Bulletin Spring‧Summer 2001

Asthma Prevalence Related to the Environment Asthma is the commonest chronic childhood diseaseand a major reason for the admission of children to hospital. There are approximately 120,000children in Hong Kong with varying levelsof asthma. Forty per cent of them need to visit specialty o u t p a t i e n t clinics from time to time. Those who arc subsequently hospitalized makeup 15 per cent of all children admitted to hospital. In recent years, the prevalence of asthma has been on the rise. Research at the University shows its prevalence in 1989 to be 4.8 per cent, and the figure rose to 11.2per cent in 1995. Higher Incidence Caused by the Environment Prof. Ga ry Wo ng of th e De p a r t me nt of Paediatric s p o i n t e d out that genetic alteration s a nd e n v i r o nme n t a l factors are the t w o m a i n causes of asthma. But genes do n ot u n d e r go ma j or alterations w i t h i n a pe r i od of six years, and wh i le childhood asthma i n H o n g Ko ng is less prevalent than that i n the West , it is far mo re prevalent than that on the ma i n l and, w h i c h has a similar gene pool. A l l this indicates that the environment is the ma i n reason for the drastic increase i n c h i l dhood asthma prevalence i n the t e r r i t o ry i n recen t years. Statistics i n th e U K a nd Au s t r a l ia also s h ow that c h i l d h o od a s t hma has d o u b l ed i n the past 10 years or so, w h i c h f u r t h er c o n f i r ms the en v i r onmen t al influence. Prof. Wo ng said, ' En v i r o nme n t al asthma allergens are v e ry complex. There have been v e ry f ew studies on asthma i n Chinese children i n the past, especially large-scale studies.' I n 1994 he conducted a small s t udy c omp a r i ng the prevalence of c h i l d h o od asthma i n Beijing, Guang z hou , and H o n g Ko n g. The results s h ow that the prevalence of the c o n d i t i on i n H o n g K o n g is three times that i n Gu a n g z h o u . Th is s t u dy t r i g g e r ed a large-scale c omp a r a t i ve s t u d y i n 1996 to investigate the role p l a y e d b y en v i r onmen t al risk factors. The project was s uppo r t ed b y a grant of HK$692,000 f r o m the Research Grants Counci l and l e d b y Prof. Wong. The other team members included Prof. Fok Tai-fai of the Department of Paediatrics a nd Prof. Joseph L au of the Centre for Clinical Trials a nd Ep i dem i o l og i c al Research. A Large-scale Comprehensive Study The study, a collaboratio n w i t h the Capital Institute o f Beijing and the Gu a n g z h ou Institute of Respiratory Disease, covered 11,000 c h i l d r en aged 9 to 11 f r om the three cities. T h e subjects, w h o come f r o m different areas of the three places, were selected b y r a n d om sampling. We asked their parents to give details about th e children's l i v i ng en v i r onment since b i r th a nd their allergic reactions, i n c l u d i ng eye, skin, and nose allergies, wh e t h e r there is rash a nd coughing , wh e t h er 29