| Objective1. To asssess the prevalence of bronchial asthma and allergic rhinitisin 13-14 year old adolescents in Guangzhou city.2. To assess the prevalence of bronchial asthma and allergic rhinitis in 13-14 year old adolescents in Conghua rural area.3. To investigate the changes of the prevalence of bronchial asthma and allergic rhinitis in 13-14 year old children in Guangzhou during the past 15 years.4. To compare the differences of prevalence for bronchial asthma and allergic rhinitis in 13-14 year old children between Guangzhou city and Conghua rural area.MethodsPart One : Epidemiological survey in prevalence of asthma and rhinitis and their trends among adolescents in Guangzhou city.A cross-sectional study using the International Study of Asthma and Allergies in Children (ISAAC) protocol was conducted at 2009. 6928 junior students of grade one and grade two, mostly aged 13-14 years old, chosen from the same 10 secondary schools in four Guangzhou central districts as the previous studies in 1994(ISAAC PhaseⅠ) and 2001(ISAAC PhaseⅢ), were recruited from November to December in 2009, also as the same seasons as the previous studies. All subjects completed the identical and validated ISAAC questionnaires(core written questionnaires and video questionnaires) about the symptoms related to asthma and allergic rhinitis in the classrooms of the schools. The results were compared with those obtained in previous two surveys. Three hundred and twenty nine adolescents (age12-15 years) were ramdomly selected to receive skin prick testing (SPT). The methods were identical and eleven common airborne allergens were test.Part two : Epidemiological survey in the prevalence of asthma and rhintis among adolescents in Chonghua rural area and comparison of the different prevalence of those in Guangzhou city. .A cross-sectional study using the same protocol as Guangzhou was conducted from November 2009 to January 2010. A total of 5841 questionnaires completed by junior students of grade one and grade two in middle school , most of them aged 13-14 years old, which were from 4 secondary schools in 4 Chonghua towns were collected. The same Chinese ISAAC questionnaires(core written questionnaires and video questionaires) about the symptoms related asthma and allergic rhinitis were used to estimate the prevalence of the above conditions as those in Guangzhou.Part three: A Comparative Study on the result of the further Clinical objective examination among adolescents between Chonghua rural area and Guangzhou city. .A total of 860 adolescents,including 417 adolescents in Guangzhou and 443 adolescents in Chonghua respectively, were underwent the physical examnations, skin prick testing (SPT) with 11 common airborn-allegens, serum eosinophils count and bronchial provocation test(BPT). The results from two areas were compared.Statistical analysis: Statistic analysis was carried out with the use of SPSS version 18.0 (SPSS Inc. Chicago, IL, USA). Prevalence rate of each symptom was calculated by the ratio of positive counts /totalcounts and 95% confidence interval (95%CI) of the prevalence rate was also calculated.. Binary logistic regression , chi-square test and t-test was used to compare the difference of symptom prevalence between those in Chonghua and Guangzhou, A p-value less than 0.05 was considered to be significant.ResultsPart one:1. A total of 6928 students participated in the survey with the response rate of 96.7%. Of the total students, 87.5% were aged 13-14years old with the average age was 13.3±0.64 years old. There were 3524 boys and 3424 girls, accouted for 50.6% and 49.4% of the subject respectively. Sex ratio and mean age were similar with those of the previous studies.2. In the present survey, with the written questionnairs, the prevalence rate of physician diagnosis asthma was 6.9%, and the prevalence rate of wheeze in the past years were 6.1% as compared with 3.9% and 17.4% respectively in 1994 (p<0.05), and 4.8% and 4.6% respectively in 2001 (p<0.05). 3. In the present survey, with the video questionnaire, the prevalence of wheeze at rest in the past years was 4.9%, which was significantly higher than 2% of 1994 and 3.8% of 2001 respectively (p<0.05).The prevalence rate of exercise-induced wheeze was 13.7% , increased significantly when compared with 6.9% of 1994 and 11.3%of 2001 respectively (p<0.05).4. In the present survey, the prevalence rates of physician diagnosis of allergic rhinitis and hayfever in the lifetime were 25.1% and 5.3%, which were significantly higher than 17.4% and 2.9% respectively in 1994, also higher 22.7% and 4.1% respectively in 2001(p<0.05). The prevalence rates of symptoms of rhinitis and rhinoconjunctivitis in the past 12 months were 43.2%, 10.4%, 1.9%, which were significantly higher than those of 1994(p<0.05), and without significant difference when compared with those of 2001(p>0.05). The prevalence rate of allergic rhinitis in the past 12 months in 2009 was lower than that of 2001 .5. The prevalence of sensitization (positive response to at lease one allergen with SPT )increased from 46.3% in 2002 to 62.2% in 2010(p<0.001). The pattern of sensitization remained similar, and sensitization rate to house dust mite (Der f )was most common in both years with 44.9% and 55.2% respectively. Sensitization to cats and cockroaches were the second and third common allergens in the surveys from both period of times.Part two:1. A Total of 5841 questionnaires were collected with the response rate of 96% with average age of 13.3±0.64 years old. Among them, 4815 adolescents were at 13-14 years old, accounted for 87.5% of the total subjects. There were 2953 boys and 2888 girls, accounted for 50.6% and 49.6% of the subjects respectively.2. The prevalence rates of physician-diagnosis-asthma and all the asthmatic symptoms in Conghua were significantly lower than those Guangzhou. The prevalence rates of physicians-diagnosis-asthma, wheeze in the past year and wheeze at rest in Conghua were 3.4%, 1.5% and 1.7% respectively, as compared with 6.9%, 6.1% and 4.9% in Guangzhou respectively (p<0.01). No significant difference was found in those prevalences between the boys and girls.3. The prevalence rates of physicians-diagnosis-allergic rhinitis, hayfever and the prevalence rates of allergic rhinitis symptom in Guangzhou were 25.1%, 5.3% and 42.3% respectively, as compared with 4.4%, 2.6% and 25.8% in Chonghua (p<0.01).Part three:The eosinophil counts in Conghua were 0.19×109/L and 0.27×109/L in Guangzhou. The prevalence rate of sensitization by SPT and BHR in Conghua were 51.1% and 3.1% respectively , those were 66.4% and 20.2% in Guangzhou respectively (p<0.05). Adolescents in Conghua rural area had lower prevalence of real asthma (2.4%) when compared with that in Guangzhou (7.4%) as combination of having physician- diagnosis-asthma and BHR (p<0.01).Conlusion1. The prevalence of bronchial asthma and allergic rhinitis is consistent increased over 15 year among adolescents in Guangzhou city.2. The prevalence of allergic sensitization to common allergens increased significantly in the adolescents from 2001 to 2009.3. The prevalence of asthma and allergic disease in Conghua were significantly lower than that in Guangzhou.4. Atopy or sensitivity to mite allergens are the risk factors of asthma and allergic rhinitis. |
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