Prevalence of allergic diseases of schoolchildren in central taiwan. From ISAAC surveys 5 years apart.

The prevalence of allergic disorders is increasing around the world. This study used the standardized written questionnaire from International Study of Asthma and Allergies in Childhood (ISAAC, phase III) to collect two cross-sectional appraisals of schoolchildren 5 years apart-one performed 2002 and another on 2007, to focus on the secular trends in prevalence of allergies in central Taiwan. This questionnaire was administered to schoolchildren from over 46 schools across Changhwa County in 2002, and again in 2007. The present study is a follow-up study and uses data collected from a previously reported study conducted in the year 2002 of the same location using the same methodology. Although the repeated cross-sectional survey after a 5-year lapse suggests a mere increase of diagnosed asthma cases from 7.1% to 7.4%, the prevalence of its related symptoms--nocturnal cough, rhinitis, and eczema--was found to increase significantly by 2.6% (p < 0.0001), 6.8% (p < 0.001), and 5.9% (p < 0.001), respectively. Additionally, comparing the secular trends in asthma prevalence, rhinitis, and eczema between several polluted areas in Changhwa County with its less polluted neighbors in 2002 and 2007 indicates that schoolchildren in TaiHao area, which is noted to be polluted by a petrochemical company, has a significantly increased prevalence of wheezing (3.7%, p < 0.05) and nocturnal cough (3.6%, p < 0.05). For schoolchildren living in the coastal areas, a 6% (p < 0.05) increase in the prevalence of rhinitis is noted. The prevalence of eczema uniformly increased for all areas of Changhwa County (p < 0.01). In the downtown areas, besides eczema, the prevalence of asthma and rhinitis also increased significantly (p < 0.05). Of note is the consistent finding in these two periods of the higher prevalence of childhood asthma, rhinitis, and eczema in the downtown areas compared with that from both the polluted and coastal areas. The secular trends in prevalence of asthma, rhinitis, and eczema in these two periods seem to correlate to environmental factors. While the symptoms of asthma, rhinitis, and eczema in schoolchildren affected boys more than girls, it is observed that affected girls have more marked manifestations, although it did not reach statistical significance.