University of Oulu

Rantala, Aino K; Magnus, Maria C; Karlstad, Øystein; Stigum, Hein; Håberg, Siri E; Nafstad, Pera; Nystad, Wenche; Jaakkola, Jouni J. K. Is the Association of Early Day Care Attendance with Childhood Asthma Explained by Underlying Susceptibility?, Epidemiology: May 2020, Volume 31, Issue 3, p 451-458, doi: 10.1097/EDE.0000000000001163

Is the association of early day care attendance with childhood asthma explained by underlying susceptibility?

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Author: Rantala, Aino K.1,2,3; Magnus, Maria C.4,5,6; Karlstad, Øystein1;
Organizations: 1Division of Mental and Physical Health, Norwegian Institute of Public Health, Oslo, Norway
2Center for Environmental and Respiratory Health Research, University of Oulu, Oulu, Finland
3Medical Research Center Oulu, Oulu, Finland
4Centre for Fertility and Health, Norwegian Institute of Public Health, Oslo, Norway
5MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, United Kingdom
6Population Health Science, Bristol Medical School, Bristol, United Kingdom
7Department of Community Medicine, University of Oslo, Oslo, Norway
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.5 MB)
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Language: English
Published: Wolters Kluwer, 2020
Publish Date: 2020-06-29


Background: Previous studies of early day care attendance and asthma development are inconsistent, which may be explained by inadequate control of confounding and effect modification. We examined the effect of early day care on the risk of asthma taking into account the underlying susceptibility to asthma.

Methods: The study included 55,404 children participating in the Norwegian Mother, Father and Child Cohort Study. Asthma at age 7 was defined by dispensed asthma medications in the Norwegian Prescription Database. We defined a disease risk score (DRS) to account for an underlying susceptibility to asthma including a range of hereditary and nonhereditary predictors of asthma. We assessed confounding and modifying effects of DRS on the association between day care and asthma.

Results: Day care before 18 months was associated with a lower risk of asthma by age 7 (adjusted risk ratio [RR] = 0.85; 95% confidence interval [CI] = 0.78, 0.92) when compared with home care. DRS modified the estimated effect of day care on asthma risk. Among the 80% of children with DRS between 0.03 and 0.16, day care was associated with a reduced asthma risk (RRs between 0.79 and 0.87), whereas among 0.5% of children with a high DRS (above 0.28), estimated effect of day care on asthma increased gradually (RR for the highest DRS 2.2; 1.0–4.9).

Conclusions: In our study, among most children, early day care was associated with reduced asthma risk at 7 years, and increased risk in a small group of children with very high underlying susceptibility to asthma.

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Series: Epidemiology
ISSN: 1044-3983
ISSN-E: 1531-5487
ISSN-L: 1044-3983
Volume: 31
Issue: 3
Pages: 451 - 458
DOI: 10.1097/EDE.0000000000001163
Type of Publication: A1 Journal article – refereed
Field of Science: 3142 Public health care science, environmental and occupational health
Funding: The Norwegian Mother, Father and Child Cohort Study is supported by the Norwegian Ministry of Health and Care Services and the Ministry of Education and Research, National Institute of Health (NIH)/National Institute of Environmental Health Sciences (NIEHS) (contract number N01-ES-75558), NIH/National Institute of Neurological Disorders and Stroke (NINDS) (grant number 1 UO1 NS 047537-01 and grant number 2 UO1 NS 047537-06A1). This work was partly supported by the Research Council of Norway Centres of Excellence funding scheme, project number 262700. This work was supported by the Medical Research Center Oulu, University of Oulu, Finland and the European Respiratory Society, Short-Term Research Fellowship (STRF) October 2018 (fellowship grants to A.K.R), and by the Norwegian Research Council (grant number 221097 to W.N.).
Copyright information: © 2020 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.