Congenital anomaly surveillance in England—ascertainment deficiencies
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《英国医生杂志》
1 National Perinatal Epidemiology Unit, University of Oxford, Oxford OX3 7LF, 2 London School of Hygiene and Tropical Medicine, London WC1E 7HT, 3 Faculty of Life and Health Sciences, University of Ulster, Newtonabbey, Co Antrim, BT37 0QB, 4 Office for National Statistics, London SW1V 2QQ, 5 North Thames Perinatal Public Health Unit, Northwick Park Hospital, Harrow, HA1 3UJ, 6 School of Population and Health Sciences, Faculty of Medicine, University of Newcastle, Newcastle NE2 4HH, 7 International Agency for Research on Cancer, 150, Cours Albert Thomas, 69372 Lyons, Cedex 08, France, 8 Wessex Clinical Genetics Service, Princess Anne Hospital, Southampton SO16 5YA
Correspondence to PA Boyd patricia.boyd@perinat.ox.ac.uk
Abstract
A major congenital anomaly affects 2-3% of newborn babies. Congenital anomalies are an important cause of fetal, neonatal, and child mortality and morbidity, accounting for 21% of perinatal and infant deaths in the United Kingdom in 2001.1 Monitoring of anomalies is vital to identify possible clusters and trends and to address concerns about putative environmental teratogens. The importance of registering the type and number of congenital anomalies has been recognised for many years; in Birmingham, information on congenital anomalies has been collected since 1949. A national register for England and Wales, now called the National Congenital Anomaly System (NCAS), was proposed by the minister of health in 1963 after the thalidomide "epidemic," and this is run by the Office for National Statistics (ONS; www.statistics.gov.uk).2
Notification of anomalies in live and stillbirths to NCAS is voluntary and usually done through a standard paper form (SD56) filled in by midwives, health visitors, and other health professionals. Local congenital anomaly registers have been set up alongside the NCAS, partly to deal with the known under-ascertainment3-6 and partly to meet local needs and research needs, such as the audit of prenatal diagnosis and research into putative teratogens. Some 50% of births in England are covered by local congenital anomaly registers. These registers are all members of the British Isles Network of Congenital, Anomaly Registers (BINOCAR, www.statistics.gov.uk/binocar/) and belong to EUROCAT (the European Network of Congenital Anomaly Registers, www.eurocat.ulster.ac.uk). In contrast to the NCAS, these local registers record fetuses terminated for fetal anomaly. Ascertainment of cases to the local registers is actively sought and provided from multiple sources, such as cytogenetic and postmortem reports; prenatal diagnosis; and paediatric, neonatal, orthopaedic, and surgical units.
As part of a study of the geographical variation in the prevalence of birth defects7 we measured the extent to which the under-ascertainment in the NCAS data compared with four local registers, varied by defect, geographical area, and socioeconomic deprivation, during the period 1991-9. We also assessed the impact of the absence of data on pregnancies terminated because of fetal anomaly from the national data set.
Methods
Ascertainment by NCAS was 40% (42% for non-chromosomal anomalies and 34% for chromosomal anomalies) when terminations of pregnancy were excluded from register data. This varied markedly by register, hospital catchment area (not shown), and congenital anomaly subgroup (table, fig 1); all variations were significant (P < 0.001).
Fig 1 Percentage of all defects in the NCAS compared with local registers, by register
When terminations of pregnancy were included in register data, ascertainment of cases by NCAS (compared with the registers) was 27% (31% for non-chromosomal anomalies and 19% for chromosomal anomalies; table) and again varied markedly by register (fig 1), hospital catchment areas within register areas (fig 2), and congenital anomaly subgroup; all variations were significant (P < 0.001).
Fig 2 Ascertainment ratios to NCAS by hospital catchment area for all cases. (a) Termination of pregnancy excluded. (b) Termination of pregnancy cases included. Ascertainment ratios are shown for each hospital catchment, with 95% confidence intervals. Catchments with fewer than 10 anomalies identified by either source were omitted, to avoid distracting imprecise ratios
The lowest ascertainment was for neural tube defects (11% when terminations are in the local register data, 68% when terminations are removed) and cardiac defects (12% with termination included and 13% with termination excluded from local data). The highest ascertainment to NCAS was for cleft lip (75% and 83% with termination included and excluded from local data, respectively) and for limb reduction defects (73% and 88% with terminations included and excluded from local data, respectively).
