Prevalence of asthma, rhinitis and eczema in children from the Bangkok area using the ISAAC (International Study for Asthma and Allergy in Children) questionnaires.

Within the past three decades, there has been a rising trend for prevalences of asthma and allergic diseases worldwide, particularly from developed and industrializing countries. In Thailand, limited studies on epidemiology of atopic diseases have indicated relatively low prevalences of these conditions among the Thais. Recently, a standardized phase I questionnaire of the International Study of Asthma and Allergies in Childhood (ISAAC) has been developed to study and to compare geographical and temporal trend for prevalences of asthma, allergic rhinitis and eczema in children. The objectives of phase I ISAAC study in Thailand are to study prevalence of the three most common allergic diseases i.e. asthma, allergic rhinitis and eczema among Thai children of the two age groups (i.e., 6-7 and 13-14 years) living in the Bangkok metropolitan area and to collect basic epidemiologic data of these diseases among these children. The Thai translated version of phase I ISAAC questionnaires was administered to Thai children of the two age groups as above. Questionnaires were answered by parents of younger children, whereas, they were self-administered by 13-14 years old children. In addition, the validated international video questionnaires were used with older children. Fourteen primary schools and 13 secondary schools were randomly selected to cover the entire Bangkok metropolitan area. A total of 7341 questionnaires were eligible for the analysis (3628 from the younger age group and 3713 from the older age group). Data were entered and analysed by the Epi-Info program. The cumulative and 12 month period prevalences of the three conditions for all children were as follows; wheezing, 18.3 per cent, 12.7 per cent; rhinitis, 44.2 per cent, 38.7 per cent; and eczema, 15.4 per cent, 14.0 per cent, respectively. The period prevalence of wheezing for older children (13.6%) was higher than for younger children (11.7%). Prevalences of severe wheeze and exercise wheeze were more common among older children (4.0% and 15.7%). Both age groups reported high percentages for night cough (23.6% and 28.6%). A significantly large number of children from both groups reported symptoms of rhinitis with the majority indicating that symptoms were severe enough to limit their daily activities. Nevertheless, when confined only to those with eye symptoms, the prevalence decreased to 13.1 per cent. Eczema, in contrast to the other two conditions, occurred more frequently among younger children than among older children (period prevalence of 16% vs 9.1%). The rash was of a relatively mild nature since 77 per cent of children reporting symptoms indicated that the rash had cleared within the past 12 months. Allergic conditions are very common among children residing in Bangkok. Compared to the last survey in 1990, the period prevalence of wheezing has increased 4 fold, allergic rhinitis has increased nearly 3 fold whereas, eczema has remained stable. A large number of children in Bangkok are suffering from rhinitis symptoms. Results of this phase I ISAAC study indicate that allergic diseases are perhaps the most common childhood diseases in Thailand and could lead to a substantial economical loss for the country. There is an urgent need for an in-depth study to define epidemiological factors responsible for this increase.