RESUMEN
BACKGROUND AND OBJECTIVES: In some studies, the prevalence of hay fever and asthma has been found to be lower in children from rural areas than in children from an urban environment. We hypothesized that living on a farm might be protective against development of allergic sensitization and allergic diseases. METHODS: In a cross-sectional survey, parents of 2283 children aged 8-10 years from a mostly rural area in Austria answered a standardized questionnaire on allergic diseases and environmental factors. 1137 children performed a skin prick test to seven local allergens. RESULTS: The prevalence of hay fever (3.1 vs 10.3%, P = 0.0002), asthma (1.1 vs 3.9%, P = 0.017) and a positive skin prick reactivity to at least one of the common local allergens (18.8 vs 32.7%, P = 0. 001) was significantly lower in children living on a farm than in children from a non-farming environment. In a multivariate logistic regression model, adjusting for genetic background, parent education, living and housing conditions and dietary factors did not change the odds ratio for the association of farming and allergic sensitization. Only after including 'regular contact with livestock and poultry' into the model did the odds ratio change significantly (cOR 0.48 95% CI 0.30-0.75 to aOR 0.75 95% CI 0.37-1.52) indicating an association between regular contact with farm animals and reduced risk of atopic sensitization. CONCLUSION: Possible explanations for the lower prevalence of hay fever, asthma and allergic sensitization in children living on a farm might be the development of immunotolerance or the stimulation of TH1 cells and suppression of TH2 cells by increased exposure of farm children to microbial antigens in the stables or farmhouses.
Asunto(s)
Alérgenos/inmunología , Asma/epidemiología , Hipersensibilidad/epidemiología , Rinitis Alérgica Estacional/epidemiología , Salud Rural , Austria/epidemiología , Niño , Estudios Transversales , Femenino , Humanos , Hipersensibilidad/inmunología , Modelos Logísticos , Masculino , Análisis Multivariante , Prevalencia , Pruebas Cutáneas , Encuestas y CuestionariosRESUMEN
As part of the International Study of Asthma and Allergies in Childhood (ISAAC), the aim of our study was to determine the prevalence and severity of asthma, allergic rhinitis and eczema in Austrian schoolchildren, using an international standardised protocol. A questionnaire concerning symptoms and prior diagnosis of asthma, allergic rhinitis and eczema was completed by the parents of 3581 children aged 6-8 years. 3357 adolescents aged 12-15 years completed a written and video questionnaire at school. We also measured airway responsiveness to 4.5% saline in 519 adolescents selected from 8 randomly chosen schools. The prevalence of "wheezing in the last 12 months" was 9.9% (6-8 yrs) and 11.9% (12-15 yrs), the prevalence of "ever having had a diagnosis of asthma" was 4.4% and 6.3% in the above mentioned age groups. While 80% of the pupils had mild asthma (defined as less than 4 attacks of wheezing in the last year), 13% had moderate (4-12 attacks) and 7% had severe asthma (> 12 attacks). The 12-month prevalence of symptoms of allergic rhinitis was 13.4% (6-8 yrs) and 22.5% (12-15 yrs), a diagnosis of "hayfever at any time" was reported in 8.9% and 20.4%. The prevalence of a chronic rash in the past year was 6.9% (6-8 yrs) and 6.7% (12-15 yrs), while 10.4% and 5%, respectively, had had a diagnosis of "eczema at any time". Among 12- to 15-year-old adolescents in the entire study population (n = 3371), the calculated prevalence of bronchial hyperresponsiveness was 13.7%. The prevalence of asthma symptoms, rhinitis and eczema in Austrian schoolchildren is higher than that estimated so far and similar to other European countries except the UK. Further, the results show that the 12-month prevalence of asthma symptoms is twice as high as the lifetime prevalence of a diagnosis of asthma, suggesting that the condition is frequently underdiagnosed.
Asunto(s)
Asma/epidemiología , Dermatitis Atópica/epidemiología , Rinitis Alérgica Perenne/epidemiología , Rinitis Alérgica Estacional/epidemiología , Adolescente , Austria/epidemiología , Niño , Estudios Transversales , Femenino , Humanos , Incidencia , MasculinoRESUMEN
The results of a recent epidemiological study in Salzburg (Austria) showed that the prevalence of bronchial hyperresponsiveness (BHR) to hypertonic saline (HS) was 13.7% in schoolchildren aged 12-15 years. In the same study the prevalence of wheezing in the last 12 months was 11.9% and asthma had been diagnosed in 6.3%. To audit the relevance of these results and to offer medical treatment to children with newly diagnosed asthma, we invited all children who had had a positive bronchial provocation test (n = 99) or an abnormal lung function (defined as an FEV1 < 80% of the predicted value; n = 33) for clinical investigation. Seventy-five out of 99 children with BHR and 27/33 with an FEV1 < 80% of the predicted value attended the Respiratory Laboratory and a paediatric pulmonologist assessed the diagnosis on the basis of respiratory symptoms, physical examination and lung function test. In 26/53 children with asthma, the diagnosis was unknown. Although most children had mild asthma and normal lung function, half of these children had reduced physical activity. In 27/53 children with asthma, the diagnosis had already been known but, according to the specialist, had not been adequately treated. In 21/27 children with an FEV1 < 80% of the predicted value, this finding was clinically not relevant. The audit of the epidemiological study supported the assumption that asthma might be underdiagnosed and undertreated in our population.
Asunto(s)
Asma/epidemiología , Rinitis Alérgica Perenne/epidemiología , Rinitis Alérgica Estacional/epidemiología , Adolescente , Asma/diagnóstico , Austria/epidemiología , Pruebas de Provocación Bronquial , Niño , Estudios Transversales , Femenino , Estudios de Seguimiento , Volumen Espiratorio Forzado , Humanos , Incidencia , Masculino , Rinitis Alérgica Perenne/diagnóstico , Rinitis Alérgica Estacional/diagnósticoRESUMEN
The prevalence of asthma in school children has been reported to have increased, with wide variations between countries. To allow comparison of prevalence data, objective markers of asthma should be measured. Therefore, we assessed the prevalence of bronchial hyperresponsiveness (BHR) to hypertonic saline and its relation to asthma and allergy symptoms in 507 Austrian school children, aged 12-15 yrs in a cross-sectional, community based survey. These children were selected from 3,371 children who had answered a self-administered written questionnaire on asthma, hay fever, eczema and environmental factors. The prevalence of BHR to hypertonic saline was 14% and the majority (70%) of the children had mild BHR. The prevalence of wheeze in the last 12 months was 12% and of a diagnostic label of asthma was 6%. Fifty three per cent of the children with symptoms in the last 12 months and a diagnostic label of asthma had BHR, and 33% of those with symptoms in the last 12 months regardless of a diagnostic label of asthma showed a positive response to hypertonic saline. Atopic dermatitis, a diagnostic label of asthma, night cough apart from colds, wheeze in the past 12 months (but not "former wheeze") and male gender were significantly associated with increased response to 4.5% saline in the final logistic regression model. These results show that the prevalence of asthma symptoms in the last 12 months and the prevalence of bronchial hyperresponsiveness to hypertonic saline are twice that of a diagnosis of asthma and that asthma might be underdiagnosed in the present population. The response to hypertonic saline is most strongly associated with current asthma and allergy symptoms. A combination of a "diagnostic label of asthma" and "asthma symptoms in the last 12 months" might best reflect "current asthma" in epidemiological studies in this population.