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Biomedical subjects

G M Leung

Publications and source records attributed to G M Leung.

At least 19 recordsLinked to original sources
PubMed2006

Seroprevalence of IgG antibodies to SARS-coronavirus in asymptomatic or subclinical population groups.

We systematically reviewed the current understanding of human population immunity against SARS-CoV in different groups, settings and geography. Our meta-analysis, which included all identified studies except those on wild animal handlers, yielded an overall seroprevalence of 0.10% [95% confidence interval (CI) 0.02-0.18]. Health-care workers and others who had close contact with SARS patients had a slightly higher degree of seroconversion (0.23%, 95% CI 0.02-0.45) compared to healthy blood donors, others from the general community or non-SARS patients recruited from the health-care setting (0.16%, 95% CI 0-0.37). When analysed by the two broad classes of testing procedures, it is clear that serial confirmatory test protocols resulted in a much lower estimate (0.050%, 95% CI 0-0.15) than single test protocols (0.20%, 95% CI 0.06-0.34). Potential epidemiological and laboratory pitfalls are also discussed as they may give rise to false or inconsistent results in measuring the seroprevalence of IgG antibodies to SARS-CoV.

Antibody Formation↗
PubMed2006

Parity and the metabolic syndrome in older Chinese women: the Guangzhou Biobank Cohort Study.

OBJECTIVE: To examine whether parity or gravidity contributes to the development of the metabolic syndrome (MS). METHODS: The first phase of the Guangzhou Biobank Cohort Study recruited 7352 women and 3065 men aged 50-93 years in 2003-4. Data on the number of live births and pregnancies, other reproduction-associated factors and socioeconomic and lifestyles factors were collected by standardized interview. The MS components were determined through physical examination and measurement of fasting blood samples. MS was identified if waist circumference was >or= 90 cm for men or >or= 80 cm for women, plus any two of: (a) raised triglyceride (TG) level (1.7 mmol/l) or specific treatment for this lipid abnormality; (b) reduced high density lipoprotein (HDL)-cholesterol (< 1.03 mmol/l in males or < 1.29 mmol/l in females) or specific treatment for this lipid abnormality; (c) raised blood pressure (BP, systolic BP >or= 130 mmHg or diastolic BP >or= 85 mmHg) or hypertension therapy; and (d) raised fasting glucose (>or= 5.6 mmol/l) or previously diagnosed type 2 diabetes. RESULTS: Before adjustment for potential confounders, we found associations between the number of births and lifestyle and socioeconomic factors in both sexes. However, in women, but not in men, body mass index (BMI), waist-hip ratio, triglyceride and glucose were positively associated with the number of birth after adjusting for a range of potential confounders. The age-adjusted prevalence of the MS increased with the number of births and pregnancies in women, but the gradient for birth was steeper than that for pregnancies [odds ratio change per birth 1.16, 95% confidence interval (CI) 1.11-1.22, P < 0.001; odds ratio change per pregnancy 1.11, 95% CI 1.06-1.16, P < 0.001], although attenuating the association adjustment did not affect the significance of these findings. There was no association in men with regard to the number of their partners' live births given the same analysis and similar shared living background with the women. CONCLUSION: Higher parity or gravidity was associated with a consistent increase in the risk of MS in Chinese women. As the association persisted after adjustment for lifestyle factors and there was no association between the risk of MS and the number of births associated with the partners of the males, the association in women may represent a biological response to pregnancy.

Abortion, Spontaneous↗
PubMed2006

Domestic health expenditure in Hong Kong: 1989/90 to 2001/02.

