Original article Are asthma and allergies in children and adolescents increasing? Results from ISAAC phase I and phase III surveys in Mu¨nster, Germany There is a wide consensus that asthma and allergies are witnessing a rising trend among children especially in western societies (1, 2). In some western countries asthma and allergies have reached alarming proportions, affect- ing up to one-third of children within the general population (3). Although most of the information about the increase in asthma and allergies come from studies on school children, recent evidence from the UK suggests that wheezing disorders, including viral wheeze, are increasing in preschool children as well, indicating a generalized trend (4). Asthma and allergies rank high on the public health agenda in many countries, highlighting the need for continuous monitoring and assessment of the dynamics of these disorders and factors that influence their trends (5). In Leipzig, Germany, surveys conducted between 1991 and 1996 showed a substantial increase in the prevalence of hay fever and atopic sensitization, but not asthma (6). While there is general agreement on the increasing trends of asthma and allergies in western countries, a lot of factors can affect our assessment of those trends such as changes in severity, changes in medical care practices, and changes of diagnostic labelling of these disorders (7, 8). On the other hand, despite extensive research devoted to studying time trends in asthma and allergies, methodological problems, especially those related to comparability and generalizability of research results, still hinder the establishment of a reliable picture about the epidemiology of asthma and allergies worldwide (9, 10). Having such reliable data is instrumental for the generation of valid concepts about possible driving forces, intervention strategies, and for the assessment of costs of asthma and allergies within the society. A considerable amount of effort, therefore, has been devoted in the last decade or so to the development and refinement of standardized, sensitive, and practical survey tools that can be widely applied to measure the burden of, and factors associated with, these disorders in different populations and to allow for reliable assessment of disease trends spatially and secularly (9–11). The International Study of Asthma and Allergies in Childhood (ISAAC) is one of the pioneer and most comprehensive efforts aiming at the creation of a reliable map on the international trends in asthma and allergies Objective: To assess time trends in symptoms of asthma, allergic rhinitis, and atopic eczema among children in Mu¨nster, Germany. Methods: Two cross-sectional surveys 5-years apart (1994/1995, 1999/2000) using ISAAC core written and video questionnaires and applying the ISAAC protocol. Two main age groups (6–7 and 13–14 year olds) were designated with information collected by parental and self-report for both age groups, respect- ively. A school-based sample of 7744 participants in the 1994/1995 survey and 7962 participants in the 1999/2000 survey was recruited. In the first and second surveys, response rates for the 6–7 year olds were 81 and 82%, respectively, while for the 13–14 year olds response rates were 94% in both. Analyses focus on the change in 12-month prevalence of symptoms of asthma, rhinitis, and eczema. Results: There is a tendency towards an increase in current symptoms for all three conditions and in both age groups, but more so among girls. Indices of diagnosis either remained the same or increased in parallel to the increase in symptoms. Indices of severity also showed a homogenous increase in the 5-year study period. Conclusions: Our study shows that symptoms of asthma, rhinitis, and eczema are increasing, reflecting a change in the morbidity of these conditions in our population. W. Maziak 1 , T. Behrens 1 , T. M. Brasky 2 , H. Duhme 1 , P. Rzehak 3 , S. K. Weiland 3 , U. Keil 1 1 Institute of Epidemiology and Social Medicine, University of Münster, Germany; 2 Department of Epidemiology, School of Public Health and Health Sciences, University of Massachusetts-Amherst, MA, USA; 3 Department of Epidemiology, University of Ulm, Ulm, Germany Key words: allergic rhinitis; asthma; cross-sectional study; eczema; ISAAC; prevalence. Ulrich Keil Institute of Epidemiology and Social Medicine University of Münster Domagkstr. 3, 48129 Münster Germany Accepted for publication 27 January 2003 Allergy 2003: 58: 572–579 Printed in UK. All rights reserved Copyright Ó Blackwell Munksgaard 2003 ALLERGY ISSN 0105-4538 572