Prevalence of asthma and bronchial hyperreactivity in Danish schoolchildren: no change over 10 years

Aim: To describe the point prevalence of current physician-diagnosed asthma and bronchial hyperreactivity (BHR) in 2001 among unselected Danish schoolchildren aged 6-17 years, compared with the prevalence from a similar study from 1990 to 1991. Methods: Cross-sectional study using parental questionnaire on asthma and respiratory symptoms combined with a 6-min free running test with peak expiratory flow rate (PEFR) measurement (n = 1051, response rate 89.3%). Results were compared with those of a similar study in the same area from 1990 to 1991. Main outcome measures were current physician-diagnosed asthma or BHR in children without physician-diagnosed asthma measured by either a decrease in lung function after standardized running test and/or variability in PEFR on home monitoring. Results: The prevalence of current physician-diagnosed asthma was 4.0% [95% confidence interval (CI) 2.7-5.3%] in 1990-1991 and 3.6% (95% CI 2.4-4.8%) in 2001. The prevalence of BHR was 3.2% (95% CI 2.0-4.4%) in 1990-1991 and 2.0% (95% CI 1.1-2.9%) in 2001. The combined prevalence was 7.2% (95% CI 5.4-8.9%) in 1990-1991 and 5.6% (95% CI 4.2-7.1%) in 2001. Conclusion: The point prevalence of current physician-diagnosed asthma and BHR among unselected Danish schoolchildren aged 6-17 years was unchanged over 10 years between 1990-1991 and 2001.