[A follow-up study of six years' outcome of children with asthma in urban area of Beijing].

Objective: To understand the outcome of asthma in children from urban area of Beijing and the factors associated with the outcome. Methods: A total of 497 children with asthma diagnosed in the epidemiological survey of childhood asthma in urban area of Beijing in 2010 were selected in this study. Telephone follow-up was conducted in 2016 to obtain information about asthma attack, emergency visit, hospitalization, medication and disease control, and data of comorbidities of allergic diseases from 1 year earlier. Enumeration data were compared using chi-square test, measurement data were compared by rank sum test. The multi-factor logistic regression analysis was employed for the relationship between the related factors and asthma, Kaplan-Meier survival analysis and COX regression was employed to understand the relationship between the related factors and the course of the disease. Results: Questionnaires were conducted in 366 children, of whom 66.7% (244/366) were male, and 33.3% (122/366) were female.Compared with 2010, the rate of asthma attack and emergency room visits in children in last 12 months were significantly lower (19.1%(70/366) vs . 57.1%(284/497), and 3.0% (11/366) vs .19.7% (98/497), χ(2)=125.910 and 53.352, both P< 0.01). There was no significant change in the proportion of allergic rhinitis and atopic dermatitis in last 12 months compared with that 6 years ago (both P >0.05). The number of children with clinical remission (2 years and above) was 75.4% (276/366). The number of children without remission within 2 years was 24.6% (90/366). The majority of children without remission were less than 12 years old boys (52.4% (33/63) vs . 30.9% (56/181) , χ(2)=9.273, P< 0.01) . The proportion of children without remission associated with allergic rhinitis (67.8%(61/90)), atopic dermatitis (30.0%(27/90)), first-degree relatives with asthma (68.9%(62/90)) was higher than that of children with remission (51.8%(143/276), 17.0%(47/276), and 54.7%(151/276), respectively, χ(2)=7.013, 7.079, 5.608, respectively, all P< 0.05). The proportion of children without remission who used control drugs was (33.3%(30/90)), which was higher than that in children with remission (7.2%(20/276), χ(2)=39.158, P< 0.01). Multiple logistic regression showed that boy ( OR= 2.402 (1.611-3.580), P< 0.05), later onset ( OR= 4.339 (>3-6 years old vs . 0-3 years old), OR= 2.630(>6 years old vs . 0-3 years old), χ(2)=18.512, 31.371, 6.510, all P< 0.05) were independent risk factors for asthma remission. COX regression analysis showed that the use of control drugs ( HR =0.705 (0.515-0.964), χ(2)=4.795, P< 0.05) was the relevant factor in the course of the disease. Conclusions: With the increase of age, the incidence of asthma in children in Beijing city in recent 12 months reduced. Male and late onsets were independent risk factors for asthma remission. The use of control drugs was the relevant factor in the course of the disease.