Caregivers' Experience of End-of-Life Stage Elderly Patients: Longitudinal Qualitative Interview.

OBJECTIVES: This study seeks to provide an understanding of the changing experiences in caregivers of end-of-life patients in Hong Kong through exploring their caregiving journey. METHODS: Using longitudinal individual qualitative interviews, a total of 14 caregivers of community-dwelling elderly patients receiving end-of-life care were recruited between 2015 and 2016. A series of in-depth interviews and observations were conducted in 14 cases during the end-of-life journey. RESULTS: A thematic analysis revealed four sequential experiential stages, abbreviated as "CAPE" that caregivers confronted: Stage 1 Certainty, (1a) lack of certainty regarding the progression of decline at the end-stage of life (1b) feelings of despair as patients' function decreased; Stage 2 Ambivalence, (2a) feelings of ambivalence after decisions were made regarding EOL care, (2b) struggle over care responsibility within families; Stage 3 Perturbed, (3a) varied in quality of EOL care, (3b) depressed mood arisen from frequent exposure to the suffering of elderly patients; and Stage 4 Expectation, (4a) losing the caregiving role as patients showing signs of imminent death. CONCLUSIONS: These findings increase our understanding of caregivers' in-depth experience over time that arise within the structural context of end-of-life care. Our data highlights the need for end of life related knowledge and information, provision of a caring atmosphere and communication, and professional-led detachment in creating caregiving-friendly service in healthcare system, thus as to provide support and alleviate stress for caregivers with their critical responsibility and role during the course of end-of-life care.

Long-term effectiveness of elderly health care voucher scheme strategies: a system dynamics simulation analysis.

BACKGROUND: The elderly healthcare voucher (EHCV) scheme is expected to lead to an increase in the number of elderly people selecting private primary healthcare services and reduce reliance on the public sector in Hong Kong. However, studies thus far have reported that this scheme has not received satisfactory responses. In this study, we examined changes in the ratio of visits between public and private doctors in primary care (to measure reliance on the public sector) for different strategic scenarios in the EHCV scheme. METHODS: Based on comments from an expert panel, a system dynamics model was formulated to simulate the impact of various enhanced strategies in the scheme: increasing voucher amounts, lowering the age eligibility, and designating vouchers for chronic conditions follow-up. Data and statistics for the model calibration were collected from various sources. RESULTS: The simulation results show that the current EHCV scheme is unable to reduce the utilization of public healthcare services, as well as the ratio of visits between public and private primary care among the local aging population. When comparing three different tested scenarios, even if the increase in the annual voucher amount could be maintained at the current pace or the age eligibility can be lowered to include those aged 60 years, the impact on shifts from public-to-private utilization were insignificant. The public-to-private ratio could only be marginally reduced from 0.74 to 0.64 in the first several years. Nevertheless, introducing a chronic disease-oriented voucher could result in a significant drop of 0.50 in the public-to-private ratio during the early implementation phase. However, the effect could not be maintained for an extended period. CONCLUSIONS: Our findings will assist officials in improving the design of the EHCV scheme, within the wider context of promoting primary care among the elderly. We suggest that an additional chronic disease-oriented voucher can serve as an alternative strategy. The scheme must be redesigned to address more specific objectives or provide a separate voucher that promotes under-utilized healthcare services (e.g., preventive care), instead of services designed for unspecified reasons, which may lead to concerns regarding exploitation.

Healthcare inequalities in emergency visits and hospitalisation at the end of life: a study of 395 019 public hospital records.

