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Improving case ascertainment of congenital anomalies: findings from a prospective birth cohort with detailed primary care record linkage
  1. Chrissy Bishop1,
  2. Neil Small1,
  3. Dan Mason2,
  4. Peter Corry2,
  5. John Wright2,
  6. Roger C Parslow2,3,
  7. Alan H Bittles4,5,
  8. Eamonn Sheridan6
  1. 1 Faculty of Health Studies, University of Bradford, Bradford, UK
  2. 2 Bradford Institute for Health Research, Bradford Royal Infirmary, Bradford, UK
  3. 3 Division of Epidemiology and Biostatistics, University of Leeds, Leeds, UK
  4. 4 Centre for Comparative Genomics, Murdoch University, Perth, Western Australia, Australia
  5. 5 School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
  6. 6 Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, UK
  1. Correspondence to Chrissy Bishop; c.bishop1{at}


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.

  • comm child health
  • congenital abnorm
  • data collection

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  • Contributors CB, RP, JW and NS conceived the idea and designed the protocol, with advice from DM on primary care database linkage and conversion of Read codes. ES, RP and PC reviewed all anomalies reported. CB did the statistical analysis, which was overseen by RP with additional interpretation by AHB. All authors contributed to and have approved the final analyses.

  • Funding This work was supported by a Bradford University studentship, in conjunction with the White Rose Consortium, and the National Institute for Health Research, Collaboration for Leadership in Applied Health Research and Care Yorkshire and Humber programme ‘Healthy Children Healthy Families Theme’ (IS-CLA-0113–10020). The sponsors of this study had no role in the study design, data collection, analysis or interpretation or writing of the report.

  • Competing interests None declared.

  • Ethics approval Ethics approval for the cohort study was provided by Bradford Local Research Ethics Committee (reference 06/Q1202/48).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Additional information is available on request from the corresponding author

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