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H Dolk

Publications and source records attributed to H Dolk.

At least 19 recordsLinked to original sources
PubMed2005

Prenatal diagnosis of severe structural congenital malformations in Europe.

OBJECTIVES: To assess at a population-based level the frequency with which severe structural congenital malformations are detected prenatally in Europe and the gestational age at detection, and to describe regional variation in these indicators. METHODS: In the period 1995-1999, data were obtained from 17 European population-based registries of congenital malformations (EUROCAT). Included were all live births, fetal deaths and terminations of pregnancy diagnosed with one or more of the following malformations: anencephalus, encephalocele, spina bifida, hydrocephalus, transposition of great arteries, hypoplastic left heart, limb reduction defect, bilateral renal agenesis, diaphragmatic hernia, omphalocele and gastroschisis. RESULTS: The 17 registries reported 4366 cases diagnosed with the 11 severe structural malformations and of these 2300 were live births (53%), 181 were fetal deaths (4%) and 1863 were terminations of pregnancy (43%); in 22 cases pregnancy outcome was unknown. The overall prenatal detection rate was 64% (range, 25-88% across regions). The proportion of terminations of pregnancy varied between regions from 15% to 59% of all cases. Gestational age at discovery for prenatally diagnosed cases was less than 24 weeks for 68% (range, 36-88%) of cases. There was a significant relationship between high prenatal detection rate and early diagnosis (P < 0.0001). For individual malformations, the prenatal detection rate was highest for anencephalus (469/498, 94%) and lowest for transposition of the great arteries (89/324, 27%). Termination of pregnancy was performed in more than half of the prenatally diagnosed cases, except for those with transposition of the great arteries, diaphragmatic hernia and gastroschisis, in which 30-40% of the pregnancies with a prenatal diagnosis were terminated. CONCLUSION: European countries currently vary widely in the provision and uptake of prenatal screening and its quality, as well as the "culture" in terms of decision to continue the pregnancy. This inevitably contributes to variation between countries in perinatal and infant mortality and in childhood prevalence and cost to health services of congenital anomalies.

Abortion, Induced↗
PubMed2005

Prevalence of congenital anomalies in five British regions, 1991-99.

AIMS: To describe trends in total and live birth prevalence, regional differences in prevalence, and outcome of pregnancy of selected congenital anomalies. METHODS: Population based registry study of 839,521 births to mothers resident in five geographical areas of Britain during 1991-99. Main outcome measures were: total and live birth prevalence; pregnancy outcome; proportion of stillbirths due to congenital anomalies; and secular trends. RESULTS: The sample consisted of 10,844 congenital anomalies, giving a total prevalence of 129 per 10,000 registered births (95% CI 127 to 132). Live birth prevalence was 82.2 per 10,000 births (95% CI 80.3 to 84.2) and declined significantly with time. The proportion of all stillbirths with a congenital anomaly was 10.5% (453 stillbirths). The proportion of pregnancies resulting in a termination increased from 27% (289 cases) in 1991 to 34.7% (384 cases) in 1999, whereas the proportion of live births declined from 68.2% (730 cases) to 58.5% (648 cases). Although similar rates of congenital anomaly groups were notified to the registers, variation in rates by register was present. There was a secular decline in the total prevalence of non-chromosomal and an increase in chromosomal anomalies. CONCLUSIONS: Regional variation exists in the prevalence of specific congenital anomalies. For some anomalies this can be partially explained by ascertainment variation. For others (neural tube defects, diaphragmatic hernia, gastroschisis), higher prevalence rates in the northern regions (Glasgow and Northern) were true differences. Live birth prevalence declined over the study due to an increase in terminations of pregnancy.

Abortion, Spontaneous↗
PubMed2005

EUROCAT: 25 years of European surveillance of congenital anomalies.