Figure 1 shows the variation in ascertainment in NCAS across local register areas. The highest ascertainment to NCAS was from the regions covered by NTW and WANDA and the lowest from the OXCAR area. However, ascertainment from the different locations was not consistent when individual defects were compared. For example, ascertainment for cleft lip (overall ascertainment 75%) was highest (91%) from NorCAS area and lowest (44%) from OXCAR. Ascertainment of atresias and fistulas of the digestive system (overall ascertainment 40%) was highest from WANDA and OXCAR areas (57% and 69%) and lowest from NTW and NorCAS (33% and 37%).
The proportion of cases ascertained by NCAS varied little by area deprivation (fig 3), certainly less than could be explained by chance (P > 0.1). This pattern did not change on adjustment for differences in ascertainment by registry and hospital catchment area.
Fig 3 Ascertainment by National Congenital Anomaly System compared with local registers, by area deprivation
Discussion
Macfarlaine A, Mugford M. Birthcounts. Statistics of pregnancy and childbirth. London Stationery Office, 2000.
Congenital malformations statistical notifications 1994. London: Stationery Office, 1997. (Series MB3, No 10.)
Payne JN. Limitations of the OPCS congenital malformation notification systems illustrated by examination of congenital malformations of the cardiovascular systems in districts within the Trent region. Public Health 1992;106: 437-48.
Knox EG, Armstrong EH, Lancashire R. The quality of notification of congenital malformations. J Epidemiol Community Health 1984;38: 296-305.
Office for Population Censuses and Surveys. The OPCS monitoring scheme for congenital malformations occasional paper 43. A review by a working group of the registrar general's medical advisory committee. London: OPCS, 1995.
Busby A, Dolk H, Collin R, Barry Jones R, Winter R. Compiling a national register of babies born with anophthalmia/microphthalmia in England 1988-94. Arch Dis Child Fetal Neonatal Ed 1998;79: F168-73.
Dolk H, Armstrong B, Vrijheid M, Stone D, Rankin J, Abramsky L, et al. A study of the geographical variation in overall rates of congenital abnormalities and the rates of specific abnormalities. Report to Department of Health, 2003. www.eurocat.ulster.ac.uk/pubdata (accessed 16 Nov 2004).
Abramsky L, Chapple J, Golightly S, Noble J, Roberts S, Williamson-North H. North Thames perinatal public health annual report—2001 data. North Thames Perinatal Public Health Unit, Kennedy Galton Centre, Northwick Park Hospital, 2003.
Northern Region Steering Group. Fetal abnormality: an audit of its recognition and management. Arch Dis Child 1992;67: 770-4.
Wellesley D, Styles L. Wessex antenatally detected anomalies register: 10 years of data, 1994-2003. Southampton: Wessex Clinical Genetics Service, Princess Anne Hospital, 2003.
Boyd PA, Chamberlain P Report of the Oxford congenital anomaly register 1991-2001. Oxford: National Perinatal Epidemiology Unit, 2003
Carstairs V, Morris R. Deprivation and health in Scotland. Health Bull (Edin) 1991;48: 162-75.
Tan KH, Kilby MD, Whittle MJ, Beattie BR, Booth IW, Botting BJ. Congenital anterior wall defects in England and Wales 1987-93: retrospective analysis of OPCS data BMJ 1996;313: 903-6.
Vrijheid M, Armstrong B, Dolk H, van Tongeren M, Botting B. Risk of hypospadias in relation to maternal occupational exposure to potential endocrine disrupting chemicals. Occup Environ Med 2003;60: 543-50.
Botting B. The impact of more complete data from Wales on the national congenital anomaly system. Health Stat Q 2000;5: 7-9.
Elliott P, Briggs D, Morris S, de Hoogh C, Hurt C, Jensen TK, et al. Risk of adverse birth outcomes in populations living near landfill sites. BMJ 2001;323: 363-8.