OBJECTIVE: To estimate the total domestic health expenditure in Hong Kong between fiscal years 1989/90 and 2001/02, with breakdown by financing source, provider, and function over time. METHODS: The standard health accounting methods as per the Organisation for Economic Co-operation and Development System of Health Accounts guidelines of 2000 were adopted. RESULTS: Total domestic health expenditure was $68,620 million in the fiscal year 2001/02. In real terms, expenditure grew at an average rate of 7% while gross domestic product increased by 4% during the same period. This indicates a growing share of health spending relative to gross domestic product, from 3.8% in 1989/90 to 5.5% in 2001/02. This upward trend was largely driven by increased public spending that rose 208% in real terms over the period, compared with 76% for private spending. Out-of-pocket payments by households accounted for about 70% of private spending while employers and insurance accounted for 28%. Private insurance plays an increasingly important role in financing private spending whereas household expenditure has shown a corresponding decrease during the period. Expenditure incurred at providers of ambulatory services and hospitals accounted for more than 70% of total health expenditure during the observed period. Hospitals' share of total spending increased by 18%, reaching 45% of total expenditure in 2001/02, whilst the share of providers of ambulatory services reduced to 30% in 2001/02. The two largest functional components of total health expenditure were ambulatory care (35-41%) and in-patient curative care (20-27%). Public spending generally financed in-patient curative care and ambulatory services; private spending was concentrated on ambulatory services and medical goods outside the patient care setting. CONCLUSION: These data provide important information for the public, policymakers, and researchers to assess the performance of the health care system longitudinally, and to evaluate health expenditure-related policies.

Ambulatory Care↗
PubMed2005

SARS incubation and quarantine times: when is an exposed individual known to be disease free?

The setting of a quarantine time for an emerging infectious disease will depend on current knowledge concerning incubation times. Methods for the analysis of information on incubation times are investigated with a particular focus on inference regarding a possible maximum incubation time, after which an exposed individual would be known to be disease free. Data from the Hong Kong SARS epidemic are used for illustration. The incorporation of interval-censored data is considered and comparison is made with percentile estimation. Results suggest that a wide class of models for incubation times should be considered because the apparent informativeness of a likelihood depends on the choice and generalizability of a model. There will usually remain a probability of releasing from quarantine some infected individuals and the impact of early release will depend on the size of the epidemic.

Biometry↗
PubMed2005

Modelling the impact of population-based cytologic screening on cervical cancer incidence and mortality in Hong Kong: an age--period--cohort approach.

Cervical cancer incidence and mortality statistics in Hong Kong during 1972-2001 were examined to estimate the potential number of cancer cases that can be averted and years of life saved after the launch of an organised, population-based cytologic screening recall programme in 2004 with projections to 2016. Incidence rates under the status quo of opportunistic screening were projected by an age-period-cohort model, using maximum likelihood and Bayesian methods. Modelled rates were translated into numbers of cancer cases and deaths using mid-year population figures and age-period-specific mortality to incidence ratios. We applied International Agency for Research on Cancer risk reduction estimates for different screening strategies to these base case figures to estimate the number of incident cancers potentially averted and years of life saved attributable to organised screening incremental to the current status quo. The estimated numbers of cases projected to be preventable by the maximum likelihood (Bayesian) approach from 2002 to 2016 were 4226 (4176), 3778 (3728) and 2334 (2287) with organised screening every 1, 3 and 5 years, compared to haphazard screening currently. Correspondingly, 33,000 (32,800), 29,500 (29,300) and 18,200 (17,900) years of life could potentially be saved.

Adult↗
PubMed2005

Methods for estimating the case fatality ratio for a novel, emerging infectious disease.

During the course of an epidemic of a potentially fatal disease, it is important that the case fatality ratio be well estimated. The authors propose a novel method for doing so based on the Kaplan-Meier survival procedure, jointly considering two outcomes (death and recovery), and evaluate its performance by using data from the 2003 epidemic of severe acute respiratory syndrome in Hong Kong, People's Republic of China. They compare this estimate obtained at various points in the epidemic with the case fatality ratio eventually observed; with two commonly quoted, naïve estimates derived from cumulative incidence and mortality statistics at single time points; and with estimates in which a parametric mixture model is used. They demonstrate the importance of patient characteristics regarding outcome by analyzing subgroups defined by age at admission to the hospital.

Communicable Diseases, Emerging↗
PubMed2005

Overweight, obesity, weight-related concerns and behaviours in Hong Kong Chinese children and adolescents.