The surveillance of congenital anomalies serves two main purposes: to facilitate the identification of teratogenic (malformation causing) exposures and to assess the impact of primary prevention and prenatal screening policy and practice at a population level. EUROCAT, the European network of population based registers for the epidemiological surveillance of congenital anomalies, now covers 1.2 million births per year, a quarter of births in Europe. The added value of European collaboration is particularly great for congenital anomalies, coming from the opportunity to pool data, to compare data between regions and countries, to give a common response to European public health questions, and to share expertise and resources, including computing tools. EUROCAT provides essential epidemiological information on congenital anomalies in Europe, facilitates the early warning of teratogenic exposures, evaluates the effectiveness of primary prevention, assesses the impact of developments in prenatal screening, acts as an information and resource centre regarding clusters, provides a ready collaborative network and infrastructure for research, and acts as a catalyst for the setting up of registries throughout Europe.

Congenital Abnormalities↗
PubMed2005

An aetiological classification of birth defects for epidemiological research.

BACKGROUND: Congenital anomaly registers collect data on antenatally and postnatally detected anomalies for surveillance, research, and public health purposes. Each anomaly is coded using the International Statistical Classification of Diseases and Related Health Problems (ICD-9/ICD-10) based on body systems, allowing accurate comparisons between registers for individual anomalies. When commencing an environmental, epidemiological study, it became clear to us that there is no standard classification that takes aetiology into account. This paper describes a new classification for use in studies addressing aetiology. METHOD: A classification system was evolved and piloted using cases in a study of geographical variation in congenital anomaly prevalence.1 Cases that were difficult to categorise were noted, and after discussion with a team of experts, the classification was adjusted accordingly. RESULTS AND CONCLUSION: A robust, hierarchical method of classifying birth defects into eight categories has been produced, for use at source of data registration in conjunction with, but independent of, ICD coding.

Congenital Abnormalities↗
PubMed2005

Trends and geographic inequalities in the prevalence of Down syndrome in Europe, 1980-1999.

BACKGROUND: EUROCAT is a network of population-based registries for the epidemiologic surveillance of congenital anomalies covering approximately one quarter of births in the European Union. Down syndrome constitutes approximately 8% of cases of registered congenital anomaly in Europe, with over 7000 affected pregnancies in the 15 current member states of the European Union each year. In this paper, we aim to examine trends in the live birth prevalence of Down syndrome in Europe in the light of trends in maternal age and in prenatal diagnosis. METHODS: Descriptive analysis of data from 24 EUROCAT registries, covering 8.3 million births 1980-99. Cases include live births, stillbirths and terminations of pregnancy following prenatal diagnosis. RESULTS: Since 1980, the proportion of births to mothers of 35 years of age and over has risen quite dramatically from 8 to 14% for the European Union as a whole, with steeper rises in some regions. By 1995-1999, the proportion of "older" mothers varied between regions from 10% to 25%, and the total prevalence (including terminations of pregnancy) of Down syndrome varied from 1 to 3 per 1000 births. Some European regions have shown a more than twofold increase in total prevalence of Down syndrome since 1980. The proportion of cases of Down syndrome which were prenatally diagnosed followed by termination of pregnancy in 1995-1999 varied from 0% in the three regions of Ireland and Malta where termination of pregnancy is illegal, to less than 50% in 14 further regions, to 77% in Paris. The extent to which terminations of pregnancy were concen trated among older mothers varied between regions. The live birth prevalence has since 1980 increasingly diverged from the rising total prevalence, in some areas remaining approximately stable, in others decreasing over time. CONCLUSION: The rise in average maternal age in Europe has brought with it an increase in the number of pregnancies affected by Down syndrome. The widespread practice of prenatal screening and termination of pregnancy has in most of the regions covered by EUROCAT counteracted the effect of maternal age in its effect on live birth prevalence. Under the joint influences of maternal age and prenatal screening the pattern of geographic inequalities in Down syndrome live birth prevalence in Europe has also been changed.

Adult↗
PubMed2004

Congenital anomaly surveillance in England--ascertainment deficiencies in the national system.

