Both low and high temperature may increase the risk of stroke mortality

Top 10 Research Priorities in Spatial Lifecourse Epidemiology

The International Initiative on Spatial Lifecourse Epidemiology (ISLE) convened its first International Symposium on Lifecourse Epidemiology and Spatial Science at the Lorentz Center in Leiden, Netherlands, 16–20 July 2018. Its aim was to further an emerging transdisciplinary field: Spatial Lifecourse Epidemiology. This field draws from a broad perspective of scientific disciplines including lifecourse epidemiology, environmental epidemiology, community health, spatial science, health geography, biostatistics, spatial statistics, environmental science, climate change, exposure science, health economics, evidence-based public health, and landscape ecology. The participants, spanning 30 institutions in 10 countries, sought to identify the key issues and research priorities in spatial lifecourse epidemiology. The results published here are a synthesis of the top 10 list that emerged out of the discussion by a panel of leading experts, reflecting a set of grand challenges for spatial lifecourse epidemiology in the coming years. https://doi.org/10.1289/EHP4868.

Impact of ambient temperature on hospital admissions for cardiovascular disease in Hefei City, China

Many studies have quantified the hospitalization risk for cardiovascular disease (CVD) caused by temperature, but the results of most studies are not consistent. In this study, we evaluate the effect of temperature on CVD hospitalizations. We use a quasi-Poisson regression with a distributed-lag nonlinear model (DLNM) to evaluate the effect of temperature on CVD hospitalizations between July 1, 2015, and October 31, 2017, in Hefei City, China. We found that the cold effect and heat effect of temperature can impact CVD hospital admissions. Compared with the 25th percentile of temperature (10.3 °C), the cumulative relative risk (RR) of extremely low temperature (first percentile of temperature, 0.075 °C) over lags 0-27 days was 0.616 (95% CI 0.423-0.891), and the cumulative RR of moderate low temperature (10th percentile of temperature, 5.16 °C) was 1.081 (95% CI 1.019-1.147) over lags 0-7 days. Compared with the 75th percentile of temperature (25.6 °C), the cumulative RR of extremely high temperature (99th percentile of temperature, 33.7 °C) was 1.078 (95% CI 0.752-1.547) over lags 0-27 days, and the cumulative RR of moderate-high temperature (90th percentile of temperature, 29.0 °C) was 1.015 (95% CI 0.988-1.043) over lag 0 day. In the subgroup, the < 65-year group and male were more susceptible to low temperature; however, the ≥ 65-year group and female were more vulnerable to high temperature. The high temperature's impact on CVD hospital admissions was found to be more obvious in female and the ≥ 65-year group compared to male and the < 65-year group. However, the < 65-year group and men are more sensitive to low temperature.

A systematic review and meta-analysis of the association between daily mean temperature and mortality in China

PURPOSE

We summarized the evidence on the effects of heat and cold exposures on mortality in China. We included studies published on this topic in both Chinese and English, thereby filling a gap in knowledge using data from a country that consists of one-fifth of the world's population.

METHODS

We conducted a systematic search of peer-reviewed studies on the association between daily mean temperature and mortality published from 2001 up to July 2018. We searched one Chinese database (China National Knowledge infrastructure, http://www.cnki.net) and three English databases (PubMed, Scopus, Web of Science). We converted the effect estimates of heat/cold to rate ratios (RRs) associated with 1° increase/decrease beyond the heat/cold reference temperatures. For studies that provided lag-specific estimates, we used both the maximum and minimum of RR estimates. We calculated summary effect estimates for all-cause and cause-specific mortalities, as well as RRs stratified by sex, age, and socioeconomic status. We also investigated patterns of heat and cold adaptation at different latitudes, and at different reference temperatures.

RESULTS

In total, 45 articles were included in this systematic review. For every 1° temperature increase/decrease beyond reference points, the rate of non-accidental mortality increased by 2% (RR, 1.02; 95% confidence interval (95% CI [1.01-1.02]) for heat and 4% (RR, 1.04; 95% CI [1.03-1.04]) for cold, respectively; the rate of cardiovascular mortality increased 3% (RR, 1.03; 95% CI [1.03-1.04]) for heat and 6% (RR, 1.06; 95% CI [1.04-1.07]) for cold; the rate of respiratory mortality increased 2% (RR, 1.02; 95% CI [1.01-1.03]) for heat and 2% (RR, 1.02; 95% CI [1.00-1.04]) for cold; the rate of cerebrovascular mortality increased 2% (RR, 1.02; 95% CI [1.02-1.03]) for heat and 3% (RR, 1.03; 95% CI [1.02-1.04]) for cold. We identified a variation in optimal temperature range related to latitude of the residential area, and differences in people's capability to adapt to heat versus cold.

CONCLUSION

We found consistent evidence of the association between temperature and mortality, as well as evidence of patterns in human adaptation, and we discussed the implications of our findings.

A time series analysis of the relationship between apparent temperature, air pollutants and ischemic stroke in Madrid, Spain

The understanding of the role of environment on the pathogenesis of stroke is gaining importance in the context of climate change. This study analyzes the temporal pattern of ischemic stroke (IS) in Madrid, Spain, during a 13-year period (2001-2013), and the relationship between ischemic stroke (admissions and deaths) incidence and environmental factors on a daily scale by using a quasi-Poisson regression model. To assess potential delayed and non-linear effects of air pollutants and Apparent Temperature (AT), a biometeorological index which represents human thermal comfort on IS, a lag non-linear model was fitted in a generalized additive model. The mortality rate followed a downward trend over the studied period, however admission rates progressively increased. Our results show that both increases and decreases in AT had a marked relationship with IS deaths, while hospital admissions were only associated with low AT. When analyzing the cumulative effects (for lag 0-14 days), with an AT of 1.7 °C (percentile 5%) a RR of 1.20 (95% CI, 1.05-1.37) for IS mortality and a RR of 1.09 (95% CI, 0.91-1.29) for morbidity is estimated. Concerning gender differences, men show higher risks of mortality in low temperatures and women in high temperatures. No significant relationship was found between air pollutant concentrations and IS morbi-mortality, but this result must be interpreted with caution, since there are strong spatial fluctuations of the former between nearby geographical areas that make it difficult to perform correlation analyses.

Impact of heat on mortality and morbidity in low and middle income countries: A review of the epidemiological evidence and considerations for future research

Heat waves and high air temperature are associated with increased morbidity and mortality. However, the majority of research conducted on this topic is focused on high income areas of the world. Although heat waves have the most severe impacts on vulnerable populations, relatively few studies have studied their impacts in low and middle income countries (LMICs). The aim of this paper is to review the existing evidence in the literature on the impact of heat on human health in LMICs. We identified peer-reviewed epidemiologic studies published in English between January 1980 and August 2018 investigating potential associations between high ambient temperature or heat waves and mortality or morbidity. We selected studies according to the following criteria: quantitative studies that used primary and/or secondary data and report effect estimates where ambient temperature or heat waves are the main exposure of interest in relation to human morbidity or mortality within LMICs. Of the total 146 studies selected, eighty-two were conducted in China, nine in other countries of East Asia and the Pacific, twelve in South Asia, ten in Sub-Saharan Africa, eight in the Middle East and North Africa, and seven in each of Latin America and Europe. The majority of studies (92.9%) found positive associations between heat and human morbidity/mortality. Additionally, while outcome variables and study design differed greatly, most utilized a time-series study design and examined overall heath related morbidity/mortality impacts in an entire population, although it is notable that the selected studies generally found that the elderly, women, and individuals within the low socioeconomic brackets were the most vulnerable to the effects of high temperature. By highlighting the existing evidence on the impact of extreme heat on health in LMICs, we hope to determine data needs and help direct future studies in addressing this knowledge gap. The focus on LMICs is justified by the lack of studies and data studying the health burden of higher temperatures in these regions even though LMICs have a lower capacity to adapt to high temperatures and thus an increased risk.

Ambient Coarse Particulate Matter and Hospital Admissions for Ischemic Stroke

Background and Purpose—

Evidence on the effects of coarse particulate matter (PM 10–2.5 ) on ischemic stroke is limited and inconsistent. We evaluated the acute effects of PM 10–2.5 exposure on hospital admissions for ischemic stroke in China.