OBJECTIVES: To investigate whether there were any socioeconomic disparities in utilisation of hospital care services during end of life in Hong Kong. METHODS: Secondary data analyses were conducted using frequency of the accident and emergency (A&E) department visits and hospital admissions during the last year of life in all public hospitals from 2004 to 2014 in Hong Kong. A total of 1 237 044 A&E records from 357 853 patients, and 1 878 982 admission records from 375 506 patients were identified for analyses. In total, 395 019 unique deceased patients were identified from both datasets. RESULTS: Regression analyses showed that comprehensive social security assistance (CSSA) recipients used A&E services 1.29 times more than the non-recipients. Being either a CSSA recipient or an elderly home resident was more likely to be admitted to hospitals and stayed longer. Elderly home residents tended to stay longer than those from the community in the earlier months during the last year of life regardless of CSSA status; however, non-elderly home residents surpassed the residents in the duration of stay at hospitals towards the later months of the last year of life. There were also significant differences in hospital utilisation across various districts of residence. CONCLUSIONS: People of lower socioeconomic position tend to have higher emergency visits and hospitalisation during their last year of life in Hong Kong, implying the presence of health inequality during end of life. However, due to Hong Kong's largely pro-rich primary care system, the predominantly public A&E and inpatient services may inadvertently act as a mitigator of such health inequalities.

Scoping Review: Intergenerational Resource Transfer and Possible Enabling Factors.

We explore the intergenerational pattern of resource transfer and possible associated factors. A scoping review was conducted of quantitative, peer-reviewed, English-language studies related to intergenerational transfer or interaction. We searched AgeLine, PsycINFO, Social Work Abstracts, and Sociological Abstracts for articles published between Jane 2008 and December 2018. Seventy-five studies from 25 countries met the inclusion criteria. The scoping review categorised resource transfers into three types: financial, instrumental, and emotional support. Using an intergenerational solidarity framework, factors associated with intergenerational transfer were placed in four categories: (1) demographic factors (e.g., age, gender, marital status, education, and ethno-cultural background); (2) needs and opportunities factors, including health, financial resources, and employment status; (3) family structures, namely, family composition, family relationship, and earlier family events; and (4) cultural-contextual structures, including state policies and social norms. Those factors were connected to the direction of resource transfer between generations. Downward transfers from senior to junior generations occur more frequently than upward transfers in many developed countries. Women dominate instrumental transfers, perhaps influenced by traditional gender roles. Overall, the pattern of resource transfer between generations is shown, and the impact of social norms and social policy on intergenerational transfers is highlighted. Policymakers should recognise the complicated interplay of each factor with different cultural contexts. The findings could inform policies that strengthen intergenerational solidarity and support.

Quality of Palliative and End-Of-Life Care in Hong Kong: Perspectives of Healthcare Providers.

BACKGROUND: In response to population aging, there is a need for health systems to focus on care for chronic disease, specifically palliative care, while focusing on people-centered care. The objective of this study is to explore the healthcare system enablers and barriers to the provision of quality palliative and end-of-life care from the perspective of healthcare professionals. MATERIALS AND METHODS: Using purposive sampling, fifteen focus group interviews and nine individual interviews involving 72 healthcare providers were conducted. Primary qualitative data were collected between May 2016 and July 2017. All recorded discussions were transcribed verbatim and analyzed. A thematic framework was developed. RESULTS: The provision of quality palliative and end-of-life care is influenced by the interaction and integration of nine sub-themes under four identified themes: (1) political context; (2) organization setting; (3) support to patients, caregivers, and family members, and (4) healthcare workers and the public. CONCLUSIONS: Integration of palliative and end-of-life care is an important pillar of healthcare service to improve quality of life by addressing patients' values, wishes and preference, and assist their family to handle challenges at the end stage of life. Further improvements to the service framework would be required, specifically in the political framework, multidisciplinary approach, and readiness and competence in healthcare workers and community. These were highlighted in our study as key components in service provision to ensure that patients can receive continuous and integrated care between hospitals and the community as well as dignified care at the end stage of life.

Examining the Gaps and Issues of End-of-Life Care among Older Population through the Lens of Socioecological Model-A Multi-Method Qualitative Study of Hong Kong.

