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Biomedical subjects

T W Wong

Publications and source records attributed to T W Wong.

At least 19 recordsLinked to original sources
PubMed2006

Mortality from non-malignant respiratory diseases among people with silicosis in Hong Kong: exposure-response analyses for exposure to silica dust.

OBJECTIVES: To examine the exposure-response relationships between various indices of exposure to silica dust and the mortality from non-malignant respiratory diseases (NMRDs) or chronic obstructive pulmonary diseases (COPDs) among a cohort of workers with silicosis in Hong Kong. METHODS: The concentrations of respirable silica dust were assigned to each industry and job task according to historical industrial hygiene measurements documented previously in Hong Kong. Exposure indices included cumulative dust exposure (CDE) and mean dust concentration (MDC). Penalised smoothing spline models were used as a preliminary step to detect outliers and guide further analyses. Multiple Cox's proportional hazard models were used to estimate the dust effects on the risk of mortality from NMRDs or COPDs after truncating the highest exposures. RESULTS: 371 of the 853 (43.49%) deaths occurring among 2789 workers with silicosis during 1981-99 were from NMRDs, and 101 (27.22%) NMRDs were COPDs. Multiple Cox's proportional hazard models showed that CDE (p = 0.009) and MDC (p<0.001) were significantly associated only with NMRD mortality. Subgroup analysis showed that deaths from NMRDs (p<0.01) and COPDs (p<0.05) were significantly associated with both CDE and MDC among underground caisson workers and among those ever employed in other occupations with high exposure to silica dust. No exposure-response relationship was observed for surface construction workers with low exposures. A clear upward trend for both NMRDs and COPDs mortality was found with increasing severity of radiological silicosis. CONCLUSION: This study documented an exposure-response relationship between exposure to silica dust and the risk of death from NMRDs or COPDs among workers with silicosis, except for surface construction workers with low exposures. The risk of mortality from NMRDs increased significantly with the progression of International Labor Organization categories, independent of dust effects.

Adult↗
PubMed2006

Influenza-related deaths and hospitalizations in Hong Kong: a subtropical area.

BACKGROUND: While influenza vaccination has been widely used in developed countries to reduce mortality and morbidity in high-risk populations, the lack of regional data on the health burden of influenza and the uncertainty of the applicability of data from temperate areas have been major impediments to establishing an evidence-based policy on the wider use of influenza vaccine in tropical and subtropical regions of the world. OBJECTIVES: The aim of this study was to estimate the annual excess deaths and hospitalizations related to influenza in the Hong Kong Special Administrative Region (HKSAR) for the years 1999 and 2000. STUDY DESIGN AND METHODS: Correlation and regression models were used to estimate the excess deaths and hospitalizations related to influenza in the general population of HKSAR for the years 1999 and 2000, using routinely collected mortality and hospitalization data, and virological laboratory data collected by the HKSAR Influenza Surveillance System. RESULTS: The annual mean excess numbers of deaths related to influenza in Hong Kong were estimated to be 613 for pneumonia and influenza, and 2302 for respiratory and circulatory diseases. The mean excess numbers of hospitalizations attributable to influenza were 4051 for pneumonia and influenza, and 15,873 for respiratory and circulatory diseases. The crude influenza-related mortality and hospitalization rates in Hong Kong, a subtropical area, exceeded those documented in temperate regions. CONCLUSIONS: The finding of significant mortality and morbidity related to influenza in a subtropical area is in accordance with the results of previous studies in tropical and subtropical regions. This simple methodology can be used for the development of influenza immunization policy in many developing countries in tropical and subtropical regions. The enormous potential of influenza vaccination in saving lives and reducing suffering warrants serious consideration of the expanded use of influenza vaccine in tropical and subtropical regions.

Climate↗
PubMed2006

Association between air pollution and general practitioner visits for respiratory diseases in Hong Kong.

BACKGROUND: Few studies have explored the relation between air pollution and general practitioner (GP) consultations in Asia. Clinic attendance data from a network of GPs were studied, and the relationship between daily GP consultations for upper respiratory tract infections (URTI) and non-URTI respiratory diseases and daily air pollutant concentrations measured in their respective districts was examined. METHODS: A time series study was performed in 2000-2002 using data on daily patient consultations in 13 GP clinics distributed over eight districts. A Poisson regression model was constructed using the generalised additive model approach for each GP clinic, and associations with daily numbers of first visits for URTI were sought for daily concentrations of the following air pollutants: SO(2), NO(2), O(3), PM(10,) and PM(2.5). A summary relative risk of first visits to the GP for URTI per unit increase in concentration for each air pollutant was derived using a random effect model. First visits for non-URTI respiratory diseases were analysed in three GP clinics. RESULTS: Significant associations were observed between first visits for URTI and an increase in the concentrations of NO(2), O(3), PM(10), and PM(2.5). The excess risk was highest for NO(2) (3.0%), followed by O(3) (2.5%), PM(2.5) (2.1%), and PM(10) (2.0%). Similar associations with these air pollutants were found for non-URTI respiratory diseases. CONCLUSIONS: These results provide further evidence that air pollution contributes to GP visits for URTI and non-URTI respiratory diseases in the community.