Methods—

We conducted a national time-series analysis of associations between daily PM 10–2.5 concentrations and daily hospital admissions for ischemic stroke in China between January 2014 and December 2016. Hospital admissions for ischemic stroke were identified from the database of Urban Employee Basic Medical Insurance, which contains data from 0.28 billion beneficiaries. We applied a city-specific Poisson regression to examine the associations of PM 10–2.5 and daily ischemic stroke admissions. We combined the city-specific effect estimates with a random effects meta-analysis, and further evaluated the exposure-response relationship curve and potential effect modifiers.

Results—

We identified >2 million hospital admissions for ischemic stroke in 172 Chinese cities. A 10 μg/m 3 increase in PM 10–2.5 concentrations (lag day 0) was associated with a 0.91% (95% CI, 0.73–1.10) increase in hospital admissions for ischemic stroke. The association remained significant after adjusting for PM 2.5 (percentage change, 0.96%; 95% CI, 0.75–1.18). The exposure-response relationship was approximately linear, with a moderate response at lower levels (<200 μg/m 3 ) and a steeper response at higher levels. The association was stronger in cities with lower PM 10–2.5 concentrations, higher temperatures, or higher relative humidity.

Conclusions—

This nationwide study provides robust evidence of the short-term association between exposure to PM 10–2.5 and increased hospital admissions for ischemic stroke and supports the hypothesis that the association differs by city characteristics.

Earth Observation: Investigating Noncommunicable Diseases from Space

The United Nations has called on all nations to take immediate actions to fight noncommunicable diseases (NCDs), which have become an increasingly significant burden to public health systems around the world. NCDs tend to be more common in developed countries but are also becoming of growing concern in low- and middle-income countries. Earth observation (EO) technologies have been used in many infectious disease studies but have been less commonly employed in NCD studies. This review discusses the roles that EO data and technologies can play in NCD research, including ( a) integrating natural and built environment factors into NCD research, ( b) explaining individual-environment interactions, ( c) scaling up local studies and interventions, ( d) providing repeated measurements for longitudinal studies including cohorts, and ( e) advancing methodologies in NCD research. Such extensions hold great potential for overcoming the challenges of inaccurate and infrequent measurements of environmental exposure at the level of both the individual and the population, which is of great importance to NCD research, practice, and policy.

Incidence of retinal vein occlusion with long-term exposure to ambient air pollution

This study aimed to investigate whether long-term exposure to airborne hydrocarbons, including volatile organic compounds, increases the risk of developing retinal vein occlusion (RVO) among the population of Taiwan. A retrospective cohort study involving 855,297 people was conducted. Cox proportional hazards regression analysis fitted the multiple pollutant models for two targeted pollutants, including total hydrocarbons (THC), nonmethane hydrocarbons (NMHC) were used, and the risk of RVO was estimated. The chi-squared test and one-way analysis of variance were used to test differences in demographics and comorbidity distribution among tertiles of the targeted pollutants. Before controlling for multiple pollutants, hazard ratios for the overall population were 19.88 (95% CI: 17.56-22.50) at 0.51-ppm increases in THC and 4.33 (95% CI: 3.97-4.73) at 0.27-ppm increases in NMHC. The highest adjusted hazard ratios for different multiple pollutant models of each targeted pollutant were statistically significant (all p values were ≤0.05) for all patients at 29.67 (95% CI: 25.57-34.42) for THC and 16.24 (95% CI: 14.14-18.65) for NMHC. Our findings suggest that long-term exposure to THC and NMHC contribute to RVO development.

Long-term ambient hydrocarbons exposure and incidence of ischemic stroke

Exposure to air pollutants is known to have adverse effects on human health; however, little is known about the association between hydrocarbons in air and an ischemic stroke (IS) event. We investigated whether long-term exposure to airborne hydrocarbons, including volatile organic compounds, increased IS risk. This retrospective cohort study included 283,666 people aged 40 years or older in Taiwan. Cox proportional hazards regression analysis was used to fit single- and multiple-pollutant models for two targeted pollutants, total hydrocarbons (THC) and nonmethane hydrocarbons (NMHC), and estimated the risk of IS. Before controlling for multiple pollutants, hazard ratios (HRs) of IS with 95% confidence intervals for the overall population were 2.69 (2.64-2.74) at 0.16-ppm increase in THC and 1.62 (1.59-1.66) at 0.11-ppm increase in NMHC. For the multiple-pollutant models controlling for PM2.5, the adjusted HR was 3.64 (3.56-3.72) for THC and 2.21 (2.16-2.26) for NMHC. Our findings suggest that long-term exposure to THC and NMHC may be a risk factor for IS development.

Long-Term Exposure to Ambient Hydrocarbons Increases Dementia Risk in People Aged 50 Years and above in Taiwan

BACKGROUND

Alzheimer's disease, the most common cause of dementia among the elderly, is a progressive and irreversible neurodegenerative disease. Exposure to air pollutants is known to have adverse effects on human health, however, little is known about hydrocarbons in the air that can trigger a dementia event.

OBJECTIVE

We aimed to investigate whether long-term exposure to airborne hydrocarbons increases the risk of developing dementia.

METHOD

The present cohort study included 178,085 people aged 50 years and older in Taiwan. Cox proportional hazards regression analysis was used to fit the multiple pollutant models for two targeted pollutants, including total hydrocarbons and non-methane hydrocarbons, and estimated the risk of dementia.

RESULTS

Before controlling for multiple pollutants, hazard ratios with 95% confidence intervals for the overall population were 7.63 (7.28-7.99, p <0.001) at a 0.51-ppm increases in total hydrocarbons, and 2.94 (2.82-3.05, p <0.001) at a 0.32-ppm increases in non-methane hydrocarbons. The highest adjusted hazard ratios for different multiple-pollutant models of each targeted pollutant were statistically significant (p <0.001) for all patients: 11.52 (10.86-12.24) for total hydrocarbons and 9.73 (9.18-10.32) for non-methane hydrocarbons.

CONCLUSION

Our findings suggest that total hydrocarbons and non-methane hydrocarbons may be contributing to dementia development.

Association between extreme temperature and acute myocardial infarction hospital admissions in Beijing, China: 2013-2016

Over the past few decades, a growing body of epidemiological studies found the effects of temperature on cardiovascular disease, including the risk for acute myocardial infarction (AMI). Our study aimed to investigate whether there is an association between extremely temperature and acute myocardial infarction hospital admission in Beijng, China. We obtained 81029 AMI cases and daily temperature data from January 1, 2013 to December 31, 2016. We employed a time series design and modeled distributed lag nonlinear model (DLNM) to analyze effects of temperature on daily AMI cases. Compared with the 10th percentile temperature measured by daily mean temperature (Tmean), daily minimum temperature (Tmin) and daily minimum apparent temperature (ATmin), the cumulative relative risks (CRR) at 1st percentile of Tmean, Tmin and ATmin for AMI hospitalization were 1.15(95% CI: 1.02, 1.30), 1.24(95% CI: 1.11, 1.38) and 1.41(95% CI: 1.18, 1.68), respectively. Moderate low temperature (10th vs 25th) also had adverse impact on AMI events. The susceptive groups were males and people 65 years and older. No associations were found between high temperature and AMI risk. The main limitation of the study is temperature exposure was not individualized. These findings on cold-associated AMI hospitalization helps characterize the public health burden of cold and target interventions to reduce temperature induced AMI occurrence.

Acute Effects of Particulate Air Pollution on Ischemic Stroke and Hemorrhagic Stroke Mortality

Background and Purpose: A large body of literature reported the association of particulate matter (PM) with stroke in high-income countries. Few studies have examined the association between PM and stroke in middle- and low-income countries and considered the types of stroke. In this study, we examined the short-term effects of particulate matter <2.5 μm in diameter (PM_2.5) and particulate matter <10 μm in diameter (PM₁₀) on ischemic stroke mortality and hemorrhagic stroke mortality in Beijing, China.

Methods: We used an ecological study design and quasi-Poisson generalized additive models to evaluate the association of PM_2.5 and PM₁₀ and cerebrovascular diseases mortality, as well as ischemic- and hemorrhagic stroke mortality. In the model, we controlled long-term and season trends, temperature, and relative humidity, the day of the week and air pollution. For cerebrovascular diseases mortality, we examined the effects stratified by sex and age with different lag days.

