Are Hong Kong doctors following the Global Initiative for Asthma guidelines: a questionnaire "Survey on Asthma Management"?

OBJECTIVE: To assess the standard of asthma management by doctors in Hong Kong. DESIGN: Cross-sectional postal questionnaire survey. SETTING: Hong Kong. PARTICIPANTS: Practising doctors registered with the Medical Council of Hong Kong were sent a questionnaire between August and December 2007. MAIN OUTCOME MEASURES: Respondents' responses to questions on demographic data, parameters routinely used to assess asthma control, the pattern of asthma medication prescribing, and seven different case scenarios assessing their ability to classify asthma control and management. RESULTS. We received 410 completed questionnaires from general practitioners (55%), internists (22%), paediatricians (11%), and other specialists (12%). The majority (82%) explained the pathology of asthma to at least some of their patients and tried to identify aggravating factors of the asthma (91%). Fewer observed the inhalation technique of their patients (68%) and prescribed a written asthma management plan (33%). The main medications prescribed to adults and children with asthma were inhaled corticosteroids, inhaled short-acting beta-2 agonists, and combinations of an inhaled corticosteroid and a long-acting beta-2 agonist. In adults and children, long-acting beta-2 agonist alone (without inhaled corticosteroid) was being used to treat asthma by 45% and 36% of the doctors, respectively. Also, 94% of the respondents correctly classified the control status in four out of the seven case scenarios and 31% chose the correct medications when responding to seven of the 14 questions asked. CONCLUSIONS: Asthma management practice of Hong Kong doctors falls short of the standards recommended by international guidelines. More effort in improving their knowledge is urgently warranted.

Global variation in the prevalence and severity of asthma symptoms: phase three of the International Study of Asthma and Allergies in Childhood (ISAAC).

BACKGROUND: Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC) measured the global prevalence and severity of asthma symptoms in children. METHODS: A cross-sectional questionnaire survey of 798 685 children aged 13-14 years from 233 centres in 97 countries, and 388 811 children aged 6-7 years from 144 centres in 61 countries, was conducted between 2000 and 2003 in >90% of the centres. RESULTS: The prevalence of wheeze in the past 12 months (current wheeze) ranged from 0.8% in Tibet (China) to 32.6% in Wellington (New Zealand) in the 13-14 year olds, and from 2.4% in Jodhpur (India) to 37.6% in Costa Rica in the 6-7 year olds. The prevalence of symptoms of severe asthma, defined as >or=4 attacks of wheeze or >or=1 night per week sleep disturbance from wheeze or wheeze affecting speech in the past 12 months, ranged from 0.1% in Pune (India) to 16% in Costa Rica in the 13-14 year olds and from 0% to 20.3% in the same two centres, respectively, in the 6-7 year olds. Ecological economic analyses revealed a significant trend towards a higher prevalence of current wheeze in centres in higher income countries in both age groups, but this trend was reversed for the prevalence of severe symptoms among current wheezers, especially in the older age group. CONCLUSION: Wide variations exist in the symptom prevalence of childhood asthma worldwide. Although asthma symptoms tend to be more prevalent in more affluent countries, they appear to be more severe in less affluent countries.

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 (FEV(1)) differed among patients with different control status (p < 0.001 for C-ACT and DSS; p = 0.014 for FEV(1)). Logistic regression confirmed that UA was associated with DSS (p < 0.001), PEF (p = 0.002), C-ACT (p = 0.011), and FEV(1) (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 FEV(1) (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.

Prevalence and risk factors of airflow obstruction in an elderly Chinese population.

It is common practice to use a forced expiratory volume in one second (FEV(1))/ forced vital capacity (FVC) ratio of <70% as evidence of airflow obstruction. As the FEV(1)/FVC ratio falls with age, the lower limit of normal range (LLN), defined as the bottom 5% in a health reference population, of FEV(1)/FVC ratio has been suggested as a better index to reduce over-diagnosis of chronic obstructive pulmonary disease (COPD), particularly in the elderly. However, there are no large scale studies that focus on the diagnosis of COPD in the elderly based on these definitions. The present prospective epidemiological study involved 1,149 elderly subjects aged > or =60 yrs in the community. Detailed questionnaires, pre- and post-bronchodilator spirometry were performed. In total, 1,008 subjects (mean age 74.2+/-6.4 yrs; 271 males) completed satisfactory spirometry testing. Airflow obstruction was present in 25.9% as defined by the post-bronchodilator FEV(1)/FVC ratio of <70% and in 12.4% defined by the LLN of FEV(1)/FVC ratio. Moderate COPD, at least, was found in 14.0% of patients according to the post-bronchodilator FEV(1)/FVC ratio of <70% and in 8.5% of patients according to LLN of FEV(1)/FVC ratio. In the present elderly Chinese population (mostly females, with low education level and previous exposure to biomass during formative years), the prevalence of chronic obstructive pulmonary disease varied markedly depending on definitions adopted. Further longitudinal studies are needed to determine the precise definition of chronic obstructive pulmonary disease.

