Asthma and allergy: a worldwide problem of meanings and management?

Descriptive epidemiology of asthma

Towards prevention

Considerable variation in the prevalence of childhood asthma and allergic conditions has been shown in previous studies. These differences may in part be attributable to methodological problems in defining childhood asthma and wheezing illnesses. However, the results of recent surveys using identical study instruments suggest that the variation in the distribution of the disease is real. In western societies serial prevalence studies have furthermore shown an increasing trend in the prevalence of childhood asthma and airway hyperresponsiveness. A concomitant increase in the prevalence of hay fever and atopic eczema has been reported by others. Moreover, hospitalization rates for childhood wheezing illnesses have increased in affluent countries suggesting that indeed the morbidity from these causes has increased in the last decades. Interestingly, areas of low prevalence of asthma and atopic conditions have recently been identified in developing countries and in Eastern Europe. In Eastern Germany where drastic changes towards westernization of living conditions have occurred after reunification an increase in the prevalence of hay fever and atopic sensitization has been documented over the last 4-5 years in children aged between 9 and 10 years of age. The prevalence of asthma and airway hyperresponsiveness, however, remained virtually unchanged in this age group. These children spent their first 3 years of life under socialist living conditions and were exposed to a western lifestyle only after their third birthday. Therefore, environmental factors may affect an individual's inherited susceptibility for the development of asthma and hay fever at different ages inducing changes in the prevalence of atopic diseases in populations in a time- and age-dependent way.

What drives the allergic march?

Roles of pollution in the prevalence and exacerbations of allergic diseases in Asia

BackgroundThere has been research about the prevalence and risk factors of eczema, hay fever, and asthma in children, but little is known about these conditions in adults in China.ObjectivesTo explore the prevalence of adult eczema/atopic dermatitis (AD) and its risk factors in northern China.MethodsA cluster sampling randomized population-based survey was conducted using a face-to-face questionnaire combined with skin prick tests of ten common aeroallergens including nine pollen allergens and Dermatophagoides pteronyssinu (Dp) allergen. The questionnaire was designed by specialists and included questions on the prevalence of eczema, hay fever, and asthma, socioeconomic risk factors, family history of atopy and environmental exposures. The prevalence of eczema with asthma and/or hay fever (EAH) was applied as a proxy of AD in this study.ResultsOverall, 2096 subjects were enrolled and completed the study. The prevalence of eczema was 15.7% (95% CI 14.3–17.4), while the prevalence of hay fever and asthma were 20.6% (95% CI 18.9–22.4) and 6.5% (95% CI 5.5–7.6), respectively. In particular, the prevalence of EAH was 5.1% (95% CI 4.4–7.0). The prevalence of eczema and EAH was significantly associated with younger age, atopy family history, high education level, urbanization, and antibiotic overuse (P < 0.05, logistic regression). The sensitization rate was higher in EAH compared with eczema (48.2% vs 41.0%, P = 0.018), with weed pollen sensitization being the most common. Subjects with two or more concomitant allergic diseases had increased risk of eczema and EAH (P < 0.001). Allergen sensitization increased the risk of eczema and EAH (P < 0.001, both).ConclusionsAdult eczema and EAH are prevalent in northern China under high pollen exposure. Socioeconomic and environmental factors affected the prevalence of adult AD in China. Dp had a particular impact on the prevalence of eczema/AD in the grassland region.

Objective: To estimate trends between 1972–6 and 1996 in the prevalences of asthma and hay fever in adults.Design: Two epidemiological surveys 20 years apart. Identical questions were asked about asthma,...

