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Childhood asthma prevalence: cross-sectional record linkage study comparing parent-reported wheeze with general practitioner-recorded asthma diagnoses from primary care electronic health records in Wales
  1. Lucy J Griffiths1,
  2. Ronan A Lyons2,
  3. Amrita Bandyopadhyay2,
  4. Karen S Tingay2,
  5. Suzanne Walton1,
  6. Mario Cortina-Borja3,
  7. Ashley Akbari2,
  8. Helen Bedford1 and
  9. Carol Dezateux1,4
  1. 1 Life Course Epidemiology and Biostatistics, UCL Great Ormond Street Institute of Child Health, London, UK
  2. 2 Farr Institute, Swansea University Medical School, Swansea, UK
  3. 3 Clinical Epidemiology, Nutrition and Biostatistics, UCL Great Ormond Street Institute of Child Health, London, UK
  4. 4 Centre for Primary Care and Public Health, Barts and the London School of Medicine and Dentistry, Queen Mary University London, London, UK
  1. Correspondence to Professor Carol Dezateux; c.dezateux{at}


Introduction Electronic health records (EHRs) are increasingly used to estimate the prevalence of childhood asthma. The relation of these estimates to those obtained from parent-reported wheezing suggestive of asthma is unclear. We hypothesised that parent-reported wheezing would be more prevalent than general practitioner (GP)-recorded asthma diagnoses in preschool-aged children.

Methods 1529 of 1840 (83%) Millennium Cohort Study children registered with GPs in the Welsh Secure Anonymised Information Linkage databank were linked. Prevalences of parent-reported wheezing and GP-recorded asthma diagnoses in the previous 12 months were estimated, respectively, from parent report at ages 3, 5, 7 and 11 years, and from Read codes for asthma diagnoses and prescriptions based on GP EHRs over the same time period. Prevalences were weighted to account for clustered survey design and non-response. Cohen’s kappa statistics were used to assess agreement.

Results Parent-reported wheezing was more prevalent than GP-recorded asthma diagnoses at 3 and 5 years. Both diminished with age: by age 11, prevalences of parent-reported wheezing and GP-recorded asthma diagnosis were 12.9% (95% CI 10.6 to 15.4) and 10.9% (8.8 to 13.3), respectively (difference: 2% (−0.5 to 4.5)). Other GP-recorded respiratory diagnoses accounted for 45.7% (95% CI 37.7 to 53.9) and 44.8% (33.9 to 56.2) of the excess in parent-reported wheezing at ages 3 and 5 years, respectively.

Conclusion Parent-reported wheezing is more prevalent than GP-recorded asthma diagnoses in the preschool years, and this difference diminishes in primary school-aged children. Further research is needed to evaluate the implications of these differences for the characterisation of longitudinal childhood asthma phenotypes from EHRs.

  • paediatric asthma
  • asthma epidemiology
  • asthma in primary care

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  • Contributors Study design: CD. Data curation and processing: AA, KST, AB, RAL, SW, LJG. Data Analysis: LJG, MC-B, CD. Draft manuscript: CD, LJG. Manuscript review: AA, AB, HB, MC-B, CD, LJG, RAL, KST, SW. Supervision: CD. Funding acquisition: CD, RAL.

  • Funding This work was supported by the Wellcome Trust (grant no. 087389/B/08/Z). CD, RAL and AA are supported by awards establishing the Farr Institute of Health Informatics Research from the MRC, in partnership with Arthritis Research UK, the British Heart Foundation, Cancer Research UK, the Economic and Social Research Council, the Engineering and Physical Sciences Research Council, the National Institute of Health Research, the National Institute for Social Care and Health Research (Welsh Assembly Government), the Chief Scientist Office (Scottish Government Health Directorates) and the Wellcome Trust (MRC grants MR/K006584/1 and MR/K006525/1, respectively). RAL is also funded by the Asthma UK Centre for Applied Research (AUK-AC-2012-01). The Millennium Cohort Study is funded by grants to the Centre for Longitudinal Studies at the Institute of Education from the Economic and Social Research Council and a consortium of government departments. The study sponsors played no part in the design, data analysis and interpretation of this study, and the writing of the article or the decision to submit the paper for publication; the authors’ work was independent of their funders.

  • Competing interests None declared.

  • Ethics approval Ethical approval for the fourth survey of the Millennium Cohort Study was received from the Northern and Yorkshire Research Ethics Committee (07/MRE03/32). Access to linked SAIL data was approved by the SAIL Information Governance Review Panel (project 232/410).

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

  • Data sharing statement Millennium Cohort data can be accessed from the UK Data Archive (

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