End-of-life (EOL) care for terminal illness and life-limiting conditions is a sector in the health service spectrum that is drawing increased attention. Despite having the world's longest life expectancy and an ever-escalating demand for long-term care, Hong Kong's EOL care was underdeveloped. The current study aims to provide a holistic picture of gaps and issues to EOL care in Hong Kong. Data collection was conducted using a multi-method qualitative approach that included focus groups and in-depth interviews with key informants and stakeholders, and longitudinal case studies with patients and families. Deductive thematic analysis was used to examine service gaps in current EOL care through the lens of a socioecological model where gaps and issues in various nested, hierarchical levels of care as well as the relationships between these levels were studied in detail. Using the model, we identified gaps and issues of EOL care among older populations in Hong Kong at the policy, legal, community, institutional, as well as intrapersonal and interpersonal levels. These include but are not limited to a lack of overarching EOL care policy framework, ambiguity in the legal basis for mental incapacity, legislative barriers for advance directives, inadequate capacity, resources, and support in the community to administer EOL care, inadequate knowledge, training, and resources for EOL care in health and social care sectors, inadequate medical-social interface, general reluctance and fear of death and dying, as well as the cultural interpretation of filial piety that may lengthen the suffering of the dying patients. Findings highlight the multi-level gaps and issues of EOL care in a place where western and eastern culture meet, and shed light on how best to design more effective and comprehensive policy interventions that will likely have a more sustainable and instrumental impact on facilitating person-centered EOL care during the end of life.

Governance Functions to Accelerate Progress toward Universal Health Coverage (UHC) in the Asia-Pacific Region.

Many countries in the Asia-Pacific region have committed to universal health coverage (UHC), which is reflected in both their political commitment and the governance actions they have taken in steering their health systems toward the goals of universal access to care and protection from financial hardship. Countries throughout the region are at different stages of development and have different political and governance contexts, which in turn shape how they pursue governance for UHC. This article reviews the governance functions deployed in the Asia-Pacific and finds that, in many, governance reforms adapting their health systems toward greater regulation, accountability, oversight, and stewardship of the health system have been part of their wider move toward UHC. Countries have not followed a set pattern, but shared aspects include establishing UHC as a goal in national policy making and priority setting; the creation of new roles and/or new institutions within the health system; establishing systems of monitoring and evaluation; and putting in place mechanisms to facilitate collaboration and ensure greater accountability. The relationship between governance and UHC in the Asia-Pacific region is found to be complex, negotiated, and shaped by a number of factors in both the internal and external environment, including broader governance arrangements in the public sector (institutional changes and decentralization are particularly prominent factors) and the ability of governments to implement policies and steer the health system.

Knowledge, Attitudes, and Preferences of Advance Decisions, End-of-Life Care, and Place of Care and Death in Hong Kong. A Population-Based Telephone Survey of 1067 Adults.

OBJECTIVES: According to the 2015 Quality of Death Index published by the Intelligence Unit of the Economist, Hong Kong is ranked 22nd in terms of quality of palliative care in the world, behind many other major developed countries in Asia, including Taiwan, Singapore, Japan, and South Korea. The objectives of the present study were to describe the knowledge, attitude, and preferences of the general Hong Kong adult population across different age groups regarding end-of-life (EOL) care decisions, place of care and death, as well as advance directive (AD). METHODS: This was a population-based cross-sectional survey conducted by telephone. A total of 1067 adults over 30 years old were contacted through residential telephone lines using a random sampling method and were interviewed. Information on sociodemographic factors, general health status, chronic diseases, knowledge, attitude and preferences of advance decisions, EOL care, and place of death were collected. RESULTS: A total of 85.7% had not heard of AD, but 60.9% would prefer to make their own AD if legislated after explanation; and for those who did not prefer to have an AD, the predominant concern was the possible change of mind afterward. Adjusted logistic regression suggested that female participants were less willing to make an AD, whereas those with prior knowledge of do-not-attempt-cardiopulmonary-resuscitation significantly increased the chance of making an AD. In terms of life-sustaining treatments, a predominant 87.6% preferred to receive appropriate palliative care that gives comfort rather than to prolong life if being diagnosed to be terminally ill; 43% disagreed that doctors should generally try to keep patients alive for as long as possible; and 86.2% agreed that the patient's own wishes should determine what treatment he/she should receive. Adjusted logistic regression showed that palliative care was more preferred by age groups 50 years or above but was less preferred by those who did not care for their family members with chronic diseases. Regarding place of death, 31.2% of the participants would choose to die at home, and among those, 19.5% would still prefer to die at home even if they did not have sufficient support. Adjusted logistic regression showed a decreased trend for all older age groups from 40-49 years to 80+ years, as well as having poor self-rated health, to prefer to die at home. Being a female participant and having education level of tertiary or above, however, had higher preference for death at home. CONCLUSIONS: This is the first population-representative survey of the general Hong Kong adult population on the knowledge, attitude, and preferences of AD, EOL care, and place of care/death. The main implication of this study was that preferences to have autonomy over own EOL care, to receive palliative care, and to die at home were greater than the actual practice currently, highlighting the service gaps for better EOL care in the future.