The prevalence of asthma and atopy in schoolchildren from Porto Alegre, Brazil, has plateaued

To compare the prevalence of asthma, hay fever and atopy in Asian immigrants in Melbourne with that in Australian-born non-Asians and Australian-born Asians, and to investigate the association of these conditions with atopic status, length of stay in Australia and IgE levels in Asian immigrants. We performed a cross-sectional study by telephone interviews, using standard questionnaire items on respiratory and allergic symptoms. A random sample of 636 recent Asian immigrants of ethnic Chinese origin, 109 Australian-born Asians and 424 Australian-born non-Asians were selected from the 1991 Melbourne Telephone Directory, using a presumptive surname list. Skin tests to determine atopic status were performed on 269 Asian immigrants and 167 of these also had serum levels of total and specific IgE estimated. In the under 20 years age group the prevalence of wheeze or asthma ever was higher in Australian-born non-Asians and Australian-born Asians than in Asian immigrants (P < 0.001), and the prevalence of hay fever was higher in Asian immigrants and Australian-born Asians than in Australian-born non-Asians. In those older than 20 years, hay fever was almost twice as common in Asian immigrants as in Australian-born non-Asians (P < 0.001 for 20-40 years age group; P < 0.01 for > 40 years). The prevalence of hay fever and, to a lesser degree, asthma in Asian immigrants increased significantly with length of stay in Australia, independent of age at arrival, sex and atopic status (trend test: P < 0.001 for hay fever; P = 0.05 for asthma). Atopy was more common in Asian immigrants and Australian-born Asians than in Australian-born non-Asians (P < 0.001) and was very strongly associated with both hay fever and asthma, irrespective of length of stay. Pollen and mite sensitivities were more common in Asian subjects (twice as common for Asian-born and 1.5 times for Australian-born) than non-Asian subjects (P < 0.01). Among Asian immigrants, elevated total IgE level (> 100 IU/mL) was strongly associated with a history of hay fever (P < 0.01) and wheeze or asthma ever (P < 0.05), atopy (P < 0.001) and the presence of specific IgE antibodies to grass pollen, dust mite, cockroach and Ascaris antigens (P < 0.05 for all). We found substantial differences in the prevalence of asthma, hay fever and atopy between Asian immigrants, Australian-born Asians and non-Asians. The prevalence of hay fever and asthma in Asian immigrants was strongly associated with length of stay in Australia, suggesting that environmental factors are important in the pathogenesis of these diseases.