Results: A total of 48,122 deaths for cerebrovascular disease (32,799 deaths for ischemic stroke and 13,051 deaths for hemorrhagic stroke) were included in the study. PM_2.5 was associated with stroke mortality. The 10 μg/m³ increase of PM_2.5 was associated with the increase of mortality, 0.27% (95% CI, 0.12–0.43%) for cerebrovascular diseases, 0.23% (95% CI, 0.04–0.42%) for ischemic stroke and 0.37% (95% CI, 0.07–0.67%) for hemorrhagic stroke -. The associations between PM₁₀ and mortality were also detected for cerebrovascular diseases and ischemic stroke, but not in hemorrhagic stroke. The stratified analysis suggested age and gender did not modify the effects of PM on mortality significantly.

Conclusions: Our study suggested that short-term exposure to ambient PM was associated with the risk of stroke mortality.

Assessment of heat- and cold-related emergency department visits in cities of China and Australia: Population vulnerability and attributable burden

BACKGROUND

Non-optimal ambient temperature has detrimental impacts on mortality worldwide, but little is known about the difference in population vulnerability to non-optimal temperature and temperature-related morbidity burden between developing and developed countries.

OBJECTIVES

We estimated and compared the associations of emergency department visits (EDV) with non-optimal temperature in terms of risk trigger temperature, the average slope of exposure-risk function and attributable risk in 12 cities from China and Australia.

METHODS

We modelled the associations of EDV with heat during warm season and with cold during cold season, separately, using generalized additive model. Population vulnerability within a given region was quantified with multiple risk trigger points including minimum risk temperature, increasing risk temperature and excessive risk temperature, and average coefficient of exposure-risk function. Fraction of EDV attributable to heat and cold was also calculated.

RESULTS

We found large between- and within-country contrasts in the identified multiple risk trigger temperatures, with higher heat and cold trigger points, except excessive risk temperature, observed in Australia than in China. Heat was associated with a relative risk (RR) of 1.009 [95% confidence interval (CI):1.007, 1.011] in China, which accounted for 5.9% of EDV. Higher RR of heat was observed in Australia (1.014, 95% CI: 1.010, 1.018), responsible for 4.0% of EDV. For cold effects, the RR was similar between two countries, but the attributable fraction was higher in China (9.6%) than in Australia (1.5%).

CONCLUSIONS

Exposure to heat and cold had adverse but divergent impacts on EDV in China and Australia. Further mitigation policy efforts incorporating region-specific population vulnerability to temperature impacts are necessary in both countries.

Seasonal Variations in Neurological Severity and Outcomes of Ischemic Stroke - 5-Year Single-Center Observational Study

BACKGROUND

Seasonal variations in the severity and outcomes of stroke remain unclarified.

METHODS AND RESULTS

A total of 2,965 acute ischemic stroke patients from a single-center prospective registry were studied. Among the total patients, stroke onset did not vary by season, though it varied with a peak in winter when limited to patients >75 years old (P=0.026), when limited to patients with moderate-to-severe initial neurological deficits (National Institutes of Health Stroke Scale Score ≥10, P=0.014), and when limited to those with cardioembolic stroke (n=1,031, P=0.010). In 1,934 patients with noncardioembolic stroke, stroke onset did not vary by season. After multivariable adjustment, moderate-to-severe neurological deficits were more common in winter (odds ratio 1.37, 95% confidence interval 1.10-1.72) and spring (1.27, 1.01-1.60), and death at 1 year was more common in summer than in fall (1.55, 1.03-2.36); death or dependency (modified Rankin Scale score 3-6) and death or bedridden (score of 5-6) were not differently common among the seasons.

CONCLUSIONS

Overall ischemic stroke showed a fairly even distribution among the 4 seasons. Cardioembolic stroke was more common in winter. Ischemic stroke patients had more moderate-to-severe initial neurological deficits in winter and spring. Poor clinical outcomes at 1 year were generally similar among the seasons. Ischemic stroke is not necessarily a winter-dominant disease.

The burden of ambient temperature on years of life lost: A multi-community analysis in Hubei, China

BACKGROUND

Compared with death rates, years of life lost (YLL) has been widely used as a more informative indicator to quantify the burden of premature death. In the context of global climate change, existing evidence linking ambient temperatures and YLL was very scarce across the globe.

METHODS

Daily mortality and meteorological data during 2009-2012 were obtained from 12 communities across Hubei Province in central China. A two-stage approach was used for statistical analysis. At the first stage, a generalized linear regression combined with distributed lag non-linear model was applied to estimate community-specific temperature-YLL associations. A second-stage multivariable meta-analysis was then conducted to pool the community-specific estimates of temperature-related effects on YLL.

RESULTS

A pooled J- or U-shaped association was observed between ambient temperature and YLL due to different mortality categories. Heat effects occurred immediately and only persisted for several days, whereas cold effects were delayed and much longer-lasting. At the provincial level, heat effect (per 1°C increase from 75th to 99th percentile of temperature) at lag 0-2days and cold effect (per 1°C decrease from 25th to 1st percentile of temperature) at lag 0-21days was associated with an increase of 1.91% (95% CI: 0.83, 3.00) and 5.09% (2.79, 7.40) in YLL due to non-accidental deaths, respectively. Much greater effect estimates of cold than heat were also observed for other mortality-specific YLLs (except for respiratory mortality). Heat effects on YLL were higher for males and the youth, while cold effects were greater for females and the elderly. Additionally, relatively stronger associations between heat, cold and YLL were consistently observed in low-educated persons.

CONCLUSIONS

This multi-community study strengthened the evidence that both cold and hot temperatures were associated with increased years of life lost. Our findings may have important implications for better understanding the burden of premature death related to temperature extremes.

Mapping relative humidity, average and extreme temperature in hot summer over China

Air temperature and relative humidity are the key variables in environmental health research. Both of them are difficult to map especially at national scale because of spatial heterogeneity. This paper presents a methodology for mapping relative humidity, average and extreme temperature in hot summer (June to August) over China. Several data as explanatory variables were applied to random forest regression models to predict relative humidity and temperatures, including surface reflectance, land cover, digital elevation model (DEM), enhanced vegetation index (EVI), latitude, nighttime lights (NLs), as well as buffer zones of road, railroad, river system and administration center. Results based on cross-validation reflect acceptable prediction errors in estimating relative humidity (RMSE=7.4%), average temperature (RMSE=2.4°C), average maximum temperature (RMSE=2.5°C), and extreme maximum temperature (RMSE=2.6°C). Despite the strong correlation between average and extreme temperatures, significant differences exist in their spatial distribution along the latitude direction, especially in the areas such as Hebei, Szechwan, Hubei, Henan, Shandong, and Inner Mongolia. Specifically, social economic activity, relative humidity and vegetation tend to affect extreme heat events, and both latitude and DEM (i.e., geographical position) determine the average level of temperature. Compared with interpolation technology and statistical methods, the proposed methodology demonstrates the ability to generate relative humidity and temperature maps with finer gradients in hot summer over China.

Using big data to improve cardiovascular care and outcomes in China: a protocol for the CHinese Electronic health Records Research in Yinzhou (CHERRY) Study

INTRODUCTION

Data based on electronic health records (EHRs) are rich with individual-level longitudinal measurement information and are becoming an increasingly common data source for clinical risk prediction worldwide. However, few EHR-based cohort studies are available in China. Harnessing EHRs for research requires a full understanding of data linkages, management, and data quality in large data sets, which presents unique analytical opportunities and challenges. The purpose of this study is to provide a framework to establish a uniquely integrated EHR database in China for scientific research.

METHODS AND ANALYSIS

The CHinese Electronic health Records Research in Yinzhou (CHERRY) Study will extract individual participant data within the regional health information system of an eastern coastal area of China to establish a longitudinal population-based ambispective cohort study for cardiovascular care and outcomes research. A total of 1 053 565 Chinese adults aged over 18 years were registered in the health information system in 2009, and there were 23 394 deaths from 1 January 2009 to 31 December 2015. The study will include information from multiple epidemiological surveys; EHRs for chronic disease management; and health administrative, clinical, laboratory, drug and electronic medical record (EMR) databases. Follow-up of fatal and non-fatal clinical events is achieved through records linkage to the regional system of disease surveillance, chronic disease management and EMRs (based on diagnostic codes from the International Classification of Diseases, tenth revision). The CHERRY Study will provide a unique platform and serve as a valuable big data resource for cardiovascular risk prediction and population management, for primary and secondary prevention of cardiovascular events in China.

