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Understanding Social Inequalities in Childhood Asthma: Quantifying the Mediating Role of Modifiable Early-Life Risk Factors in Seven Birth Cohorts in the EU Child Cohort Network
26 Pages Posted: 26 Mar 2024
More...Abstract
Background: Children growing up in disadvantaged socioeconomic circumstances (SECs) have an increased risk of asthma. This study aimed to increase our understanding of the pathways to inequalities in asthma and potential targets for intervention by i) examining how the social patterning of asthma and its early-life risk factors varies across country contexts; ii) quantifying the mediation of observed inequalities by early-life risk factors.
Methods: We used data for 107,884 mother-child dyads from seven European birth cohorts across six countries. Maternal education was the primary exposure measure of early-life SECs. The outcome was current asthma at school-age (4-12y). Inequalities were examined using multivariable regression and random effects meta-analysis. The mediating effects of early-life risk factors (maternal smoking during pregnancy, adverse birth outcomes and breastfeeding duration) were examined using counterfactual mediation analysis.
Results: In meta-analysis, children of mothers with low/medium versus high education had a 17% (95% CI 8%-27%, I2=21·6%) increased risk of asthma. Cohort-specific risk ratios ranged between 1·07 (0·97–1·18, DNBC-Denmark) and 1·61 (1·08–2·40, EDEN-France). The early-life risk factors were similarly socially patterned, but with greater heterogeneity across cohorts (I2 range=66·2-95·3%). The mediation analysis suggested that these factors play a relevant role in mediating observed inequalities (proportion mediated range: 0·08-0·72).
Interpretation: There was a consistent tendency for children from less advantaged SECs to be at greater risk of asthma in the European cohorts examined. Our results suggest that public health interventions in the perinatal period may potentially reduce these inequalities.
Funding: AP was supported by a Lundbeck Foundation Postdoctoral Fellowship (R264-2017-3099) and an NHLI Research Fellowship during the study. DTR is funded by an NIHR Research Professorship (NIHR302438) and by the NIHR School for Public Health Research (PD-SPH-2015). This study has received funding from the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 733206 LifeCycle, Grant Agreement No. 824989 EUCAN-Connect).
Declaration of Interest: All authors declare no competing interests.
Keywords: childhood asthma, socioeconomic inequalities, socioeconomic circumstances, mediators, mediation analysis, early-life, cross-cohort analysis, birth cohort, lifecourse epidemiology
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