[A cross-section study of severe asthma in eight provinces of China].

Objective: To analyze the prevalence of severe asthmain China. Methods: The epidemiological data was collected from 2 034 asthmatics who were diagnosed in the last epidemiological survey from 2009 to 2010 in 8 provinces. Results: According to the questionnaire survey, among the 2 034 patients, the previously diagnosed patients accounted for 72.47% (1 474/2 034) and the percentage of newly-diagnosed patients was 27.53% (560/2 034). In those 1 474 previously diagnosed asthmatics, 122 (8.28%) were classified into severe asthma, while 6.00% (122/2 034) of all asthmatics and 0.07% (122/164 215) of total respondents presented as severe cases. Statistically, there was no difference in the prevalence of severe patients between men and women. The morbidity rate of severe asthma was the lowest in the 21-30 year old group and the highest in 61-70 year old group (0.85% and 8.31% respectively). The difference among ages was statistically significant (χ(2)=18.791, P=0.005). In addition, the prevalence rates of severe asthma were also significantly diverged among patients with different education background(χ(2)=24.639, P<0.000 1). A negative relation was found between education level and the proportion of severe cases. Moreover, the morbidity of severe asthma in smoking patients and non-smoking patients were significantly different as well (χ(2)=7.447, P<0.05). Compared with asthma patients who do not smoke, smokers were more likely to suffer severe asthma (OR=1.663, 95% CI 1.150-2.404). Conclusions: The prevalence rate of severe asthma in China is similar to that in other countries.Elderly patients have higher risk of severe asthma. Smoking is considered as a risk factor for severe asthma.