Asthma is a chronic disease in childhood that affects virtually every facet of a patient's life and school activities, and every member of the family. It imposes a substantial socio-economic burden and demands many special considerations. Despite frequent updates on the current concepts of asthma management and its natural history, the prevalence of childhood asthma has increased worldwide in recent decades. More recently, however, comparable data on the prevalence of childhood asthma showed little change or a plateau in the incidence in some countries, including Korea. For example, the prevalence of asthma symptoms in the past 12 months in 13- to 14-year-old school children was 8.7% in Korea, compared with 8.8% in the entire Asia-Pacific region.1 As part of collaborative international studies in 1995, 2000, and 2005, national and regional cross-sectional surveys of asthma were performed using the Korean versions of the International Study of Asthma and Allergies in Childhood (ISAAC) written and video questionnaires. The ISAAC involves epidemiological studies enthusiastically carried out by the contributing members of the Korean Academy of Pediatric Allergy and Respiratory Diseases. There is little doubt regarding the prevalence of asthma determined by the ISAAC using the Korean versions of the written and video questionnaires.2,3 The lifetime prevalence of wheezing fell from 19.3% in 1995 to 14.4% in 2000 in Korea, whereas the number of affected children increased during this period in other countries.4 In addition, the prevalence of wheezing in the previous 12 months decreased from 10.5% in 1995 to 5.2% in 2000 in Korea.4 In contrast to the increased prevalence of asthma in 13- to 14-year-old children in Japan, the prevalence decreased in Korea. This decrease was partially attributable to a greater awareness of symptoms, early diagnosis, and proper management of childhood asthma by caregivers and physicians, following a successful Nationwide Asthma Campaign. In this issue, Kwon et al.5 showed that there was little change in asthma prevalence between 2005 Lessons Learned from the Prevalence of Childhood Asthma in Korea Ha-Baik Lee Department of Pediatrics, Hanyang University College of Medicine, Seoul, Korea (13.0%) and 2008 (11.7%) based on the results of an epidemiological study conducted in metropolitan Seoul in 2008, using the same methodologies. A comparison of asthma prevalence among sequential phases of the ISAAC revealed similar trends. The rate for any diagnosis of asthma ever was 8.7% in 1995, 9.4% in 2000, 7.6% in 2005, and 7.9% in 2008. The prevalence of asthma treatments during the previous 12 months was 3.5% in 1995, 3.3% in 2000, 3.0% in 2005, and 2.7% in 2008. Several risk factors are important in the development of asthma in children, and although some childhood asthmatics 'outgrow' the disease, asthma more commonly persists throughout adulthood. Both genetic susceptibility and environmental factors contribute to the development and persistence of asthma symptoms in children.6 Arruda et al.7 reported that risk factors for asthma include early sensitization to airborne allergens, a history of atopic dermatitis or allergic rhinitis, maternal smoking during pregnancy, passive smoking, lower respiratory infections, air pollution, and various genetic polymorphisms. The risk factors for asthma symptoms in Korean children are similar to those identified in Phase Three of the ISAAC; these include body mass index, passive smoking, and pets.8 In this paper, striking risk factors for asthma development were male gender; a history of atopic dermatitis, allergic rhinitis, or viral bronchiolitis; parental asthma; use of antibiotics during infancy; exposure to molds in the house during infancy; and moving to a new house, especially in genetically susceptible individuals.5 These results offer an opportunity to better understand asthma development. In general, medical research has made progress in many human diseases, and advances in asthma research have reduced the toll of the disease. Nevertheless, much work remains. One common goal is to refocus attention on the prevalence and risk factors based on epidemiological studies of childhood asthma. However, efforts must still be directed toward better prevention and management of the disease, with a goal of minimizing the potential deterioration of lung function. It is important to educate the public and the medical community regarding more effective preventive measures and therapies for asthma.

ABSTRACTBackground: There is a lack of information on the prevalence, severity and risk factors of asthma, rhinitis and eczema in Chinese children. Objective: To establish baseline data for a major longitudinal study of factors affecting asthma, rhinitis and eczema in a large group of children from the industrialized city of Shijiazhuang, China. Methods: We used the International Study of Asthma and Allergies in Childhood questionnaire and studied 10 338 children, ages 6–18, from Shijiazhuang. Results: The prevalence of childhood asthma, rhinitis and eczema is 1.2%, 13.5% and 11.8%, respectively. Boys had higher prevalence of these conditions than girls and younger children had higher prevalence of asthma and eczema but lower prevalence of rhinitis than older children. Breastfed children had lower prevalence of asthma and rhinitis, but not eczema, than non-breastfed children. Overweight children had higher prevalence of asthma and rhinitis than those who were not overweight. Children exposed to paternal smoking had higher prevalence of rhinitis and eczema than those not exposed; children exposed to pets had higher prevalence of asthma and rhinitis than those not exposed. Conclusions: The prevalence of asthma in this study group is low, but the prevalence of rhinitis is high, and could be considered a major public health problem. The prevalence of asthma, rhinitis and eczema is generally higher in boys and younger children generally have higher prevalence of asthma and eczema but lower prevalence of rhinitis. Exposure to pets is a risk factor for rhinitis, being overweight is a risk factor for asthma and rhinitis, and exposure to parental smoking is a risk factor for asthma, rhinitis and eczema in these children.

