High prevalence of asthma and atopy in the Canary Islands, Spain.

Objective: To evaluate the prevalence of and risk factors for asthma and related conditions in the Canaries, Spain.

Methods: From a randomised sample of 9506 adults aged 20-44 years who answered a short questionnaire, a random sample corresponding to 20% of the original was taken. Subjects classified as symptomatic in the previous survey and who were not included in the random sample were also invited to participate. The subjects completed a respiratory questionnaire, and underwent spirometry, bronchial hyperresponsiveness (BHR) test, skin tests and immunoglobulin E (IgE) measurements.

Results: The random sample included 593 subjects. The prevalence of skin sensitisation to mites was 30.3% (95%CI 26.7-34.2) and the prevalence of IgE to mites 30.5% (95%CI 26.2-35.2). A prevalence of 40.6% (95%CI 35.9-45.5) was found for atopy, 14.1% (95%CI 11.1-17.1) for BHR and 4.2% (95%CI, 2.5-5.9) for asthma. The risk factors most strongly associated with asthma were atopy (OR 4.89, 95%CI 3.07-7.78) and respiratory infection before the age of 5 years (OR 2.78, 95%CI 1.66-4.67).

Conclusion: This study shows a high prevalence of sensitisation to mites, atopy, BHR and asthma in the Canaries, similar to that observed in English-speaking countries. We suggest that these findings could partially result from climatic conditions.