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Notes: Background Many studies have reported an increase in the prevalence of asthma and related atopic disorders. The lack of standardized methodologies and ‘objective’ measurements make reliable comparison and monitoring of trends of asthma very difficult.Methods In this study, a total of 3321 schoolchildren aged 13–14 years were recruited for study using the Phase III Protocol of the International Study of Asthma and Allergic discase in Childhood (ISAAC). The results were compared with those obtained in the Phase I ISAAC study (1994–95), which used the identical and validated core questionnaires.Results The prevalence rates of physicians' diagnosis of asthma were similar in the two surveys (11.2% and 10.2%), but the prevalence rates of wheeze (written questionnaire) in the past year have decreased from 12.4% in 1994–95 to 8.7% in 2002 (P〈0.001). For the video questionnaire, all asthmatic symptoms in the preceding 12 months were significantly lower in 2002 when compared with those in 1994–95. Among the subjects with diagnosed asthma, the prevalence rates of wheeze in the past 12 months (written questionnaire) has decreased from 39.1% to 27.6% (P〈0.001). The prevalence rates of having wheezing attack at least once per month (video questionnaire) has decreased from 10.5% to 5.6% (P=0.013).Conclusion Using the same standardized and validated ISAAC questionnaire, the prevalence rates of asthma symptoms in Hong Kong Chinese schoolchildren have decreased since 1994. The exact reasons for such trend remain to be explored.

Notes: 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.Methods Levels of eNO in a sample of 531 schoolchildren aged 11–18 years recruited from five schools (three international schools) in Hong Kong were measured online by a chemiluminescence analyser according to ERS/ATS standard. Each student also completed an International Study of Asthma and Allergic disease in Childhood questionnaire.Results Among the children without a physician's diagnosis of asthma or symptoms of wheeze, rhinitis and eczema, there were 258 Chinese and 33 Caucasians. In control Chinese children, the eNO level (median: interquantile range) was significantly higher (P〈0.001) in males (17.0 parts per billion (p.p.b.); 10.7–36.6) than in females (10.8 p.p.b.; 7.8–17.6). When compared with Caucasian control males (11.6 p.p.b.; 8.2–19.3) and females (9.1 p.p.b.; 7.5–11.9), the Chinese children had significantly higher eNO levels for both males (P=0.011) and females (P=0.037). For Chinese asthmatic males, the median eNO (interquartile range) was 39.8 p.p.b. (12.5–73.8), and for asthmatic females, 18.0 (9.6–56.3). After controlling for sex in Chinese controls, eNO did not have any significant correlation with height, weight and body mass index or body surface area.Conclusions This study demonstrates a gender difference of eNO level in healthy Chinese schoolchildren. When compared with Caucasians, Chinese children have significantly higher eNO levels.

Notes: Background Nitric oxide (NO) is a key factor for balancing T-helper type 1/T-helper type 2 immunity. Single nucleotide polymorphisms (SNPs) in nitric oxide synthase (NOS) genes have been associated with atopy and exhaled NO concentrations in Caucasians. We investigated the association between asthma traits and genetic polymorphisms in neuronal NO synthase (NOS1) and endothelial NO synthase (NOS3) in Chinese children.Methods Asthmatic children between 5 and 18 years of age and non-allergic controls were recruited. Plasma total IgE was measured by microparticle immunoassay, whereas allergen-specific IgEs were measured by fluorescent enzyme immunoassay. Fractional exhaled NO concentration (FeNO) was measured by a chemiluminescence analyser. NOS1 C5266T and NOS3 G894T were genotyped by restriction fragment length polymorphism, and (AAT)n polymorphism in intron 20 of NOS1 was determined by GeneScan analysis.Results The mean (SD) ages of 295 asthmatics and 174 controls were 11.1 (3.8) years and 11.6 (4.0) years, respectively (P=0.162). NOS1 C5266T and NOS3 G894T were not associated with asthma, atopy or FeNO. However, significantly more subjects with T/T in NOS1 C5266T had increased plasma total IgE as compared with those with C/T or C/C (P=0.017). This SNP was also associated with sensitization to Dermatophagoides pteronyssinus (P=0.049). Among asthmatic patients, log-transformed plasma total IgE levels were significantly higher among those homozygous for 5266T of NOS1 [mean (SD): 2.84 (0.44) for T/T, 2.68 (0.42) for C/T, 2.59 (0.69) for C/C; P=0.021]. This study found a significant inter-ethnic difference in the allele frequencies of AAT repeats, and this polymorphism was associated with high plasma total IgE levels (P=0.044) but not FeNO (P=0.158). NOS3 G894T was not associated with any asthma or atopy phenotype.Conclusions NOS1 C5266T and AAT repeats affect plasma IgE concentrations in Chinese children. On the other hand, neither NOS1 nor NOS3 SNP was associated with FeNO or the risk of having asthma.

