The epidemiology of adverse food reactions (AFRs), including the potentially life-threatening food allergy (FA), in Asia is unclear. AFR is believed to be less prevalent than in Caucasians. This study determines the prevalence, clinical features and risk factors for parent-reported AFR in Chinese pre-school children in Hong Kong. Children aged 2-7 yr living in Hong Kong were recruited through local nurseries and kindergartens to ascertain the occurrence and clinical spectrum of AFR and other atopic disorders. Subjects' parents answered a self-administered questionnaire that was modified and validated based on the International Study of Asthma and Allergy in Childhood. A total of 3827 children from 21 nurseries and kindergartens returned the study questionnaires, and information on AFR was analyzable for 3677 (96.1%) children. The prevalence rates of parent-reported AFR and parent-reported, doctor-diagnosed AFR were 8.1% and 4.6%, respectively, whereas 5.0% of pre-schoolers had doctor-diagnosed asthma. The six leading causes of AFR were shellfish (15.8%), egg (9.1%), peanut (8.1%), beef (6.4%), cow's milk (5.7%), and tree nuts (5.0%). When compared with children born and raised in Hong Kong, children born in mainland China (n = 253) had less parent-reported AFR (4.0% vs. 6.7%; p = 0.016). On logistic regression, parent-reported AFR was associated with younger age (p = 0.010), born in mainland China (p = 0.038), and AFR history in father (p = 0.001), mother (p < 0.001), siblings (p = 0.020), and paternal history of rhinitis (p = 0.044). This study shows that AFR is a common atopic disorder in Hong Kong pre-school children, and prevalence rates are comparable to the Caucasians.

This study demonstrates a gender difference of eNO level in healthy Chinese schoolchildren. When compared with Caucasians, Chinese children have significantly higher eNO levels.

Epidemiologic studies suggest increased asthma prevalence in obese subjects. However, the relation between obesity and airway inflammation remains unclear. This cross‐sectional study aims to investigate the relation between obesity indices and exhaled nitric oxide (ENO) and leukotriene B4 (LTB4) in children with asthma. Asthmatic patients aged 7–18 yr old were recruited. Weight‐for‐height Z score was calculated from anthropometry. ENO was measured by online single‐breath method using a chemiluminescence analyzer, whereas LTB4 concentrations in exhaled breath condensate (EBC) were quantified using competitive enzyme immunoassay. Ninety‐two asthmatics and 23 controls were recruited. The mean ENO and LTB4 concentrations in EBC were higher in asthmatic patients (87 p.p.b. and 40.5 pg/ml) than controls (25 p.p.b. and 18.7 pg/ml) (p < 0.0001 for both). Obesity, as defined by weight >120% median weight‐for‐height, was not associated with any alteration in ENO or LTB4 concentrations in patients with asthma. Besides, these inflammatory markers did not differ between asthmatics in the highest and lowest quartiles of weight‐for‐height Z score. On multivariate analysis, ENO showed significant correlation with age (β = 0.511, p < 0.0001), peripheral blood eosinophil count (β = 0.222, p = 0.019), plasma total IgE concentration (β = 0.187, p = 0.050) and forced expiratory volume in 1‐s (FEV1; β = −0.221, p = 0.014). None of the factors was associated with LTB4 concentration in EBC. In conclusion, ENO and LTB4 concentration in EBC are increased in childhood asthma. However, these inflammatory markers did not differ between obese and non‐obese children with asthma.

Summary. Exhaled breath condensate (EBC) pH appears to be a robust measure of asthma. However, the association between EBC pH and clinical factors and airway inflammatory markers remains unclear. The objectives of this study were to investigate the factors determining EBC pH in asthmatic children, and the reproducibility and effects of collection devices on EBC pH in nine healthy, nonsmoking adults. EBC was collected once from asthmatic children using EcoScreen, and from adults over 3 consecutive days using both RTubes and EcoScreen. EBC pH was measured immediately in non-deaerated samples by microelectrode pH meter. Concentrations of 8-isoprostane, cysteinyl leukotrienes (cys-LT), and leukotriene B4 (LTB 4 ) were measured using enzyme immunoassay. Exhaled nitric oxide concentration (FeNO) was measured by chemiluminescence. Fifty-eight asthmatics (16 intermittent, 12 mild persistent, and 30 moderate-to-severe persistent) were recruited. EBC pH was lower among patients with moderate-to-severe persistent than intermittent asthma (P ¼ 0.046). This marker correlated inversely with disease severity score (r ¼ À0.276, P ¼ 0.036), but not FeNO or other EBC biomarkers. Bland-Altman analyses found pH but not other EBC biomarkers to be reproducible, which were confirmed by its low coefficient of variation (2.7%; range, 0.4-5.2%). There was poor correlation between pH in EBC collected by RTube and EcoScreen (r ¼ 0.059, P ¼ 0.784). Factor analysis selected four factors that explained 67.5% of the total variance, and EBC pH clustered with both cys-LT and LTB 4 . In conclusion, our results suggest that pH in non-deaerated EBC is influenced by asthma severity in children. EBC pH measurement is reproducible, but is dependent on the collection devices used. Pediatr Pulmonol.