Congenital eye anomaly surveillance in England and Wales. How effective is the national system? SP Shah 1,2 , B Botting 3 , A Taylor 1 , Y Abou-Rayyah 2 , J Rahi 4,5 and CE Gilbert 1 Eye (2011) 25, 1247–1249; doi:10.1038/eye.2011.207 Surveillance is defined as ‘the ongoing systematic collection, analysis, interpretation, and dissemination of data, reflecting the current status of a community or population’. 1 Congenital anomaly surveillance is important in improving the health of children, 2 and anomaly registers are well established in many high-income countries. The data collected can be used to detect geographical clustering of cases or temporal trends, both of which may indicate change in exposure to harmful environmental agents. The data also serve to inform service planning and medical/ epidemiological research. Routine reporting of surveillance data for congenital anomalies in England and Wales has been performed by the National Congenital Anomaly System (NCAS) run by the Office for National Statistics (ONS). 3 NCAS notification 3 systems were complex, but essentially, there were two tiers, (a) an original system of voluntary notifications (completed by any health professional) using the ‘SD56’ reporting form, and (b) contribution of data to the NCAS scheme by regional anomaly registers. 4 Regional anomaly registers have been established at different times, with different purposes, and with different funding arrangements. They only started to exchange data with NCAS in 1998, and they are recognised as having more complete case ascertainment 5 than the ‘SD56’ system. Congenital eye anomalies are an important cause of visual impairment in children worldwide, and are responsible for approximately 15–20% of blindness and severe visual impairment in children. 6 The majority of these anomalies have an unknown aetiology, but both genetic and environmental factors have a role. 7–9 The completeness in ascertainment of eye anomalies by NCAS has not been examined since the inclusion of regional register data. The purpose of this study was to compare the number of children identified in a national active surveillance study (ascertained through the British Ophthalmic Surveillance Unit (BOSU) 10 ) with an equivalent NCAS data set. In the BOSU study, ophthalmologists reported all children aged 16 years, newly diagnosed with anophthalmos, microphthalmos, and/or coloboma (AMC). The NCAS data set included children with the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) codes applicable to eye anomalies (ie, Q10 to Q15 11 ). The two methods of case ascertainment were compared using a method described by Rahi and Botting. 12 The comparison was restricted to children born in England and Wales between 1 January 2007 and 31 December 2007, and four identifiers were used to match children. Each child in the BOSU data set was assigned one of four outcomes, three in which the child’s identifiers matched those in the NCAS data set, and one when no match was present (Table 1). Children in the NCAS data set, but who were not in the BOSU data set, were also identified. The BOSU data set included 55 children, but only eight (14.5%) of them were listed in the NCAS data set as having an AMC code (ie, outcome 1; Table 1). The majority of children in the BOSU data set (81.8%) did not match any child in the NCAS data set. Eleven children were in the NCAS data set, but not in the BOSU data set. Children with systemic anomalies were more likely to be on the NCAS register than those Meeting presentation: The Royal College Of Ophthalmologists Annual Congress 2009 1 International Centre for Eye Health, London School of Hygiene and Tropical Medicine, London, UK 2 Moorfields Eye Hospital, London, UK 3 Office For National Statistics, London, UK 4 MRC Centre of Epidemiology for Child Health, Institute of Child Health, University College London, (UCL), London, UK 5 Ulverscroft Vision Research Group, Institute of Child Health, UCL, London, UK Correspondence: SP Shah, International Centre for Eye Health, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK. Tel: þ 44 797 366 2745; Fax: þ 44 207 958 8325; E-mail: Shaheen.shah@ lshtm.ac.uk Eye (2011) 25, 1247–1249 & 2011 Macmillan Publishers Limited All rights reserved 0950-222X/11 www.nature.com/eye EDITORIAL