Air Pollution↗
PubMed2006

Demographic and lifestyle factors associated with dioxin-like activity (CALUX-TEQ) in human breast milk in Hong Kong.

Maternal exposure to dioxins and related compounds before conception may affect the health of the fetus. To identify factors affecting dioxin body load in Hong Kong, in 2002, total dioxin-like activity was estimated in 250 individual milk samples at 2-6 weeks postpartum, from a representative group of primiparous mothers, aged 18-42 years (mean 29 +/- 5 years), by a chemically activated luciferase expression (CALUX) bioassay. Associations between the CALUX-TEQ and 20 socio-demographic and dietary variables were examined separately in mothers younger than 30 years (n = 114) and 30 years or older (n = 119), by multiple linear regression analysis. CALUX-TEQ (mean 14.5 +/- 5.8 pg/g fat) significantly increased by 0.4-0.5 pg/g fat for every year of the mother's age. Mothers born in Guangdong province of China had a significantly higher CALUX-TEQ. Higher seafood consumption (older mothers; p = 0.07) and having a female baby (younger mothers; p = 0.002) were associated with a higher maternal CALUX-TEQ level. Age was the strongest factor affecting human dioxin levels in Hong Kong. Birthplace and residence are important indicators of variations in exposure to environmental pollution in the Asia Pacific region. Temporal trends in body loads of dioxins remain to be established and continuous monitoring of dioxins in humans and foods is necessary as a precautionary approach to guide environmental control measures and prevent exposure to infants.

Adolescent↗
PubMed2006

Non-invasive detection of significant coronary artery disease with multi-section computed tomography angiography in patients with suspected coronary artery disease.

AIM: The objective of this prospective study was to compare the accuracy of multi-section computed tomography (MSCT) coronary angiography with invasive selective coronary angiography in the detection of significant coronary stenosis (> or =50% lumen diameter narrowing). METHODS: Thirty consecutive patients (mean age 59+/-10 years) with suspected coronary artery disease underwent both invasive coronary angiography and MSCT using a 40-section multidetector row machine with temporal resolution of 53ms. Reconstruction images were performed in eight phases of the cardiac cycle. Images of MSCT and invasive coronary angiography were analysed using the 16-segment model of the American Heart Association. RESULTS: A total of 480 segments from 30 patients were evaluated. Coronary segments distal to a vessel occlusion and segments with coronary stent were not considered for analysis (20 segments in total). Ninety-four (20.4%) segments showed significant (> or =50%) stenosis by invasive coronary angiogram. The accuracy of coronary MSCT was computed on a per segment basis. Average sensitivity, specificity, positive predictive value, and negative predictive value of MSCT were 99, 98, 94, and 99%, respectively. CONCLUSION: This study demonstrated that MSCT is as reliable as coronary angiography at detecting significant obstructive coronary artery disease. In selected groups of patients, it may replace the more invasive and potentially more dangerous conventional coronary angiography.

Coronary Angiography↗
PubMed2006

Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems.

UNLABELLED: Effective ventilation in general hospital wards is important for controlling the airborne transmission of infectious respiratory diseases. Experiments have been carried out to increase our understanding of the interaction of the breathing flows of two individuals in a full-scale experimental hospital ward with three ventilation systems, i.e. mixing, downward and displacement ventilation. Two life-size breathing thermal manikins were used to simulate a source patient and a receiving patient. The exhalation jet from a bed-lying manikin was visualized using smoke. N2O was used as tracer gas to simulate the droplet nuclei exhaled by patients; and the spatial distribution of its concentrations was measured. Our experimental results show that for both mixing and downward ventilation, the exhaled jet penetrates a short distance and is diluted quickly by ventilation air. The exhaled droplet nuclei are well mixed in the ward. Bed distance does not affect the personal exposure of the receiving patient. For displacement ventilation, the exhaled jet can penetrate a long distance. A high concentration layer of exhaled droplet nuclei because of thermal stratification locking has also been observed with displacement ventilation. This work is useful for identifying an appropriate ventilation method that can remove droplet nuclei more effectively and minimize the risk of cross-infections in a hospital ward environment. PRACTICAL IMPLICATIONS: As one of the major potential sources for infectious droplet nuclei in a hospital environment, exhalation flows of an infected patient can interact with the respiratory activities of other close individuals and with the room ventilation systems. Our latest results provide information on the penetration of exhalation jets into the ambient environment in different ventilation systems. This work is useful in identifying an appropriate and effective ventilation method for removing droplet nuclei more effectively, and thus minimizing the risk of cross-infections in hospital wards with multiple beds.

