A systematic review of asthma case definitions in 67 birth cohort studies

Andrew Dubovyi; Carol Chelimo; William Schierding; Yuriy Bisyuk; Carlos A Camargo Jr; Cameron C Grant

doi:10.1016/j.prrv.2019.12.005

A systematic review of asthma case definitions in 67 birth cohort studies

Paediatr Respir Rev. 2021 Mar:37:89-98. doi: 10.1016/j.prrv.2019.12.005. Epub 2020 Feb 21.

Authors

Andrew Dubovyi¹, Carol Chelimo², William Schierding³, Yuriy Bisyuk⁴, Carlos A Camargo Jr⁵, Cameron C Grant⁶

Affiliations

¹ Centre for Longitudinal Research, University of Auckland, Auckland, New Zealand; Department of Paediatrics: Child & Youth Health, University of Auckland, Auckland, New Zealand.
² Department of Paediatrics: Child & Youth Health, University of Auckland, Auckland, New Zealand.
³ Liggins Institute, University of Auckland, Auckland, New Zealand.
⁴ Shupyk National Medical Academy of Postgraduate Education, Kyiv, Ukraine.
⁵ Massachusetts General Hospital, Harvard Medical School, Boston, USA.
⁶ Centre for Longitudinal Research, University of Auckland, Auckland, New Zealand; Department of Paediatrics: Child & Youth Health, University of Auckland, Auckland, New Zealand; General Paediatrics, Starship Children's Hospital, Auckland, New Zealand. Electronic address: cc.grant@auckland.ac.nz.

PMID: 32653466
DOI: 10.1016/j.prrv.2019.12.005

Abstract

Background: Birth cohort studies are a valuable source of information about potential risk factors for childhood asthma. To better understand similarities and variations in findings between birth cohort studies, the methodologies used to measure asthma require consideration.

Objective: To review and appraise the definitions of "asthma" used in birth cohort studies.

Methods: A literature search, conducted in December 2017 in the MEDLINE database and birth cohort repositories, identified 1721 citations published since 1990. Information extracted included: study name, year of publication, sample size, sample age, prevalence of asthma (%), study region, source of information about asthma, measured outcome, and asthma case definition. A meta-analysis evaluated whether asthma prevalence in cohorts from Europe and North America varied by the studies' definition of asthma and by their data sources.

Results: The final review included 67 birth cohorts, of which 48 (72%) were from Europe, 14 (21%) from North America, 3 (5%) from Oceania, 1 (1%) from Asia and 1 (1%) from South America. We identified three measured outcomes: "asthma ever", "current asthma", and "asthma" without further specification. Definitions of "asthma ever" were primarily based upon an affirmative parental response to the question whether the child had ever been diagnosed with asthma by a physician. The most frequently used definition of "current asthma" was "asthma ever" and either asthma symptoms or asthma medications in the last 12 months. This definition of "current asthma" was used in 16 cohorts. There was no statistically significant difference in the pooled asthma prevalence in European and North American cohorts that used questionnaire alone versus other data sources to classify asthma.

Conclusion: There is substantial heterogeneity in childhood asthma definitions in birth cohort studies. Standardisation of asthma case definitions will improve the comparability and utility of future cohort studies and enable meta-analyses.

Keywords: Asthma; Birth cohorts; Case definition; Children.

Publication types

Meta-Analysis
Review
Systematic Review

MeSH terms

Asthma* / diagnosis
Asthma* / epidemiology
Child
Cohort Studies
Humans
Parents
Prevalence
Risk Factors