Ignatius Tak-sun Yu

Effects of Coarse Particulate Matter on Emergency Hospital Admissions for Respiratory Diseases: A Time-Series Analysis in Hong Kong

Background: Many epidemiological studies have linked daily counts of hospital admissions to particulate matter (PM) with an aerodynamic diameter ≤ 10 μm (PM10) and ≤ 2.5 μm (PM2.5), but relatively few have investigated the relationship of hospital admissions with coarse PM (PMc; 2.5–10 μm aerodynamic diameter). Objectives: We conducted this study to estimate the health effects of PMc on emergency hospital admissions for respiratory diseases in Hong Kong after controlling for PM2.5 and gaseous pollutants. Methods: We conducted a time-series analysis of associations between daily emergency hospital admissions for respiratory diseases in Hong Kong from January 2000 to December 2005 and daily PM2.5 and PMc concentrations. We estimated PMc concentrations by subtracting PM2.5 from PM10 measurements. We used generalized additive models to examine the relationship between PMc (single- and multiday lagged exposures) and hospital admissions adjusted for time trends, weather conditions, influenza outbreaks, PM2.5, and gaseous pollutants (nitrogen dioxide, sulfur dioxide, and ozone). Results: A 10.9-μg/m3 (interquartile range) increase in the 4-day moving average concentration of PMc was associated with a 1.94% (95% confidence interval: 1.24%, 2.64%) increase in emergency hospital admissions for respiratory diseases that was attenuated but still significant after controlling for PM2.5. Adjusting for gaseous pollutants and altering models assumptions had little influence on PMc effect estimates. Conclusion: PMc was associated with emergency hospital admissions for respiratory diseases in Hong Kong independent of PM2.5 and gaseous pollutants. Further research is needed to evaluate health effects of different components of PMc.

Meta-analysis on night shift work and risk of metabolic syndrome

This study aims to quantitatively summarize the association between night shift work and the risk of metabolic syndrome (MetS), with special reference to the dose–response relationship with years of night shift work. We systematically searched all observational studies published in English on PubMed and Embase from 1971 to 2013. We extracted effect measures (relative risk, RR; or odd ratio, OR) with 95% confidence interval (CI) from individual studies to generate pooled results using meta‐analysis approach. Pooled RR was calculated using random‐ or fixed‐effect model. Downs and Black scale was applied to assess the methodological quality of included studies. A total of 13 studies were included. The pooled RR for the association between ‘ever exposed to night shift work’ and MetS risk was 1.57 (95% CI = 1.24–1.98, pheterogeneity = 0.001), while a higher risk was indicated in workers with longer exposure to night shifts (RR = 1.77, 95% CI = 1.32–2.36, pheterogeneity = 0.936). Further stratification analysis demonstrated a higher pooled effect of 1.84 (95% CI = 1.45–2.34) for studies using the NCEP‐ATPIII criteria, among female workers (RR = 1.61, 95% CI = 1.10–2.34) and the countries other than Asia (RR = 1.65, 95% CI = 1.39–1.95). Sensitivity analysis confirmed the robustness of the results. No evidence of publication bias was detected. The present meta‐analysis suggested that night shift work is significantly associated with the risk of MetS, and a positive dose–response relationship with duration of exposure was indicated.

Why Did Outbreaks of Severe Acute Respiratory Syndrome Occur in Some Hospital Wards but Not in Others

Abstract Background. Most documented “superspreading events” of severe acute respiratory syndrome (SARS) occurred in hospitals, but the underlying causes remain unclear. We systematically analyzed the risk factors for nosocomial outbreaks of SARS among hospital wards in Guangzhou and Hong Kong, China. Methods. A case-control study was conducted. Case wards were hospital wards in which superspreading events of SARS occurred, and control wards were wards in which patients with SARS were admitted, but no subsequent nosocomial outbreaks occurred. Information on environmental and administrative factors was obtained through visits to the wards and interviews with ward managers or nursing officers. Relevant information about host factors was abstracted from the medical records. Logistic regression analyses were used to identify the major risk factors for superspreading events. Results. Eighty-six wards in 21 hospitals in Guangzhou and 38 wards in 5 hospitals in Hong Kong were included in the study. Six risk factors were significant in the final multiple-logistic regression model: minimum distance between beds of ≤1 m (odds ratio [OR], 6.94; 95% confidence interval [CI], 1.68–28.75), availability of washing or changing facilities for staff (OR, 0.12; 95% CI, 0.02–0.97), whether resuscitation was ever performed in the ward (OR, 3.81; 95% CI, 1.04–13.87), whether staff members worked while experiencing symptoms (OR, 10.55; 95% CI, 2.28–48.87), whether any host patients (index patient or the first patient with SARS admitted to a ward) required oxygen therapy (OR, 4.30; 95% CI, 1.00–18.43), and whether any host patients required bi-level positive airway pressure ventilation (OR, 11.82; 95% CI, 1.97–70.80). Conclusions. Our results revealed that factors that were associated with the ward environment and administration were important in nosocomial outbreaks of SARS. The lessons learned from this study remain very important and highly relevant to the daily operation of hospital wards if we are to prevent nosocomial outbreaks of other respiratory infections in the future.

