Allergic sensitization is generally agreed to be an important risk factor for allergic diseases. It has been demonstrated in most of the children attending allergy clinics in Thailand but has never been studied in Thai general populations. The objectives were (i) to describe the prevalence of sensitization to common indoor allergens in Thai female-high-school students and (ii) to evaluate the association of allergic sensitization to allergic diseases in these students. cross-sectional analytic study was designed. Seven hundred and six schoolgirls were enrolled during May-June 2002. Written ISAAC questionnaires were completed by the students and skin prick tests were performed in 344 (48.7%) students with a battery of seven common allergens including Dermatophagoides pteronyssinus, Dermatophagoides farinae, American cockroach, Cat, Cladosporium, Penicillium, and Aspergillus. Positive test was defined as a mean wheal diameter of at least 3 mm at the 15 min reading. The adjusted odds ratios (OR) and 95% confidence intervals (CI) were obtained from multiple regression analysis for the independent effect of sensitization to each allergen on allergic diseases. A total of 154 (44.8%) students had evidence of allergic sensitization on skin prick tests. The prevalence rates of sensitization to various groups of allergens were as follows; mites 43.0%, cockroach 12.8%, cat 4.1%, and molds 1.2%. The independent effect of allergic sensitization on allergic diseases was observed only in mite sensitization on nose problem (OR = 1.73, CI = 1.07-2.78 for nose problem ever and OR = 1.85, CI = 1.13-3.02 for nose problem in 12 months). The risk of nose problem was also increased with the number of positive reactions.
Conclusion: We found that sensitization to the four common allergen groups were weakly associated with the presence of allergic diseases in Thai schoolgirls. This confirms the observation that the development of allergic diseases is not solely attributable to allergic sensitization.