Breastfeeding may lower risk of childhood asthma exacerbations
Breastfeeding in children with asthma was associated with a reduced risk of asthma exacerbations, especially in children with a family history of asthma, according to the PACMAN* study.
Compared with asthmatic children who were never breastfed, those who had been breastfed were 45 percent less likely to experience asthma exacerbations at age 4–12 years (adjusted odds ratio [OR], 0.55; p=0.01), after adjusting for age and eczema. The proportion of children with asthma exacerbations were also significantly lower in those who were ever-breastfed vs never-breastfed (9 vs 15 percent; p=0.007). [Pediatr Allergy Immunol 2017;doi:10.1111/pai.12760]
When the analysis was stratified by family asthma history, the association between asthma exacerbations and breastfeeding was only significant in children with a positive history (OR, 0.34; p=0.001), but not in those without (OR, 1.08; p=0.82).
“[T]he relation might be explained by the influence of breastfeeding on the immune system. Changes in the composition and activity of the gut microbiome in early life can influence the immune system and these changes might indirectly lead to changes in asthma later in life," said study principal investigator Prof Anke-Hilse Maitland-van der Zee from the Department of Respiratory Medicine at the University of Amsterdam in the Netherlands.
Stratifying the analysis by the duration of breastfeeding, the researchers found that breastfeeding for up to 6 months was significantly associated with a lower risk of asthma exacerbations in children (OR, 0.48; p=0.01) while the association was no longer significant for a breastfeeding duration of ≥6 months (OR, 0.71; p=0.20).
However, no association was found between breastfeeding and the likelihood for poor asthma control as assessed by Asthma Control Questionnaire (ACQ)-6 after controlling for family asthma history (OR, 1.04; p=0.83). The results remained even after stratifying the analysis by duration of breastfeeding.
The study involved 960 children (mean age 8.4 years, 62 percent boys, 74 percent breastfed) who were using regular asthma medication for the past 2 years in the Netherlands. Breastfeeding exposure and duration were self-reported by the parents based on questionnaire. Asthma exacerbations in the previous year and asthma control based on ACQ-6 within the last week of visit were also documented.
“Although in our study breastfeeding was shown to be a protective factor for asthma exacerbations, it is still unclear whether there is a causal relation between breastfeeding and asthma exacerbations,” said Maitland-van der Zee.
“[An] important limitation is the cross-sectional nature of our study. When exposure and outcome are measured at one moment (or period) in time, the risk of reverse causality would be a major problem … The optimal design for this study is a prospective longitudinal design,” said Maitland-van der Zee and co-authors.
They also added that questionnaire-based data are subjected to recall bias and suggested further studies be conducted to confirm the association and understand the underlying mechanisms.