Notes: Background Asthma is a common chronic disease and information on its management practices at the community level is helpful in identifying problems and improving asthma care.Objective To assess the severity status and management of the asthma symptom of wheeze of children at the community level in Hong Kong (HK) and Guangzhou (GZ).Methods Cross-sectional study of children aged 10 years using the International Study of Asthma and Allergic disease in Childhood (ISAAC Phase II protocol). Asthma management and lung function were assessed in 178 (98 from HK and 80 from GZ) randomly selected children with wheeze over the past 12 months.Results Eighty-three percent, 11%, 6% and 0% of children suffered from intermittent, mild persistent, moderate persistent and severe persistent asthma, respectively, according to the frequency of their symptoms. Addition of spirometric parameter only changed the asthma severity classification in 2.8% of children. Medications were used by 30.6% and 71.3% of children for wheeze in HK and GZ, respectively. In HK, inhaled β2-agonist (73.3% among the drug users) was the commonest medication used followed by inhaled corticosteroid (ICS) (23.3%). In GZ, inhaled β2-agonist was used by 75.4% of children, but use of ICS (26.3%), oral β2-agonist (26.3%), oral theophylline (45.6%), oral ketotifen (36.8%) and oral steroid (35.1%) were also common. ICS was only used by 11.4% of children with persistent asthma. Ten percent and 18.7% of children in HK and GZ, respectively, had emergency department visits, while 16.3% and 11.6% of children in HK and GZ, respectively, had missed school secondary to asthma over the past 1 year.Conclusions Most children in the community had intermittent asthma and addition of lung function to symptoms did not significantly affect classification of asthma severity. Significant morbidity was seen even in this group of children with mostly intermittent and mild persistent asthma.

Notes: Background Type 2 helper T lymphocyte-specific chemokines including macrophage-derived chemokine (MDC), thymus and activation-regulated chemokine (TARC) and eotaxin are important mediators for allergic airway inflammation.Objective We investigated whether these chemokines can be detected in exhaled breath condensate (EBC) and their relation to childhood asthma.Methods Asthmatics recruited from paediatric clinics of a university teaching hospital were classified into intermittent asthma (IA) and persistent asthma (PA) according to Global Initiative for Asthma guidelines. EBC was collected by a disposable collection kit, whereas fractional exhaled nitric oxide (FENO) was measured by a chemiluminescence analyser. Concentrations of MDC, TARC and eotaxin in both EBC and plasma were measured using sandwich enzyme immunoassay. The intra-subject reproducibility of exhaled chemokine measurements was determined by co-efficients of variation (CV).Results Forty-eight patients with PA, 36 children with IA and 18 controls were recruited. MDC and eotaxin were present in EBC from nearly all subjects, whereas TARC could be measured in EBC from 33 (32%) subjects only. The median MDC concentration in EBC was higher in PA (117 pg/mL) as compared with IA (106 pg/mL) and controls (105 pg/mL; P=0.003 for both). The median plasma MDC concentration in PA (648 pg/mL) was also higher than that in IA (520 pg/mL; P=0.002) and controls (490 pg/mL; P=0.008). The median plasma TARC concentration was also increased in PA as compared with IA (72 pg/mL vs. 35 pg/mL; P=0.004). MDC concentrations in EBC were lower in patients with PA who received high-dose inhaled corticosteroid (P=0.005). FENO was significantly higher in asthmatics than controls (P〈0.0001), but it was not associated with chemokines in EBC or plasma. The mean (range) CV for measuring MDC, TARC and eotaxin in EBC (n=6) were 5.5 (2.0−7.2%), 8.8 (3.6−14.4%) and 5.2 (2.8−7.9%), respectively.Conclusions Our results suggest that MDC in EBC and MDC and TARC in plasma are increased in children with PA as compared with IA or control. MDC concentrations in EBC are suppressed in patients on high-dose inhaled corticosteroid treatment.