ETHICS AND DISSEMINATION

The CHERRY Study was approved by the Peking University Institutional Review Board (IRB00001052-16011) in April 2016. Results of the study will be disseminated through published journal articles, conferences and seminar presentations, and on the study website (http://www.cherry-study.org).

Environmental Risk Factors for Stroke and Cardiovascular Disease

Besides the classical individual stroke risk factors a new class has appeared, the environmental risk factors. After a review of the evidences demonstrating that air pollution is a potent risk factor (Part 1), we propose an update of other physical, chemical, and biological factors, now considered as risk factors (Part 2). One of the challenges is to precise their specific roles as they can be combined in their noxious impacts (traffic air pollution + noise + weather + infections). This knowledge has practical consequences; From now on, medical advices cannot be limited to individual recommendations but must also deal with environmental public health issues.

The cold effect of ambient temperature on ischemic and hemorrhagic stroke hospital admissions: A large database study in Beijing, China between years 2013 and 2014-Utilizing a distributed lag non-linear analysis

The effects of ambient temperature on stroke death in China have been well addressed. However, few studies are focused on the attributable burden for the incident of different types of stroke due to ambient temperature, especially in Beijing, China. We purpose to assess the influence of ambient temperature on hospital stroke admissions in Beijing, China. Data on daily temperature, air pollution, and relative humidity measurements and stroke admissions in Beijing were obtained between 2013 and 2014. Distributed lag non-linear model was employed to determine the association between daily ambient temperature and stroke admissions. Relative risk (RR) with 95% confidence interval (CI) and Attribution fraction (AF) with 95% CI were calculated based on stroke subtype, gender and age group. A total number of 147, 624 stroke admitted cases (including hemorrhagic and ischemic types of stroke) were documented. A non-linear acute effect of cold temperature on ischemic and hemorrhagic stroke hospital admissions was evaluated. Compared with the 25th percentile of temperature (1.2 °C), the cumulative RR of extreme cold temperature (first percentile of temperature, -9.6 °C) was 1.51 (95% CI: 1.08-2.10) over lag 0-14 days for ischemic type and 1.28 (95% CI: 1.03-1.59) for hemorrhagic stroke over lag 0-3 days. Overall, 1.57% (95% CI: 0.06%-2.88%) of ischemic stroke and 1.90% (95% CI: 0.40%-3.41%) of hemorrhagic stroke was attributed to the extreme cold temperature over lag 0-7 days and lag 0-3 days, respectively. The cold temperature's impact on stroke admissions was found to be more obvious in male gender and the youth compared to female gender and the elderly. Exposure to extreme cold temperature is associated with increasing both ischemic and hemorrhagic stroke admissions in Beijing, China.

The mortality burden of hourly temperature variability in five capital cities, Australia: Time-series and meta-regression analysis

BACKGROUND

Unstable weather, such as intra- and inter-day temperature variability, can impair the health and shorten the survival time of population around the world. Climate change will cause Earth's surface temperature rise, but has unclear effects on temperature variability, making it urgent to understand the characteristics of the burden of temperature variability on mortality, regionally and nationally.

OBJECTIVES

This paper aims to quantify the mortality risk of exposure to short-term temperature variability, estimate the resulting death toll and explore how the strength of temperature variability effects will vary as a function of city-level characteristics.

METHODS

Ten-year (2000-2009) time-series data on temperature and mortality were collected for five largest Australia's cities (Sydney, Melbourne, Brisbane, Perth and Adelaide), collectively registering 708,751 deaths in different climates. Short-term temperature variability was captured and represented as the hourly temperature standard deviation within two days. Three-stage analyses were used to assess the burden of temperature variability on mortality. First, we modelled temperature variability-mortality relation and estimated the relative risk of death for each city, using a time-series quasi-Poisson regression model. Second, we used meta-analysis to pool the city-specific estimates, and meta-regression to explore if some city-level factors will modify the population vulnerability to temperature variability. Finally, we calculated the city-specific deaths attributable to temperature variability, and applied such estimates to the whole of Australia as a reflection of the nation-wide death burden associated with temperature variability.

RESULTS

We found evidence of significant associations between temperature variability and mortality in all cities assessed. Deaths associated with each 1°C rise in temperature variability elevated by 0.28% (95% confidence interval (CI): 0.05%, 0.52%) in Melbourne to 1.00% (95%CI: 0.52%, 1.48%) in Brisbane, with a pooled estimate of 0.51% (95%CI: 0.33%, 0.69%) for Australia. Subtropical and temperate regions showed no apparent difference in temperature variability impacts. Meta-regression analyses indicated that the mortality risk could be influenced by city-specific factors: latitude, mean temperature, population density and the prevalence of several chronic diseases. Taking account of contributions from the entire time-series, temperature variability was estimated to account for 0.99% to 3.24% of deaths across cities, with a nation-wide attributable fraction of 1.67% (9.59 deaths per 100, 000 population per year).

CONCLUSIONS

Hourly temperature variability may be an important risk factor of weather-related deaths and led to a sizeable mortality burden. This study underscores the need for developing specific and effective interventions in Australia to lessen the health consequences of temperature variability.

Heat and mortality for ischemic and hemorrhagic stroke in 12 cities of Jiangsu Province, China

BACKGROUND

Little evidence exists on the relationship between heat and subtypes of stroke mortality, especially in China. Moreover, few studies have reported the effect modification by individual characteristics on heat-related stroke mortality. In this study, we aimed to evaluate the effect of heat exposure on total, ischemic, and hemorrhagic stroke mortality and its individual modifiers in 12 cities in Jiangsu Province, China during 2009 to 2013.

METHODS

We first used a distributed lag non-linear model with quasi-Poisson regression to examine the city-specific heat-related total, ischemic, and hemorrhagic stroke mortality risks at 99th percentile vs. 75th percentile of daily mean temperature in the whole year for each city, while adjusting for long-term trend, season, relative humidity, and day of the week. Then, we used a random-effects meta-analysis to pool the city-specific risk estimates. We also considered confounding by air pollution and effect modification by gender, age, education level, and death location.

RESULTS

Overall, the heat-related mortality risk in 12 Jiangsu cities was 1.54 (95%CI: 1.44 to 1.65) for total stroke, 1.63 (95%CI: 1.48 to 1.80) for ischemic stroke, and 1.36 (95%CI: 1.26 to 1.48) for hemorrhagic stroke, respectively. Estimated total, ischemic, and hemorrhagic stroke mortality risks were higher for women versus men, older people versus younger people, those with low education levels versus high education levels, and deaths that occurred outside of hospital. Air pollutants did not significantly influence the heat-related stroke mortality risk.

CONCLUSIONS

Heat exposure significantly increased both ischemic and hemorrhagic stroke mortality risks in Jiangsu Province, China. Females, the elderly, and those with low education levels are particularly vulnerable to this effect.

Hypertension modifies the short-term effects of temperature on morbidity of hemorrhagic stroke

BACKGROUND

This study estimated the effects of ambient temperature on hospital admissions for hemorrhagic stroke during 2004-2009 in Jinan, China, and the effect modification of hypertension status.

METHODS

The exposure-response relationship between temperature and hemorrhagic stroke was firstly examined, and then the association between daily mean temperature and hemorrhagic stroke was investigated using a generalized additive model. Stratified analyses were conducted to examine the potential effect modification of hypertension.

RESULTS

A total of 1577 hemorrhagic stroke cases were observed between 2004 and 2009, among which, 1058 were hypertensive and 519 were non-hypertensive. We found an approximately linear relationship between ambient temperature and hemorrhagic stroke. Each 1°C decrease in the current day's temperature was associated with 1.63% (95% CI: 0.33%, 2.95%) increase in daily hemorrhagic stroke. The stratified analyses observed that the association was significant among hypertensive hemorrhagic stroke, each 1°C decrease in the current day's temperature was associated with 2.26% (95% CI: 0.57%, 3.98%) increase in daily hypertensive hemorrhagic stroke. While no significant effect was observed for non-hypertensive hemorrhagic stroke.

CONCLUSIONS

Low temperature might be one risk factor for hemorrhagic stroke and hypertension may be one effect modifier of this association in Jinan, China.