Worldwide burden of COPD in high- and low-income countries. Part III. Asia-Pacific studies.

Chronic obstructive pulmonary disease (COPD) is a global health problem that poses a heavy burden on most countries in the Asia-Pacific region. When compared to industrialised Western countries, the COPD burden in the Asia-Pacific region is higher in terms of the number of deaths, years spent living with disability and years of life lost. Given the high prevalence of tobacco smoking, poor indoor and outdoor air quality and the aging population in many Asian countries, urgent actions need to be taken to reduce the development, morbidity and mortality of this disease.

Candidate genetic polymorphisms for asthma in Chinese schoolchildren from Hong Kong.

BACKGROUND: Polymorphisms in several genes have been associated with asthma, atopy and bronchial hyperresponsiveness in white and Japanese populations. In this study we tested for associations of 11 polymorphisms with wheeze and asthma in 10-year-old Chinese schoolchildren. METHODS: The subjects were 107 children who had wheeze in the last 12 months and 118 without wheeze in the last 12 months. They were randomly selected from 3110 children who took part in Phase II of the International Study of Asthma and Allergies in Childhood. These schoolchildren underwent questionnaire, spirometry and methacholine challenge testing. RESULTS: The A allele of the tumor necrosis factor-alpha (TNFA) G-308A polymorphism was significantly associated with wheeze in the last 12 months (odds ratio [OR] 2.1, P = 0.04) and current asthma (OR 2.6, P = 0.006). When stratified by gender, these associations were only seen in the female study participants. In girls, the OR for the TNFA-308A allele and wheeze in the last 12 months was 3.6 (P = 0.01) and for current asthma it was 6.0 (P = 0.0006). CONCLUSION: The A allele of the TNFA G-308A polymorphism was a risk factor for asthma-related phenotypes in girls but not boys.

Cephalometric assessment of craniofacial morphology in Chinese patients with obstructive sleep apnoea.

OBJECTIVE: To compare the differences in craniofacial morphology in Chinese patients with and without obstructive sleep apnoea (OSA). METHOD: We performed lateral cephalometric radiographs on 94 consecutive patients (77 males) referred with snoring or other symptoms suggestive of OSA for polysomnography (PSG). Significant OSA was defined as an apneoa-hypopnoea index (AHI) > or = 10/h of sleep on overnight PSG. The cephalometric data were compared between those with and without significant OSA. RESULTS: (mean +/- SD) There were 69 (56 males) with significant OSA with mean age 53 +/- 12 years, body mass index (BMI) 28.6 +/- 5.0 kg/m2, AHI 36.5 +/- 20.6/h, and minimum SaO2 76 +/- 14%. There were 25 controls (21 males) without significant OSA with similar age and BMI. The mandibular plane to hyoid bone distance (MPH) and the perpendicular distance from hyoid bone to the line connecting C3 vertebra and retrognathion (HHI) were significantly longer in the OSA patients. The angle measurement from sella to nasion to point A (SNA) was smaller in the OSA group. MPH distance was the only independent variable for significant OSA with an odds ratio of 3.47 (95% CI 1.39-8.66). Abnormalities of the MPH and SNA were more marked in the OSA patients with BMI > or = 30 kg/m2. CONCLUSIONS: Significant differences in craniofacial morphology are noted between OSA patients and non-apnoeic controls. An inferiorly positioned hyoid bone and a retropositioned maxilla may predispose obese patients to more severe OSA.

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. METHODS: Children aged 2-6 years living in Hong Kong were recruited through the local nurseries and kindergartens for this study to ascertain the presence of symptoms of asthma and various possible risk factors. The parental questionnaire was developed based on the International Study of Asthma and Allergies in Childhood questionnaire. RESULTS: A total of 3089 children (1506 boys) from 14 nurseries and kindergartens participated in this study. The prevalence of wheeze ever and current wheeze were 16.7% and 9.3%. Two hundred and thirty-four subjects were born in mainland China and migrated to Hong Kong subsequently. When compared with children born and raised in Hong Kong, children born in mainland China had significantly lower prevalence of current wheeze (3.4% vs. 9.6%, P<0.01). Two environmental factors in the first year of life were associated with wheezing attacks within the last 12 months. They were the use of foam pillow (Odds ratio: 1.45; 95% Confidence interval: 1.04-2.00) and the use of gas as cooking fuel (1.68; 1.03-2.75). Frequent use of paracetamol was also associated with wheezing attack in the past 12 months. CONCLUSIONS: This study confirms the high prevalence of symptoms of atopic disorders in preschool children from Hong Kong. Early environmental exposure factors are important determinants of subsequent development of asthma symptoms in the preschool years. Further studies are needed to evaluate the possible pathogenetic role of the identified risk factors.