Air Movements↗
PubMed2006

Triage rapid initial assessment by doctor (TRIAD) improves waiting time and processing time of the emergency department.

AIM: To evaluate the effect of triage rapid initial assessment by doctor (TRIAD) on waiting time and processing time of an emergency department (ED) without extra staff. METHOD: A senior emergency doctor was put into triage instead of a consultation cubicle for seven shifts of 9 hours each. All the patients were assessed and necessary interventions started at the time of triage. Waiting time and processing time of various categories of patients were compared with a control group that was sampled during the week before the trial period. RESULTS: In total, there were 1310 cases in the trial period and 1355 controls. Over a quarter (27%) of the patients received triage doctor interventions. The average waiting time was reduced by 38% and the average processing time by 23%. Patients without triage intervention also had a 24% shorter waiting time because of overall improvement in efficiency. Trauma patients and patients needing radiography particularly benefited from the new system. The waiting time and processing time of category 4 and 5 patients improved significantly as a result of more efficient processing of more urgent cases. CONCLUSION: The waiting time and processing time of the ED were greatly reduced by TRIAD without extra manpower.

Emergency Service, Hospital↗
PubMed2006

Renal MALToma: an unusual lymphoma in a patient with lupus.

Non-Hodgkin's Lymphomas (NHL) have been reported in association with autoimmune disorders particularly Sjogren's syndrome. We report a case of renal MALToma, an unusual NHL in an 84-year-old Caucasian lady with long-standing, non-aggressive Systemic Lupus Erythematosis with no associated Sjorgen's syndrome and who never received cytotoxics.

Aged, 80 and over↗
PubMed2005

Role of air distribution in SARS transmission during the largest nosocomial outbreak in Hong Kong.

UNLABELLED: Severe acute respiratory syndrome (SARS) is primarily transmitted by bio-aerosol droplets or direct personal contacts. This paper presents a detailed study of environmental evidence of possible airborne transmission in a hospital ward during the largest nosocomial SARS outbreak in Hong Kong in March 2003. Retrospective on-site inspections and measurements of the ventilation design and air distribution system were carried out on July 17, 2003. Limited on-site measurements of bio-aerosol dispersion were also carried out on July 22. Computational fluid dynamics simulations were performed to analyze the bio-aerosol dispersion in the hospital ward. We attempted to predict the air distribution during the time of measurement in July 2003 and the time of exposure in March 2003. The predicted bio-aerosol concentration distribution in the ward seemed to agree fairly well with the spatial infection pattern of SARS cases. Possible improvement to air distribution in the hospital ward was also considered. PRACTICAL IMPLICATIONS: Our study revealed the need for the development of improved ventilation and air-conditioning systems in an isolation ward or a general hospital ward for infectious respiratory diseases. The outbreak in Ward 8A, which was in a general hospital and could house nearly 40 patients, demonstrated the cross-infection risks of respiratory infectious diseases in hospitals if a potential highly infectious patient was not identified and isolated. Our example simulation, which extended the SARS Busters' design for an isolation room to Ward 8A, demonstrated that there was room for improvement to minimize cross-infection in large general hospital wards.

Aerosols↗
PubMed2005

Multi-zone modeling of probable SARS virus transmission by airflow between flats in Block E, Amoy Gardens.

UNLABELLED: More than 300 residents of a private high-rise housing estate were infected with severe acute respiratory syndrome within a short period during the 2003 epidemic in Hong Kong. The outbreak occurred after the identified index patient visited a flat on a middle floor in Block E of the Amoy Gardens estate on two nights. Approximately 45% of the subsequently infected people resided in Block E, while the other 55% of infected cases mainly resided in six other blocks close to Block E. The distribution of the infected flats in Block E conformed to a non-uniform spatial pattern. Probable environmental causes for airborne transmission associated with the air movements between flats in Block E are identified. The well-established multi-zone airflow modeling method was used to analyze the virus-laden bio-aerosol dispersion between flats through door and window leakage areas in Block E under six different scenarios. The distribution of infection risk in Block E matched with the virus concentrations in flats predicted with the use of multi-zone modeling. Our study shows the importance of ventilation design in high-rise residential apartments. PRACTICAL IMPLICATIONS: The present study on the Amoy Gardens outbreak presented a scenario in which crowded living spaces might lead to infection disasters. There is a need to improve the current sanitary drainage design and maintenance standards to avoid any leakage of foul gas into the indoor environments. Our study revealed the need for a review of indoor air quality and ventilation design in buildings including offices, homes and hotels. The study has implications to public health in, for example, the control of other airborne respiratory infectious diseases such as influenza, and in bio-terror safety in buildings.

