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.