Prevalence of and major risk factors for adult bronchial asthma in Taipei City.

BACKGROUND AND PURPOSE: The prevalence of bronchial asthma has been on the rise worldwide, but the prevalence of adult asthma in Taiwan has not been reported. The objective of this study was to determine the current 1-year and lifetime asthma prevalence rates, and to identify major risk factors for adult asthma in Taiwan.

METHODS

A cluster sampling was conducted in 1999, where 21 clusters and 4549 adults (age > or = 18 years) were selected randomly. Face-to-face interviews were conducted with a total of 2076 adults (45.6%; men/women, 987/1089) using a questionnaire designed to assess asthma and asthma-like symptoms adapted from the American Thoracic Society with minor modifications to include information about current asthma status.

RESULTS

The results showed that 50 cases had a previous diagnosis of asthma and 94 had been classified as probably having asthma with intermittently audible wheezing. The lifetime prevalence rate of asthma in adults in Taipei City was 7.8%. Seventy three out of 144 patients had asthmatic symptoms or wheezing in the past 12 months. The 1-year prevalence of asthma was 4.1%. A multiple logistic regression model showed the odds ratio (95% confidence interval) of a history of maternal asthma to be 5.8 (2.77 to 12.18), that of allergic rhinitis to be 3.2 (2.03 to 5.16), that of paternal asthma to be 2.2 (0.91 to 5.21), that of older age (> or = 50 years) to be 2.0 (1.25 to 3.19), and that of smoking habit to be 1.7 (1.02 to 2.72).

CONCLUSIONS

The lifetime prevalence rate of adult bronchial asthma in Taipei City was 7.8% and related to both genetic and environmental factors, which included maternal or paternal history of asthma, history of allergic rhinitis, older age (> or = 50 years), and smoking habits.