TY - JOUR T1 - Improving case ascertainment of congenital anomalies: findings from a prospective birth cohort with detailed primary care record linkage JF - BMJ Paediatrics Open DO - 10.1136/bmjpo-2017-000171 VL - 1 IS - 1 SP - e000171 AU - Chrissy Bishop AU - Neil Small AU - Dan Mason AU - Peter Corry AU - John Wright AU - Roger C Parslow AU - Alan H Bittles AU - Eamonn Sheridan Y1 - 2017/11/01 UR - http://bmjpaedsopen.bmj.com/content/1/1/e000171.abstract N2 - Background Congenital anomalies (CAs) are a common cause of infant death and disability. We linked children from a large birth cohort to a routine primary care database to detect CA diagnoses from birth to age 5 years. There could be evidence of underreporting by CA registries as they estimate that only 2% of CA registrations occur after age 1 year.Methods CA cases were identified by linking children from a prospective birth cohort to primary care records. CAs were classified according to the European Surveillance of CA guidelines. We calculated rates of CAs by using a bodily system group for children aged 0 to <5 years, together with risk ratios (RRs) with 95% CIs for maternal risk factors.Results Routinely collected primary care data increased the ascertainment of children with CAs from 432.9 per 10 000 live births under 1 year to 620.6 per 10 000 live births under 5 years. Consanguinity was a risk factor for Pakistani mothers (multivariable RR 1.87, 95% CI 1.46 to 2.83), and maternal age >34 years was a risk factor for mothers of other ethnicities (multivariable RR 2.19, 95% CI 1.36 to 3.54). Education was associated with a lower risk (multivariable RR 0.78, 95% CI 0.62 to 0.98).Conclusion 98% of UK CA registrations relate to diagnoses made in the first year of life. Our data suggest that this leads to incomplete case ascertainment with a further 30% identified after age 1 year in our study. Risk factors for CAs identified up to age 1 year persist up to 5 years. National registries should consider using routine data linkage to provide more complete case ascertainment after infancy. ER -