A robust parameter estimation method for estimating disease burden of respiratory viruses.

BACKGROUND: Poisson model has been widely applied to estimate the disease burden of influenza, but there has been little success in providing reliable estimates for other respiratory viruses. METHODS: We compared the estimates of excess hospitalization rates derived from the Poisson models with different combinations of inference methods and virus proxies respectively, with the aim to determine the optimal modeling approach. These models were validated by comparing the estimates of excess hospitalization attributable to respiratory viruses with the observed rates of laboratory confirmed paediatric hospitalization for acute respiratory infections obtained from a population based study. RESULTS: The Bayesian inference method generally outperformed the classical likelihood estimation, particularly for RSV and parainfluenza, in terms of providing estimates closer to the observed hospitalization rates. Compared to the other proxy variables, age-specific positive counts provided better estimates for influenza, RSV and parainfluenza, regardless of inference methods. The Bayesian inference combined with age-specific positive counts also provided valid and reliable estimates for excess hospitalization associated with multiple respiratory viruses in both the 2009 H1N1 pandemic and interpandemic period. CONCLUSIONS: Poisson models using the Bayesian inference method and virus proxies of age-specific positive counts should be considered in disease burden studies on multiple respiratory viruses.

Health impact assessment of exposure to fine particulate matter based on satellite and meteorological information.

Air pollution in China, especially in the Pearl River Delta (PRD) region, has drastically increased in recent years. We modelled annual mean ground-level PM2.5 concentrations based on worldwide satellite information and meteorological data from 40 cities outside the PRD. The model of PM2.5 concentration (R = 0.845) was best explained by aerosol optical thickness (43.8%). We validated the spatial-temporal dimensions of the model and estimated that the annual mean PM2.5 concentration in PRD ranged between 22 and 65 µg m(-3). Then we used meta-analysis to obtain the pooled excess risks of mortality in China and assessed the health impacts. We found an inverse association between short-term excess risks of mortality and annual mean PM2.5 concentrations. Based on the above models and analyses, the associated excess deaths for all-cause and cardiopulmonary diseases were 3386 and 2639 respectively. The corresponding risk-standardized excess death rates were 2006 and 1069 per million people.

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.

Lung function and exposure to workplace second-hand smoke during exemptions from smoking ban legislation: an exposure-response relationship based on indoor PM2.5 and urinary cotinine levels.

BACKGROUND: The effects of workplace second-hand smoke (SHS) on lung function remain uncertain because of a lack of objective measures for SHS exposures. OBJECTIVE: To determine whether an exposure-response association exists between lung function and two different markers of SHS based on indoor fine particulate (PM(2.5)) and urinary cotinine levels in non-smoking catering workers. DESIGN: A cross-sectional study during a 1.5-year exemption of licensed catering premises from smoke-free legislation. Participants 186 non-smoking catering workers aged 18-65 years in Hong Kong were recruited. A declared non-smoking status was accepted in workers with exhaled breath carbon monoxide levels <6 ppm and urinary cotinine levels <100 ng/ml. MAIN OUTCOME MEASURES: Lung function measures of forced expiratory volume in 1s (FEV(1) in litres), forced vital capacity (FVC in litres) and forced expiratory flow as 25-75% of FVC (FEF(25-75) in l/s) were recorded. RESULTS: Indoor fine particulate (PM(2.5)) concentrations were 4.4 times as high in smoking premises (267.9 µg/m(3)) than in non-smoking premises (60.3 µg/m(3)) and were strongly associated with the probability of permitted smoking (R(2)=0.99). Smoking was the dominant source of particulates (R(2)=0.66). Compared with workers exposed to the lowest indoor PM(2.5) stratum (<25 µg/m(3)), lung function was lower in the three higher PM(2.5) strata (25-75, 75-175, >175 µg/m(3)) with FEV(1) -0.072 (95% CI -0.123 to -0.021), -0.078 (95% CI -0.132 to -0.024), -0.101 (95% CI -0.187 to -0.014); FEF(25-75) -0.368 (95% CI -0.660 to -0.077), -0.489 (95% CI -0.799 to -0.179), -0.597 (95% CI -0.943 to -0.251); and FEV(1)/FVC (%) -2.9 (95% CI -4.8 to -1.0), -3.2 (95% CI -5.1 to -1.4) and -4.4 (95% CI -7.4 to -1.3), respectively. Urinary cotinine was associated positively with indoor PM(2.5) but negatively with lung function. Consistently lower values for lung function per unit increase of indoor PM(2.5) were found. CONCLUSION: Lung function is inversely associated with workplace SHS. Workplace exemptions and delays in implementing smoke-free policies and current moves to relax legislation are a major threat to the health of workers.

Daily visibility and mortality: assessment of health benefits from improved visibility in Hong Kong.

