Edmund Yung

Parent-reported adverse food reactions in Hong Kong Chinese pre-schoolers: epidemiology, clinical spectrum and risk factors

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.

The relation between obesity and asthmatic airway inflammation

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.

Analysis of growth factors and inflammatory cytokines in exhaled breath condensate from asthmatic children.

Background: Vascular endothelial growth factor (VEGF), AA isoform of platelet-derived growth factor (PDGF-AA), and epidermal growth factor (EGF) are involved in the pathogenesis of airway inflammation in asthma. These molecules are closely associated with cytokines such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-4. This study investigates the relation between childhood asthma and levels of these mediators in exhaled breath condensate (EBC). Methods: EBC was collected from asthmatic children and controls using a disposable collection kit, and the concentrations of VEGF, PDGF-AA, EGF, TNF-α and IL-4 in EBC were measured using sandwich enzyme immunoassays. Exhaled nitric oxide concentration was measured by a chemiluminescence analyzer. Results: Thirty-five asthmatic patients aged between 7 and 18 years and 11 controls were recruited. Sixteen patients had intermittent asthma (IA) whereas 19 of them suffered from persistent asthma (PA). A significant correlation was found between IL-4 and TNF-α in EBC (ρ = 0.374, p = 0.010). PDGF-AA levels in EBC were higher in subjects with diminished FEV1 (p = 0.023) whereas IL-4 concentrations were increased in asthmatics (p = 0.007) as well as subjects with increased plasma total IgE (p = 0.033). Patients with PA receiving high-dose inhaled corticosteroid (ICS) had higher EBC IL-4 concentration than those on low-dose ICS (p = 0.007). Linear regression revealed that PDGF-AA levels in EBC were negatively associated with FEV1 percentage (β = –0.459, p = 0.006) among the asthmatic patients. Conclusions: IL-4 in EBC is increased in childhood asthma, and growth factors are detectable in a significant proportion of these children. Increased PDGF-AA is found in asthmatics with more severe airflow limitation.

Symptoms of asthma and atopic disorders in preschool children: prevalence and risk factors

Background Published epidemiological data suggested that asthma and allergies may be increasing in preschool children. Identification of the risk factors is important for planning possible early intervention to prevent asthma. This study was designed to measure the prevalence of, and risk factors for, asthma and atopic disorders in preschool children from Hong Kong.

Asthma and atopy are associated with DEFB1 polymorphisms in Chinese children

Human β-defensin (HBD)-1 is constitutively expressed in the airway, and hBD-1 plays crucial roles in innate immunity against respiratory pathogens. Asthma was associated with DEFB1 polymorphisms in Caucasians. This study investigates whether three single nucleotide polymorphisms (SNPs) in 5′-untranslated region of DEFB1 are associated with asthma phenotypes in Chinese children. Subjects aged 5–18 years were recruited from general pediatric clinics. Plasma IgE concentrations were measured by immunoassays. DEFB1 SNPs were characterized by restriction fragment length polymorphism. In all, 305 asthmatics and 156 controls were recruited. For asthma diagnosis, atopy and plasma total IgE, higher percentages of subjects with these outcomes had the minor alleles −20A and −52G (P=0.041–0.0002). For log-transformed total IgE, the covariate was positive and significant for G-20A under recessive model (P=0.001) and for G-52A under both recessive and codominant models (P=0.008 and 0.035). The recessive model covariate was also positive and significant (P=0.020) for C-44G on peripheral blood eosinophil count. The GCA haplotype of DEFB1 was significantly associated with asthma (odds ratio (95% confidence interval): 1.64 (1.05–2.57); P=0.029). These results suggest that DEFB1 is a candidate gene for asthma and atopy in children.

CTLA‐4 gene A–G polymorphism and childhood Graves’ disease

objective Graves’ disease is associated with a polymorphism at position 49 in exon 1 of the cytotoxic T‐lymphocyte‐associated antigen‐4 (CTLA‐4) gene in Caucasians and Japanese. A high incidence of childhood Graves’ disease has been documented in Hong Kong Chinese. The aims of this study were to investigate the CTLA‐4 gene A–G polymorphism association in Chinese children with Graves’ disease.

Quality-of-life assessment in Chinese families with food-allergic children

Background Caucasian families with food‐allergic children have a compromised quality of life (QoL) for fear of life‐threatening food reactions. Such data are limited in Asian children. Based on our recent questionnaire‐based survey, 8.1% of young children recruited from local nurseries and kindergartens had parent‐reported adverse food reactions (AFRs).

Identifying uncontrolled asthma in young children: clinical scores or objective variables?

Objective. Several international asthma guidelines emphasize the importance of assessing asthma control. However, there is limited data on the usefulness of available assessment tools in indicating disease control in young asthmatics. This study investigated the ability of Chinese version of Childhood Asthma Control Test (C-ACT) and other disease-related factors in identifying uncontrolled asthma (UA) in young children. Methods. During the same clinic visit, asthma patients 4 to 11 years of age completed C-ACT and underwent exhaled nitric oxide and spirometric measurements. Blinded to these results, the same investigator assigned Disease Severity Score (DSS) and rated asthma control according to Global Initiative for Asthma. Results. The mean (SD) age of 113 recruited patients was 9.1 (2.0) years, and 35% of them had UA. C-ACT, DSS and forced expiratory volume in 1 second (FEV1) differed among patients with different control status (p < 0.001 for C-ACT and DSS; p = 0.014 for FEV1). Logistic regression confirmed that UA was associated with DSS (p < 0.001), PEF (p = 0.002), C-ACT (p = 0.011), and FEV1 (p = 0.012). By ROC analysis, C-ACT and DSS were the best predictors for UA (p < 0.001), followed by PEF (p = 0.006) and FEV1 (p = 0.007). When analyzed by the Classification and Regression Tree (CART) approach, the sequential use of DSS and C-ACT had 77% sensitivity and 84% specificity in identifying UA. Conclusions. C-ACT is better than objective parameters in identifying young Chinese children with UA.

Association between candidate genes and lung function growth in Chinese asthmatic children.

Background Asthma is caused by a complex interaction between multiple candidate genes and environmental factors. The Childhood Asthma Management Program reported lung function decline in a significant proportion of Caucasian asthmatic children, but such a relation has not been studied in other populations. Our group recently reported that interleukin‐13 (IL13), interleukin‐4 receptor‐α and thymus and the activation‐regulated chemokine interacted to influence asthma and raised plasma total IgE. However, there has not been any study that has addressed the genetic influences for longitudinal lung function growth.

Frequency of food group consumption and risk of allergic disease and sensitization in schoolchildren in urban and rural China

Diet is a potential determinant of allergic diseases.