National Down syndrome cytogenetic register 2002 annual report. London: NDSCR, 2003. www.smd.qmul.ac./wolfson/ndscr/NDCSRreport.pdf (accessed 3 Nov 2004).
Hey K, O'Donnell M, Murphy M, Jones N, Botting B. Use of local neural tube defect registers to interpret national trends. Arch Dis Child 1994;71: F198-F202.(P A Boyd, clinical geneticist1, B Armstr)
Correspondence to PA Boyd patricia.boyd@perinat.ox.ac.uk
Abstract
A major congenital anomaly affects 2-3% of newborn babies. Congenital anomalies are an important cause of fetal, neonatal, and child mortality and morbidity, accounting for 21% of perinatal and infant deaths in the United Kingdom in 2001.1 Monitoring of anomalies is vital to identify possible clusters and trends and to address concerns about putative environmental teratogens. The importance of registering the type and number of congenital anomalies has been recognised for many years; in Birmingham, information on congenital anomalies has been collected since 1949. A national register for England and Wales, now called the National Congenital Anomaly System (NCAS), was proposed by the minister of health in 1963 after the thalidomide "epidemic," and this is run by the Office for National Statistics (ONS; www.statistics.gov.uk).2
Notification of anomalies in live and stillbirths to NCAS is voluntary and usually done through a standard paper form (SD56) filled in by midwives, health visitors, and other health professionals. Local congenital anomaly registers have been set up alongside the NCAS, partly to deal with the known under-ascertainment3-6 and partly to meet local needs and research needs, such as the audit of prenatal diagnosis and research into putative teratogens. Some 50% of births in England are covered by local congenital anomaly registers. These registers are all members of the British Isles Network of Congenital, Anomaly Registers (BINOCAR, www.statistics.gov.uk/binocar/) and belong to EUROCAT (the European Network of Congenital Anomaly Registers, www.eurocat.ulster.ac.uk). In contrast to the NCAS, these local registers record fetuses terminated for fetal anomaly. Ascertainment of cases to the local registers is actively sought and provided from multiple sources, such as cytogenetic and postmortem reports; prenatal diagnosis; and paediatric, neonatal, orthopaedic, and surgical units.
As part of a study of the geographical variation in the prevalence of birth defects7 we measured the extent to which the under-ascertainment in the NCAS data compared with four local registers, varied by defect, geographical area, and socioeconomic deprivation, during the period 1991-9. We also assessed the impact of the absence of data on pregnancies terminated because of fetal anomaly from the national data set.
Methods
Ascertainment by NCAS was 40% (42% for non-chromosomal anomalies and 34% for chromosomal anomalies) when terminations of pregnancy were excluded from register data. This varied markedly by register, hospital catchment area (not shown), and congenital anomaly subgroup (table, fig 1); all variations were significant (P < 0.001).
Fig 1 Percentage of all defects in the NCAS compared with local registers, by register
When terminations of pregnancy were included in register data, ascertainment of cases by NCAS (compared with the registers) was 27% (31% for non-chromosomal anomalies and 19% for chromosomal anomalies; table) and again varied markedly by register (fig 1), hospital catchment areas within register areas (fig 2), and congenital anomaly subgroup; all variations were significant (P < 0.001).
Fig 2 Ascertainment ratios to NCAS by hospital catchment area for all cases. (a) Termination of pregnancy excluded. (b) Termination of pregnancy cases included. Ascertainment ratios are shown for each hospital catchment, with 95% confidence intervals. Catchments with fewer than 10 anomalies identified by either source were omitted, to avoid distracting imprecise ratios
The lowest ascertainment was for neural tube defects (11% when terminations are in the local register data, 68% when terminations are removed) and cardiac defects (12% with termination included and 13% with termination excluded from local data). The highest ascertainment to NCAS was for cleft lip (75% and 83% with termination included and excluded from local data, respectively) and for limb reduction defects (73% and 88% with terminations included and excluded from local data, respectively).