OBJECTIVE: Firstly, to assess the completeness of ascertainment in the National Congenital Anomaly System (NCAS), the basis for congenital anomaly surveillance in England and Wales, and its variation by defect, geographical area, and socioeconomic deprivation. Secondly, to assess the impact of the lack of data on pregnancies terminated because of fetal anomaly. DESIGN: Comparison of the NCAS with four local congenital anomaly registers in England. SETTING: Four regions in England covering some 109,000 annual births. PARTICIPANTS: Cases of congenital anomalies registered in the NCAS (live births and stillbirths) and independently registered in the four local registers (live births, stillbirths, fetal losses from 20 weeks' gestation, and pregnancies terminated after prenatal diagnosis of fetal anomaly). MAIN OUTCOME MEASURE: The ratio of cases identified by the national register to those in local registry files, calculated for different specified anomalies, for whole registry areas, and for hospital catchment areas within registry boundaries. RESULTS: Ascertainment by the NCAS (compared with data from local registers, from which terminations of pregnancy were removed) was 40% (34% for chromosomal anomalies and 42% for non-chromosomal anomalies) and varied markedly by defect, by local register, and by hospital catchment area, but not by area deprivation. When terminations of pregnancy were included in the register data, ascertainment by NCAS was 27% (19% for chromosomal anomalies and 31% for non-chromosomal anomalies), and the geographical variation was of a similar magnitude. CONCLUSION: The surveillance of congenital anomalies in England is currently inadequate because ascertainment to the national register is low and non-uniform and because no data exist on termination of pregnancy resulting from prenatal diagnosis of fetal anomaly.

Abortion, Induced↗
PubMed2004

What influences physiotherapy use by children with cerebral palsy?

AIM: To investigate factors that influence the frequency of physiotherapy currently used by a population of children with moderate to severe cerebral palsy (CP). METHODS: A survey using a postal questionnaire was sent to 212 parents of children with moderate to severe CP. The families were identified from a geographically defined case register of children with CP in Northern Ireland (the Northern Ireland Cerebral Palsy Register). Eighty-five per cent of parents responded. One-third of parent responses regarding their child's use of physiotherapy were validated with their child's physiotherapist and the level of agreement was high. RESULTS: Ninety-four per cent (169/180) of children received conventional physiotherapy from a statutory source during the school term. Of these, 61% (104/169) used 'intense' levels of physiotherapy (defined as at least twice a week). A higher proportion of intense users were children with severe CP compared with moderate CP (69% vs. 47%; P < 0.01); with moderate intellectual impairment (IQ </= 70 > 50) compared with severe (IQ </= 50) or no intellectual impairment (IQ > 70) (81% vs. 64% vs. 39% respectively; P < 0.01) and at schools for physical disability (PD) compared with severe learning disability (SLD) or mainstream (MS) schools (82% vs. 66% vs. none respectively; P < 0.001). After controlling for severity of motor impairment and the presence and severity of intellectual impairment, children with CP at MS schools used on average significantly less physiotherapy compared with children with similar levels of motor impairment at PD schools (P < 0.001). CONCLUSIONS: Children with CP in MS schools use less physiotherapy compared with children with similar levels of disability in special schools. Organizing services around special schools may limit the degree to which children with CP and other disabilities are successfully integrated into MS education.

Adolescent↗
PubMed2003

Risk of hypospadias in relation to maternal occupational exposure to potential endocrine disrupting chemicals.

BACKGROUND: Reported rises in the prevalence of hypospadias and other abnormalities of the male reproductive system may be a result of exposure to endocrine disrupting chemicals. AIMS: To analyse the relation between risk of hypospadias and maternal occupation, particularly with regard to exposure to potential endocrine disrupting chemicals (EDCs). METHODS: Data (1980-96) from the National Congenital Anomaly System (NCAS) were used to analyse the proportion of all congenital anomaly cases (n = 35 962) which were notified with hypospadias (n = 3471) by occupational codes (348 individual job titles) and by categories of exposure to potential EDCs from a job exposure matrix. RESULTS: Five individual occupations (of 348) showed nominally statistically significant excesses, none of which had possible or probable exposure to potential EDCs. Odds ratios for "possible" or "probable" compared to "unlikely" exposure to potential EDCs did not show statistically significant increases in any of the EDC categories after adjustment for social class of the mother and father, nor was there evidence of an upward trend in risk with likelihood of exposure. In the 1992-96 time period odds ratios were increased for hairdressers (the largest group exposed to potential EDCs) and for probable exposure to phthalates (of which hairdressers form the largest group) before social class adjustment. CONCLUSIONS: There was little evidence for a relation between risk of hypospadias and maternal occupation or occupational exposure to potential EDCs, but as the exposure classification was necessarily crude, these findings should be interpreted with caution.

