title: Detection and investigation of temporal clusters of congenital anomaly in Europe: seven years of experience of the EUROCAT surveillance system.
abstract: Detection and investigation of congenital anomaly clusters is one part of surveillance to detect new or changing teratogenic exposures in the population. The EUROCAT (European Surveillance of Congenital Anomalies) cluster monitoring system and results are described here. Monitoring was conducted annually from 2007 to 2013 for 18 registries covering an annual birth population up to 0.5 million births. For each registry and 72 anomaly subgroups, the scan "moving window" technique was used to detect clusters in time occurring within the last 2 years based on estimated date of conception. Registries conducted preliminary investigations using a standardised protocol to determine whether there was cause for concern, and expert review was used at key points. 165 clusters were detected, a rate of 3.4% of all 4823 cluster tests performed over 7 years, more than expected by chance. Preliminary investigations of 126 new clusters confirmed that 35% were an unusual aggregation of cases, while 56% were explained by data quality or diagnostic issues, and 9% were not investigated. For confirmed clusters, the registries' course of action was continuing monitoring. Three confirmed clusters continued to grow in size for a limited period in subsequent monitoring. This system is best suited to early detection of exposures which are sudden, widespread and/or highly teratogenic, and was reassuring in demonstrating an absence of a sustained exposure of this type. Such proactive monitoring can be run efficiently without overwhelming the surveillance system with false positives, and serves an additional purpose of data quality control.
authors.affiliation: EUROCAT Central Registry, WHO Collaborating Centre for Surveillance of Congenital Anomalies, Institute for Nursing and Health Research, Ulster University, Shore Rd, Newtownabbey, BT370QB, UK. h.dolk@ulster.ac.uk.
authors.forename: Helen
authors.initials: H
authors.lastname: Dolk
authors.affiliation: EUROCAT Central Registry, WHO Collaborating Centre for Surveillance of Congenital Anomalies, Institute for Nursing and Health Research, Ulster University, Shore Rd, Newtownabbey, BT370QB, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Loane
authors.affiliation: Department Public Health and Primary Care, Trinity College Dublin, Dublin, Ireland.
authors.forename: Conor
authors.initials: C
authors.lastname: Teljeur
authors.affiliation: Biomedical Computing Ltd, St. Leonards-on-Sea, UK.
authors.forename: James
authors.initials: J
authors.lastname: Densem
authors.affiliation: EUROCAT Central Registry, WHO Collaborating Centre for Surveillance of Congenital Anomalies, Institute for Nursing and Health Research, Ulster University, Shore Rd, Newtownabbey, BT370QB, UK.
authors.forename: Ruth
authors.initials: R
authors.lastname: Greenlees
authors.affiliation: EUROCAT Central Registry, WHO Collaborating Centre for Surveillance of Congenital Anomalies, Institute for Nursing and Health Research, Ulster University, Shore Rd, Newtownabbey, BT370QB, UK.
authors.forename: Nichola
authors.initials: N
authors.lastname: McCullough
authors.affiliation: Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK.
authors.forename: Joan
authors.initials: J
authors.lastname: Morris
authors.affiliation: Provinciaal Instituut voor Hygiëne, Antwerp, Belgium.
authors.forename: Vera
authors.initials: V
authors.lastname: Nelen
authors.affiliation: Unit of Epidemiology, CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Bianchi
authors.affiliation: Department Public Health and Primary Care, Trinity College Dublin, Dublin, Ireland.
authors.forename: Alan
authors.initials: A
authors.lastname: Kelly
mesh_terms: D000013:Congenital Abnormalities / Q000453:epidemiology*; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D011159:Population Surveillance / Q000379:methods*; D011247:Pregnancy; D012042:Registries / Q000706:statistics & numerical data*; D013029:Space-Time Clustering
keywords: Clusters; Congenital anomalies; Surveillance
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