The prevalence of asthma and allergies in Singapore; data from two ISAAC surveys seven years apart.

BACKGROUND AND AIMS Over the past few decades, the prevalence of asthma has been increasing in the industrialised world. Despite the suggestion of a similar increase in Singapore, the 12 month prevalence of wheeze among schoolchildren in 1994 was 2.5-fold less than that reported in western populations. It was hypothesised that with increasing affluence in Singapore, the asthma prevalence would further increase and approach Western figures. A second ISAAC survey was carried out seven years later to evaluate this hypothesis. METHODS The cross-sectional data from two ISAAC questionnaire based surveys conducted in 1994 (n = 6238) and in 2001 (n = 9363) on two groups of schoolchildren aged 6-7 and 12-15 years were compared. The instruments used were identical and the procedures standardised in both surveys. RESULTS Comparing data from both studies, the change in the prevalence of current wheeze occurred in opposing directions in both age groups--decreasing in the 6-7 year age group (16.6% to 10.2%) but increasing to a small extent in the 12-15 year age group (9.9% to 11.9%). The 12 month prevalence of rhinitis did not change; there was an increase in the current eczema symptoms in both age groups. CONCLUSION The prevalence of current wheeze, a surrogate measure of asthma prevalence, has decreased significantly in the 6-7 year age group. Eczema was the only allergic disease that showed a modest increase in prevalence in both age groups.