The effect of high temperature on cause-specific mortality: A multi-county analysis in China

Although existing studies have linked high temperature to mortality in a small number of regions, less evidence is available on the variation in the associations between high temperature exposure and cause-specific mortality of multiple regions in China. Our study focused on the use of time series analysis to quantify the association between high temperature and different cause-specific mortalities for susceptible populations for 43 counties in China. Two-stage analyses adopting a distributed lag non-linear model (DLNM) and a meta-analysis allowed us to obtain county-specific estimates and national-scale pooled estimates of the nonlinear temperature-mortality relationship. We also considered different populations stratified by age and sex, causes of death, absolute and relative temperature patterns, and potential confounding from air pollutants. All of the observed cause-specific mortalities are significantly associated with higher temperature. The estimated effects of high temperature on mortality varied by spatial distribution and temperature patterns. Compared with the 90th percentile temperature, the overall relative risk (RR) at the 99th percentile temperature for non-accidental mortality is 1.105 (95%CI: 1.089, 1.122), for circulatory disease is 1.107 (95%CI: 1.081, 1.133), for respiratory disease is 1.095 (95%CI: 1.050, 1.142), for coronary heart disease is 1.073 (95%CI: 1.047, 1.099), for acute myocardial infarction is 1.072 (95%CI: 1.042, 1.104), and for stroke is 1.095 (95%CI: 1.052, 1.138). Based on our findings, we believe that heat-related health effect in China is a significant issue that requires more attention and allocation of existing resources.

Nonlinear relationship between extreme temperature and mortality in different temperature zones: A systematic study of 122 communities across the mainland of China

BACKGROUND

Numerous previous studies have reported that human health risk is extremely sensitive to temperature. Very few studies, however, have characterized the relationship between temperature and mortality in different temperature zones due to the previous conclusions deduced from a regional or administrative division. A research covers different temperature zones was indispensable to have a comprehensive understanding of regional ambient temperature effect on public health.

METHODS

Based on the mortality dataset and meteorological variables of 122 communities in China from 2007 to 2012, a distributed lag nonlinear model (DLNM) was utilized to estimate the temperature effect on non-accidental mortality at the community level. Then, a meta-regression analysis was applied to pool the estimates of community-specific effects in various latitude-effected temperature zones.

RESULTS

At the community level, the mean value of relative extreme cold risk (1.63) of all 122 communities was higher than that of extreme high temperature (1.15). At regional level, we found temperature-mortality relationship (e.g., U- or J-shaped) varied in different temperature zones. Meanwhile, the minimum-mortality temperature of each zone was near the 75th percentile of local mean temperature except the north subtropics (50th percentiles). Lag effect was also obvious, especially for cold effect. An interesting M-shaped curve for the relationship between cold risk and temperature was detected, while an inverted "U" shaped with a right tail for the heat effect. Such different responses might be attributed to the difference in social-economic status of temperature zones.

CONCLUSION

The temperature-mortality relationship showed a distinct spatial heterogeneity along temperature zones across the Chinese mainland. Different characteristics of mortality responding to cold and heat stress highlighted the fact that, apart from the circumstance of temperature, the social-economic condition was also linked with health risk. Our findings suggest decision-makers should take more adaptive and effective measures to reduce health risks in China.

Relationship of meteorological factors and acute stroke events in Kaunas (Lithuania) in 2000-2010

Some researchers have hypothesised that meteorological factors may have an impact on acute cerebrovascular diseases. The aim of this study was to determine an impact of some meteorological factors on occurrence of acute cerebrovascular events in the middle-aged Kaunas population. Kaunas stroke register data were used. Data on meteorological factors for the time period from 2000 to 2010 were obtained from the Lithuanian Hydrometeorological Service Kaunas Meteorological Station. We analysed 4038 cases with stroke. Ischemic strokes composed 80.4% and haemorrhagic strokes-19.6%. According to Poisson regression analysis, significant negative correlation between ischemic, haemorrhagic and all types of stroke and ambient air temperature was found (β coefficient - 0.007, -0.016, -0.009, p < 0.001, respectively). Results of ARIMA showed that ambient temperature of the day of stroke onset was associated with the occurrence of ischemic, haemorrhagic and all types of stroke: when temperature was lower, the risk of stroke was higher (-0.006, -0.003, -0.009, p < 0.001, respectively). Low temperature on the event day and 1 and 2 days before the event was associated with higher incidence of haemorrhagic stroke in women. Low ambient temperature on the event day increased incidence of haemorrhagic stroke in subjects 55-64 years. High wind speed on the event day was associated with higher incidence of ischemic stroke in older subjects. Meteorological factors may have some impact on the risk of acute cerebrovascular events. Health care providers should focus on preventive measures, which can reduce these risks.

Effects of ambient temperature on stroke hospital admissions: Results from a time-series analysis of 104,432 strokes in Guangzhou, China

BACKGROUND

Stroke is a main cause of death and public health burden in China. The evidence on the burden of different strokes attack attribute to ambient temperature in China is limited. This study aimed to show the characteristics of stroke attack and the attributable risk due to temperature based on hospital admission data in Guangzhou, one of the most developed cities in China.

MATERIAL AND METHODS

From January 1, 2013 to December 31, 2015, 104,432 stroke hospitalizations in Guangzhou residents from 67 hospitals for stroke sentinel surveillance were registered. Characteristics of hospital admissions by gender, age group, calendar year and stroke subtype were analyzed, and distributed lag non-linear models were applied to evaluate the effects of temperature on stroke attack admissions.

RESULTS

Stroke attack admissions increased from 31,851 to 36,755 through 2013 to 2015, increasing by 15.4%. An increasing trend in the risk of stroke attack with age was observed, irrespectively of stroke subtype and calendar year. People with hypertension were more likely to have an associated stroke than people without that. The effects of cold temperature on attack admissions for CBI and ICH strokes were significant. Overall, the percentages of CBI and ICH attack admissions attribute to cold temperature were 9.06% (95% CI: 1.84, 15.00) and 15.09% (95% CI: 5.86, 21.96), respectively. Besides, elderly people were more vulnerable to cold temperature than the young.

CONCLUSIONS

Measures should be taken to increase public awareness about the ill effects of cold temperature on stroke attack, and educate the public about self-protection.

Gaseous Air Pollution and the Risk for Stroke Admissions: A Case-Crossover Study in Beijing, China

Background: Though increasing evidence supports association between gaseous air pollution and stroke, it remains unclear whether the effects differ in season, sex and age. The aim of this study was to examine the associations of gaseous air pollution with stroke admissions in Beijing, 2013–2014 in different subgroups. Methods: Case-crossover design and conditional logistic regression were used to perform the analyses. We examined the exposure-response relationship between air pollution and stroke. Stratified analyses were performed in different seasons, sex, and age groups. Results: There were 147,624 stroke admissions during the study period. In the whole study period, percent changes of stroke admissions were 0.82% (95% CI: 0.52% to 1.13%) and 0.73% (95% CI: 0.44% to 1.03%) per 10 μg/m³ increase in the same day conentration of nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). The positive associations were higher in warm seasons and with patients >65 years (p < 0.05). Contrary effects of carbon monoxide (CO) and ozone on stroke admissions were observed in different seasons. Conclusions: NO₂ and SO₂ were positively associated with stroke admissions, with stronger effects in warm seasons and with patients >65 years. The associations of CO and ozone with stroke admissions differed across seasons.

The burden of extreme heat and heatwave on emergency ambulance dispatches: A time-series study in Huainan, China

BACKGROUND

Although studies have well documented increased mortality risk during extreme heat and heatwaves, few have examined their impacts on emergency ambulance dispatches under different temperature metrics. Additionally, evidence on the attributable risk of emergency ambulance dispatches due to extreme heat and heatwaves is scarce around the world.

METHODS

A distributed lag nonlinear model (DLNM) was applied to quantify the impact of extreme heat and heatwaves on emergency ambulance dispatches in Huainan, China, during 2011-2013. Several local extreme heat and heatwave definitions were tested by using percentile of daily mean temperature (i.e., 95th, 97.5th and 99th) and duration (i.e.,≥2 consecutive days and ≥3 consecutive days). The fraction of emergency ambulance dispatches attributable to extreme heat and heatwaves was also quantitatively estimated.

