Prevalence and comorbidity of allergic diseases in preschool children

Original article Korean J Pediatr 2013;56(8):338-342 http://dx.doi.org/10.3345/kjp.2013.56.8.338 eISSN 1738-1061•pISSN 2092-7258 Korean J Pediatr Prevalence and comorbidity of allergic diseases in preschool children Hyeong Yun Kim, MD1, Eun Byul Kwon, MD1, Ji Hyeon Baek, MD2, Youn Ho Shin, MD2, Hye Yung Yum, MD3, Hye Mi Jee, MD2, Jung Won Yoon, MD2, Man Yong Han, MD2 1 Department of Pediatrics, Bundang Jesaeng General Hospital, Seongnam, 2Department of Pediatrics, CHA University College of Medicine, Seongnam, 3Department of Pediatrics, Seoul Medical Center, Seoul, Korea Purpose: Allergic disease and its comorbidities significantly influence the quality of life. Although the comorbidities of allergic diseases are well described in adult populations, little is known about them in preschool children. In the present study, we aimed to assess the prevalence and comorbidity of allergic diseases in Korean preschool children. Methods: We conducted a cross-sectional study comprising 615 Korean children (age, 3 to 6 years). Symptoms of allergic diseases were assessed using the Korean version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire that was modified for preschool children. Comorbidities of allergic diseases were assessed by ‘In the last 12 months, has your child had symptoms?’. Results: The prevalence of symptoms of asthma, allergic rhinitis, and atopic dermatitis as recorded using the ISAAC questionnaire, within the last 12 months was 13.8%, 40.7%, and 20.8%, respectively. The symptom rates of allergic conjunctivitis, food allergy, and drug allergy were 14.8%, 10.4%, and 0.8%, respectively. The prevalence of allergic rhinitis in children with asthma was 64.3% and that of asthma in children with allergic rhinitis was 21.6%. The prevalence of rhinitis in children with conjunctivitis was 64.8% and that of conjunctivitis in children with rhinitis was 23.6%. Conclusion: The prevalence of current rhinitis in our preschool children is shown to be higher than that previously reported. Allergic conjunctivitis is closely associated with asthma and allergic rhinitis. However, further studies are warranted to determine the prevalence and effects of these comorbidities on health outcomes in preschool children. Corresponding author: Man Yong Han, MD Department of Pediatrics, CHA Bundang Medical Center, CHA University College of Medicine, 59 Yatap-ro, Bundang-gu, Seongnam 463-712, Korea Tel: +82-31-780-6262 Fax: +82-31-780-5239 E-mail: Received: 5 March, 2012 Revised: 22 February, 2013 Accepted: 8 May, 2013 Key words: Asthma, Allergic rhinitis, Preschool child, Prevalence, Comorbidity Introduction Asthma and allergic diseases are among the most common disorders in children, and their prevalence has increased in most parts of the world1,2). The International Study of Asthma and Allergies in Childhood (ISAAC) found that the prevalence of allergic diseases in children aged 6 and 14 years varies significantly from 0.3% to 20.5%, but is gradually increasing3,4). A National Survey on the prevalence of symptoms of allergic diseases on Korean children aged 6 and 14 years has demonstrated that the prevalence of asthma and allergic diseases is on the rise5). However, little data are available on the prevalence of allergic diseases in preschool children. There are distinct epidemiological parallels between atopic dermatitis, asthma, and allergic rhinitis. Generally, childhood eczema precedes the development of asthma and allergic rhinitis in the so-called atopic march6). Furthermore, asthma and allergic rhinitis 338 http://dx.doi.org/10.3345/kjp.2013.56.8.338 Copyright © 2013 by The Korean Pediatric Society This is an open-access article distributed under the terms of the Creative Commons Attribution NonCommercial License (http://creativecommons.org/ licenses/by-nc/3.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Korean J Pediatr 2013;56(8):338-342 frequently coexist7-10). In adult studies, allergic rhinitis is found in 30% to 90% of patients with asthma9,10). Thus, the clinical signs of asthma and allergic diseases follow each other and can cooccur11,12). Although the comorbidities of allergic diseases have been well described in adult and children populations, less is known about such conditions in preschool children7,8,13). A few previous studies have indicated that comorbidities in Western countries differ from those in Korean populations14,15). Little data are avail able in preschool children to evaluate prevalence of asthma, allergic rhinitis, atopic dermatitis, allergic conjunctivitis, food allergy, drug allergy, and comorbidities. In addition, assessing the comorbidities of allergic diseases may help clinicians reco gnize symptoms of allergic diseases early and prompt treatment. Therefore, we hypothesized that asthma and other allergic diseases might coexist in preschool children and the prevalence of allergic diseases in our children differed from those of other regions. The aim of the present study was to determine the prevalence of allergic diseases and their comorbidities in preschool children using the standard ISAAC questionnaire, and to compare our results with previous studies. Materials and methods 1. Subjects The source population comprised 629 preschool children aged 3 to 6 years who were recruited from randomly selected 5 daycare centers in Seongnam from April to June of 2009. We used the Korean version of ISAAC questionnaire and the questionnaires were distributed and collected through each daycare center. Their parents filled out the ISAAC questionnaire at home and returned it within few days. A total of 615 subjects (97.7%) returned the questionnaires with valid answers. The study was approved by the ethics committee of the CHA University, and written informed consent was obtained from the parents of all participating children. 2. Methods 1) Questionnaires The Korean version of the ISAAC questionnaire16) was used to determine the presence of symptoms of wheezing, allergic rhinitis, atopic dermatitis, allergic conjunctivitis, food allergy, and drug allergy. Questions regarding body mass index (BMI), a family history of allergic disease, secondhand smoking, and pet ownership were also asked. 2) Definition of allergic diseases In this study, we estimated the prevalence of allergic diseases, such as, asthma, allergic rhinitis and atopic dermatitis, based on positive answers to written questions per Hong et al.17): 1) ‘Has your child ever had symptoms?’ (symptom, ever); 2) ‘In the last 12 months, has your child had symptoms?’ (symptom, last 12 months); 3) ‘Has your child been diagnosed by a physician as ever having the disorder?’ (diagnosis, ever); and 4) ‘In the last 12 months, Has your child been treated by a physician for the disorder?’ (treatment, last 12 months). “Current” was defined as a positive response to ‘symptom, last (...truncated)