Effects of air pollution on asthma hospitalization rates in different age groups in Hong Kong.

AIMS: To assess the relationship between levels of ambient air pollutants and hospitalization rates for asthma in Hong Kong (HK). METHODS: This is a retrospective ecological study. Data of daily emergency hospital admissions to 15 major hospitals in HK for asthma and indices of air pollutants [sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)), particulates with an aerodynamic diameter of <10 microm particulate matter (PM(10)) and 2.5 microm (PM(2.5))] and meteorological variables from January 2000 to December 2005 were obtained from several government departments. Analysis was performed by the generalized additive models with Poisson distribution. The effects of time trend, season, other cyclical factors, temperature and humidity were adjusted. Autocorrelation and overdispersion were corrected. RESULTS: Altogether, 69 716 admissions were assessed. Significant associations were found between hospital admissions for asthma and levels of NO(2), O(3), PM(10) and PM(2.5). The relative risks (RR) for hospitalization for every 10 microg/m(3) increase in NO(2), O(3), PM(10) and PM(2.5) were 1.028, 1.034, 1.019 and 1.021, respectively, at a lag day that ranged from cumulative lag 0-4 to 0-5. In a multi-pollutant model, O(3) was significantly associated with increased admissions for asthma. The younger age group (0-14 years) tended to have a higher RR for each 10 microg/m(3) increase in pollutants than those aged 15-65 years. The elderly (aged >/=65 years) had a shorter 'best' lag time to develop asthma exacerbation following exposure to pollutants than those aged <65 years. CONCLUSION: Adverse effects of ambient concentrations of air pollutants on hospitalization rates for asthma are evident. Measures to improve air quality in HK are urgently needed.

Exhaled breath condensate levels of eotaxin and macrophage-derived chemokine in stable adult asthma patients.

BACKGROUND: Asthma is associated with esoinophilic airway inflammation and overproduction of T-helper type 2 (Th2) lymphocyte-related cytokines. OBJECTIVE: This study assessed the eosinophil chemoattractant eotaxin and Th2-specific macrophage-derived chemokine (MDC) in the adult asthmatic airway. Eotaxin and MDC levels were determined in exhaled breath condensate (EBC) obtained from adult patients with asthma. METHODS: Fifty-four asthmatics (20 male, mean (SD) age 40 (12) years and percentage predicted forced expiratory volume in 1 s (FEV(1)) 81.7 (20.8)) and 20 age- and sex-matched controls were studied. EBC was collected using EcoScreen by 10 min of tidal breathing with a nose clip. Concentrations of eotaxin and MDC were measured by ELISA. RESULTS: Asthma patients on inhaled corticosteroid (ICS) had a higher median interquartile range (IQR) level of eotaxin than the steroid-naïve asthmatics (18.5 (17.7-20.1) vs. 17.9 (17.0-18.6) pg/mL, P=0.02) and controls (18.5 (17.7-20.1) pg/mL vs 17.4 (16.3-18.0) pg/mL, P=0.001). Eotaxin level in EBC had a significant negative correlation with the FEV(1)/forced vital capacity ratio (r=-0.43, P=0.03) in steroid-naïve asthmatics. EBC MDC level was higher in subjects on ICS than the steroid naïve asthmatics (120 (118-125) vs. 117 (116-119) pg/mL, P=0.01) and the controls (120 (118-125) vs. 117 (116-120) pg/mL, P=0.02). CONCLUSIONS: Eotaxin and MDC could be measured in EBC of adults with asthma. EBC eotaxin and MDC levels were higher in asthmatics on ICS than the steroid-naïve asthmatics or controls. Exhaled chemokines may be potential non-invasive markers for assessing airway inflammation in asthmatics.

Increasing COPD awareness.