AIM: To study the prevalence of overweight and obesity, and weight-related concerns and behaviours among overweight, obese and non-overweight children and adolescents. METHODS: We carried out a cross-sectional survey of all Chinese students in primary schools in the Central and Western District of Hong Kong in March 2002. Thirty-one of 32 schools participated, and 5402 boys and 5371 girls aged 8 to 15 y who completed a standardized questionnaire were included. We used the International Obesity Task Force definition (IOTF reference) to define overweight and obesity. RESULTS: The prevalence (95% CI) of overweight was 16.4% (15.7-17.1%) (19.9% in boys, 12.9% in girls), and that of obesity was 7.7% (7.2-8.2%) (10.3% in boys and 5.1% in girls). The combined prevalence of overweight and obesity was similar to that based on the local reference. Overweight children had more concerns about their weight than obese children. They were more likely than obese children to feel fat, wish to be lighter, diet and exercise to lose weight. Although obese children were heavier, they did not make more effort to lose weight than overweight children. CONCLUSIONS: The differences in weight-related concerns and behaviours among overweight, obese and non-overweight children suggested good validity of the IOTF reference and the self-reported data. The differences between overweight and obese children suggested that the two groups had different psychological states and that they needed different weight management programmes and other intervention strategies.

Adolescent↗
PubMed2005

Secondhand smoke and respiratory ill health in current smokers.

BACKGROUND: Numerous studies have concluded that secondhand smoke (SHS) is harmful to non-smokers but controversy persists regarding its effects on smokers. The impact of SHS exposure on the acute respiratory health of current active smokers was examined using a cross sectional design. METHODS: 9923 uniformed staff in the Hong Kong Police Force completed a standardised questionnaire on current and past smoking, SHS exposure at home and at work, acute respiratory symptoms, and recent physician consultation. 3999 male current smokers were included in the analysis. RESULTS: About 5% of the smokers were exposed to SHS at home only, 53% were exposed at work only, and 30% were exposed both at home and at work. The prevalence ratios for respiratory symptoms (throat and nasal problems, cough, phlegm, and wheeze), physician consultation, and self medication were higher for those who were exposed to SHS at home or at work. The odds ratios of reporting one or more respiratory symptoms, for SHS exposures at home or at work, were 1.33 (95% confidence interval (CI) 1.12 to 1.59) and 1.66 (95% CI 1.36 to 2.02) respectively, after adjusting for age, marital status, education, rank and duties, exposure to self perceived dusty or polluted environment in previous job, and total dose of active smoking. The adjusted odds ratios showed significant positive dose-response gradients with SHS exposure at home, at work, and at both places combined. CONCLUSIONS: SHS exposure is strongly associated with increased acute respiratory symptoms and recent outpatient service utilisation in current smokers. If the association is causal, public health action to limit SHS exposure could also benefit smokers.

Acute Disease↗
PubMed2004

Identifying barriers to the adoption of evidence-based medicine practice in clinical clerks: a longitudinal focus group study.

OBJECTIVE: To identify and explore common barriers to the adoption of evidence-based medicine (EBM) practice in the undergraduate setting. DESIGN: Nested longitudinal, focus group-based, qualitative study. Setting The University of Hong Kong Medical School, Hong Kong, China. PARTICIPANTS: A group of 39 Year 4 medical undergraduates who participated in an EBM intervention cluster randomised crossover trial. MAIN OUTCOME MEASURES: Students' attitudes, opinions and perceptions of barriers to EBM use. RESULTS: General attitudes towards EBM and the teaching intervention were positive. Four sets of barriers to greater EBM use were identified as follows. (1) Learning environment including prevailing norms for student learning involving examination-oriented, textbook learning, prior availability of clinical practice guidelines, lack of encouragement from teachers and economy of time by utilising teacher expertise. (2) Limitations of evidence consisting of poor point-of-care access to medical literature, difficulty in locating evidence and the perceived low relevance of overseas evidence to Chinese patients. (3) Lack of opportunity to practise EBM due to lack of continuity of care and anxieties about negative teacher attitudes towards EBM use at the point-of-care. (4) Time constraints such as competing study demands and long evidence search time. CONCLUSIONS: Significant barriers to the successful implementation of EBM learning in the clinical clerkship setting were identified. These can be specifically targeted to ameliorate any inhibition of clinical learning they may impose.

Attitude↗
PubMed2004

Smoking and depressive symptoms in Chinese elderly in Hong Kong.