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.

Physical activity inversely associated with the presence of depression among urban adolescents in regional China.

BackgroundAn inverse relationship between physical activity (PA) and depression among adolescents has been reported in developed communities without consideration of sedentary behaviors (SB, including sitting for course study, viewing TV, and sleeping). We explored the association between recreational PA time (hr/wk) and depression after adjustment with SB and other possible confounders among Chinese adolescents.MethodsA population-based cross-sectional study was conducted in Nanjing municipality of China in 2004 using a multi-stage cluster sampling approach. A total of 72 classes were randomly selected from 24 urban junior high schools and all students completed the structured questionnaire. Adolescent depression was examined by the Childrens Depression Inventory (CDI) of Chinese version with cutoff point value of 20 or above as the presence of depression. Recreational PA time was measured by a question on weekly hours of PA outside of school. Descriptive statistics, multivariate logistic and linear regression models were used in analysis.ResultsThe overall prevalence of depression was 15.7% (95%CI: 14.3%, 17.1%) among 2,444 eligible participants. It was found that physical activity was negatively associated with depression. After adjustment for sedentary behaviors and other potential confounders, participants who spent 1–7 hr/wk, 8–14 hr/wk and 15+ hr/wk for recreational PA, respectively, had odds ratios of 0.70 (95% CI = 0.57, 0.86), 0.68 (95% CI = 0.53, 0.88) and 0.66 (95% CI = 0.50, 0.87) for likelihood of being depressive, compared to their counterparts who spent 0–0.9 hr/wk for PA. This inverse relationship between PA time and depression remained statistically significant by gender and grade.ConclusionThis study, conducted among Chinese adolescents, strengthened the evidence that physical activity was inversely associated with depression. Our study has important implications for health officers and public health professionals to pay much attention to the relationship between physical activity and depression in Mainland China.

Hypertension prevalence, awareness, treatment, control, and associated factors in adults in southern China.

BACKGROUND Hypertension is the most important risk factor for cardiovascular diseases. Little information exists on the status of hypertension among southern Chinese. We therefore investigated the hypertension prevalence, awareness, treatment, control, and associated factors in a southern Chinese population with 85 million residents. METHODS Stratified multistage cluster sampling with probability proportional to size method was used in this survey. A representative sample of 13,889 residents aged 20 years or above with completed questionnaire and blood pressure (BP) measurement was obtained. BP was measured in accordance with the 1999 World Health Organization/International Society of Hypertension Guidelines. Information related to history of diagnosis and treatment of hypertension was collected through questionnaire. RESULTS The prevalence of hypertension in this population was 20.5% (16.5%, 24.4%), which translated to 9.8 million adults suffering from hypertension in Guangdong province. The urban population had higher prevalence of hypertension than the rural population (25.1 vs. 16.1%). The prevalence of awareness, treatment, and control of hypertension in hypertensive patients living in urban regions were 42.8, 37.9, and 13.5%, respectively, which were higher than those in rural regions (the corresponding figures were 17.6, 10.4, and 3.4%, respectively). Nearly 50% urban adults and 80% rural adults did not measure their BP in the last 12 months. Frequency of BP measurement was associated with both awareness and treatment. CONCLUSIONS Hypertension was prevalent in southern China. The prevalence of awareness, treatment, and control of hypertension is low. Urgent strategies are needed to improve prevention, detection, and treatment of hypertension in this large Chinese population.

Temporal-Spatial Analysis of Severe Acute Respiratory Syndrome among Hospital Inpatients

Abstract Background. We report the temporal-spatial spread of severe acute respiratory syndrome (SARS) among inpatients in a hospital ward during a major nosocomial outbreak and discuss possible mechanisms for the outbreak. Methods. All inpatients who had stayed in the same ward as the initial index case patient for any duration before isolation were recruited into a cohort and followed up to document the occurrence of SARS. The normalized concentration of virus-laden aerosols at different locations of the ward was estimated by use of computational fluid dynamics modeling. The attack rates in the various subgroups stratified by bed location were calculated. Multivariate Cox proportional hazards regression was used to document important risk factors. Results. The overall attack rate of SARS was 41% (30 of 74 subjects). It was 65%, 52%, and 18% in the same bay, adjacent bay, and distant bays, respectively (P = .001). Computation fluid dynamics modeling indicated that the normalized concentration of virus-laden aerosols was highest in the same bay and lowest in the distant bays. Cox regression indicated that staying in the ward on 6 or 10 March entailed higher risk, as well as staying in the same or adjacent bays. The epidemic curve showed 2 peaks, and stratified analyses by bed location suggested >1 generation of spread. Conclusions. The temporal-spatial spread of SARS in the ward was consistent with airborne transmission, as modeled by use of computational fluid dynamics. Infected health care workers likely acted as secondary sources in the latter phase of the outbreak.