Uncovering Hidden Topics in Hong Kong Clinical Research Through Hospital Authority Convention Publications.

Uncovering clinical research trends allows us to understand the direction of healthcare services and is essential for longer-term healthcare planning. The Hospital Authority Convention is a mainstream annual healthcare conference that gathers up-to-date Hong Kong medical research. We propose to use state-of-the-art medical document mining and topic modelling methods to uncover latent themes and structures in the publications. We collected 742 articles from HA Convention from the year 2013 to 2016 and selected 56 publications from the category of "Clinical Safety and Quality Service" for further analysis. Applying natural language processing and Latent Dirichlet Allocation (LDA) methods, we identified 7 potential topics, namely: surgical operation, hospital discharge, medical error, nursing procedure, service performance assessment, patient and staff engagement, and admission algorithm and standardisation. This exploratory study demonstrates that key themes exist in the annual HA Convention and we observe potential changes in healthcare services focus over the years in the selected category.

Assessing spatial associations between thermal stress and mortality in Hong Kong: a small-area ecological study.

AIMS: Physiological equivalent temperature (PET) is a widely used index to assess thermal comfort of the human body. Evidence on how thermal stress-related health effects vary with small geographical areas is limited. The objectives of this study are (i) to explore whether there were significant patterns of geographical clustering of thermal stress as measured by PET and mortality and (ii) to assess the association between PET and mortality in small geographical areas. METHODS: A small area ecological cross-sectional study was conducted at tertiary planning units (TPUs) level. Age-standardized mortality rates (ASMR) and monthly deaths at TPUs level for 2006 were calculated for cause-specific diseases. A PET map with 100 m × 100 m resolution for the same period was derived from Hong Kong Urban Climatic Analysis Map data and the annual and monthly averages of PET for each TPU were computed. Global Moran's I and local indicator of spatial association (LISA) analyses were performed. A generalized linear mixed model was used to model monthly deaths against PET adjusted for socio-economic deprivation. RESULTS: We found positive spatial autocorrelation between PET and ASMR. There were spatial correlations between PET and ASMR, particularly in the north of Hong Kong Island, most parts of Kowloon, and across New Territories. A 1°C change in PET was associated with an excess risk (%) of 2.99 (95% CI: 0.50-5.48) for all natural causes, 4.75 (1.14-8.36) for cardiovascular, 7.39 (4.64-10.10) for respiratory diseases in the cool season, and 4.31 (0.12 to 8.50) for cardiovascular diseases in the warm season. CONCLUSIONS: Variations between TPUs in PET had an important influence on cause-specific mortality, especially in the cool season. PET may have an impact on the health of socio-economically deprived population groups. Our results suggest that targeting policy interventions at high-risk areas may be a feasible option for reducing PET-related mortality.

Excess winter mortality and cold temperatures in a subtropical city, Guangzhou, China.