Air Movements↗
PubMed2005

Impact of occupational stress and other psychosocial factors on musculoskeletal pain among Chinese offshore oil installation workers.

AIMS: To explore the relation between psychosocial factors and musculoskeletal pain in Chinese offshore oil installation workers. METHODS: Half of all offshore workers (being a representative sample) in a Chinese oil company were invited to complete a self-administered questionnaire providing information on sociodemographic characteristics, occupational stressors, type A behaviour, social support, coping style, health related behaviour, past injuries, and musculoskeletal pain. Factor analysis was used to identify the sources of occupational stress and the domains of type A behaviour and coping style. Logistic regression analyses were used to study the relations between psychosocial factors and musculoskeletal pain in each body region. RESULTS: The prevalence of musculoskeletal pain over the previous 12 months varied between 7.5% for elbow pain and 32% for low back pain; 56% workers had at least one complaint. Significant associations were found between various psychosocial factors and musculoskeletal pain in different body regions after adjusting for potential confounding factors. Occupational stressors, in particular stress from safety, physical environment, and ergonomics, were important predictors of musculoskeletal pain, as was coping by eating behaviour. CONCLUSIONS: These observations supported the widely accepted biopsychosocial model of musculoskeletal disorders and suggested that in future studies of work related musculoskeletal disorders, psychosocial factors must be given due consideration.

Adaptation, Psychological↗
PubMed2004

A survey on the involvement of accident and emergency doctors in medicolegal work in Hong Kong.

This study reports the results from a questionnaire survey on the pattern of medico-legal work undertaken by doctors working in Accident & Emergency Departments (ED) and their self-evaluation of competency in forensic medicine. A total of 155 questionnaires were returned with a response rate of 46%. Only 30% (46) respondents were fellows of the Hong Kong College of Emergency Medicine but 46% (71) had more than 6 years of experience working in the ED. Most of the requests for medical report came from police and insurance companies. Fellows had more experience writing reports on homicide, sexual assault and child abuse than non-fellows did. Nearly all fellows and three quarters (74%) of non-fellows had given evidence in courts of law. Physical assault was the commonest and sexual assault the least common experience. Most respondents had experience of attending district court (83%), followed by coroner inquest (67%), magistracy (66%) and high court (45%). Respondents were asked to rate themselves on their competence in various subject areas. It can be seen that respondents were less comfortable in areas like homicide, child abuse and sexual assault. On the job coaching by a senior seems to be the major mode of training. Both fellows (61%) and non-fellows (36%) favored some form of courses with a hands-on workshop element in future.

Attitude of Health Personnel↗
PubMed2004

Pertussis--a re-emerging infection?

Seven cases of pertussis in patients aged between 1 and 6 months detected over 3 months were reported. Paroxysmal cough (six cases), post-tussive vomiting (three cases) and poor feeding (three cases) were the most common presenting symptoms. Bordetella pertussis was isolated from six patients. The total leucocyte counts were mildly increased (10.8-15.6x10(9)/L). The lymphocyte counts were markly raised (59-73%) and appear to be useful indicators of pertussis. It appears that herd immunity does not offer adequate protection to the vulnerable group even in well-vaccinated populations. High vaccination coverage should be maintained, and vaccination should be given as early an age as possible. Aggressive efforts to identify cases and contacts are essential. Health care workers should have a high index of suspicion for pertussis, in particular for those with paroxysmal cough and high lymphocyte counts so as to give timely diagnosis and treatment.

Bordetella pertussis↗
PubMed2004

Household gas cooking: a risk factor for respiratory illnesses in preschool children.

