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Association between airborne pollen and epidemic asthma in Madrid, Spain: a case–control study
  1. Iñaki Galán1,
  2. Alicia Prieto2,
  3. María Rubio2,
  4. Teresa Herrero2,
  5. Patricia Cervigón3,
  6. Jose Luis Cantero1,
  7. Maria Dolores Gurbindo4,
  8. María Isabel Martínez5,
  9. Aurelio Tobías1,6
  1. 1Department of Epidemiology, Consejería de Sanidad de la Comunidad de Madrid, Spain
  2. 2Department of Allergy, Hospital General Universitario Gregorio Marañón, Consejería de Sanidad de la Comunidad de Madrid, Madrid, Spain
  3. 3Department of Environmental Health, Consejería de Sanidad de la Comunidad de Madrid, Madrid, Spain
  4. 4Department of Immunopediatrics, Hospital General Universitario Gregorio Marañón, Consejería de Sanidad de la Comunidad de Madrid, Madrid, Spain
  5. 5Department of Child Allergy, Hospital General Universitario Gregorio Marañón, Consejería de Sanidad de la Comunidad de Madrid, Madrid, Spain
  6. 6Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), Barcelona, Spain
  1. Correspondence to Iñaki Galán Labaca, Servicio de Epidemiología, Consejería de Sanidad, Comunidad de Madrid, C/ Julián Camarillo 4 B 28037 Madrid, Spain; inaki.galan{at}salud.madrid.org

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.

  • Asthma
  • outbreaks
  • pollen
  • case-control
  • asthma epidemiology

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Footnotes

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the bioethics committee of the Hospital General Universitario Gregorio Marañón.

  • Provenance and peer review Not commissioned; externally peer reviewed.