The Association between the Occurrence of Asthma and Antecedents of Exposure to Environmental Tobacco Smoke in the Previous Year in Children: An Incidence-Density Study.

Hayat Bentouhami,Lidia Casas,Joost Weyler

doi:10.3390/ijerph19052888

Abstract

In previous studies, the strength of the association between childhood asthma and environmental tobacco smoke (ETS) differed depending on the way ETS was assessed and the type of study conducted. We investigated the relationship between asthma occurrence in children and recent exposure to ETS based on an incidence-density study driven by the explicit formulation of a theoretical design. Additionally, we assessed whether the relationship is modified by perinatal ETS exposure and parental inhalation atopy. The event was conceptualized as ‘first doctor’s diagnosis of asthma’. Population time was probed by sampling population moments. Exposure to ETS was conceptualized as recent exposure (1 year prior to diagnosis or at sampling) and perinatal exposure (in utero and/or during the first year of life). Thirty-nine events and 117 population moments were included. There was no indication for effect modification by perinatal exposure to ETS or parental inhalation atopy. After adjustment for confounding, an association was observed between occurrence of a first asthma diagnosis and recent ETS exposure: incidence-density ratio 4.94 (95% confidence interval 1.21, 20.13). Asthma occurrence in children is associated with recent exposure to ETS, and this association seems not to be modified by perinatal ETS exposure or parental inhalation atopy.

Highlights

According to the Global Burden of Disease (GBD) study, asthma affected approximately 262 million people and caused 461,000 deaths in 2019 [1,2]
The aim of the study led to the following research question: What is the relationship between asthma occurrence in children and antecedents of recent exposure to environmental tobacco smoke (ETS) (1 year prior to diagnosis), and is this relationship modified by perinatal exposure to ETS and parental inhalation atopy?
In order to be able to answer the research question, a theoretical design was formulated: current incidence of asthma in children as a function of prior exposure (1 year prior) to ETS taking into account effect modification by perinatal exposure to ETS and parental inhalation atopy and adjusting for confounding by age, sex, parental education and daycare attendance, and in case of no indication for effect modification for perinatal exposure to ETS and parental inhalation atopy

Summary

Introduction

According to the Global Burden of Disease (GBD) study, asthma affected approximately 262 million people and caused 461,000 deaths in 2019 [1,2]. Asthma is the most common chronic disease [1]. Asthma is a heterogeneous disease which is (usually) characterized by chronic airway inflammation and defined by a history of respiratory symptoms (wheezing, shortness of breath, chest tightness and cough). These symptoms can vary over time and in intensity, and occur together with variable expiratory airflow limitation [3]. The underlying causal mechanisms in the development of asthma are still not completely understood. There is general consensus among experts that the inception and persistence of asthma is influenced by gene–environment interactions and that a ‘window of opportunity’ exists during the perinatal period (i.e., in utero and during the first year of life) when the immune system is still developing and environmental risk factors have the opportunity to influence this development, and as a consequence may influence the onset of asthma [3]

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Conclusion