Visibility in Hong Kong has deteriorated significantly over 40 years with visibility below 8km in the absence of fog, mist, or precipitation, increasing from 6.6 days in 1968 to 54.1 days in 2007. We assessed the short-term mortality effects of daily loss of visibility. During 1996-2006, we obtained mortality data for non-accidental and cardiorespiratory causes, visibility recorded as visual range in kilometers, temperature, and relative humidity from an urban observatory, and concentrations of four criteria pollutants. A generalized additive Poisson regression model with penalized cubic regression splines was fitted to control for time variant covariates. For non-accidental mortality, an interquartile range (IQR) of 6.5km decrease in visibility at lag0-1 days was associated with an excess risk (ER%) [95% CI] of 1.13 [0.49, 1.76] for all ages and 1.37 [0.65, 2.09] for ages 65 years and over; for cardiovascular mortality of 1.31 [0.13, 2.49] for all ages, and 1.72 [0.44, 3.00] for ages 65 years and over; and for respiratory mortality of 1.92 [0.49, 3.35] for all ages and 1.76 [0.28, 3.25] for ages 65 years and over. The estimated ER% for daily mortality derived from both visibility and air pollutant data were comparable in terms of magnitude, lag pattern, and exposure-response relationships especially when using particulate matter with aerodynamic diameter < or = 10 microm to predict the mortality associated with visibility. Visibility provides a useful proxy for the assessment of environmental health risks from ambient air pollutants and a valid approach for the assessment of the public health impacts of air pollution and the benefits of air quality improvement measures in developing countries where pollutant monitoring data are scarce.

The effects of air pollution on mortality in socially deprived urban areas in Hong Kong, China.

BACKGROUND: Poverty is a major determinant of population health, but little is known about its role in modifying air pollution effects. OBJECTIVES: We set out to examine whether people residing in socially deprived communities are at higher mortality risk from ambient air pollution. METHODS: This study included 209 tertiary planning units (TPUs), the smallest units for town planning in the Special Administrative Region of Hong Kong, China. The socioeconomic status of each TPU was measured by a social deprivation index (SDI) derived from the proportions of the population with a) unemployment, b) monthly household income < US$250, c) no schooling at all, d) one-person household, e) never-married status, and f ) subtenancy, from the 2001 Population Census. TPUs were classified into three levels of SDI: low, middle, and high. We performed time-series analysis with Poisson regression to examine the association between changes in daily concentrations of ambient air pollution and daily number of deaths in each SDI group for the period from January 1996 to December 2002. We evaluated the differences in pollution effects between different SDI groups using a case-only approach with logistic regression. RESULTS: We found significant associations of nitrogen dioxide, sulfur dioxide, particulate matter with aerodynamic diameter < 10 mum, and ozone with all nonaccidental and cardiovascular mortality in areas of middle or high SDI (p < 0.05). Health outcomes, measured as all nonaccidental, cardiovascular, and respiratory mortality, in people residing in high SDI areas were more strongly associated with SO(2) and NO(2) compared with those in middle or low SDI areas. CONCLUSIONS: Neighborhood socioeconomic deprivation increases mortality risks associated with air pollution.

Air pollution: costs and paths to a solution in Hong Kong--understanding the connections among visibility, air pollution, and health costs in pursuit of accountability, environmental justice, and health protection.

Air quality has deteriorated in Hong Kong over more than 15 yr. As part of a program of public accountability, photographs on Poor and Better visibility days were used as representations of the relationships among visibility, air pollution, adverse health effects, and community costs for health care and lost productivity. Coefficients from time-series models and gazetted costs were used to estimate the health and economic impacts of different levels of pollution. In this population of 6.9 million, air quality improvement from the annual average to the lowest pollutant levels of Better visibility days, comparable to the World Health Organization air quality guidelines, would avoid 1335 deaths, 60,587 hospital bed days, and 6.7 million doctor visits for respiratory complaints each year. Direct costs and productivity losses avoided would be over US$240 million a year. The dissemination of these findings led to increased demands for pollution controls from the public and legislators, but denials of the need for urgent action arose from the government. The outcome demonstrates the need for more effective translation of the scientific evidence base into risk communication and public policy.

Socioeconomic disparities in air pollution-associated mortality.

This study aimed to determine whether individuals with lower socioeconomic status (SES) were more susceptible to the acute effects of ambient air pollution than those with higher SES. We included 24,357 Hong Kong Chinese aged 30 or above who died of natural causes in 1998. Information on individual socioeconomic characteristics was obtained by interviewing proxy informants with a standardized questionnaire in all four death registries. Individual SES was indicated by three measures: type of housing, occupational group and education attainment. Poisson regression was performed to assess the short-term effects of ambient air pollution measured by PM(10), NO(2), SO(2) and O(3) on mortality for each SES group. The differences in the effects between SES groups were estimated by the interaction between air pollution and SES. We found that PM(10) and NO(2) were associated with greater risk of mortality on people living in public rental housing than in private housing. The effects of all four pollutants were significantly greater in blue-collar workers than the never-employed and white-collar groups (p<0.05). However, we found no compelling evidence of effect modification by education attainment. Our results provide new evidence on the role of individual's SES as effect modifiers of the short-term effects of air pollution on mortality. The reduction of risks associated with air pollution for socially disadvantaged populations should be a high priority in public health and environmental policies.