RESULTS

Both extreme heat and heatwaves were significantly associated with increases in emergency ambulance dispatches, and their effects appeared to be acute. For extreme heat effects, the relative risks (RRs) of emergency ambulance dispatches at lag0 steadily increased from 95th percentile of daily mean temperature (1.03, 95% confidence interval (CI): 1.01-1.05) to 99th percentile (1.07, 95% CI: 1.05-1.10). For heatwave effects, we observed that RRs of emergency ambulance dispatches at lag0 fluctuated between 1.03 and 1.05 across different heatwave definitions. Notably, the fraction of emergency ambulance dispatches attributable to extreme heat decreased with higher percentile of daily mean temperature, dropping from 2.24% (95% CI: 1.41%-2.99%) at 95th percentile to 0.69% (95% CI: 0.45%-0.92%) at 99th percentile. Likewise, we found that heatwaves with higher intensity and (or) longer duration accounted for lower fraction of emergency ambulance dispatches, varying between 0.51%-1.52%.

CONCLUSIONS

Our findings may have important implications for the development of local heat warming systems and public health interventions to lessen the impact of extreme heat events on population health.

Risk Prediction for Epithelial Ovarian Cancer in 11 United States-Based Case-Control Studies: Incorporation of Epidemiologic Risk Factors and 17 Confirmed Genetic Loci

Previously developed models for predicting absolute risk of invasive epithelial ovarian cancer have included a limited number of risk factors and have had low discriminatory power (area under the receiver operating characteristic curve (AUC) < 0.60). Because of this, we developed and internally validated a relative risk prediction model that incorporates 17 established epidemiologic risk factors and 17 genome-wide significant single nucleotide polymorphisms (SNPs) using data from 11 case-control studies in the United States (5,793 cases; 9,512 controls) from the Ovarian Cancer Association Consortium (data accrued from 1992 to 2010). We developed a hierarchical logistic regression model for predicting case-control status that included imputation of missing data. We randomly divided the data into an 80% training sample and used the remaining 20% for model evaluation. The AUC for the full model was 0.664. A reduced model without SNPs performed similarly (AUC = 0.649). Both models performed better than a baseline model that included age and study site only (AUC = 0.563). The best predictive power was obtained in the full model among women younger than 50 years of age (AUC = 0.714); however, the addition of SNPs increased the AUC the most for women older than 50 years of age (AUC = 0.638 vs. 0.616). Adapting this improved model to estimate absolute risk and evaluating it in prospective data sets is warranted.

The association between wind-related variables and stroke symptom onset: A case-crossover study on Jeju Island

BACKGROUND

Although several studies have investigated the effects of ambient temperature on the risk of stroke, few studies have examined the relationship between other meteorological conditions and stroke. Therefore, the aim of this study was to analyze the association between wind-related variables and stroke symptoms onset.

METHODS

Data regarding the onset of stroke symptoms occurring between January 1, 2006, and December 31, 2007 on Jeju Island were collected from the Jeju National University Hospital stroke registry. A fixed-strata case-crossover analysis based on time of onset and adjusted for ambient temperature, relative humidity, air pressure, and pollutants was used to analyze the effects of wind speed, the daily wind speed range (DWR), and the wind chill index on stroke symptom onset using varied lag terms. Models examining the modification effects by age, sex, smoking status, season, and type of stroke were also analyzed.

RESULTS

A total of 409 stroke events (381 ischemic and 28 hemorrhagic) were registered between 2006 and 2007. The odds ratios (ORs) for wind speed, DWR, and wind chill among the total sample at lag 0-8 were 1.18 (95% confidence interval (CI): 1.06-1.31), 1.08 (95% CI: 1.02-1.14), and 1.22 (95% CI: 1.07-1.39) respectively. The ORs for wind speed, DWR, and wind chill for ischemic stroke patients were slightly greater than for patients in the total sample (OR=1.20, 95% CI: 1.08-1.34; OR=1.09, 95% CI: 1.03-1.15; and OR=1.22, 95% CI: 1.07-1.39, respectively). Statistically significant season-specific effects were found for spring and winter, and various delayed effects were observed. In addition, age, sex, and smoking status modified the effect size of wind speed, DWR, and wind chill.

CONCLUSIONS

Our analyses showed that the risk of stroke symptoms onset was associated with wind speed, DWR, and wind chill on Jeju Island.

The Short-Term Effect of Ambient Temperature on Mortality in Wuhan, China: A Time-Series Study Using a Distributed Lag Non-Linear Model

Less evidence concerning the association between ambient temperature and mortality is available in developing countries/regions, especially inland areas of China, and few previous studies have compared the predictive ability of different temperature indictors (minimum, mean, and maximum temperature) on mortality. We assessed the effects of temperature on daily mortality from 2003 to 2010 in Jiang'an District of Wuhan, the largest city in central China. Quasi-Poisson generalized linear models combined with both non-threshold and double-threshold distributed lag non-linear models (DLNM) were used to examine the associations between different temperature indictors and cause-specific mortality. We found a U-shaped relationship between temperature and mortality in Wuhan. Double-threshold DLNM with mean temperature performed best in predicting temperature-mortality relationship. Cold effect was delayed, whereas hot effect was acute, both of which lasted for several days. For cold effects over lag 0-21 days, a 1 °C decrease in mean temperature below the cold thresholds was associated with a 2.39% (95% CI: 1.71, 3.08) increase in non-accidental mortality, 3.65% (95% CI: 2.62, 4.69) increase in cardiovascular mortality, 3.87% (95% CI: 1.57, 6.22) increase in respiratory mortality, 3.13% (95% CI: 1.88, 4.38) increase in stroke mortality, and 21.57% (95% CI: 12.59, 31.26) increase in ischemic heart disease (IHD) mortality. For hot effects over lag 0-7 days, a 1 °C increase in mean temperature above the hot thresholds was associated with a 25.18% (95% CI: 18.74, 31.96) increase in non-accidental mortality, 34.10% (95% CI: 25.63, 43.16) increase in cardiovascular mortality, 24.27% (95% CI: 7.55, 43.59) increase in respiratory mortality, 59.1% (95% CI: 41.81, 78.5) increase in stroke mortality, and 17.00% (95% CI: 7.91, 26.87) increase in IHD mortality. This study suggested that both low and high temperature were associated with increased mortality in Wuhan, and that mean temperature had better predictive ability than minimum and maximum temperature in the association between temperature and mortality.

Ambient Temperature and the Risk of Preterm Birth in Guangzhou, China (2001-2011)

BACKGROUND

Although effects of weather changes on human health have been widely reported, there is limited information regarding effects on pregnant women in developing countries.

OBJECTIVE

We investigated the association between maternal exposure to ambient temperature and the risk of preterm birth (< 37 weeks of gestation) in Guangzhou, China.

METHODS

We used a Cox proportional hazards model to estimate associations between preterm birth and average temperature during each week of gestation, with weekly temperature modeled as a time-varying exposure during four time windows: 1 week (the last week of the pregnancy), 4 weeks (the last 4 weeks of the pregnancy), late pregnancy (gestational week 20 onward), and the entire pregnancy. Information on singleton vaginal birth between 2001 and 2011 was collected. Daily meteorological data during the same period were obtained from the Guangzhou Meteorological Bureau.

RESULTS

A total of 838,146 singleton vaginal births were included, among which 47,209 (5.6%) were preterm births. High mean temperatures during the 4 weeks, late pregnancy, and the entire pregnancy time windows were associated with an increased risk of preterm birth. Compared with the median temperature (24.4°C), weekly exposures during the last 4 weeks of the pregnancy to extreme cold (7.6°C, the 1st percentile) and extreme heat (31.9°C, the 99th percentile) were associated with 17.9% (95% CI: 10.2, 26.2%) and 10.0% (95% CI: 2.9, 17.6%) increased risks of preterm birth, respectively. The association between extreme heat and preterm birth was stronger for preterm births during weeks 20-31 and 32-34 than those during weeks 35-36.

CONCLUSIONS

These findings might have important implications in preventing preterm birth in Guangzhou as well as other areas with similar weather conditions.

CITATION

He JR, Liu Y, Xia XY, Ma WJ, Lin HL, Kan HD, Lu JH, Feng Q, Mo WJ, Wang P, Xia HM, Qiu X, Muglia LJ. 2016. Ambient temperature and the risk of preterm birth in Guangzhou, China (2001-2011). Environ Health Perspect 124:1100-1106; http://dx.doi.org/10.1289/ehp.1509778.

The burden of stroke mortality attributable to cold and hot ambient temperatures: Epidemiological evidence from China

BACKGROUND

Few data are available on the attributable burden, such as absolute excess or relative excess, of stroke death due to temperature.