Endocrine Glands↗
PubMed2002

Chromosomal congenital anomalies and residence near hazardous waste landfill sites.

Previous findings of the EUROHAZCON study showed a 33% increase in risk of non-chromosomal anomalies near hazardous waste landfill sites. Here, we studied 245 cases of chromosomal anomalies and 2412 controls who lived near 23 such sites in Europe. After adjustment for confounding by maternal age and socioeconomic status, we noted a higher risk of chromosomal anomalies in people who lived close to sites (0-3 km) than in those who lived further away (3-7 km; odds ratio 1.41, 95% CI 1.00-1.99). Our results suggest an increase in risk of chromosomal anomalies similar to that found for non-chromosomal anomalies.

Abnormalities, Drug-Induced↗
PubMed2002

Use of physiotherapy and alternatives by children with cerebral palsy: a population study.

OBJECTIVES: To describe the use of physiotherapy services and alternative therapies by a population of children with moderate to severe cerebral palsy (CP). DESIGN: Descriptive cross-sectional survey. SUBJECTS: A total of 212 parents of children aged 4-14 years with moderate to severe CP were identified from the Northern Ireland Cerebral Palsy Register (NICPR) and a random subsample of their paediatric physiotherapists. MAIN MEASURES: A standardized description of motor impairment or assessment form; a postal questionnaire to parents and paediatric physiotherapists (to validate parents' reports of service use). RESPONSE RATES: In total, 85% of parent questionnaires were returned and 100% of paediatric physiotherapists responded. RESULTS: Service use among families was high; on average the families had contact with approximately seven services in a 6-month time interval. The overwhelming majority of children (96%) received physiotherapy during the school term and most (59%) received treatment at least twice a week for 30 min; 43% of children had their physiotherapy discontinued over the summer holidays. Over one-quarter (28%) of families had opted out of the NHS and bought alternatives like conductive education (21%) or private forms of conventional physiotherapy (16%). Children with more severe forms of CP, in special education, particularly at schools for physical disability, were high-intensity users of the physiotherapy service. Despite this, 74% of parents wanted more physiotherapy for their child. CONCLUSIONS AND IMPLICATIONS: The demand for physiotherapy services is likely to continue given the relatively stable prevalence rate of CP, the proportion of children with disabling CP and the level of parent interest in the service. A number of quality aspects and gaps in the service have been identified.

Adolescent↗
PubMed2002

Hazard potential ranking of hazardous waste landfill sites and risk of congenital anomalies.

BACKGROUND: A 33% increase in the risk of congenital anomalies has been found among residents near hazardous waste landfill sites in a European collaborative study (EUROHAZCON). AIMS: To develop and evaluate an expert panel scoring method of the hazard potential of EUROHAZCON landfill sites, and to investigate whether sites classified as posing a greater potential hazard are those with a greater risk of congenital anomaly among nearby residents relative to more distant residents. METHODS: A total of 1270 cases of congenital anomaly and 2308 non-malformed control births were selected in 14 study areas around 20 landfill sites. An expert panel of four landfill specialists scored each site in three categories-overall, water, and air hazard-based on readily available, documented data on site characteristics. Tertiles of the average ranking scores defined low, medium, and high hazard sites. Calculation of odds ratios was based on distance of residence from the sites, comparing a 0-3 km "proximate" with a 3-7 km "distant" zone. RESULTS: Agreement between experts measured by intraclass correlation coefficients was 0.50, 0.44, and 0.20 for overall, water, and air hazard before a consensus meeting and 0.60, 0.56, and 0.53 respectively after this meeting. There was no evidence for a trend of increasing odds ratios with increasing overall hazard or air hazard. For non-chromosomal anomalies, odds ratios by water hazard category showed an increasing trend of borderline statistical significance (p = 0.06) from 0.79 in the low hazard category, 1.43 in the medium, to 1.60 in the high water hazard category. CONCLUSIONS: There is little evidence for a relation between risk of congenital anomaly in proximate relative to distant zones and hazard potential of landfill sites as classified by the expert panel, but without external validation of the hazard potential scoring method interpretation is difficult. Potential misclassification of sites may have reduced our ability to detect any true dose-response effect.