BACKGROUND: A significant increase in mortality was observed during cold winters in many temperate regions. However, there is a lack of evidence from tropical and subtropical regions, and the influence of ambient temperatures on seasonal variation of mortality was not well documented. METHODS: This study included 213,737 registered deaths from January 2003 to December 2011 in Guangzhou, a subtropical city in Southern China. Excess winter mortality was calculated by the excess percentage of monthly mortality in winters over that of non-winter months. A generalized linear model with a quasi-Poisson distribution was applied to analyze the association between monthly mean temperature and mortality, after controlling for other meteorological measures and air pollution. RESULTS: The mortality rate in the winter was 26% higher than the average rate in other seasons. On average, there were 1,848 excess winter deaths annually, with around half (52%) from cardiovascular diseases and a quarter (24%) from respiratory diseases. Excess winter mortality was higher in the elderly, females and those with low education level than the young, males and those with high education level, respectively. A much larger winter increase was observed in out-of-hospital mortality compared to in-hospital mortality (45% vs. 17%). We found a significant negative correlation of annual excess winter mortality with average winter temperature (rs=-0.738, P=0.037), but not with air pollution levels. A 1 °C decrease in monthly mean temperature was associated with an increase of 1.38% (95% CI:0.34%-2.40%) and 0.88% (95% CI:0.11%-1.64%) in monthly mortality at lags of 0-1 month, respectively. CONCLUSION: Similar to temperate regions, a subtropical city Guangzhou showed a clear seasonal pattern in mortality, with a sharper spike in winter. Our results highlight the role of cold temperature on the winter mortality even in warm climate. Precautionary measures should be strengthened to mitigate cold-related mortality for people living in warm climate.

Quantifying the burden of disease due to premature mortality in Hong Kong using standard expected years of life lost.

BACKGROUND: To complement available information on mortality in a population Standard Expected Years of Life Lost (SEYLL), an indicator of premature mortality, is increasingly used to calculate the mortality-associated disease burden. SEYLL consider the age at death and therefore allow a more accurate view on mortality patterns as compared to routinely used measures (e.g. death counts). This study provides a comprehensive assessment of disease and injury SEYLL for Hong Kong in 2010. METHODS: To estimate the SEYLL, life-expectancy at birth was set according to the 2004 Global Burden of Disease study at 82.5 and 80 years for females and males, respectively. Cause of death data for 2010 were corrected for misclassification of cardiovascular and cancer causes. In addition to the baseline estimates, scenario analyses were performed using alternative assumptions on life-expectancy (Hong Kong standard life-expectancy), time-discounting and age-weighting. To estimate a trend of premature mortality a time-series analysis from 2001 to 2010 was conducted. RESULTS: In 2010 524,706.5 years were lost due to premature death in Hong Kong with 58.3% of the SEYLL attributable to male deaths. The three overall leading single causes of SEYLL were "trachea, bronchus and lung cancers", "ischaemic heart disease" and "lower respiratory infections" together accounting for about 29% of the overall SEYLL. Further, self-inflicted injuries (5.6%; ranked 5) and liver cancer (4.9%; ranked 7) were identified as important causes not adequately captured by classical mortality measures. Scenario analyses highlighted that by using a 3% time-discount rate and non-uniform age-weights the SEYLL dropped by 51.6%. Using Hong Kong's standard life-expectancy values resulted in an overall increase of SEYLL by 10.8% as compared to the baseline SEYLL. Time-series analysis indicates an overall increase of SEYLL by 6.4%. In particular, group I (communicable, maternal, perinatal and nutritional) conditions showed highest increases with SEYLL-rates per 100,000 in 2010 being 1.4 times higher than 2001. CONCLUSIONS: The study stresses the mortality impact of diseases and injuries that occur in earlier stages of life and thus presents the SEYLL measure as a more sensitive indicator compared to classical mortality indicators. SEYLL provide useful additional information and supplement available death statistics.

Part 4. Interaction between air pollution and respiratory viruses: time-series study of daily mortality and hospital admissions in Hong Kong.

