Prevalence, severity, and time trends of allergic conditions in 6-to-7-year-old schoolchildren in Taipei.

BACKGROUND

Atopic diseases, including asthma, allergic rhinitis, and atopic eczema, are major illnesses among children. Recent studies conducted worldwide have shown diverse trends in the prevalence of asthma, with a steady increase detected in industrialized countries. Other studies, however, have revealed a leveling trend or even a declining prevalence.

OBJECTIVE

The purpose of this study was to evaluate the current prevalence of allergic conditions in 6-to7-year-old schoolchildren in Taipei, Taiwan, and to analyze time trends.

METHODS

We evaluated the prevalence and severity of asthma and other allergic conditions using a phase I International Study of Asthma and Allergies in Childhood core written questionnaire previously administered in Taipei in 1994 and 2002.

RESULTS

A total of 24 999 first-grade students from 153 elementary schools completed the questionnaire. The proportion of children with wheeze ever and nocturnal cough in the past 12 months was significantly increased in 2007 compared to 1994 and 2002. No significant differences were detected in the prevalence of current wheeze or physician-diagnosed asthma. The prevalence of severe wheezing symptoms in the past 12 months (> or = 4 attacks of wheeze, > or = 1 night of sleep disturbance due to wheeze per week, wheeze-limiting speech, and exercise-induced wheeze) decreased significantly. The prevalence and severity of rhinitis symptoms increased significantly during the 13-year period analyzed. The prevalence of eczema symptoms-defined as recurrent itchy rash and typical atopic eczema distribution in the past 12 months--also increased.

CONCLUSIONS

We observed an increase only in the prevalence and severity of current allergic symptoms in allergic rhinitis and atopic eczema.