Objective To investigate the prevalence of food allergy among children living in metropoli-ses aged 0-14 years. Methods In this cross-sectional study a questionnaire was distributed to parents taking care of children aged 0-14 years from China′s 31 metropolises to get the parents reported prevalence. Results A total of 337560 children aged 0-14 years participated in the survey. There are 19676 children reported with food aller-gy(5. 83%). In different regions,the parents reported prevalence of food allergy had significant difference(χ2 =657. 01,P<0. 001). It was highest in the eastern (7. 38%,5259) and the northeastern (7. 03%,2916) part of China,and was lowest in the northwestern part of China,which was 4. 35%. Of all the 31 surveyed metropolises, the parents reported prevalence of food allergy was highest in Qingdao,and lowest in Lhasa,which was 9. 11%(917/10066),and 2. 33% (116/4984)respectively. The prevalence of food allergy in males and females was 5. 87% and 5. 79% respectively,with no significant difference (χ2 =1. 078,P=0. 299). The prevalence of food allergy in preschool children (3-5 years old,6. 65%) was higher than other ages (χ2 =46. 469,P<0. 001). Of children reported to have food allergy,38. 5% had a history of eczema,23. 0% had a history of allergic rhinitis, and 37. 7% had a family history of allergic diseases. Conclusion The parents reported prevalence of food aller-gy among children 0-14 years old from 31 metropolises in China was 5. 83%. In different regions cities and a-ges,there′s significant difference of the reported prevalence. There′s no significant difference of parents reported prevalence between males and females. The study would have great significance in reflecting and evaluating the prevalence of food allergy among children.

Objective:To explore the cutoff value for assessing small airway dysfunction in children with asthma.Methods:A total of 364 asthmatic children aged 5 to 14 years, with normal ventilatory function, followed up at the Asthma Clinic of the Children′s Hospital of Capital Institute of Pediatrics from January 2017 to January 2018, were selected as the case group. Concurrently, 403 healthy children of the same age range and without any symptoms in the community were chosen as the control group, and pulmonary function tests were conducted. The values of forced expiratory volume in 1 second (FEV 1), forced vital capacity (FVC), forced expiratory flow at 50% of FVC (FEF 50), forced expiratory flow at 75% of FVC (FEF 75) and maximum mid-expiratory flow (MMEF) were compared between case group and control group. Statistical tests such as t-test, χ2 test, or Mann-Whitney U test were used to analyze the differences between the groups. Receiver operating characteristic (ROC) curves were constructed, and the maximum Youden Index was utilized to determine the optimal cutoff values and thresholds for identifying small airway dysfunction in asthmatic children. Results:This study comprised 364 children in the case group (220 boys and 144 girls) and 403 children in the control group (198 boys and 205 girls). The small airway parameters (FEF 50%pred, FEF 75%pred, MMEF%pred) in the asthmatic group were significantly lower than in the control group (77% (69%, 91%) vs. 95% (83%, 109%), 67% (54%, 82%) vs. 84% (70%, 102%), 76% (66%, 90%) vs. 97% (86%, 113%), Z=12.03, 11.35, 13.66, all P<0.001). The ROC curve area under the curve for FEF 50%pred, FEF 75%pred, MMEF%pred was 0.75, 0.74, and 0.79, respectively. Using a cutoff value of 80% for FEF 50%pred achieved a sensitivity of 56.9% and specificity of 81.4%. A cutoff value of 74% for FEF 75%pred resulted in a sensitivity of 67.3% and specificity of 69.2%. Finally, using a cutoff value of 84% for MMEF%pred achieved a sensitivity of 67.9% and specificity of 77.2%. Conclusion:In the presence of normal ventilatory function, utilizing FEF 50<80% predicted or MMEF<84% predicted can accurately serve as criteria for identifying small airway dysfunction in children with controlled asthma.