The changing epidemiology of asthma in Shanghai, China

To investigate the prevalence of bronchial asthma in Putuo district in Shanghai, China.

Cross-sectional, community-based study was performed with random sampling of a district with a population of one million. The subjects were residents of the district and six or more years of age. Questionnaire and spirometry were completed in all subjects. Asthma was defined as physician-diagnosed asthma. The results were compared with the asthma study of 40,000 population completed by the same team in Pudong area of Shanghai in 1997.

We surveyed 27,042 participants. The prevalence of asthma was 1.8% (488/27,042), much higher than the 0.41% (163/40,000) found in the 1997 survey in Pudong area of Shanghai. In subjects with asthma, current smoking, obesity, gender distribution and the combination of allergic diseases between the two studies had no differences. The most prominent causes of asthma exacerbation were cold air, respiratory infection and dust inhalation. Pulmonary function for 428 asthma patients in Putuo survey was analyzed: 228 (53.3%) patients had FEV1%pred lower than 80%. Asthmatics older than 65 years had lower FEV1%pred than other age groups (p < 0.01).

The prevalence of physician-diagnosed asthma in urban of Shanghai has increased in recent years. The most important causes of asthma exacerbations were cold air, respiratory infection and dust exposure. The proportion of individuals with decreased percent predicted forced expiratory volume of first second increased with age. Strengthening the prevention and treatment of asthma, especially in children with asthma, may decrease the health burden of asthma in the urban Chinese population.