Towards a better understanding of childhood asthma

The burden of asthma in Australia

In 1997, 27% of Australian children had current wheeze, and this is increasing by 1.4% per year. The prevalence of wheeze among adults is lower and appears to be stable. The prevalence of persistent asthma (wheezing episodes with abnormal airway function between episodes) in children has increased from 5% to 9% in the past 20 years. In adults, the prevalence is 5%-6%. Up to 80% of adults with persistent asthma have abnormal lung function. Asthma deaths in Australia have fallen 28% since peaking in 1989, but the mortality rate is still twice that of England.

Bronchial hyperresponsiveness to 4.5% hypertonic saline indicates a past history of asthma-like symptoms in children

SUMMARY. To evaluate the importance of a past history of asthma-like symptoms over a period of 2 years and current bronchial hyperreactivity (BHR), 538 randomly selected schoolchildren, initially aged 7-8 years, were examined. At yearly intervals, three standardized questionnaires, including items from the ISAAC panel, were answered by parents. Following the last questionnaire, BHR to 4.5% hypertonic saline (HS) was recorded. In survey 1, lifetime prevalence of asthma was 4.9%. During the 12-month period, prevalence of wheeze and dyspnea ranged between 9.3 and 5.2% (Survey 1) and 5.9% and 4.4% (Survey 2). Among children with wheeze or dyspnea in Survey 3, BHR (defined as a fall of baseline FEV(1) > or = 15%) was significantly more frequent (50.0% and 60.7%, respectively) than among children without these symptoms (12.8%, P < 0.001, and 12.8%, P < 0.001, respectively). The negative predictive value of BHR to have neither wheeze nor dyspnea was about 88% and did not vary throughout the study (Survey 1, 87%; Survey 2, 88%; Survey 3, 88%). The relative risk of showing BHR was significantly increased in children with wheeze (survey 2, odds ratio (OR) 3.0 (95% confidence interval (CI) 1.0-8.7)) or dyspnea (Survey 1: OR 5.9 (95% CI 1.9-18.5), Survey 3: 5.2 (1.7-16.2), but not in children with dry cough or nocturnal cough (data not shown). Wheeze and dyspnea occurred repeatedly in the same individuals with BHR in a high percentage of children (83.3% and 76.5%, respectively). In conclusion, there is a strong association between recent and previous dyspnea and current BHR, and it indicates intraindividual persistence of symptom history.

Lung function measures and their relationship to respiratory symptoms in 7- and 8-year-old children

Abnormal pulmonary function in childhood is a well-known risk factor for lung function impairment in adult life. It is therefore of clinical interest to recognize lower pulmonary function in childhood. We investigated the association between asthma-like respiratory symptoms and the lung function parameters FVC, FEV1, and FEF(25-75) in a population-based sample of 402 schoolchildren, aged 7 and 8 years, using linear regression analyses. Without accounting for other respiratory symptoms, wheeze, exercise-induced wheeze, chronic cough, and history of wheezy bronchitis or lower respiratory infections in early childhood were significantly associated with reduced lung function. After stepwise elimination of symptoms from the regression models, only exercise-induced wheeze (FEV1, -15%pred, FEF(25-75), -21%pred) and a history of chronic cough (FEV1, -5%pred; FEF(25-75), -11%pred) remained significant predictors of decreased lung function. After adjustment for different variability, no significant differences were seen between the effects of symptoms on the flow measurements FEV1 and FEF(25-75). We conclude that children who report exercise-induced wheeze and/or chronic cough may have a considerable deficit in lung function at early school age.