Early diagnosis and smoking cessation are the only available methods to stop the progression of chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate the effects of early detection of airflow limitation (AL) in a population with high risk for COPD, using spirometric screening. Smokers aged 40 yrs with a smoking history of 10 pack-yrs were invited to visit a local outpatient chest clinic for simple spirometry (forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)). Smoking history was recorded, followed by smoking cessation advice relating the results of spirometry to the smoking behaviour. Subjects who did not fulfil the above criteria (younger and/or nonsmokers) were also screened. A total 110,355 subjects were investigated; they were aged 53.5+/-11.5 yrs and 58.2% were males. Of the total amount of subjects, 64% were current smokers, 25.1% were former smokers and 10.9% were lifelong nonsmokers. Spirometry tests were within normal values for 70.3%, and 20.3% showed signs of AL: this was mild in 7.6%, moderate in 6.7% and severe in 5.9%. The remaining 8.3% of subjects presented with a restrictive pattern of ventilatory impairment. Airflow limitation was found in 23% of smokers aged 40 yrs with a history of 10 pack-yrs. This study concluded that large-scale voluntary spirometry screening of the population with high risk for COPD detects a large number of subjects with AL.

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. 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.

Wheezing in Chinese schoolchildren: disease severity distribution and management practices, a community-based study in Hong Kong and Guangzhou.

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 beta(2)-agonist (73.3% among the drug users) was the commonest medication used followed by inhaled corticosteroid (ICS) (23.3%). In GZ, inhaled beta(2)-agonist was used by 75.4% of children, but use of ICS (26.3%), oral beta(2)-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.

Home mechanical ventilation in Hong Kong.

Home mechanical ventilation (HMV) is increasingly used to treat chronic respiratory failure. This present study was aimed to examine the trend, the disease categories treated and the outcomes of HMV use in Hong Kong. In the year 2002, all adult respiratory units in Hong Kong were invited to report to a multicentre retrospective survey of HMV use. A total of 249 patients (156 males, mean age 62.7 +/- 13.8 yrs) were treated since 1980, with 197 (79%) continuing with HMV at the time of the survey. Cumulative number of HMV grew as a cubic function of time since 1980. Currently, there are 2.9 users per 100,000 population. The predominant mode of HMV was noninvasive ventilation by bilevel pressure support ventilators (n=236). Chronic obstructive pulmonary disease accounted for 48.6% of all cases. The overall 3-yr HMV continuation rate was 66.2%. Death was the main reason for discontinuation. A rapidly rising trend of home mechanical ventilation use is observed in Hong Kong. In contrast to other series, chronic obstructive pulmonary disease was the major group treated and bilevel pressure support ventilation was the predominant mode chosen. Most patients tolerate home mechanical ventilation reasonably well, with approximately two-thirds continuing with its use at 36 months.

Individual allergens as risk factors for asthma and bronchial hyperresponsiveness in Chinese children.

The role of allergen sensitization in the development of asthma in the Chinese is not clear. This study aims to determine the relationship of sensitization to individual allergens, and the development of asthma and bronchial hyperresponsiveness (BHR) in schoolchildren from three Chinese cities: Hong Kong, Beijing and Guangzhou. Community-based random samples of 10-yr-old schoolchildren from three Chinese cities were recruited for study using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol. Subjects were studied by parental questionnaires (n=10,902), skin-prick tests (n=3,479), and methacholine challenge tests (n=608). The prevalence rates of wheeze in the past 12 months (Hong Kong, 5.8%; Beijing, 3.8%; Guangzhou, 3.4%) and atopy (Hong Kong, 41.2%; Beijing, 23.9%; Guangzhou, 30.8%) were highest in schoolchildren from Hong Kong. Multivariate logistic regression analyses revealed that sensitization to Dermatophagoides pteronyssinus (odds ratio (OR)=4.48; 95% confidence interval (CI): 3.02-6.66), cat (2.59; 1.67-4.03), Dermatophagoides farinae (2.41; 1.65-3.51) and mixed grass pollen (2.85; 1.24-6.50) were significantly associated with current wheeze. Atopy, defined as having > or = 1 positive skin-prick tests, was not an independent risk factor for current wheeze in children from any of the three cities. Furthermore, atopy (OR=2.53; 95% CI: 1.07-5.97), sensitization to cat (3.01; 1.39-6.52) and D. farinae (3.67; 1.93-6.97) were significantly associated with BHR. The authors confirmed that sensitization to house dust mite and cat was significantly associated with current wheeze and bronchial hyperresponsiveness in Chinese schoolchildren. However, the difference in the prevalence rate of atopic sensitization cannot explain the higher prevalence of childhood asthma in Hong Kong, when compared with those children from Beijing and Guangzhou.

Prevalence of wheeze, bronchial hyper-responsiveness and asthma in the elderly Chinese.

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 > or = 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.

