Lifetime Exposure to Cigarette Smoking and the Development of Adult-onset Atopic Dermatitis

From The British Journal of Dermatology

C.H. Lee; H.Y. Chuang; C.H. Hong; S.K. Huang; Y.C. Chang; Y.C. Ko; and H.S. Yu
Abstract

Adult-onset atopic dermatitis (AD) has recently been recognized as a distinct disease entity, but its risk factors have not yet been clearly defined.
Although gestational and perinatal exposure to tobacco smoking may be associated with the development of classic AD, the association between active/passive smoking and adult-onset AD remains controversial.
Objectives
To determine if exposure to smoking, including environmental tobacco smoke (ETS), is associated with the risk of adult-onset AD.
Methods
Tobacco smoking and exposure to ETS were measured in a case–control association analysis in 83 patients with physician-diagnosed adult-onset AD and 142 age- and sex-matched controls.
Results
Multiple logistic regression analyses showed that, among the potential environmental risk factors, both current and ever smoking were significant risk factors for adult-onset AD [odds ratio (OR) 4·994 and 3·619, respectively], compared with never smoking. Also, packs per year was significantly associated with adult-onset AD (OR 1·058, 95% confidence interval 1·028–1·089), suggesting a lifelong cumulative risk in current smokers. Moreover, nonsmokers with adult-onset AD reported significantly more exposure to ETS.
Conclusions
Early and/or current exposure to cigarette smoking may contribute cumulatively to the development of adult-onset AD.
Exposure to ETS in childhood is associated with the development of adult-onset AD. Adults should be discouraged from smoking to prevent adult-onset AD in themselves and their family members.

Introduction

Atopic dermatitis (AD) is characterized by chronic relapses of dermatitis in patients with a personal or family history of atopic disease.
The onset of AD commonly occurs in early childhood, although symptoms can persist or begin in adulthood.
Depending on the age of onset, AD preferentially affects specific locations on the skin. For example, AD usually affects flexural areas with lichenification in children, while adult-onset AD preferentially affects the face and hands.
Taking into consideration the familial tendency towards specific antigen sensitization to AD, a complex interplay of genetic and environmental factors may play an important role in the pathogenesis of AD.
Several important environmental factors are considered risks for AD, including food allergens, aeroallergens and infectious agents such as Staphylococcus aureus
This study focuses on tobacco smoking and its possible contribution to AD.

Although the development of AD was thought to occur in very early childhood, recently several groups from Japan, Australia and the U.S.A. have described adult-onset AD. Both classical AD and adult-onset AD cases present with intensive itching. However, adult-onset AD differs from classical AD by preferentially affecting the face, hands and nonflexural areas and a prurigo-like pattern occurs more frequently in adult-onset AD. Except for a study in Italy demonstrating the outcome of patch tests in patients,no risk factors have been defined for adult-onset AD.

Although there is an increased risk of asthma from gestational and perinatal exposure to smoking,studies investigating the influence of such exposure on the development of AD show mixed results.Wang et al. reported that exposure to smoke during pregnancy might increase the risk of childhood AD, but results from other reports are inconsistent with these findings. A molecular investigation found blood IgE to be elevated in infants born to mothers who smoked, and there are reports that active smoking might increase IgE in asthmatic patients.Evidence that exposure to environmental tobacco smoke (ETS) during early childhood predisposes the child to later AD has been documented,[12,13] but the association between current smoking and the development of AD remains unclear. Using mail-in questionnaires from a study population of 40 888 subjects, Bo et al. reported an association between active smoking and the development of AD in Norway [odds ratio (OR) 1·31], but the association did not reach significance. In the U.K., self-reported mail-in questionnaires from 150 patients with AD also suggested a similar but insignificant association with smoking (OR 1·1).
In France, an analysis of 14 578 subjects reported a significant association between active smoking and AD in adolescents (OR 1·8).
Although the approaches varied considerably, from very large surveys with no clinical data to smaller clinical studies, these studies consistently indicate an association of active smoking with AD.
The studies, however, did not specifically address the association of active smoking and adult-onset AD, probably because they were studying cases of classical AD in which the age of onset precedes the onset of smoking behaviour.
Moreover, self-reported questionnaire surveys are subject to inaccurate diagnosis for AD and a low response rate, and they lack a physician diagnosis.
Smoking more than 10 cigarettes per day is reported to increase the risk of hand eczema, also suggesting a potential link between smoking and adult-onset AD.
Thus, the current evidence consistently suggests a link between tobacco smoking and AD, but a more thorough investigation is required to support the link. Moreover, how adult-onset AD is associated with smoking has never been addressed.
In this hospital-based, case–control study we investigated whether exposure to tobacco smoke, including current smoking, ever smoking and ETS, is associated with the risk of adult-onset AD. It represents the first study to investigate directly the possible association between ETS exposure and adult-onset AD.