To study the inducing factors and clinical characteristics of patients hospitalized for asthma exacerbation in China.

Patients hospitalized for asthma exacerbation at 29 hospitals in China were retrospectively recruited during 2013-2014.

Clinical data of 3 240 asthmatic patients were collected and analyzed including 1 369(42.3%) males and 1 871(57.7%) females. The patients hospitalized for asthma exacerbation counted for 2.95% (6 375/215 955) of all patients hospitalized during the same period. The leading six inducing factors, in sequence, were acute upper respiratory tract infection [42.3%(1 370/3 240)], changes of weather [22.8%(738/3 240)], noxious gas [(4.3%(140/3 240), allergy challenges [3.5%(115/3 240)], strenuous exercise [1.8%(57/3 240)], and air pollution [1.5%(49/3 240)]. In older patients, more exacerbations were induced by weather changes, yet less sensitive to allergy challenges. As to middle-aged patients, they were less sensitive to upper respiratory tract infections, however the difference was not statistically significant (P>0.05). In winter more asthma patients were induced by upper respiratory tract infections, while in autumn more patients were induced by weather changes, strenuous exercise and air pollution. In spring and summer more patients were induced by allergy challenges, but the differences failed to achieve statistical significance (P>0.05). In northern cities more patients were induced by upper respiratory infections, whereas in southern cities more by noxious gases. Allergy challenges and air pollution tended to affect more patients in northern cities, but the difference was of no significance (P>0.05). The differences of inducing factors among patients of different gender, with or without a smoking history, and with different exacerbation severity didn't show any statistical significance. The patients with severe and life-threatening exacerbations counted for 20.1% (652/3 240). The percentage of patients older than 60 years was higher in patients with severe or life-threatening exacerbations than in whose with mild or moderate exacerbations, so did the percentage of male patients, of patients with disease duration longer than 10 years, with smoking history, and with a history of hospitalization or emergency department visits due to asthma exacerbation during the last year.

The acute upper respiratory tract infection ranks top among all the inducing factors. Senility, male gender, long duration of disease, smoking history, and a history of frequent hospital visits might be the risk factors for severe or life-threatening asthma exacerbations.

Asthma; Exacerbation; Inducing factor; Severity