Readmission rates and life threatening events in COPD survivors treated with non-invasive ventilation for acute hypercapnic respiratory failure.

BACKGROUND: Non-invasive ventilation (NIV) has been shown to reduce intubation and in-hospital mortality in patients with chronic obstructive pulmonary disease (COPD) and acute hypercapnic respiratory failure (AHRF). However, little information exists on the outcomes following discharge. A study was undertaken to examine the rates of readmission, recurrent AHRF, and death following discharge and the risk factors associated with them. METHODS: A cohort of COPD patients with AHRF who survived after treatment with NIV in a respiratory high dependency unit was prospectively followed from July 2001 to October 2002. The times to readmission, first recurrent AHRF, and death were recorded and analysed against potential risk factors collected during the index admission. RESULTS: One hundred and ten patients (87 men) of mean (SD) age 73.2 (7.6) years survived AHRF after NIV during the study period. One year after discharge 79.9% had been readmitted, 63.3% had another life threatening event, and 49.1% had died. Survivors spent a median of 12% of the subsequent year in hospital. The number of days in hospital in the previous year (p = 0.016) and a low Katz score (p = 0.018) predicted early readmission; home oxygen use (p = 0.002), APACHE II score (p = 0.006), and a lower body mass index (p = 0.041) predicted early recurrent AHRF or death; the MRC dyspnoea score (p<0.001) predicted early death. CONCLUSIONS: COPD patients with AHRF who survive following treatment with NIV have a high risk of readmission and life threatening events. Further studies are urgently needed to devise strategies to reduce readmission and life threatening events in this group of patients.

Declining asthma prevalence in Hong Kong Chinese schoolchildren.

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 disease 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.

Prevalence of snoring and sleep-disordered breathing in a group of commercial bus drivers in Hong Kong.

OBJECTIVES: To assess the prevalence of sleep-disordered breathing (SDB) and its associated symptoms in a group of commercial bus drivers in Hong Kong. METHODS: Two hundred and sixteen of 410 bus drivers from three different shifts were interviewed with the Sleep & Health Questionnaire (SHQ) and the Epworth sleepiness scale (ESS) at a Hong Kong bus depot. Seventeen subjects from each shift were then randomly selected for at-home sleep study using the Mesam IV device (Madaus Medizin-Elektronik, Freiburg, Germany). RESULTS: There were 207 men and nine women (mean age 42.4 +/- 7.5 years; body mass index (BMI) 25.4 +/- 4.5 kg/m2; ESS 5.3 +/- 4.2). From the SHQ it was discovered that: (i) daytime sleepiness was reported by 87 subjects (40%), (ii) snoring > or = 3 times per week was reported by 80 subjects (37%), (iii) witnessed apnoea was reported by 17 subjects (7.9%) and (iv) 29 subjects (13.4%) reported having fallen asleep during driving. Among the 51 subjects who underwent the at-home sleep study: (i) 31 subjects (61%) had respiratory disturbance index (RDI) > or = 5 per hour of sleep, (ii) 21 subjects (41%) had RDI > or = 10 per hour of sleep, (iii) 12 subjects (24%) had RDI > or = 15 per hour of sleep and (iv) 35 subjects (68.6%) snored objectively > or = 10% of the night. Ten subjects (20%) had RDI > or = 5 and sleepiness at work, while five subjects (9.8%) had RDI > or = 5 and ESS > 10. No significant differences were noted in the SHQ responses, ESS, objective snoring or RDI among the three groups. Multiple regression analysis showed that BMI and witnessed apnoea were the only positive independent predictors of RDI. CONCLUSIONS: This study showed a high prevalence of objective snoring and SDB in a group of commercial bus drivers. Neither self-reported sleepiness nor the ESS could identify subjects with SDB.

[Individual allergens as risk factors for asthma and bronchial hyperresponsiveness in Chinese children].

OBJECTIVE This study aimed to determine the relationship between individual allergens with current wheezing and bronchial hyperresponsiveness (BHR) in schoolchildren from three chinese cities: Beijing, Guangzhou and Hong Kong. METHODS Community-based random samples of 10-yr-old schoolchildren from the 3 cities were recruited for study using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol. The subjects were studied by parental questionnaires (n = 10,902), skin-prick tests (n = 3478), and methacholine challenge tests (n = 608). RESULTS The highest prevalence rates of wheezing in the past 12 months (Beijing, 3.8%; Guangzhou, 3.4%; Hong Kong, 5.8%) and atopy (Beijing, 23.9%; Guangzhou, 30.8%; Hong Kong, 41.2%, defined as having