Purpose of the Study
Surveys indicate that the prevalence of asthma and allergic diseases in children and adults is lower in eastern Europe than in western countries, suggesting that the “western lifestyle” may be an important risk factor. This study investigates time trends in the prevalence of asthma and allergic diseases among children in the eastern part of Germany in association with the tremendous changes toward western lifestyles that have occurred since unification in 1991.
In 1995–1996, 2334 (87.5%) fourth grade school children (ages 9 to 11) in Leipzig, Germany (formerly East Germany), were surveyed. Data from this cohort were compared with similar data from 1517 (81.8%) Leipzig children in 1991–1992. Substantial migration within the Leipzig population did not occur between sampling periods. The main changes affecting the population resulted from unification of Germany in 1991. Children surveyed in 1995–1996 spent their first 3 years of life under eastern living conditions and were subsequently exposed to a western lifestyle. Data from both time periods were compared with control groups in Munich, Germany, a consistent western environment.
Surveys assessing the frequency of allergic diseases (hay fever and atopic dermatitis) were sent to 44 schools of Leipzig, Germany for completion by parents of all children in the fourth grade. The children underwent skin testing to six aeroallergens (Dermatophagoides pteronyssinus, grass pollen, birch and hazel pollen, and cat and dog dander), pulmonary function testing, and morning bronchial challenge at school.
Prevalence of asthma and related symptoms did not increase between surveys. Frequency of bronchial hyperresponsiveness was virtually the same. Hay fever prevalence significantly increased from 2.3% to 5.1% between surveys. Prevalence of atopic sensitization demonstrated by skin test results increased significantly; the greatest increase occurred to pollens (14.3%–21.5% to at least one pollen) and dust mite (4.6%–8.1%). Significant changes were observed in potential risk factors: coal/wood home heating and indoor dampness decreased; while central heating, indoor gas appliances, passive cigarette smoke exposure, wall-to-wall carpeting, and cat and dog ownership all increased. First degree relatives with hay fever or eczema increased (22.7%–26.6%). First degree relatives with asthma did not increase. No significant differences were found between surveys in number of siblings, day care attendance, or breastfeeding. Increases in hay fever and atopy could not be explained by any single variable or combination of variables.
At the same time school children were exposed to a change from an eastern to a western lifestyle, allergic diseases increased while asthma prevalence remained unchanged. The changes occurred after the children were at least 3 years old. This suggests that factors associated with a “western lifestyle” can influence the development of allergic diseases even when presented after a child's third birthday. The prevalence of childhood asthma will not be similarly affected by such changes if they occur after the third birthday.
There is ongoing research and discussion regarding at what point a child develops asthma as opposed to allergic diseases in general. This study reinforces the belief that events influencing the inception of childhood asthma occur before a child is 3 years old, and that risk factors for the development of atopy can be dissociated from risk factors for the development of asthma after the age of 3 years.