Engebretsen KA, Bager P, Wohlfahrt J, Skov L, Zachariae C, Nybo Andersen AM, Melbye M, Thyssen JP. Prevalence of atopic dermatitis in infants by domestic water hardness and season of birth: Cohort study.
J Allergy Clin Immunol 2016;
139:1568-1574.e1. [PMID:
28017882 DOI:
10.1016/j.jaci.2016.11.021]
[Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 11/02/2016] [Accepted: 11/17/2016] [Indexed: 02/04/2023]
Abstract
BACKGROUND
Atopic dermatitis (AD) appears to be more common in regions with hard domestic water and in children with a fall/winter birth. However, it is unknown whether a synergistic effect exists.
OBJECTIVE
We sought to evaluate the association between domestic water hardness and season of birth, respectively, with onset of AD within the first 18 months of life in a large Danish birth cohort.
METHODS
Of children from the Danish National Birth Cohort, 52,950 were included. History of physician-diagnosed AD and population characteristics were obtained from interviews. Birth data were obtained from the Civil Registration System, and domestic water hardness data were obtained from the Geological Survey of Denmark and Greenland. The relative prevalence (RP) of AD was calculated by using log-linear binomial regression.
RESULTS
The prevalence of AD was 15.0% (7,942/52,950). The RP of AD was 5% (RPtrend, 1.05; 95% CI, 1.03-1.07) higher for each 5° increase in domestic water hardness (range, 6.60-35.90 German degrees of hardness [118-641 mg/L]). Although the RP of AD was higher in children with a fall (RP, 1.24; 95% CI, 1.17-1.31) or winter (RP, 1.18; 95% CI, 1.11-1.25) birth, no significant interaction was observed with domestic water hardness. The population attributable risk of hard domestic water on AD was 2%.
CONCLUSION
We observed that early exposure to hard domestic water and a fall/winter birth was associated with an increase in the relative prevalence of AD within the first 18 months of life. Although the 2 exposures did not interact synergistically, a dose-response relationship was observed between domestic water hardness and AD.
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