METHODS

We collected data on daily temperature and stroke mortality from 16 large Chinese cities during 2007-2013. First, we applied a distributed lag non-linear model to estimate the city-/age-/gender-specific temperature-mortality association over lag 0-14days. Then, pooled estimates were calculated using a multivariate meta-analysis. Attributable deaths were calculated for cold and heat, defined as temperatures below and above the minimum-mortality temperature (MMT). Moderate and extreme temperatures were defined using cut-offs at the 2.5th and 97.5th percentiles of temperature.

RESULTS

The city-specific MMT increased from the north to the south, with a median of 24.9(o)C. Overall, 14.5% (95% empirical confidence interval: 11.5-17.0%) of stroke mortality (114, 662 deaths) was attributed to non-optimum temperatures, with the majority being attributable to cold (13.1%, 9.7-15.7%). The proportion of temperature-related death had a decreasing trend by latitude, ranging from 22.7% in Guangzhou to 6.3% in Shenyang. Moderate temperatures accounted for 12.6% (9.1-15.3%) of stroke mortality, whereas extreme temperatures accounted for only 2.0% (1.6-2.2%) of stroke mortality. Estimates of death burden due to both cold and heat were higher among males and the elderly, compared with females and the youth.

CONCLUSIONS

The burden of temperature-related stroke mortality increased from the north to the south. Most of this burden was caused by cold temperatures. The stroke burden was higher among males and the elderly. This information has important implications for preventing stroke due to adverse temperatures in vulnerable subpopulations in China.

Aging Will Amplify the Heat-related Mortality Risk under a Changing Climate: Projection for the Elderly in Beijing, China

An aging population could substantially enhance the burden of heat-related health risks in a warming climate because of their higher susceptibility to extreme heat health effects. Here, we project heat-related mortality for adults 65 years and older in Beijing China across 31 downscaled climate models and 2 representative concentration pathways (RCPs) in the 2020s, 2050s, and 2080s. Under a scenario of medium population and RCP8.5, by the 2080s, Beijing is projected to experience 14,401 heat-related deaths per year for elderly individuals, which is a 264.9% increase compared with the 1980s. These impacts could be moderated through adaptation. In the 2080s, even with the 30% and 50% adaptation rate assumed in our study, the increase in heat-related death is approximately 7.4 times and 1.3 times larger than in the 1980s respectively under a scenario of high population and RCP8.5. These findings could assist countries in establishing public health intervention policies for the dual problems of climate change and aging population. Examples could include ensuring facilities with large elderly populations are protected from extreme heat (for example through back-up power supplies and/or passive cooling) and using databases and community networks to ensure the home-bound elderly are safe during extreme heat events.

Who is more vulnerable to death from extremely cold temperatures? A case-only approach in Hong Kong with a temperate climate

The short-term effects of ambient cold temperature on mortality have been well documented in the literature worldwide. However, less is known about which subpopulations are more vulnerable to death related to extreme cold. We aimed to examine the personal characteristics and underlying causes of death that modified the association between extreme cold and mortality in a case-only approach. Individual information of 197,680 deaths of natural causes, daily temperature, and air pollution concentrations in cool season (November-April) during 2002-2011 in Hong Kong were collected. Extreme cold was defined as those days with preceding week with a daily maximum temperature at or less than the 1st percentile of its distribution. Logistic regression models were used to estimate the effects of modification, further controlling for age, seasonal pattern, and air pollution. Sensitivity analyses were conducted by using the 5th percentile as cutoff point to define the extreme cold. Subjects with age of 85 and older were more vulnerable to extreme cold, with an odds ratio (OR) of 1.33 (95 % confidence interval (CI), 1.22-1.45). The greater risk of extreme cold-related mortality was observed for total cardiorespiratory diseases and several specific causes including hypertensive diseases, stroke, congestive heart failure, chronic obstructive pulmonary disease (COPD), and pneumonia. Hypertensive diseases exhibited the greatest vulnerability to extreme cold exposure, with an OR of 1.37 (95 % CI, 1.13-1.65). Sensitivity analyses showed the robustness of these effect modifications. This evidence on which subpopulations are vulnerable to the adverse effects of extreme cold is important to inform public health measures to minimize those effects.

Environmental variables and levels of exhaled carbon monoxide and carboxyhemoglobin in elderly people taking exercise

This article aims to analyze levels of exhaled carbon monoxide, carboxyhemoglobinand cardiopulmonary variables in old people practicing exercise in external environments, and correlate them with climate and pollution factors. Temporal ecological study with118 active elderly people in the city of Cuiabá, in the state of Mato Grosso, Brazil. Data were obtained on use of medication, smoking, anthropometric measurements, spirometry, peak flow, oxygen saturation, heart rate, exhaled carbon monoxide, carboxyhemoglobin, climate, number of farm fires and pollution. Correlations were found between on the one hand environmental temperature, relative humidity of the air and number of farmers' fires, and on the other hand levels of carbon monoxide exhaled and carboxyhemoglobin (p < 0.05).There was a correlation between heart rate and changes in environmental temperature, time of exposure to the sun and relative humidity (p < 0.05). In elderly people, environmental factors influence levels of exhaled carbon monoxide, carboxyhemoglobin and heart rate. There is thus a need for these to be monitored during exercise. The use of a carbon monoxide monitor to evaluate exposure to pollutants is suggested.

The effect of ambient temperature on diabetes mortality in China: A multi-city time series study

Few multi-city studies have been conducted to investigate the acute health effects of low and high temperatures on diabetes mortality worldwide. We aimed to examine effects of ambient temperatures on city-/gender-/age-/education-specific diabetes mortality in nine Chinese cities using a two-stage analysis. Distributed lag non-linear model was first applied to estimate the city-specific non-linear and delayed effects of temperatures on diabetes mortality. Pooled effects of temperatures on diabetes mortality were then obtained using meta-analysis, based on restricted maximum likelihood. We found that heat effects were generally acute and followed by a period of mortality displacement, while cold effects could last for over two weeks. The pooled relative risks of extreme high (99th percentile of temperature) and high temperature (90th percentile of temperature) were 1.29 (95%CI: 1.11-1.47) and 1.11 (1.03-1.19) over lag 0-21 days, compared with the 75th percentile of temperature. In contrast, the pooled relative risks over lag 0-21 days were 1.44 (1.25-1.66) for extreme low (1st percentile of temperature) and 1.20 (1.12-1.30) for low temperature (10th percentile of temperature), compared to 25th percentile of temperature. The estimate of heat effects was relatively higher among females than that among males, with opposite trend for cold effects, and the estimates of heat and cold effects were particularly higher among the elderly and those with low education, although the differences between these subgroups were not statistically significant (P>0.05). These findings have important public health implications for protecting diabetes patients from adverse ambient temperatures.

County-level heat vulnerability of urban and rural residents in Tibet, China

BACKGROUND

Tibet is especially vulnerable to climate change due to the relatively rapid rise of temperature over past decades. The effects on mortality and morbidity of extreme heat in Tibet have been examined in previous studies; no heat adaptation initiatives have yet been implemented. We estimated heat vulnerability of urban and rural populations in 73 Tibetan counties and identified potential areas for public health intervention and further research.

METHODS

According to data availability and vulnerability factors identified previously in Tibet and elsewhere, we selected 10 variables related to advanced age, low income, illiteracy, physical and mental disability, small living spaces and living alone. We separately created and mapped county-level cumulative heat vulnerability indices for urban and rural residents by summing up factor scores produced by a principal components analysis (PCA).

RESULTS

For both study populations, PCA yielded four factors with similar structure. The components for rural and urban residents explained 76.5 % and 77.7 % respectively of the variability in the original vulnerability variables. We found spatial variability of heat vulnerability across counties, with generally higher vulnerability in high-altitude counties. Although we observed similar median values and ranges of the cumulative heat vulnerability index values among urban and rural residents overall, the pattern varied strongly from one county to another.

CONCLUSIONS

We have developed a measure of population vulnerability to high temperatures in Tibet. These are preliminary findings, but they may assist targeted adaptation plans in response to future rapid warming in Tibet.

Effects of Extreme Temperatures on Cause-Specific Cardiovascular Mortality in China

OBJECTIVE

Limited evidence is available for the effects of extreme temperatures on cause-specific cardiovascular mortality in China.