Notes: Background Asthma is a common health problem affecting patients of all ages. Because of the ease of sampling, epidemiological studies have concentrated mainly on the paediatric and general population.Objective This study aimed to determine the prevalence of wheeze, bronchial hyper-responsiveness and asthma amongst our elderly population and deduce any clinical and laboratory risk factors that might identify elderly asthmatics at an earlier stage.Methods Two thousand and thirty-two elderly Chinese aged ≥ 70 years, randomly selected from a registered list of all recipients of Old Age and Disability Allowances in Hong Kong, were administered a questionnaire on lung health. Two hundred and fifty subjects were invited to attend our laboratory for skin tests and pulmonary function tests and 179 agreed. Of these, 173 (96.6%) and 176 (98.3%) had eosinophil count and serum IgE levels measured, respectively. Two definitions of asthma were used: (1) bronchial hyper-responsiveness (BHR) plus current wheeze, and (2) history of wheezing without previous diagnostic labels of emphysema or chronic bronchitis.Results Fifteen patients (out of 179: 8.4%) reported wheezing over the past 1 year. Fifty-one patients (28.5%) demonstrated BHR on spirometry or histamine challenge tests. Seven patients had both symptoms of wheezing and evidence of BHR. The prevalence of asthma using this definition is therefore 3.9% (95% CI 1.6–7.9%). Nine patients had symptoms of wheezing without previous diagnostic labels of chronic bronchitis or emphysema and, using this definition, the prevalence is 5.0% (95% CI 2.3–9.3%). Using multiple logistic regression studies, sex, social class, age, smoking habits, serum IgE levels and eosinophil counts did not predict a diagnosis of asthma using either definition. We found no association between a positive skin test and any respiratory symptoms or illnesses including asthma.Conclusion Wheeze, bronchial hyper-responsiveness and asthma are prevalent amongst our elderly population. However, there were no identifiable demographic and laboratory risk factors in this study that may help us predict a diagnosis of asthma.

Notes: Background Many epidemiological studies have shown positive association between respiratory health and current levels of outdoor air pollution in Europe and America.Objective The aim of this study was to investigate the association between air pollution and the number of childhood admissions for asthma in Hong Kong.Methods Daily counts of childhood admission for asthma to a large teaching Hospital were obtained from the computerized database for the period 1993–1994. A Poisson regression allowing for seasonal patterns and meteorological conditions was used to assess the associations between the number of Hospital admissions and the three pollutants: nitrogen dioxide, sulphur dioxide and inhalable particles (measured as PM10, particles 〈 10 µm in aerodynamic diameter).Results A total of 1217 children under 15 years of age were admitted for asthma during the study period. The calculated annual hospitalization rates were 283 and 178 per 100 000 for boys and girls, respectively. The mean PM10, NO2 and SO2 levels were 44.1 µg/m3, 43.3 µg/m3, and 12.2 µg/m3, respectively. Daily admission for asthma increased significantly with increasing ambient level of nitrogen dioxide (relative risk (RR) = 1.08 per 10 µg/m3 increase), sulphur dioxide (RR = 1.06) and inhalable particles (RR = 1.03). No association was found between hospital admission and humidity, temperature or atmospheric pressure.Conclusion This is the first daily time series study of childhood admissions for asthma and air pollution in Hong Kong. The results support that current levels of air pollution contribute to the respiratory morbidity in asthmatic children in Hong Kong.