OBJECTIVE: To examine the association between smoking and depressive symptoms among Chinese elderly in Hong Kong. METHOD: Cross-sectional data on smoking and depressive symptoms from 56,167 Chinese elderly aged 65 or over in Hong Kong were analysed using logistic regression. RESULTS: Current smokers and former smokers were more likely to have depressive symptoms than never smokers. The adjusted odds ratios (OR) and 95% confidence interval (CI) in males and females respectively were 1.62 (1.34-1.96) and 1.43 (1.20-1.70) for current smokers, and were 1.18 (0.99-1.40) and 1.29 (1.12-1.47) for former smokers. Former smokers were less likely to have depressive symptoms than current smokers (OR = 0.80, 95% CI: 0.70-0.92). CONCLUSION: Smoking is positively associated with depressive symptoms in Chinese elderly. Health care workers should be vigilant about the detection of depressive symptoms in elderly smokers.

Aged↗
PubMed2004

Understanding the spatial clustering of severe acute respiratory syndrome (SARS) in Hong Kong.

We applied cartographic and geostatistical methods in analyzing the patterns of disease spread during the 2003 severe acute respiratory syndrome (SARS) outbreak in Hong Kong using geographic information system (GIS) technology. We analyzed an integrated database that contained clinical and personal details on all 1,755 patients confirmed to have SARS from 15 February to 22 June 2003. Elementary mapping of disease occurrences in space and time simultaneously revealed the geographic extent of spread throughout the territory. Statistical surfaces created by the kernel method confirmed that SARS cases were highly clustered and identified distinct disease "hot spots." Contextual analysis of mean and standard deviation of different density classes indicated that the period from day 1 (18 February) through day 16 (6 March) was the prodrome of the epidemic, whereas days 86 (15 May) to 106 (4 June) marked the declining phase of the outbreak. Origin-and-destination plots showed the directional bias and radius of spread of superspreading events. Integration of GIS technology into routine field epidemiologic surveillance can offer a real-time quantitative method for identifying and tracking the geospatial spread of infectious diseases, as our experience with SARS has demonstrated.

Databases, Factual↗
PubMed2003

The economic burden of environmental tobacco smoke in the first year of life.

AIMS: To examine the population impact and economic costs associated with environmental tobacco smoke (ETS) in Chinese infants with non-smoking mothers. METHODS: Prospective, population based birth cohort study in Hong Kong, 1997-98. Main outcome measures were: doctor consultations and hospitalisations; adjusted odds ratios for higher utilisation by service type for each of the ETS exposure variables; corresponding population attributable risks (PARs); and associated extra health care costs. RESULTS: For the 1997 annual birth cohort, ETS exposure through the mother in utero was positively associated with higher consultation (adjusted odds ratio (OR) 1.26) and hospitalisation (OR 1.18) due to any illness. This translated into 7.4% of all inpatient episodes in the first year of life, representing an additional 1581 hospital attendances that cost over 2.1 million US dollars. The corresponding PAR for outpatient services was 7.7%, where the majority was due to respiratory or febrile illnesses, accounting for 0.44 million dollars in extra costs. Postnatal exposure to ETS at home was linked to higher rates of hospitalisations for any illness compared with non-exposed infants (OR 1.12), which led to 662 extra hospitalisations consuming 0.90 million dollars, where the associated PAR was 3.1%. CONCLUSIONS: Assuming that ETS was causally associated with health services use, about 9% of the total direct medical costs in the first year of life can be attributed to passive smoking. The community, as well as the private citizen, needs to be made aware of the costs foregone from exposure to tobacco smoke as well as the potential savings from a smoke-free society.

Cohort Studies↗
PubMed2003

Is ophthalmology evidence based? A clinical audit of the emergency unit of a regional eye hospital.

AIM: To evaluate the proportion of interventions that are evidence based in the acute care unit of a regional eye hospital. METHODS: A prospective clinical audit was carried out at Hong Kong Eye Hospital in July 2002 to investigate the extent to which ophthalmic practices were evidence based. The major diagnosis and intervention provided were identified through chart review. A corresponding literature search using Medline and the Cochrane Library was performed to assess the degree to which each intervention was based on current, best evidence. Each diagnosis intervention pair was accordingly analysed and graded. The level of best, current evidence supporting each intervention was graded and analysed. RESULTS: A total of 274 consecutive consultation episodes were examined. 22 cases were excluded since no diagnosis or intervention was made during the consultation. 108 (42.9%) patient interventions were found to be based on evidence from systematic reviews, meta-analyses, or randomised controlled trials (RCT). Evidence from prospective or retrospective observational studies supported the interventions in 86 (34.1%) patients. In 58 (23.0%) cases, no evidence or opposing evidence was found regarding the intervention. The proportion of evidence based on RCT or systematic reviews was higher for surgical interventions compared with non-surgical interventions (p=0.007). The proportion of interventions based on RCT or systematic reviews was higher for specialist ophthalmologists than trainee ophthalmologists (p=0.021). CONCLUSION: This study demonstrated that the majority of interventions in the ophthalmic unit were evidence based and comparable to the experience of other specialties.

