Confounding with familial determinants affects the association between mode of delivery and childhood asthma medication: a national cohort study
2013 (English)In: Allergy, Asthma & Clinical Immunology, ISSN 1710-1484, E-ISSN 1710-1492, Vol. 9, no 1, 14- p.Article in journal (Refereed) Published
BACKGROUND: Mode of delivery may affect the risk of asthma but the findings have not been consistent and factors shared by siblings may confound the associations in previous studies. METHODS: The association between mode of delivery and dispensed inhaled corticosteroid (ICS) (a marker of asthma) was examined in a register based national cohort (n=199 837). A cohort analysis of all first born children aged 2-5 and 6-9 years was performed. An age-matched sibling-pair analysis was also performed to account for shared genetic and environmental risk factors. RESULTS: Analyses of first-borns demonstrated that elective caesarean section was associated with an increased risk of dispensed ICS in both 2-5 (adjusted odds ratio (aOR)=1.19, 95% confidence interval (CI) 1.09-1.29) and 6-9 (aOR=1.21, 1.09-1.34) age groups. In the sibling-pair analysis, the increased risk associated with elective caesarean section was confirmed in 2-5 year olds (aOR=1.22, 1.05-1.43) but not in 6-9 year olds (aOR=1.06, 0.78-1.44). Emergency caesarean section and vacuum extraction had some association with dispensed ICS in the analyses of first-borns but these associations were not confirmed in the sibling-pair analyses. CONCLUSIONS: Confounding by familial factors affects the association between mode of delivery and dispensed ICS. Despite this confounding, there was some evidence that elective caesarean section contributed to a modestly increased risk of dispensed ICS but only up to five years of age.
Place, publisher, year, edition, pages
BioMed Central, 2013. Vol. 9, no 1, 14- p.
asthma, caesarean section, child, epidemiology, inhaled corticosteroids, sib pair analysis
Environmental Health and Occupational Health Immunology in the medical area
IdentifiersURN: urn:nbn:se:umu:diva-85028DOI: 10.1186/1710-1492-9-14ISI: 000332406200001PubMedID: 23590822OAI: oai:DiVA.org:umu-85028DiVA: diva2:691082