Figure 1 shows the variation in ascertainment in NCAS across local register areas. The highest ascertainment to NCAS was from the regions covered by NTW and WANDA and the lowest from the OXCAR area. However, ascertainment from the different locations was not consistent when individual defects were compared. For example, ascertainment for cleft lip (overall ascertainment 75%) was highest (91%) from NorCAS area and lowest (44%) from OXCAR. Ascertainment of atresias and fistulas of the digestive system (overall ascertainment 40%) was highest from WANDA and OXCAR areas (57% and 69%) and lowest from NTW and NorCAS (33% and 37%).
The proportion of cases ascertained by NCAS varied little by area deprivation (fig 3), certainly less than could be explained by chance (P > 0.1). This pattern did not change on adjustment for differences in ascertainment by registry and hospital catchment area.
Fig 3 Ascertainment by National Congenital Anomaly System compared with local registers, by area deprivation
Discussion
Macfarlaine A, Mugford M. Birthcounts. Statistics of pregnancy and childbirth. London Stationery Office, 2000.
Congenital malformations statistical notifications 1994. London: Stationery Office, 1997. (Series MB3, No 10.)
Payne JN. Limitations of the OPCS congenital malformation notification systems illustrated by examination of congenital malformations of the cardiovascular systems in districts within the Trent region. Public Health 1992;106: 437-48.
Knox EG, Armstrong EH, Lancashire R. The quality of notification of congenital malformations. J Epidemiol Community Health 1984;38: 296-305.
Office for Population Censuses and Surveys. The OPCS monitoring scheme for congenital malformations occasional paper 43. A review by a working group of the registrar general's medical advisory committee. London: OPCS, 1995.
Busby A, Dolk H, Collin R, Barry Jones R, Winter R. Compiling a national register of babies born with anophthalmia/microphthalmia in England 1988-94. Arch Dis Child Fetal Neonatal Ed 1998;79: F168-73.
Dolk H, Armstrong B, Vrijheid M, Stone D, Rankin J, Abramsky L, et al. A study of the geographical variation in overall rates of congenital abnormalities and the rates of specific abnormalities. Report to Department of Health, 2003. www.eurocat.ulster.ac.uk/pubdata (accessed 16 Nov 2004).
Abramsky L, Chapple J, Golightly S, Noble J, Roberts S, Williamson-North H. North Thames perinatal public health annual report—2001 data. North Thames Perinatal Public Health Unit, Kennedy Galton Centre, Northwick Park Hospital, 2003.
Northern Region Steering Group. Fetal abnormality: an audit of its recognition and management. Arch Dis Child 1992;67: 770-4.
Wellesley D, Styles L. Wessex antenatally detected anomalies register: 10 years of data, 1994-2003. Southampton: Wessex Clinical Genetics Service, Princess Anne Hospital, 2003.
Boyd PA, Chamberlain P Report of the Oxford congenital anomaly register 1991-2001. Oxford: National Perinatal Epidemiology Unit, 2003
Carstairs V, Morris R. Deprivation and health in Scotland. Health Bull (Edin) 1991;48: 162-75.
Tan KH, Kilby MD, Whittle MJ, Beattie BR, Booth IW, Botting BJ. Congenital anterior wall defects in England and Wales 1987-93: retrospective analysis of OPCS data BMJ 1996;313: 903-6.
Vrijheid M, Armstrong B, Dolk H, van Tongeren M, Botting B. Risk of hypospadias in relation to maternal occupational exposure to potential endocrine disrupting chemicals. Occup Environ Med 2003;60: 543-50.
Botting B. The impact of more complete data from Wales on the national congenital anomaly system. Health Stat Q 2000;5: 7-9.
Elliott P, Briggs D, Morris S, de Hoogh C, Hurt C, Jensen TK, et al. Risk of adverse birth outcomes in populations living near landfill sites. BMJ 2001;323: 363-8.
National Down syndrome cytogenetic register 2002 annual report. London: NDSCR, 2003. www.smd.qmul.ac./wolfson/ndscr/NDCSRreport.pdf (accessed 3 Nov 2004).
Hey K, O'Donnell M, Murphy M, Jones N, Botting B. Use of local neural tube defect registers to interpret national trends. Arch Dis Child 1994;71: F198-F202.(P A Boyd, clinical geneticist1, B Armstr)