Adolescent↗
PubMed2003

The impact of community psychological responses on outbreak control for severe acute respiratory syndrome in Hong Kong.

OBJECTIVE: To examine the public's knowledge and perception of SARS and the extent to which various precautionary measures have been adopted. DESIGN: Cross sectional survey. SETTING: General population of Hong Kong at the height of the SARS outbreak (29 March to 6 April 2003). PARTICIPANTS: 1115 ethnic Chinese adults. MAIN RESULTS: Forty per cent did not recognise fomites as a possible mode of transmission whereas 55.1% believed that the infection could be transmitted airborne. A large proportion (30.1%) believed they were very or somewhat likely to contract SARS while only one quarter believed they were very likely to survive if they contracted the disease, benchmarked against an actual case fatality ratio of 2.8% at the time of the survey and 15%-20% according to current best estimates. Precautionary measures directed against person to person droplet spread were generally adopted by most while the prevention of transmission through fomites was not practised as frequently. Respondents with higher risk perceptions and a moderate level of anxiety were most likely to take comprehensive precautionary measures against the infection, as were older, female, more educated people as well as those with a positive contact history and SARS-like symptoms. CONCLUSIONS: The findings demonstrate that the promotion of protective personal health practices to interrupt the self sustaining transmission of the SARS virus in the community must take into account background perceptions of risk and anxiety levels of the public at large. Continuing public education about preventive measures should be targeted at the identified groups with low current uptake of precautions.

Adaptation, Psychological↗
PubMed2003

The economics of Alzheimer disease.

Economic assessments of health and healthcare have become an integral part of policy decisions in the last decade. Increasingly, this trend is extending to medical decision-making in day-to-day patient-provider interactions. Alzheimer disease (AD) offers a potent example of the clinical and economic issues at stake with its diagnostic techniques, pharmacotherapies, and public health and policy implications. This review introduces basic economic concepts in examining the impact of AD and related care. It presents a summary of the latest economics research on cost estimates of AD and on economic evaluations of diagnostic and management interventions in terms of cost-of-illness and cost-effectiveness studies respectively. Empirical and conceptual issues about the interpretation of costs and the uses of evaluative methods are also discussed. We found that the economic costs attributable to AD care is highly variable mostly due to non-standardised methodologies and geographical variations in care patterns. There is, however, little doubt that the impact is substantial and is expected to worsen with the demographic, epidemiologic, technologic and economic transitions worldwide. There are comparatively fewer studies on the cost-effectiveness of interventions in AD. Most of the published work revolves around pharmacotherapeutics while relatively little has been done on diagnostics, patient care programmes and programmes for caregivers. We conclude that there are significant opportunities to strengthen research on standardised cost-of-illness analyses and new cost-effectiveness studies on a broader range of AD interventions.

Alzheimer Disease↗
PubMed2002

Trends in breast cancer incidence in Hong Kong between 1973 and 1999: an age-period-cohort analysis.

Hong Kong has the highest breast cancer incidence in Asia and studying secular changes in its rates may lead to hypotheses regarding disease aetiology and also predictions of future trends for China. We examined statistics from the Hong Kong Cancer Registry based on 26 566 cases of invasive breast cancer from 1973 to 1999. The trends in breast cancer incidence were studied using log-linear longitudinal models. We further analysed the independent effects of chronological age, time period and birth cohort on incidence trends using age-period-cohort modelling. The average annual per cent change of the age-standardised incidence was 3.6% during 1973-1999. Age-period-cohort modelling indicated the incidence development was predominantly a cohort effect, where the rise in relative risk was seemingly linear in successive birth cohorts, showing a 2-3-fold difference when comparing women born in the 1960's with those born around 1900. Our results suggest that direct and indirect consequences of westernisation may have been responsible for most of the observed increase in breast cancer incidence. As China moves towards a more westernised way of life, we can expect an emerging epidemic of breast cancer as Hong Kong's experience has demonstrated.

Adult↗