The relationship between atopic dermatitis

The relationship between atopic dermatitis and exposure to antibiotics in early life

The increased use of antibiotics has raised the question of their relationship to atopic dermatitis. This study investigated the antibiotic exposure among Swedish children during pregnancy and in the first year of life.

MWENYA MUBANGA is PhD and Postdoctoral researcher at Department of Medical Epidemiology and Biostatistics at Karolinska Institutet in Sweden.

Atopic dermatitis is a persistent skin disease that commonly begins in childhood. It is characterized by intense itching, eczematous and irritating dryness of the skin. Although a predisposition to atopic dermatitis may be inherited, there have been inconsistent findings in studies investigating the relationship between atopic dermatitis and common environmental factors, including exposure to antibiotics. Theory of antibiotic exposure and risk of atopic dermatitis

The challenges in conducting research that investigates the use of antibiotics, specifically in early childhood, include studying small sample sizes, the use of homogenous populations, failure to consider different types of antibiotics and insufficient information about both maternal and childhood factors.

CONCLUSION: Our findings are interesting in view of the increased use of antibiotics around the world. Further understanding is needed as to how exactly antibiotics affect the pathways that activate the onset of atopic dermatitis. It has been suggested that the effect of antibiotics may vary depending on how antibiotics act on the skin, the gut, duration of use, their mode of action and route of administration. It may also be important to see if the use of multiple drugs at the same time has a different effect than single dosed agents.2

Against this background, we recently published a scientific article in JAMA network open1 using a nationwide study to test the theory that the use of antibiotics during pregnancy or during the first year of life is associated with an increased risk of atopic dermatitis.

We included all children born in Sweden between March 2006 and December 2012 and followed them up to the study end of December 2015. This study is possible in Sweden because individual-level information on every resident is collected in centralized administrative registers that can be used for research. The registers contain information such as mother-child pairs, age, area of residence, income, migration, prescribed medications and health outcomes.

Additionally, we extended this investigation to a smaller population of sibling-pairs that we identified via the birth registers. This was done in order to help us determine whether results obtained in the general population were related to environmental and familial factors, including genetic predisposition, or could be mainly attributed to antibiotic exposure. Exposure to antibiotics or environmental factors?

In the total population which comprised more than 700,000 singleton children aged between 3 and 9 years, we found that exposure to antibiotics during pregnancy or the first year of life was associated with a higher risk of atopic dermatitis during early childhood. However, when we accounted for familial and other environmental factors by sibling analysis, we found that exposure to antibiotics in pregnancy was not associated with a greater risk of atopic dermatitis. However, exposure during the first year of life was still associated with a moderate risk of atopic dermatitis. Furthermore, when we consider the association of the number of doses prescribed to each mother during the study period, there was a greater risk of atopic dermatitis in those who were prescribed more doses than those with few ones. However, this was not observed when we accounted for familial and environmental factors.

References:

1. Mubanga M, Lundholm C, D’Onofrio BM, et al. Association of Early Life Exposure to Antibiotics With Risk of Atopic Dermatitis in Sweden. JAMA Netw Open. 2021;4(4): e215245-e45. DOI:10.1001/jamanetworkopen.2021.5245. 2. Grada A, Bunick CG. Spectrum of Antibiotic Activity and Its Relevance to the Microbiome. JAMA Netw Open. 2021;4(4): e215357. DOI:10.1001/jamanetworkopen.2021.5357.