of livebirth children with chromosomal anomalies.     

Origin of trisomy 21 in Down syndrome cases from a Spanish population registry

We have carried out a population-based study on the origin of the extra chromosome 21 in 38 families with Down syndrome (DS) offspring in El Vallès (Spain). From 1991 to 1994, a higher prevalence of DS (22.7/10000 live births, stillbirths and induced abortions) was found compared to the majority of EUROCAT registries. The distribution of trisomy 21 by origin was 88% maternal (90.6% meiosis I, 6.2% meiosis II, 3.1% maternal mosaicism), 5.6% paternal (50% meiosis I, 50% meiosis II) and 5.6% mitotic. The percentage of parental mosaicism was 2.7%. These percentages are similar to those previously reported. Recombination study revealed a maternal meiosis I genetic map of 32.68 cM (approximately one-half the length of the normal female map). Mean maternal age among non-recombinant cases involving MI errors was significantly lower (31.1 years) than among those cases showing one observable crossover (36.1 years) (P<0.05); this could support the hypothesis that 'achiasmate' chromosomes may be subject to aberrant segregation regardless of maternal age.     

Inheritance of congenital heart disease

Congenital heart defects (CHD) are the most common developmental anomalies and are the leading noninfectious cause of mortality in newborn babies. It has been estimated that between four and ten live-born infants per 1000 have a cardiac malformation (0.4 to 1.0%), 40% of which are diagnosed in the first year of life. The European Registration of Congenital Anomalies (EUROCAT) reported a prevalence of 58.9/10,000 live births in the northern part of the Netherlands (0.6%). Hoffman estimated that the true prevalence of CHD may be as high as 53 per 1000 pregnancies (5.3%), including a 20% occurrence of heart defects in spontaneous abortion, a 10% occurrence in stillbirth, and a 1% occurrence in live birth.     

Genetic disorders in children and young adults: a population study.

The data base of an ongoing population-based registry with multiple sources of ascertainment was used to estimate the present population load from genetic disease in more than 1 million consecutive live births. It was found that, before approximately age 25 years, greater than or equal to 53/1,000 live-born individuals can be expected to have diseases with an important genetic component. This total was composed of single-gene disorders (3.6/1,000), consisting of autosomal dominant (1.4/1,000), autosomal recessive (1.7/1,000), and X-linked recessive disorders (0.5/1,000). Chromosomal anomalies accounted for 1.8/1,000, multifactorial disorders (including those present at birth and those of onset before age 25 years) accounted for 46.4/1,000, and cases of genetic etiology in which the precise mechanism was not identified accounted for 1.2/1,000. Previous studies have usually considered all congenital anomalies (ICD 740-759) as part of the genetic load, but only those judged to fit into one of the above categories were included in the present study. Data for congenital anomalies are therefore also presented separately, to facilitate comparison with earlier studies. If all congenital anomalies are considered as part of the genetic load, then greater than or equal to 79/1,000 live-born individuals have been identified as having one or other genetic disorder before approximately age 25 years. These new data represent a better estimate of the genetic load in the population than do previous studies.     

Folic acid and primary prevention of birth defects

Birth defects (BDs) are an important public health problem, due to their overall incidence, occurring in 2-3% of live births in European Union. Neural tube defects (NTDs) are among major NTDs, due to their severity and relatively high incidence; in the meanwhile NTDs are also the most effectively preventable BDs to date. In particular, an adequate folic acid (FA) intake reduces both the occurrence and the recurrence of NTDs; FA is the synthetic form of folates, naturally occurring vitamins in a number of foods, especially vegetables. The daily intake of 0.4 mg of FA should be recommended to all women of childbearing age who plan to become pregnant. The Italian Network for Primary Prevention of BDs through FA Promotion has achieved a significant improvement in FA awareness and use in the periconceptional period. Nevertheless, primary prevention of BDs needs to make further progress; the Italian National Centre for Rare Diseases participates in european sureveillance of congenital anomalies (EUROCAT) Joint Action as coordinator of activities on the effectiveness of BDs prevention. Mandatory food fortification with FA has not been introduced in any European country. The health benefits of FA in reducing the risk of NTDs are undisputed; however mechanistic and animal studies suggest a relationship between high FA intakes and increased cancer promotion, while human studies are still inconsistent and inconclusive. A Working Group organized by the European Food Safety Authority pointed out significant uncertainties about fortification safety and the need for more studies; currently, FA intake from fortified foods and supplements should not exceed 1 mg/day in adults. In conclusion, based on up-to-date scientific evidence, the Italian Network strategy pivots on periconceptional supplementation integrated with promotion of healthy eating habits, support to health education, enhancing the role of women in managing life choices about their health and pregnancy and increasing the scientific knowledge about BDs primary prevention.     

Do infants with major congenital anomalies have an excess of macrosomia?

BACKGROUND: Infants that develop congenital anomalies may also have an excess prevalence of macrosomia (birth weight > or =4,000 g). This may indicate that abnormalities of glycemic control play a role in the etiology of birth defects. This study was undertaken to determine whether all infants with congenital anomalies have an excess of macrosomia and whether it is confined to specific types of anomalies. METHODS: A case-control study was conducted, comparing the birth weights of 8,226 infants with congenital anomalies ascertained by the Texas Birth Defects Monitoring Division with those of 965,965 infants without birth defects. Odds ratios were calculated to determine the association between birth weight and congenital anomalies, for 45 specific defects, and for all these defects combined. RESULTS: For all 45 defects combined, a significant association occurred only in the highest birth weight category. Infants with congenital anomalies were more likely than infants without birth defects to have a birth weight > or =4,500 g (OR = 1.65; 95% CI = 1.39-1.96). Infants born with ventricular septal defects, atrial septal defects, ventricular hypertrophy, or anomalies of the great vessels were 1.5-2.5 times more likely to weigh > or =4,000 g than were infants without birth defects. Based on small numbers, a stronger excess of macrosomia was observed for infants with encephalocele, holoprosencephaly, anomalies of the corpus callosum, preaxial polydactyly, and omphalocele. CONCLUSIONS: Our data suggest that infants with specific congenital anomalies are more likely to be macrosomic than are infants without an anomaly. If these findings are confirmed, associations between macrosomia and specific types of birth defects may help to identify birth defects that are caused by alterations in glycemic control.     

An epidemiologic study of congenital malformations of the anterior abdominal wall in more than half a million consecutive live births.

The records of an ongoing health surveillance registry that utilizes multiple sources of ascertainment were used to study the incidence rate of congenital malformations of the anterior abdominal wall in live-born children in British Columbia during the period 1964--1978 inclusive. No overall increase in incidence rate of these anomalies was detected during the study period. The estimated live-born incidence rates were: one in 4,175 live births for omphalocoele, one in 12,328 live births for gastroschisis, and one in 29,231 live births for prune belly. The data were analyzed with regard to sex and associated anomalies. Some practical implications regarding assessment of these infants are discussed.