title: Association between airborne pollen and epidemic asthma in Madrid, Spain: a case-control study.
abstract: BACKGROUND Despite the fact that airborne pollen is an important factor in precipitating asthma attacks, its implication in increases of epidemic asthma in usual meteorological conditions has not been reported. A study was undertaken to estimate the relationship between various types of aeroallergens and seasonal epidemic asthma in the region of Madrid, Spain. METHODS A case-control study was carried out in individuals aged 4-79 years who received emergency healthcare for asthma during 2001 in a base hospital covering a population of 750 000 inhabitants of Madrid. A skin prick test was performed with grass pollen, plantain pollen, olive pollen, cypress pollen, plane tree pollen, dust mites and Alternaria and the prevalence of skin reactivity was compared between subjects with asthma requiring emergency care for asthma within (cases) and outside (controls) the seasonal epidemic period. Data were analysed using logistic regression adjusting for age and sex. RESULTS The response rate was 61.7% for cases (n=95) and 51.6% for controls (n=146). The OR of sensitisation to grass pollen for cases compared with controls was 9.9 (95% CI 4.5 to 21.5); plantain pollen: 4.5 (95% CI 2.5 to 8.2); olive pollen: 7.3 (95% CI 3.5 to 15.2); plane tree pollen: 3.6 (95% CI 2.0 to 6.4); cypress pollen: 3.5 (95% CI 2.0 to 6.2); dust mites: 1.1 (95% CI 0.6 to 1.9); Alternaria: 0.9 (95% CI 0.5 to 1.9). The association with grasses was maintained after adjusting simultaneously for the remaining aeroallergens (OR 5.0 (95% CI 1.5 to 16.4)); this was the only one that retained statistical significance (p=0.007). CONCLUSIONS These results suggest that allergy to pollen, particularly grass pollen, is associated with the epidemic increase in asthma episodes during the months of May and June in the Madrid area of Spain.
authors.affiliation: Servicio de Epidemiología, Consejería de Sanidad, Comunidad de Madrid, C/ Julián Camarillo 4 B 28037 Madrid, Spain. inaki.galan@salud.madrid.org
authors.forename: Iñaki
authors.initials: I
authors.lastname: Galán
authors.forename: Alicia
authors.initials: A
authors.lastname: Prieto
authors.forename: María
authors.initials: M
authors.lastname: Rubio
authors.forename: Teresa
authors.initials: T
authors.lastname: Herrero
authors.forename: Patricia
authors.initials: P
authors.lastname: Cervigón
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Cantero
authors.forename: Maria Dolores
authors.initials: MD
authors.lastname: Gurbindo
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Martínez
authors.forename: Aurelio
authors.initials: A
authors.lastname: Tobías
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000485:Allergens / Q000009:adverse effects* / Q000276:immunology; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology / Q000276:immunology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011058:Pollen / Q000009:adverse effects* / Q000276:immunology; D012621:Seasons; D012882:Skin Tests / Q000379:methods; D013030:Spain / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000485:Allergens