Prevalence of the Syndrome of Bronchial Hyperreactivity and Bronchial Asthma among Children of the South Ural Region

This study is dedicated to determining the prevalence of the syndrome of bronchial hyperreactivity and bronchial asthma among children of the South Ural Region. The work was carried out within the framework of Phase II of the international ISAAC program and includes epidemiological and clinical-instrumental examination of children with various respiratory and allergic symptoms. Special attention is given to the relationship between symptoms of bronchial obstruction, allergic rhinitis, and atopic dermatitis in anamnesis and the development of bronchial asthma.

During the study, external respiratory function was evaluated using provocative and pharmacological bronchodilator tests. Bronchial hyperreactivity indicators and the frequency of bronchial asthma detection were compared among children residing in areas with different ecological characteristics in the South Ural Region. The results confirm the presence of underdiagnosis of bronchial asthma among children of the South Urals and identify high-risk groups for disease development.

Allergic diseases currently occupy one of the leading positions among other forms of pathology (Chuchalin A.G., 2002; Malcolm R. Sears, 1997; Jarvis D., et al., 1996). Bronchial asthma (BA), as a manifestation of respiratory allergy, belongs to the most prevalent diseases. Approximately 4 to 8% of the world's population suffers from this pathology, with the figure among children being 5–10% (Balabolkin I.I., 2004; Drozhdev M.E. et al., 2002; Chuchalin A.G., 1999, 2002; Global Strategy, 2002; Revyakina V.A., 2001; E von Mutius, 2000).

In recent decades, a marked increase in the morbidity and severity of bronchial asthma among children has been widely observed, particularly in developed industrialized countries (Mizernitsky Yu.L., 2003; Geppe N.A. et al., 2003; Luss L.V., 2002; Knazheskaya N.P., 2001; Kulichenko T.V. et al., 2000; Ronmark E. et al., 1999). In the Russian Federation, official data on the prevalence of allergic pathology continue to be based primarily on statistical reports of medical referrals and, unfortunately, do not reflect the true situation regarding this problem (Balabolkin I.I., 2004; Zaitseva O.V., 2004; Fedoskova T.G., 2002; Kagano S.Yu. et al., 1993).

The most reliable and comparable data on the prevalence of allergic pathology in many countries of the world have been obtained through the internationally recognized ISAAC program (International Study of Asthma and Allergies in Childhood), which currently serves as the global standard for epidemiological study of bronchial asthma and other allergic diseases in children (Lin RS et al., 2001; Ramadour M. et al., 2000; Hirsch T. et al., 1999; Ronmark E. et al., 1999).

Data from epidemiological studies conducted under the ISAAC program indicate delayed diagnosis of bronchial asthma, particularly in cases of mild disease severity. At present, there are no absolute criteria for diagnosing mild asthma (Chuchalin A.G., 2002; Kagano S.Yu., 2000; Lukina O.F. et al., 1999; Fedoseev G.B., 1995). A distinctive feature of prior ISAAC studies was that the authors typically stopped at the first phase, without conducting a second phase encompassing objective examination, bronchial provocation tests, skin tests for atopy, determination of total and specific IgE levels, and other investigations. The second phase enables a clinical interpretation of epidemiological characteristics of the studied pediatric cohorts.

An important component in the pathogenesis of bronchial obstruction is increased sensitivity and reactivity of the receptor apparatus. Various respiratory diseases are characterized by different frequencies and degrees of impairment of bronchial sensitivity and reactivity (Lukina O.F., 2003; Glybin A.S., 1999; Struchkov L.V. et al., 1996; Clement R.F., 1994; Rees J., 1994). It is known that a significant proportion of children suffering from atopic dermatitis (AD) and allergic rhinitis (AR) exhibit latent impairments of bronchial patency, the emergence of which may precede the development of bronchial asthma (Molokova A.V., Kaznacheeva L.F., 2004; Balabolkin I.I., 2003; Geppe N.A., 2002; Revyakina V.A. et al., 2001). It has been demonstrated that asymptomatic bronchial hyperreactivity (BHR) is associated with an increased risk of subsequent asthma development (Boulet L-P., 2003; Holgate S.T., 2001).