METHODS

We collected data from Beijing and Shanghai, China, during 2007-2009, including the daily mortality of cardiovascular disease, cerebrovascular disease, ischemic heart disease and hypertensive disease, as well as air pollution concentrations and weather conditions. We used Poisson regression with a distributed lag non-linear model to examine the effects of extremely high and low ambient temperatures on cause-specific cardiovascular mortality.

RESULTS

For all cause-specific cardiovascular mortality, Beijing had stronger cold and hot effects than those in Shanghai. The cold effects on cause-specific cardiovascular mortality reached the strongest at lag 0-27, while the hot effects reached the strongest at lag 0-14. The effects of extremely low and high temperatures differed by mortality types in the two cities. Hypertensive disease in Beijing was particularly susceptible to both extremely high and low temperatures; while for Shanghai, people with ischemic heart disease showed the greatest relative risk (RRs = 1.16, 95% CI: 1.03, 1.34) to extremely low temperature.

CONCLUSION

People with hypertensive disease were particularly susceptible to extremely low and high temperatures in Beijing. People with ischemic heart disease in Shanghai showed greater susceptibility to extremely cold days.

Long-term variations in the association between ambient temperature and daily cardiovascular mortality in Shanghai, China

OBJECTIVE

The objective of this study was to explore the long-term variation in the association between ambient temperature and daily cardiovascular (CVD) mortality in Shanghai, China.

MATERIALS AND METHODS

We collected daily data on ambient temperature and CVD mortality from a central urban district in Shanghai, China, during the period from 1981 to 2012. We used overdispersed generalized additive Poisson regression together with a distributed lag nonlinear model to estimate potentially lagged and nonlinear effects of temperature on CVD mortality after controlling for the seasonality, relative humidity, day of the week, holidays and population size. To allow for the evaluation of long-term variations in the effects, we divided the entire study period into six sub-periods (1981-1985, 1986-1990, 1991-1995, 1996-2000, 2001-2005, and 2006-2012) and analyzed the effect estimates in each sub-period separately.

RESULTS

The association between temperature and daily CVD mortality was J-shaped with both low and high temperatures increasing the risk of CVD deaths. The effects of extremely low temperatures were delayed and persisted for two weeks, while extreme hot effects were limited to the first five days followed by a significant mortality displacement (9days). The relative risks (RRs) of extremely low, moderately low, moderately high, and extremely high temperatures comparing the 1st, 10th, 90th, and 99th percentile with the reference temperature (26°C) over the cumulative lags of 0-14days were 1.95 [95% confidence interval (CI): 1.84,2.07], 1.61 (95% CI: 1.57,1.66), 1.03 (95% CI: 1.01,1.05), and 1.14 (95% CI: 1.07,1.21). The RRs for extremely low and moderately low temperature attenuated substantially from 9.78 and 5.52 in 1981-1985 to 1.42 and 1.18 in 2006-2012, respectively, but the RRs remained almost stable for extremely high and moderately high temperatures.

CONCLUSIONS

This time-series study suggested that there might have been some human adaptation to low ambient temperature in Shanghai, China, over the last 3 decades.

The acute effects of outdoor temperature on blood pressure in a panel of elderly hypertensive patients

Higher level of blood pressure (BP) in winter than in summer has been observed, but the association between temperature and BP and its potential modifiers with adjustment of individual confounders and time trends was rarely explored. We aimed to investigate the association between outdoor temperature and BP and its potential modification factors in a longitudinal panel study in Shanghai, China. From January 2011 to December 2012, we scheduled 54 follow-ups for BP measurements per subject via home visit every other week for 50 elderly hypertensive patients. We applied linear mixed-effect models to analyze the association between temperature and BP after controlling for individual characteristics, antihypertensive medication, comorbidities, and time trends. We evaluated the potential effect modifiers by stratification analyses. For a 1 °C decrease in the average temperature on concurrent day and previous day, systolic BP increased by 0.19 mmHg (95 % confidence interval = 0.06, 0.31) and diastolic BP increased by 0.12 mmHg (95 % confidence interval = 0.03, 0.21). The effect of temperature on BP was stronger among those with older age, female sex, low socioeconomic status, and obese physique. The effect was weak and even null for those taking the angiotensin receptor blockers, angiotensin-converting enzyme inhibitor, or its combination with calcium antagonists. Further, the effect was almost restricted within those having chronic comorbidities. Our results demonstrated that an acute decrease in outdoor temperature was significantly associated with a rise in BP among elderly hypertensive patients, in Shanghai, China. Individual characteristics, antihypertensive medications, and comorbidities may modify this effect.

Anomalous equivalent potential temperature: an atmospheric feature predicting days with higher risk for fatal outcome in acute ischemic stroke-a preliminary study

Acute stroke is a life-threatening condition. Fatal outcome is related to risk factors, some of these affected by climatic changes. Forecasting potentially harmful atmospheric processes may therefore be of practical importance in the acute care of stroke patients. We analyzed the history of all patients with acute ischemic stroke (N = 184) confirmed by neuroimaging including those who died (N = 35, 15 males) at our hospital department in the winter months of 2009. Patient data were anonymized, and the human meteorologists were only aware of patients' age, gender, and exact time of death. Of the meteorological parameters, equivalent potential temperature (EPT) has been chosen for analysis. EPT is generally used for forecasting thunderstorms, but in the case of synoptic scale airflow (10(6) m), it is suitable for characterizing the air mass inflowing from different regions. The behavior of measured EPT values was compared to the climatic (30 years) averages. We developed meteorological criteria for anomalous periods of EPT and tested if such periods are associated with higher rate of fatal outcome. The duration of anomalous and non-anomalous periods was nearly equal during the studied 3 months. Stroke onset distributed similarly between anomalous and non-anomalous days; however, of the 35 deaths, 27 occurred during anomalous periods: on average, 0.56 deaths occurred on anomalous days and 0.19 on non-anomalous days. Winter periods meeting the criteria of anomalous EPT may have a significant adverse human-meteorological impact on the outcome in acute ischemic stroke.

Short-Term Effect of Ambient Temperature and the Risk of Stroke: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

The relationship between stroke and short-term temperature changes remains controversial. Therefore, we conducted a systematic review and meta-analysis to investigate the association between stroke and both high and low temperatures, and health assessment.

METHODS

We searched PubMed, Embase, Cochrane, China National Knowledge Infrastructure (CNKI) and Wanfang Data up to 14 September 2014. Study selection, quality assessment, and author-contractions were steps before data extraction. We converted all estimates effects into relative risk (RR) per 1 °C increase/decrease in temperature from 75th to 99th or 25th to 1st percentiles, then conducted meta-analyses to combine the ultimate RRs, and assessed health impact among the population.

RESULTS

20 articles were included in the final analysis. The overall analysis showed a positive relationship between 1 °C change and the occurrence of major adverse cerebrovascular events (MACBE), 1.1% (95% confidence intervals (CI), 0.6 to 1.7) and 1.2% (95% CI, 0.8 to 1.6) increase for hot and cold effects separately. The same trends can be found in both effects of mortality and the cold effect for morbidity. Hot temperature acted as a protective factor of hemorrhage stroke (HS), -1.9% (95% CI, -2.8 to -0.9), however, it acted as a risk factor for ischemic stroke (IS), 1.2% (95% CI, 0.7 to 1.8).

CONCLUSION

Short-term changes of both low and high temperature had statistically significant impacts on MACBE.

Spatial analysis of the effect of the 2010 heat wave on stroke mortality in Nanjing, China

To examine the spatial variation of stroke mortality risk during heat wave, we collected 418 stroke mortality cases with permanent addresses for a severe heat wave (July 28–August 15, 2010) and 624 cases for the reference period (July 29–August 16, 2009 and July 27–August 14, 2011) in Nanjing, China. Generalized additive models were used to explore the association between location and stroke mortality risk during the heat wave while controlling individual-level risk factors. Heat wave vulnerability was then applied to explain the possible spatial variations of heat-wave-related mortality risk. The overall risk ratio (95% confidence intervals) of stroke mortality due to the heat wave in Nanjing was 1.34 (1.21 to 1.47). Geolocation was found to be significantly associated with the heat-wave-related stroke mortality risk. Using alternative reference periods generated similar results. A district-level risk assessment revealed similar spatial patterns. The highest stroke mortality risk observed in Luhe district was due to the combination of high heat exposure and high vulnerability. Our findings provide evidence that stroke mortality risk is higher in rural areas during heat waves and that these areas require future interventions to reduce vulnerability.