International Study of Asthma and Allergies in Childhood

The International Study of Asthma and Allergies in Childhood (ISAAC) was developed to exploit the potential of epidemiology to investigate the causes of asthma and allergies in children through standardised methodology and international collaboration.

The aims of the ISAAC project are:

1. to describe the prevalence and severity of asthma, allergic rhinitis and atopic dermatitis in children in different study centres and to make comparisons between data from different study centres;
2. to establish baseline values for estimating temporal changes in the prevalence and severity of these diseases;
3. to provide a framework for further aetiological research into the importance of lifestyle, environment, genetics and medical care in the manifestation of these diseases.

The global study will be conducted in three phases. Phase I was developed to determine the prevalence and severity of asthma, allergic rhinitis and atopic dermatitis in children in as many defined populations as possible using simple but valid methods.

The aim of Phase II is to confirm the results of Phase I in selected populations with additional objective parameters (including lung function, atopic sensitisation) and to gain more precise knowledge of the risk factors for these diseases.

Phase III repeats the prevalence studies from Phase I after at least five years in order to quantify the changes over time in the prevalence and severity of asthma and allergies in children worldwide.

The results of the Phase I studies, which were conducted in a standardised manner in 155 study centres on all five continents in a total of 463,801 children aged 13-14 years and 304,796 children aged 6-7 years, show great variability in the prevalence of the disease. The centres with the highest asthma rates were in the UK, New Zealand, Australia, Canada and the USA, while the lowest rates were found in China, Greece, Albania and Indonesia. Differences in living and environmental conditions play an important role in the large fluctuations in the incidence of the disease. These are currently being investigated in more detail in so-called ecological analyses and in phase II of the ISAAC project.

Prevalence and Determinants of Asthma and Allergies in Children in Europe: International Coordination and Data Centre of the International Study of Asthma and Allergies in Childhood (ISAAC Study, Phase II)

The aim of Phase II of ISAAC is to explain the major international differences in the incidence of asthma and allergies in children found in Phase I. The coordinator of this research project, which is funded by the European Union, is Stephan Weiland.

In more than 25 study centres in 15 European countries, selected according to the results of Phase I, at least 1,000 children aged 9-11 years will be examined using skin prick tests, other skin tests, blood tests and lung function measurements with bronchial provocation as well as detailed parental questionnaires and indoor measurements in the home.

The influences of early intrauterine and neonatal factors, infections and vaccinations as well as socio-economic conditions, physical activity, diet and, last but not least, indoor air pollution and indoor exposure to allergens and endotoxins are analysed as possible causes. In addition, the importance of genetic factors will be analysed and the role they play in different populations and in explaining differences in the incidence of asthma and allergies between populations will be investigated. A third focus of this research project is to investigate the interactions between genetic influences and the environmental factors mentioned above. The aim is to gain new insights into the causes of asthma and allergies in children in order to improve the possibilities for successful preventive measures.

National joint project: Asthma and allergies in childhood and adolescence (German ISAAC Phase II study)

The national joint project is integrated into the worldwide ISAAC project (International Study of Asthma and Allergies in Childhood). It is a multi-centre project involving the Clinic for Paediatrics in Dresden, the Clinic for Paediatrics in Leipzig, the Dr. von Hauner Children's Hospital in Munich and the Federal Environment Agency in Berlin. The Institute of Epidemiology and Social Medicine at the University of Münster is the coordination and data centre for the clinical centres involved in the joint project.

The aim of the study is to collect nationally and internationally comparable data on the frequency of asthma, allergic rhinitis and neurodermatitis in children and to gain new insights into the causes of these diseases.

Data collection began in September 1995 and was completed in July 1997. Cross-sectional studies were carried out in two East German areas (Dresden, Leipzig) and one West German urban area (Munich) during the 1995/1996 school year. Approximately 3,000 fourth-graders and 3,000 first-graders were analysed at each study site.

Parental questionnaires and medical examinations of the children (measurement of lung function with bronchial provocation, skin prick test, determination of immunological blood parameters, etc.) were used as data collection instruments.

As part of a subsequent, embedded case-control study on the aetiology of bronchial asthma, the parents of 300 children each in Dresden and Munich were interviewed and the exposure to allergens and pollutants in the children's homes was measured. Funding by the Federal Ministry of Education and Research (BMBF) ended in February 1999 and further analyses of the extensive data set are currently being carried out and prepared for publication.

Determination of frequency, severity and temporal trends of skin and respiratory symptoms in childhood and adolescence as part of Phase III of the International Study of Asthma and Allergies in Childhood (ISAAC) in Münster