Gary W.K. Wong

International consensus on (ICON) pediatric asthma

Asthma is the most common chronic lower respiratory disease in childhood throughout the world. Several guidelines and/or consensus documents are available to support medical decisions on pediatric asthma. Although there is no doubt that the use of common systematic approaches for management can considerably improve outcomes, dissemination and implementation of these are still major challenges. Consequently, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), recently formed by the EAACI, AAAAI, ACAAI, and WAO, has decided to propose an International Consensus on (ICON) Pediatric Asthma. The purpose of this document is to highlight the key messages that are common to many of the existing guidelines, while critically reviewing and commenting on any differences, thus providing a concise reference. The principles of pediatric asthma management are generally accepted. Overall, the treatment goal is disease control. To achieve this, patients and their parents should be educated to optimally manage the disease, in collaboration with healthcare professionals. Identification and avoidance of triggers is also of significant importance. Assessment and monitoring should be performed regularly to re‐evaluate and fine‐tune treatment. Pharmacotherapy is the cornerstone of treatment. The optimal use of medication can, in most cases, help patients control symptoms and reduce the risk for future morbidity. The management of exacerbations is a major consideration, independent of chronic treatment. There is a trend toward considering phenotype‐specific treatment choices; however, this goal has not yet been achieved.

Prevalence of asthma and allergy in Hong Kong schoolchildren: an ISAAC study

Asthma and allergic disease in children is increasing in many Western countries but such trend has not been well-defined in Chinese populations. This paper aims to determine the prevalence of asthma and allergic disease in Hong Kong schoolchildren and compare it with previous data to identify a changing trend. We studied 4,665 schoolchildren aged 13-14 yrs using the International Study of Asthma and Allergy in Childhood (ISAAC) protocol to determine prevalence rates for asthma, wheeze, respiratory symptoms, rhinitis and eczema in 1994-1995. Additional questions on education levels of the parents and smoking status were also asked. Concordance between responses to the written and video questionnaires was good (76% for wheeze ever, 80% for current wheeze). Prevalence rates for asthma ever, wheeze ever, and current wheeze were 11, 20 and 12%, respectively, and were greater in boys (p < 0.05). Rhinitis affected slightly over half of the subjects (52%), and eczema was reported by a sixth (15%), whilst current rhinitis and current eczema were present in 44% and 3.6% of children, respectively. In multiple logistic regression: odds ratio male sex (OR) 1.47; (95% confidence interval (95% CI) 1.15-1.86); current rhinitis (OR 3.00; 95% CI 2.36-3.81); current eczema (OR 2.34; 95% CI 1.40-3.93); and active smoking (OR 2.00; 95% CI 1.38-2.89) were associated with current wheeze; whilst severe wheezing attack was associated with: current rhinitis (OR 2.72; 95% CI 1.47-5.02); current eczema (OR 6.13; 95% CI 2.82-13.33); and active smoking (OR 4.62; 95% CI 2.43-8.76). Age, parental education and passive smoking were not important factors. When compared to previous epidemiological data obtained in 1992, the prevalence rates for asthma ever and wheeze ever had increased by 71 and 255%, respectively, in Hong Kong schoolchildren. The severity of asthma and respiratory symptoms showed a similar increasing trend. Further studies should aim to identify the role of the environment in the pathogenesis of asthma.

Factors associated with difference in prevalence of asthma in children from three cities in China: multicentre epidemiological survey

Abstract Objective To determine the factors associated with difference in prevalence of asthma in children in different regions of China. Design Multicentre epidemiological survey. Setting Three cities in China. Participants 10 902 schoolchildren aged 10 years. Main outcome measures Asthma and atopic symptoms, atopic sensitisation, and early and current exposure to environmental factors. Results Children from Hong Kong had a significantly higher prevalence of wheeze in the past year than those from Guangzhou and Beijing (odds ratio 1.64, 95% confidence interval 1.35 to 1.99). Factors during the first year of life and currently that were significantly associated with wheeze were cooking with gas (odds ratio 2.04, 1.34 to 3.13), foam pillows (2.58, 1.66 to 3.99), and damp housing (1.89, 1.26 to 2.83). Factors protecting against wheeze were cotton quilts and the consumption of fruit and raw vegetables. Conclusion Environmental factors and diet may explain the differences in prevalence of asthma between children living in different regions of China.

