P R E S S   R E L E A S E

Asthma is the commonest chronic childhood disease in Hong Kong and the rest of the world.  It is also the most commonly seen conditions resulting in hospital admission.  In Hong Kong, 15% of children who are admitted to the hospital suffer from asthma.  Asthma also accounts for 40% of specialty outpatient visits.  The prevalence of this condition is increasing in Hong Kong.  Research at The Chinese University of Hong Kong documented the prevalence in 1989 is only 4.8% and that in 1995 increases to 11.2%, more than double in less that 10 years.  Though the prevalence of asthma among Hong Kong children is much lower than that of the Caucasians, asthma is not as common in Chinese children in Mainland China as in Hong Kong.

In view of the increasing prevalence of asthma, a specialist research team was formed at the Faculty of Medicine of the Chinese University to investigate the possible genetic and environmental risk factors associated with childhood asthma.

Research on Caucasians has revealed several possible genetic alternations that may increase the chance of allergic disease and asthma.  These genes also affect the effectiveness of different treatments to patients.

The research team at the Chinese University identified the gene controlling a cytokine, known as interleukin-13, which is crucial in the production of IgE that in turns determine the manifestation of allergic diseases.  Children with higher IgE levels will have greater manifestation of different atopic diseases such as asthma and eczema.  However some genetic alternations that affect the airway hypersensitivity of Caucasians children did not affect Hong Kong children.  More studies on Chinese children are needed as we cannot directly extrapolate data from Caucasians to Chinese.

"The increasing prevalence over a relatively short period of time is more likely related to environmental factors," said Professor Gary Wong Wing-kin, Associate Professor, Department of Paediatics, The Chinese University of Hong Kong.

The research team collaborated with the Capital Institute of Beijing, Beijing and the Guangzhou Institute of Respiratory Disease on a large-scale comparative study on children from these three cities for the possible environmental factors for asthma.  These subjects are genetically similar but are exposed to different environmental conditions.  11,000 children aged 9-11 from these three cities were examined by questionnaire, skin test for allergies and airway challenge test.

The study found that the prevalence of asthma in Hong Kong is twice of that in Beijing or Guangzhou.  The study also found that risk factors such as home smoking, maternal smoking during pregnancy, use of synthetic pillow (foam), synthetic bedding and use of gas as cooking fuel are closely linked with higher prevalence of asthma.  The protective factors are breast feeding (the longer duration the better) and early attendance of day care.

Although genetic alternations may explain the occurrence of asthma, the study proves that environmental factors are crucial in determining the prevalence of the disease.  Hence, possible preventive measures to control the increase of childhood asthma can be derived from these results.

"We are faced with a massive load of asthmatic patients we have to deal with.  More, we learn from experience at the Prince of Wales Hospital and other centres that asthma is under-diagnosed and under-treated.  If we can avoid those environmental risk factors, we may be able to reduce the prevalence of asthma," said Professor Wong.

Many children may gradually get better when they get older.  Chronic poor control, however, can possibly lead to permanent damage to the airways of these children.  One important note is many patients do not have wheeze.  In fact, coughing is the major symptom of asthma in children.  Asthmatic children frequently cough at night, cough with exercise and cough when the weather changes.

Our researchers also found that many patients and parents do not understand the disease very well.  They may consider the disease incurable or very difficult to control and thus making the management of the disease very poor.  The research team has designed an educational programme on the underlying and precipitating causes of asthma, the rationale of different types of medications, and the appropriate use of various devices for asthmatic patients, both adults and children.  Although we have no cure for asthma yet, the disease can easily be under good control with the use of highly effective medications.  These medications, both oral and inhaled, have little side effects and are NOT addictive when they are properly used. Patients who have gone through the programme have their asthma control improved significantly, both in the recurrence rate and manifestation of symptoms.  When asthma is properly treated, children can have a normal life style.