BACKGROUND: Populations in Asia are not only at risk of harm to their health through environmental degradation as a result of worsening pollution problems but also constantly threatened by recurring and emerging influenza epidemics and. pandemics. Situated in the area with the world's fastest growing economy and close to hypothetical epicenters of influenza transmission, Hong Kong offers a special opportunity for testing environmental management and public health surveillance in the region. In the Public Health and Air Pollution in Asia (PAPA*) project, the Hong Kong research team assessed the health effects of air pollution and influenza as well as the interaction between them. The team also assessed disparities in the health effects of air pollution between relatively deprived and more affluent areas in Hong Kong. The aim was to provide answers to outstanding research questions relating to the short-term effects of air pollution on mortality and hospital admissions; the health effects of influenza with a view to validating different measures of influenza activity according to virologic data; the confounding effects of influenza on estimates of the health effects of air pollution; the modifying effects of influenza on the health effects of air pollution; and the modifying effects of neighborhood social deprivation on the health effects of air pollution. DATA: Data on mortality and hospital admissions for all natural causes, as well as the subcategories of cardiovascular diseases (CVD) and respiratory diseases (RD), were derived from the Hong Kong Census and Statistics Department and the Hospital Authority. Daily concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with an aerodynamic diameter < or = 10 pm (PM10); and ozone (O3) were derived from eight monitoring stations with hourly data that were at least 75% complete during the study period. Three measures of influenza and respiratory syncytial virus (RSV) activity were derived from positive isolates of specimens in the virology laboratory of Queen Mary Hospital (QMH), the main clinical teaching center at The University of Hong Kong and part of the Hong Kong Hospital Authority network of teaching hospitals: influenza intensity (defined as the weekly proportion of positive isolates of influenza in the total number of specimens received for diagnostic tests); the presence of influenza epidemic (defined as a period when the weekly frequency of these positive isolates is > or = 4% of the annual total number of positive isolates [i.e., twice the expected mean value] in two or more consecutive weeks); and influenza predominance (defined as a period of influenza epidemic when the weekly frequency of RSV was less than 2% for two or more consecutive weeks). The weekly proportion of positive isolates of RSV in total specimens was determined in the same way as for influenza intensity. A social deprivation index (SDI) was defined by taking the average of the proportions of households or persons with the following six characteristics in each geographic area using the census statistics: unemployment; household income < U.S. $250 per month; no schooling at all; never-married status; one-person household; and subtenancy. A Poisson regression with quasi-likelihood to account for overdispersion was used to develop core models for daily health outcomes, with a natural spline smoothing function to filter out seasonal patterns and long-term trends in this time-series study of daily mortality and hospital admissions, and with adjustment for days of the week, temperature, and relative humidity (RH). Air pollutant concentration values were entered into the core model to assess the health effects of specific pollutants. The possible confounding effects of influenza were assessed by observing changes in magnitude of the effect estimate when each influenza measurement was entered into the model; and interactions between air pollution and influenza were assessed by entering the terms for the product of the air pollutant concentration and a measurement of influenza activity into the model. A Poisson regression analysis was performed to assess the effects of air pollution in each area belonging to low, middle, or high social deprivation strata according to the tertiles of the SDI. The differences in air pollution effects were tested by a case-only approach. RESULTS The excess risk (ER) estimates for the short-term effects of air pollution on mortality and hospitalization for broad categories of disease were greater in those 65 years and older than in the all-ages group and were consistent with other studies. The biggest health impacts were seen at the extremes of the age range. The three measures employed for influenza activity based on virologic data-one based on a proportion and the other two using frequencies of positive influenza isolates-were found to produce consistent health impact estimates, in terms of statistical significance. In general, we found that adjustment for influenza activity in air pollution health effect estimations took account of relatively small confounding effects. However, we conclude that it is worthwhile to make the adjustment in a sensitivity analysis and to obtain the best possible range of effect estimates from the data, especially for respiratory hospitalization. Interestingly, interaction effects were found between influenza activity and air pollution in the estimated risks for hospitalization for RD, particularly for 03. These results could be explained in terms of the detrimental effects of both influenza viruses and air pollutants, which may be synergistic or competing with each other, though the mechanism is still unknown. The results deserve further study and the attention of both public health policy makers and virologists in considering prevention strategies. IMPLICATIONS In Hong Kong, where air pollution may pose more of a health threat than in North American and Western European cities, the effects of air pollution also interact with influenza and with residence in socially deprived areas, potentially leading to additional harm. Asian governments should be aware of the combined risks to the health of the population when considering environmental protection and management in the context of economic, urban, and infrastructure development. This is the first study in Asia to examine the interactions between air pollution, influenza, and social deprivation from an epidemiologic perspective. The biologic mechanisms are still unclear, and further research is needed.

Seasonal effects of influenza on mortality in a subtropical city.