Possible Role of Aerosol Transmission in a Hospital Outbreak of Influenza

Abstract Background. We examined the role of aerosol transmission of influenza in an acute ward setting. Methods. We investigated a seasonal influenza A outbreak that occurred in our general medical ward (with open bay ward layout) in 2008. Clinical and epidemiological information was collected in real time during the outbreak. Spatiotemporal analysis was performed to estimate the infection risk among patients. Airflow measurements were conducted, and concentrations of hypothetical virus-laden aerosols at different ward locations were estimated using computational fluid dynamics modeling. Results. Nine inpatients were infected with an identical strain of influenza A/H3N2 virus. With reference to the index patients location, the attack rate was 20.0% and 22.2% in the “same” and “adjacent” bays, respectively, but 0% in the “distant” bay (P=.04). Temporally, the risk of being infected was highest on the day when noninvasive ventilation was used in the index patient; multivariate logistic regression revealed an odds ratio of 14.9 (95% confidence interval, 1.7–131.3; P=.015). A simultaneous, directional indoor airflow blown from the “same” bay toward the “adjacent” bay was found; it was inadvertently created by an unopposed air jet from a separate air purifier placed next to the index patients bed. Computational fluid dynamics modeling revealed that the dispersal pattern of aerosols originated from the index patient coincided with the bed locations of affected patients. Conclusions. Our findings suggest a possible role of aerosol transmission of influenza in an acute ward setting. Source and engineering controls, such as avoiding aerosol generation and improving ventilation design, may warrant consideration to prevent nosocomial outbreaks.

Occupational exposure to mixtures of organic solvents increases the risk of neurological symptoms among printing workers in Hong Kong.

Learning ObjectivesSummarize the nature and extent of exposure to organic solvents to which printing workers in this study were subjected.Compare the numbers of neurological symptoms in exposed and non-exposed workers and how they related to level of exposure, as defined by specific job title or by air sampling.Clarify the relationship between exposure to organic solvents and individual psychoneurological and other symptoms. The health effects of low-dose occupational exposure to organic solvents remains unclear. A cross-sectional survey was conducted among 762 male printing workers to assess the impacts of exposure to mixtures of n-hexane, toluene, isopropyl alcohol, and benzene on neurological and other symptoms. After controlling for age, smoking, alcohol drinking, past exposure history, working hours and shift work, current exposure to solvent mixtures was significantly associated with the total number of neurological symptoms and with the prevalence of specific symptoms of the nervous system and mucous membrane irritation. The adjusted odds ratio of neurovegetative lability (1.7–5.9), abnormal or reduced smell (1.6–4.1), memory loss (1.8), and mucous membrane irritation symptoms (1.5–4.6) significantly increased in the exposed group, especially when the summation index of exposure exceeded one.

The prevalence of metabolic syndrome and cardiovascular risk factors in adults in southern China

BackgroundThe metabolic syndrome has been shown to increase the incidence of cardiovascular disease. Little information exists on the prevalence of the metabolic syndrome for southern Chinese. We therefore investigate the prevalence of the metabolic syndrome in a southern Chinese population with 85 million residents.MethodsThe Guangdong Nutrition and Health Survey 2002 is a cross-sectional survey designed to assess the health and nutritional status of 85 million residents in Guangdong province located in southern China. Stratified multistage random sampling method was applied in this survey and a provincial representative sample of 6,468 residents aged 20 years or above was obtained in the present study. The participants received a full medical check-up including measurement of blood pressure, obesity indices, fasting lipids and glucose levels. Data describing socioeconomic and lifestyle factors was also collected through interview. Metabolic syndrome was defined in accordance with the International Diabetes Federation criteria.ResultsThe prevalence of metabolic syndrome was 7.30%, translating into a total of 4.0 million residents aged 20 years or above having the condition in this southern Chinese population. The urban population had higher prevalence of the syndrome than the rural population (10.57% vs 4.30%). Females had a higher prevalence of metabolic syndrome than males (8.99% vs 5.27%). More than 60% of the adults had at least one component of the metabolic syndrome.ConclusionsOur results indicate that a large proportion of southern Chinese adults have the metabolic syndrome and associated risk factors. The metabolic syndrome has become an important public health problem in China. These findings emphasize the urgent need to develop population level strategies for the prevention, detection, and treatment of cardiovascular risk in China.