This is the first multi-center epidemiological study on the prevalence of childhood asthma in Serbia and Montenegro. The International Study of Asthma and Allergies in Childhood (ISAAC) phase 3 is a large epidemiological multinational and multicentric study on the prevalence of asthma, allergic rhinitis and eczema in children. The 12-month period prevalence of asthma, allergic rhinitis and eczema was calculated using an ISAAC phase 3 questionnaire for two age groups: 6-7 years old and 13-14 years old. In the 13 485 children from five study centers who responded to the questionnaire, the prevalence for childhood asthma ranged from 2.5% to 9.8%, for allergic rhinoconjunctivitis (hay fever) from 4.6% to 21%, and for eczema from 8.2% to 17.2%. The prevalence of current wheezing was high in both age groups (16.5% and 12.4% respectively). The prevalence of asthma is higher in 6-7 years old school children in the urban and largest cities of Belgrade and Nis, and in 13-14 years old children in Podgorica. The prevalence of asthma, allergic rhinitis and eczema in the school children of Serbia and Montenegro seems similar to that of other countries in Central and South-Eastern Europe.

Hypothesis: decreased use of pediatric aspirin has contributed to the increasing prevalence of childhood asthma.

Ethnic origin has been reported to affect the prevalence of atopic diseases in several studies in different parts of the world. However, little is known about the prevalence of asthma and atopy in immigrants living in Europe. The objective of this study was to evaluate the prevalence of asthma and atopy in Turkish children living in Germany and to investigate the role of ethnic origin on the development of asthma and atopy in this population. In a cross-sectional survey the prevalence of physician-diagnosed asthma, atopy, skin-prick tests and bronchial hyperresponsiveness (BHR) to cold dry air challenge was assessed in 7,445 school children aged 9-11 yrs, living in Munich, south Germany. Questionnaires were distributed to the parents for self-completion and children underwent skin prick tests and cold air hyperventilation challenge. The Turkish children showed a significantly lower prevalence of asthma (5.3 versus 9.4%, p<0.05) than their German peers. Furthermore, atopy, as assessed by skin prick tests (24.7 versus 36.7%, p<0.001) and BHR (3.9 versus 7.7%, p<0.001), was less common in Turkish children. In multivariate regression models controlling for potential explanatory factors, Turkish origin still showed a significantly lower risk of developing asthma, atopic sensitization and BHR. The prevalence of childhood asthma was therefore shown to be lower in Turkish children living in Germany than in Turkey. These findings suggest that the lower prevalence of asthma and allergy in Turkish children living in Germany might be attributable to a selection bias affecting the parents of these children, as healthy individuals may have decided to come to Germany for work.

After a substantial increase in the prevalence of atopic disease in Europe, recent studies indicate that a plateau has been reached. However, variation across countries and age groups exists. We studied the prevalence and time trends of asthma and allergic disease among schoolchildren in Austria, a country with traditionally low rates of asthma, hay fever, and eczema. As part of the International Study of Asthma and Allergies in Childhood (ISAAC), symptoms and physician diagnoses of asthma and allergic disease of 13,399 Austrian children aged 6-7 yr and 1516 children aged 12-14 yr were surveyed between 1995 and 1997. A similar survey was conducted between 2001 and 2003. Among children aged 6-7 yr, significant increases were seen in the prevalence of physician-diagnosed asthma (+16%; p = 0.013), hay fever (+22%; p < 0.001), and eczema (+37%; p < 0.001) between 1995 and 2003. These changes were paralleled by an increase in the prevalence of symptoms typical for hay fever (itchy eyes and runny nose), but not by an increase in wheeze. Among children aged 12-14 yr, the lifetime prevalence of diagnosed asthma increased by 32%, of hay fever by 19%, and of eczema by 28% (all, p < 0.001). These changes were paralleled by increases in the prevalence of wheezing as documented by both questions before and after a video showing wheezing children but not by symptoms typical for hay fever such as itchy eyes and runny nose. In conclusion, in Austria, contrary to other European countries, the prevalence of asthma and allergic disease increased among schoolchildren. Additional studies are needed to continue monitoring the dynamics of the prevalence of asthma and allergic disease in Austria and to explore trends in their risk factors.