BACKGROUND: Influenza has been associated with a heavy burden of mortality. In tropical or subtropical regions where influenza viruses circulate in the community most of the year, it is possible that there are seasonal variations in the effects of influenza on mortality, because of periodic changes in environment and host factors as well as the frequent emergence of new antigenically drifted virus strains. In this paper we explored this seasonal effect of influenza. METHODS: A time-varying coefficient Poisson regression model was fitted to the weekly numbers of mortality of Hong Kong from 1996 to 2002. Excess risks associated with influenza were calculated to assess the seasonal effects of influenza. RESULTS: We demonstrated that the effects of influenza were higher in winter and late spring/early summer than other seasons. The two-peak pattern of seasonal effects of influenza was found for cardio-respiratory disease and sub-categories pneumonia and influenza, chronic obstructive pulmonary disease, cerebrovascular diseases and ischemic heart disease as well as for all-cause deaths. CONCLUSION: The results provide insight into the possibility that seasonal factors may have impact on virulence of influenza besides their effects on virus transmission. The results warrant further studies into the mechanisms behind the seasonal effect of influenza.

Modification by influenza on health effects of air pollution in Hong Kong.

BACKGROUND: Both influenza viruses and air pollutants have been well documented as major hazards to human health, but few epidemiologic studies have assessed effect modification of influenza on health effects of ambient air pollutants. OBJECTIVES: We aimed to assess modifying effects of influenza on health effects of ambient air pollutants. METHODS: We applied Poisson regression to daily numbers of hospitalizations and mortality to develop core models after adjustment for potential time-varying confounding variables. We assessed modification of influenza by adding variables for concentrations of single ambient air pollutants and proportions of influenza-positive specimens (influenza intensity) and their cross-product terms. RESULTS: We found significant effect modification of influenza (p < 0.05) for effects of ozone. When influenza intensity is assumed to increase from 0% to 10%, the excess risks per 10-microg/m(3) increase in concentration of O(3) increased 0.24% and 0.40% for hospitalization of respiratory disease in the all-ages group and >or= 65 year age group, respectively; 0.46% for hospitalization of acute respiratory disease in the all-ages group; and 0.40% for hospitalization of chronic obstructive pulmonary disease in the >or= 65 group. The estimated increases in the excess risks for mortality of respiratory disease and chronic obstructive pulmonary disease in the all-ages group were 0.59% and 1.05%, respectively. We found no significant modification of influenza on effects of other pollutants in most disease outcomes under study. CONCLUSIONS: Influenza activity could be an effect modifier for the health effects of air pollutants particularly for O(3) and should be considered in the studies for short-term effects of air pollutants on health.

A tale of two cities: effects of air pollution on hospital admissions in Hong Kong and London compared.

The causal interpretation of reported associations between daily air pollution and daily admissions requires consideration of residual confounding, correlation between pollutants, and effect modification. If results obtained in Hong Kong and London--which differ in climate, lifestyle, and many other respects--were similar, a causal association would be supported. We used identical statistical methods for the analysis in each city. Associations between daily admissions and pollutant levels were estimated using Poisson regression. Nonparametric smoothing methods were used to model seasonality and the nonlinear dependence of admissions on temperature, humidity, and influenza admissions. For respiratory admissions (> or = 65 years of age), significant positive associations were observed with particulate matter < 10 microm in aerodynamic diameter (PM(10), nitrogen dioxide, sulfur dioxide, and ozone in both cities. These associations tended to be stronger at shorter lags in Hong Kong and at longer lags in London. Associations were stronger in the cool season in Hong Kong and in the warm season in London, periods during which levels of humidity are at their lowest in each city. For cardiac admissions (all ages) in both cities, significant positive associations were observed for PM(10), NO(2), and SO(2) with similar lag patterns. Associations tended to be stronger in the cool season. The associations with NO(2) and SO(2) were the most robust in two-pollutant models. Patterns of association for pollutants with ischemic heart disease were similar in the two cities. The associations between O(3) and cardiac admissions were negative in London but positive in Hong Kong. We conclude that air pollution has remarkably similar associations with daily cardiorespiratory admissions in both cities, in spite of considerable differences between cities in social, lifestyle, and environmental factors. The results strengthen the argument that air pollution causes detrimental short-term health effects.