AIMS: To explore the association of household gas cooking and respiratory illnesses in preschool children and their relation to outdoor air pollution. METHODS: Cross-sectional study among households that used gas stoves for cooking in two housing estates with contrasting air qualities in Hong Kong. A structured questionnaire was administered to parents of 426 children aged 0-6 years on their exposure to gas cooking and passive smoking, and the prevalence of respiratory illnesses. RESULTS: A total of 111 children (26.1%) were reported to have one or more respiratory illnesses (allergic rhinitis, asthma, bronchitis, sinusitis, and pneumonia). Of these, 21 (18.9%), 41 (36.9%), and 49 (44.1%) children were from households that cooked once, twice, and three times a day with gas. Hierarchical logistic regression models adjusting for socioeconomic, demographic, and indoor risk factors including passive smoking showed that household gas cooking was positively associated with respiratory illnesses. There was a dose-response relation between the frequency of gas cooking and the prevalence of respiratory illnesses in the estate with lower outdoor air pollution (OR = 6.1 and 3.2 respectively, for cooking three and two meals a day, compared to one meal a day). This relation was not observed in the more polluted estate. The association between the presence of a cigarette smoker in the household and the prevalence of respiratory illnesses was not significant. CONCLUSIONS: As gas cooking is common in urban households, the findings could have important public health implications.

Air Pollution, Indoor↗
PubMed2004

Using child reported respiratory symptoms to diagnose asthma in the community.

AIMS: To study how respiratory symptoms reported by children, with or without spirometry, could help to discriminate those with asthma from those without. METHODS: Respiratory symptoms (frequent cough, frequent phlegm, and wheezing) reported by 1646 schoolchildren (aged 8-12 years) in a respiratory questionnaire and the FEV1:FVC ratio measured with spirometry (at three different cut-off values of 0.70, 0.75, and 0.80) were compared against the criterion standard of a physician diagnosis of asthma reported by the parents. RESULTS: The overall prevalence of asthma was 6%; more boys had asthma. Wheezing had the best discriminating ability among the three symptoms and a cut-off point at 75% was best for the FEV1:FVC ratio. Combining wheezing with an FEV1:FVC ratio <75% gave the highest discriminating ability of 83%. If the tests were applied to hypothetical populations with higher prevalence ratios of asthma, the added value of the FEV1:FVC ratio became less apparent. CONCLUSION: Respiratory symptoms, especially wheezing, reported by children had good discriminating ability for asthma and could be adopted for opportunistic screening in the primary care settings.

Asthma↗
PubMed2004

Midazolam is more likely to cause hypotension than etomidate in emergency department rapid sequence intubation.

OBJECTIVE: To compare the haemodynamic effect of low dose midazolam and etomidate as induction agent in emergency department rapid sequence intubation. METHODS: A prospective observational study in two phases. In phase one, midazolam 2-4 mg was used as induction agent and in phase two, etomidate 0.2-0.3 mg/kg was used. The haemodynamic data were recorded before and after intubation for comparison. Changes in mean systolic blood pressure were analysed with SPSS software. RESULTS: A 10% decrease in mean systolic blood pressure was observed in the midazolam group (p = 0.001) while there was no significant change in the etomidate group. Some 19.5% of patients had hypotension after being given midazolam while only 3.6% with etomidate (p = 0.002). Patients older than 70 tended to have more hypotension episodes but the difference was not statistically significant. CONCLUSIONS: Midazolam, even in low dose, was more likely than etomidate to cause significant hypotension when used as an induction agent for rapid sequence intubation. Etomidate is a better alternative.

Age Factors↗
PubMed2004

Small area variations of cancer mortality in Hong Kong--the roles of health care and socio-economic status.

Variations of cancer incidence and cancer mortality across small areas in Hong Kong were explored and attempt made to link them to socio-economic differences. The entire Hong Kong population during the period 1984-88 was divided into 65 small areas. The geographic distributions of incidence and mortality for ten most frequent sites of cancers (6 male and 4 female) were analyzed by separating the systematic variance from the random variance. A Poisson regression model was fitted for each cancer using the standardized incidence ratio (SIR) as a covariate for mortality. The geographic variations in SIR for the individual cancers were, in turn, analyzed similarly using a socio-economic score as the covariate. We found a statistically significant systematic variance in mortality for all six male cancers and three of the four female cancers studied. More than 50% of the systematic variance of mortality for nine cancers could be explained by the geographic variations in incidence, suggesting that other factors, like the provision and/or outcomes of health care services, played a minor role. There were statistically significant systematic variances in SIR for all male and female cancers. The socio-economic score accounted for over 50% of the systematic variance for three cancer sites. This study illustrated an approach to explore underlying explanations for the geographic variations of disease incidence and mortality. As more aggregate exposure data become available at the small area level, this type of ecological analysis would help in delineating the contributions of various factors and guide investigators in their search for the etiology background of diseases.

Female↗