Currently, bronchial asthma is frequently regarded as an environmentally dependent disease, with a well-established relationship between its prevalence and the level of industrial atmospheric pollution (Mizernitsky Yu.L., 2002; Luss L.V., 2002; Chuchalin A.G., 1999; Khaitov P.M. et al., 1998; Kurukulaaratchy RJ et al., 2003; Benedicte Leynaert et al., 2001; Rutherford Shannon BSc et al., 2000). At the same time, the mechanisms of pathogenic influence of xenobiotics on the organism remain insufficiently studied, and their contribution to disease development remains unproven and debated.

Aim of the study

To determine the prevalence of the syndrome of bronchial hyperreactivity and bronchial asthma among children of the South Ural Region presenting with symptoms of "bronchial obstruction," "allergic rhinitis and atopic dermatitis," based on epidemiological and clinical-instrumental investigations (Phase II ISAAC).

Research objectives

1. To determine the prevalence of the syndrome of bronchial hyperreactivity in children with a history of "bronchial obstruction" symptoms identified during Phase I of the ISAAC study.

2. To establish the prevalence of the syndrome of bronchial hyperreactivity in children with a history of "allergic rhinitis and atopic dermatitis" symptoms identified during Phase I of the ISAAC study.

3. To establish the prevalence of the syndrome of bronchial hyperreactivity and bronchial asthma among children of the South Urals depending on the ecological characterization of their place of residence.

4. To identify the prevalence of bronchial asthma in groups of children with a history of "bronchial obstruction" symptoms and "allergic rhinitis and atopic dermatitis" symptoms identified during Phase I of the ISAAC study.

Scientific novelty

For the first time, Phase II of the ISAAC study was conducted among children of the city of Chelyabinsk and Chelyabinsk Oblast.

The prevalence of bronchial hyperreactivity and bronchial asthma was identified in groups of children with a history of "bronchial obstruction" symptoms and "allergic rhinitis and atopic dermatitis" symptoms, formed based on ISAAC questionnaire data.

The prevalence of bronchial hyperreactivity and bronchial asthma was established among children residing in settlements of the South Ural Region with varying ecological characteristics.

Practical significance

The results of Phases I and II of the ISAAC study confirm the presence of underdiagnosis of bronchial asthma among children of the South Urals.

Study of external respiratory function with provocative and pharmacological bronchodilator tests in children with a history of "bronchial obstruction" symptoms and "allergic rhinitis and atopic dermatitis" symptoms allows a differentiated assessment of the likelihood of developing the syndrome of bronchial hyperreactivity and bronchial asthma in these groups.

The frequency of bronchial asthma formation is significantly higher in the group of children with "bronchial obstruction" symptoms over the past year, regardless of the ecological characterization of the district of residence.

Implementation of research results

The research results have been implemented in the practice of allergist-immunologists at the MUZ DP of the Central, Leninsky, and Kurchetov Districts of Chelyabinsk and the city of Satka, and are used in lectures and practical sessions at the Department of Pediatric Diseases No. 1 of Chelyabinsk State Medical Academy.

Dissertation defense

The main provisions of the dissertation were presented at the IV Congress of Pulmonologists of the Ural Federal District "Current Problems of Pulmonology in the Urals" (Chelyabinsk, 2004) and the III Final Scientific and Practical Conference of Young Scientists of Chelyabinsk State Medical Academy (Chelyabinsk, 2005).

Eight printed works have been published on the dissertation topic.

Main provisions submitted for defense

By the frequency of external respiratory function abnormalities, groups of children with a history of "bronchial obstruction" symptoms and "allergic rhinitis and atopic dermatitis" symptoms occupy an "intermediate" position between the group of children who had no symptoms of asthma and allergy and the group of children who indicated a diagnosis of bronchial asthma based on ISAAC questionnaire data.

The number of newly identified cases of bronchial asthma increases from the group of children with no history of "asthma and allergy" symptoms, to the group with a history of "AR and AD," and further to the group of children who reported episodes of "bronchial obstruction," suggesting the possibility of identifying high-risk groups for BA development.

No differences were found in the assessment of bronchial hyperreactivity between different ecological districts of the South Urals; however, upon analysis of individual tests and external respiratory function indicators, respiratory mechanics abnormalities were more frequently detected in ecologically disadvantaged areas.

No statistically significant differences were found in the prevalence of bronchial asthma diagnosis among children residing in settlements of the South Ural Region with different ecological characteristics.