Congenital Abnormalities↗
PubMed2001

Cerebral palsy in Northern Ireland: 1981--93.

This paper describes the method of compilation of the Northern Ireland Cerebral Palsy Register (NICPR) and outlines the epidemiology of cerebral palsy (CP) in Northern Ireland in 1981--93 based on an analysis of 784 cases. Multiple and overlapping sources of notification were used to compile the NICPR. Each case was followed up with a standardised assessment completed at age 5 years and validated by a paediatrician. Over 70% of cases were multiply notified, and paediatricians were the most important source of notification. Cases of CP most likely to be under-ascertained included those very mildly affected, cases who died before the register began (death certificates were searched but found to be unreliable) and cases who moved out of the area before their diagnosis was confirmed. The prevalence of CP for the birth period 1981--93 was 2.24 per 1000 livebirths [95% CI 2.08, 2.40]. There were no statistically significant temporal or geographic variations in the rate of CP. Almost half the cases of CP were of low birthweight (<2500 g), and this proportion increased during 1987--89, but decreased (P < 0.01) more recently (1990--93). The proportion of cases weighing <1000 g trebled from 3% in 1981--83 to 10% in 1990--93 (P < 0.01). The most common CP subtype was bilateral spastic cerebral palsy (55%). Just over a quarter (29%) of cases were unable to walk (with/without aids), and one-fifth (22%) had no useful hand/arm function. Almost half (49%) the cases had at least one other impairment (intellectual, sensory impairment or active seizures) in association with their CP. Prevalence rates and the pattern of disability in populations of people with CP can only be evaluated on the basis of the methods of case definition and ascertainment. We have demonstrated the methods necessary to ensure valid, standard and detailed information on CP for the purposes of surveillance, service planning and research.

Algorithms↗
PubMed2001

Cerebral palsy, low birthweight and socio-economic deprivation: inequalities in a major cause of childhood disability.

There is currently little and conflicting evidence concerning the existence of socio-economic inequalities in cerebral palsy prevalence, or the extent to which this is influenced by socio-economic inequalities in low birthweight, a strong risk factor for cerebral palsy. The study is based on 753 children registered with cerebral palsy, resident in the former Oxford Regional Health Authority area and born in the years 1984-90. Two population definitions were used: 1. Children with cerebral palsy resident at birth in the area, with resident births as denominator, 2. Children with cerebral palsy resident at age 5 in the area, with children of ages 1-7 resident in the area in the 1991 census as denominator. Children with cerebral palsy and all births/children were classified according to the Carstairs area deprivation index (grouped into quintiles) of their ward of residence. The prevalence among residents at birth varied from 2.08 per 1000 births in the most affluent quintile to 3.33 in the most deprived quintile (trend P < 0.001). Although there was a tendency for children to move to more affluent areas during early childhood, the socio-economic gradient was similar at age 5. A greater proportion of births in the more deprived quintiles were of low or very low birthweight, the proportion rising from 5.6% in the most affluent quintile to 8.2% in the most deprived. Within the normal birthweight category there was a trend for higher prevalence of cerebral palsy in more deprived quintiles, from 1.29 per 1000 in the most affluent quintile to 2.42 in the most deprived quintile (trend P < 0.001). Within the low birthweight and very low birthweight groups, separately or combined, there was no evidence of any relationship between cerebral palsy prevalence and deprivation. We estimate that up to 17% of cerebral palsy cases might be "preventable" in terms of the reduction to be expected if the whole population had the rate of cerebral palsy of the most affluent quintile. Although the strong socio-economic gradient for cerebral palsy was restricted to the normal birthweight category, we estimate that two-thirds of the excess cases in the population associated with greater socio-economic deprivation were normal birthweight cases, and one-third were low birthweight cases owing to the greater prevalence of low birthweight in more deprived populations. The pattern of socio-economic inequalities should be further explored in other regions, and should be taken into account in aetiological research, and in the effective delivery and evaluation of services.

