Objective: Asthma is one of the most common chronic disorders in childhood. The prevalence rate of asthma and other atopic diseases have increased steadily in many countries. The present survey was conducted to find out the prevalence of childhood asthma in urban areas in China, and to assess the influence of asthma on patients' social life and their families.
Methods: A nationwide randomized survey, covering 43 cities in 31 provinces, on the prevalence of childhood asthma was carried out by the National Pediatric Cooperative Group on Asthma Research from June to October 2000, including a population of 437,873 children aged 0-14 years. Patients who had asthma, infantile asthma, cough variant asthma and questionable asthma (including asthmatic bronchitis) were chosen as subjects.
Results: Totally 10,065 subjects were screened out as asthma associated children by means of questionnaire to the parents, physical examination and case history review. Among them 7401 (73.53%) children, aged 3 years or more, were diagnosed as asthma of children; 1109 (11.02%) infants and young children, aged less than 3 years, as asthma of infants and young children; 785 (7.80%) as cough variant asthma; and 770 (7.65%) as questionable asthma. The prevalence of the average accumulated asthma of all the 0-14 years old asthma population (including asthma of older children and of infants) in the 31 provinces, 43 cities was 1.97%. Male/female ratio was 1.75:1. There was statistically significant difference in asthma prevalence among the 43 cities, with the highest rate in Chongqing (4.63%) and the lowest in Xining (0.25%). Overall, within China, the prevalence rate in North China was relatively lower (0.99%) and was higher in South China (1.54%), the highest was seen in eastern areas of China (2.37%), 4670 patients (70.00%) of the children had their onset before three years of age. The current 2 years prevalence of Chinese urban children was 1.54%. Thirty-six of the 43 cities had received the same kind of asthma prevalence survey 10 years ago, which made a longitudinal comparison of the two surveys available. For 6370 patients (95.47%) the family members' work was affected because of their asthma attacks. One third of the patients had used inhaler corticosteroids. In about 2/3 of patients the diagnosis of asthma was correct, while only 1/3 patients' cough variant asthma was correct compared with their early diagnosis. Sixteen percent of patients were never diagnosed to have asthmatic diseases previously.
Conclusions: There has been a significantly increasing trend of asthma prevalence during the ten years, especially in the older age group. From the data of present survey it was inferred that there has been certain improvement, although not ideal, in the accuracy of diagnosis and in the practice of steroid inhalation therapy by the pediatricians in different cities.