Secular changes in standing height, sitting height and sexual maturation of Chinese—The Hong Kong growth study, 1993

In 1993 a territory-wide cross-sectional growth survey on 25,000 Chinese children from birth to 18 years was performed in Hong Kong. Compared to the last growth survey in 1963, definite secular changes were observed. There was an increase of final adult standing height of 3.6 cm in boys and 2.7 cm in girls, in which 1.8 cm and 0.5 cm respectively for boys and girls was accounted for by the sitting height. Thus most of the height increase had occurred in the leg length in girls, but in boys only half of it. The height difference was more marked during the pubertal years because secular change had brought about an earlier sexual maturation, including an advancement of median menarcheal age by 0.5 year, coupled with an earlier growth spurt. This paper also provides the first growth standards for Chinese from birth to 18 years, with percentile charts on both standing height and sexual maturation in boys and girls.

Prevalence of respiratory and atopic disorders in Chinese schoolchildren

Background Epidemiological surveys have shown that the prevalence of asthma in the Asian population is relatively low. Within the Chinese population, schoolchildren from Hong Kong were found to have the highest rate of asthma.

Comparison of the ISAAC video questionnaire (AVQ 3.0) with the ISAAC written questionnaire for estimating asthma associated with bronchial hyperreactivity

Background A standardized protocol is essential for international comparisons of asthma prevalence and severity. The International Study of Asthma and Allergies in Childhood (ISAAC) used a standardized written questionnaire (WQ) and a video questionnaire (AVQ3.0) to survey the prevalence and severity of asthma in 13–14‐year‐old schoolchildren in different countries.

The C−159T polymorphism in the CD14 promoter is associated with serum total IgE concentration in atopic Chinese children

Activation of macrophages through CD14 by microbes is crucial in inducing immunity by type 1 T helper cells. A C‐to‐T polymorphism at position −159 of CD14 was associated with serum total IgE level in Caucasians but not in Japanese subjects. The objective of this study is to determine whether this polymorphic marker is associated with atopy and asthma phenotypes in Chinese children. Restriction fragment length polymorphism was used to characterize CD14/−159 genotypes. Microparticle immunoassay was used to measure serum total IgE level; fluorescent enzyme immunoassay was performed to measure serum concentrations of specific IgE to aeroallergens; and enzyme‐linked immunosorbent assay was used to measure serum levels of soluble CD14 (sCD14). Lung function in asthmatics was assessed by spirometry. Two hundred and fifty‐eight patients and 92 control children were recruited. Their mean serum total IgE concentrations were 331 and 74 kIU/l, respectively (p < 0.0001). Atopy, defined as the presence of at least one allergen‐specific IgE in serum, was found in 220 (85%) patients and in 41 (45%) controls (p < 0.0001). Serum sCD14 levels were significantly associated with CD14/−159 genotypes (p = 0.004). Atopic subjects with CC genotype in CD14/−159 had the highest serum total IgE levels compared with CT and TT genotypes, with the respective mean values being 661, 427 and 380 kIU/l (p = 0.015). Similarly, a higher proportion of subjects with CC genotype had increased serum total IgE concentration (p = 0.039). This polymorphic marker was not associated with asthma or aeroallergen sensitization in our cohort. Our results suggest that the C−159T of CD14 was associated with serum total IgE concentration in atopic Chinese children.

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.

High levels and gender difference of exhaled nitric oxide in Chinese schoolchildren

Background Exhaled nitric oxide (eNO) may represent a useful noninvasive marker of airway inflammation, but data on the reference population values in schoolchildren are limited. No reference eNO study in Asian children has been published.

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.