Cerebral Palsy↗
PubMed2001

Stillbirth and neonatal mortality due to congenital anomalies: temporal trends and variation by small area deprivation scores in England and Wales, 1986-96.

We investigated the variation of stillbirth and neonatal mortality due to congenital anomalies in relation to small-area measures of deprivation in a population-based study in England and Wales, 1986-96. We found 10 954 stillbirths and neonatal deaths from all non-chromosomal and chromosomal anomalies during the study period out of a total of 7 487 007 live and stillbirths. The extended perinatal mortality rate (EPM rate) (defined as babies who were stillborn or died within 28 completed days after birth per 10 000 total live and stillbirths) for all chromosomal and all non-chromosomal anomalies was 1.5/10 000 and 13.2/10 000, respectively, over the whole period. The rate for non-chromosomal anomalies halved over the decade while the rate for chromosomal anomalies remained unchanged. The relative risks of EPM for chromosomal and non-chromosomal anomalies were 0.71 [0.80, 0.95] and 1.17 [95%CI 1.06, 1.30], respectively, in the group of wards with highest deprivation compared with the least deprived group. Increasing gradients of EPM with increasing deprivation were observed for (1) grouped non-chromosomal anomalies including neural tube defects, all renal and urinary anomalies, all musculoskeletal anomalies, and multiple anomalies, and (2) several specific non-chromosomal anomalies including anencephaly, limb reduction defects, diaphragm and abdominal wall defects. This study provides strong evidence that increased deprivation is associated with increased EPM due to most non-chromosomal anomalies; the finding of decreased relative risk for chromosomal anomalies is probably related to differences in maternal age distribution between deprivation groups.

Chromosome Aberrations↗
PubMed2000

Socioeconomic inequalities in risk of congenital anomaly.

AIMS: To investigate socioeconomic inequalities in the risk of congenital anomalies, focusing on risk of specific anomaly subgroups. METHODS: A total of 858 cases of congenital anomaly and 1764 non-malformed control births were collected between 1986 and 1993 from four UK congenital malformation registers, for the purposes of a European multicentre case control study on congenital anomaly risk near hazardous waste landfill sites. As a measure of socioeconomic status, cases and controls were given a value for the area level Carstairs deprivation index, by linking the postcode of residence at birth to census enumeration districts (areas of approximately 150 households). RESULTS: Risk of non-chromosomal anomalies increased with increasing socioeconomic deprivation. The risk in the most deprived quintile of the deprivation index was 40% higher than in the most affluent quintile. Some malformation subgroups also showed increasing risk with increasing deprivation: all cardiac defects, malformations of the cardiac septa, malformations of the digestive system, and multiple malformations. No evidence for socioeconomic variation was found for other non-chromosomal malformation groups, including neural tube defects and oral clefts. A decreasing risk with increasing deprivation found for all chromosomal malformations and Down's syndrome in unadjusted analyses, occurred mainly as a result of differences in the maternal age distribution between social classes. CONCLUSION: Our data, although based on limited numbers of cases and geographical coverage, suggest that more deprived populations have a higher risk of congenital anomalies of non-chromosomal origin and some specific anomalies. Larger studies are needed to confirm these findings and to explore their aetiological implications.

Case-Control Studies↗