Associations of ambient temperature with mortality for ischemic and hemorrhagic stroke and the modification effects of greenness in Shandong Province, China

Greenness mitigate cause-specific mortality associated with air pollutants in ischemic and hemorrhagic stroke patients: An ecological health cohort study

BACKGROUND

Air pollution is one of the most serious environmental risks to mortality of stroke. However, there exists a noteworthy knowledge gap concerning the different stroke subtypes, causes of death, the susceptibility of stroke patient, and the role of greenness in this context.

METHODS

We analyzed data from an ecological health cohort, which included 334,261 patients aged ≥40 years with stroke (comprising 288,490 ischemic stroke and 45,771 hemorrhagic stroke) during the period 2013-2019. We used Cox proportional hazards models with time-varying exposure to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) to assess the associations of annual average fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) with both all-cause and cause-specific mortality. Additionally, we conducted analyses to examine the effect modification by greenness and identify potential susceptibility factors through subgroup analyses.

RESULT

In multivariable-adjusted models, long-term exposure to PM2.5 and NO2 was associated with increased risk of all-cause mortality (HR: 1.038, 95% CI: 1.029-1.047 for PM2.5; HR: 1.055, 95% CI: 1.026-1.085 for NO2, per 10 μg/m3, for ischemic stroke patients; similar for hemorrhagic stroke patients). Gradually increasing effect sizes were shown for CVD mortality and stroke mortality. The HRs of mortality were slightly weaker with high versus low vegetation exposure. Cumulative exposures increased the HRs of pollutant-related mortality, and greater greenness decreased this risk. Two subtypes of stroke patients exhibited diverse patterns of benefit.

CONCLUSION

Increasing residential greenness attenuates the increased risk of mortality with different patterns due to chronic air pollutants for ischemic and hemorrhagic stroke, offering valuable insights for precise tertiary stroke prevention strategies.

Association of ambient ozone exposure and greenness exposure with hemorrhagic stroke mortality at different times: A cohort study in Shandong Province, China

Evidence on the association between long-term ozone exposure and greenness exposure and hemorrhagic stroke (HS) is limited, with mixed results. One potential source of this inconsistency is the difference in exposure time metrics. This study aimed to investigate the association between long-term exposure to ambient ozone, greenness, and mortality from HS using exposure metrics at different times. We also examined whether greenness exposure modified the relationship between ozone exposure and mortality due to HS. The study population consisted of 45771 participants aged ≥40 y residing in 20 counties in Shandong Province who were followed up from 2013 to 2019. Ozone exposure metrics (annual mean and warm season) and the normalized difference a measure of greenness exposure, were calculated. The relationship between environmental exposures (ozone and greenness exposures) and mortality from HS was assessed using time-dependent Cox proportional hazards models, and the modification of greenness exposure was examined using stratified analysis with interaction terms. The person-years at the end of follow-up were 90,663. With full adjustments, the risk of death from hemorrhagic stroke increased by 5% per interquartile range increase in warm season ozone [hazard ratio =1.05; 95 % confidence interval: 1.01-1.08]. No clear association was observed between annual ozone and mortality HS. Both the annual and summer NDVI were found to reduce the risk of HS mortality. The relationships were influenced by age, sex, and residence (urban or rural). Furthermore, greenness exposure was shown to have a modifying effect on the relationship between ozone exposure and the occurrence of HS mortality (P for interaction = 0.001). Long-term exposure to warm season O3 was positively associated with HS mortality, while greenness exposure was inversely associated with HS mortality. Greenness exposure may mitigate the negative effects of warm season ozone exposure on HS mortality.

Greenness, air pollution, and mortality risk: a retrospective cohort study of patients with lung cancer in China

The association between long-term exposure to air pollution and mortality from lung cancer has been established, yet evaluations of the potential mitigating effects of greenness on this impact are scarce. We conducted a cohort study in Pingyi County. A two-level Cox proportional hazards regression model was used to examine the associations among long-term exposure to air pollution, residential greenness, and lung cancer mortality. Among the examined pollutants, nitrogen dioxide exhibited the most significant adverse effects and highest risk of lung cancer mortality, with hazard ratio (HR) = 2.783 (95% confidence interval [CI]: 1.885-4.107) for all-cause mortality, HR = 2.492 (95%CI: 1.659-3.741) for tumour-related mortality, and HR = 2.431 (95%CI: 1.606-3.678) for lung cancer mortality. Higher greenness values were associated with a reduced risk of lung cancer mortality. These findings suggest the importance of implementing strategies for increasing greenness to reduce the health impacts of air pollution.

Burden of Stroke Attributable to Nonoptimal Temperature in 204 Countries and Territories: A Population-Based Study, 1990-2019

BACKGROUND AND OBJECTIVES

Stroke attributable to nonoptimal temperature needs more attention with dramatic climate change. The aim of this study was to estimate the global burden and distribution characteristics of the burden.

METHODS

In this ecological study, we collected data from the Climate Research Unit Gridded Time Series, the World Bank databases, and the Global Burden of Diseases study to estimate the distribution of burden. We used the joinpoint model, decomposition analysis, age-period-cohort model, panel data analysis, and health inequality analysis to assess the different types of stroke burden attributable to different climatic conditions.

RESULTS

The burden of stroke attributable to nonoptimal temperature continued to grow, and aging was a key factor in this increase. In 2019, 521,031 (95% uncertainty interval [UI] 402,433-663,996) deaths and 9,423,649 (95% UI 7,207,660-12,055,172) disability-adjusted life years [DALYs] attributable to stroke due to nonoptimal temperature were recorded globally. Globally, men (age-standardized mortality rate [ASMR] 7.70, 95% UI 5.80-9.73; age-standardized DALY rate [ASDR] 139.69, 95% UI 102.96-178.54 in 2019) had a heavier burden than women (ASMR 5.89, 95% UI 4.50-7.60; ASDR 96.02, 95% UI 72.62-123.85 in 2019). Central Asia (ASMR 18.12, 95% UI 13.40-24.53; ASDR 327.35, 95% UI 240.24-440.61 in 2019) had the heaviest burden at the regional level. In the national level, North Macedonia (ASMR 32.97, 95% UI 20.57-47.44 in 2019) and Mongolia (ASDR 568.54, 95% UI 242.03-1,031.14 in 2019) had the highest ASMR/ASDR, respectively. Low temperature currently contributes to the main burden (deaths 474,002, 95% UI 355,077-606,537; DALYs 8,357,198, 95% UI 6,186,217-10,801,911 attributable to low temperature vs deaths 48,030, 95% UI 5,630-104,370; DALYs 1,089,329, 95% UI 112,690-2,375,345 attributable to high temperature in 2019). However, the burden due to high temperature has increased rapidly, especially among people aged older than 10 years, and was disproportionately concentrated in low sociodemographic index (SDI) regions such as Africa. In addition, the rapid increase in the stroke burden due to high temperature in Central Asia also requires special attention.

DISCUSSION

This is the first study to assess the global stroke burden attributed to nonoptimal temperature. The dramatic increase in the burden due to high temperature requires special attention, especially in low-SDI countries.

Heat and Cardiovascular Mortality: An Epidemiological Perspective

As global temperatures rise, extreme heat events are projected to become more frequent and intense. Extreme heat causes a wide range of health effects, including an overall increase in morbidity and mortality. It is important to note that while there is sufficient epidemiological evidence for heat-related increases in all-cause mortality, evidence on the association between heat and cause-specific deaths such as cardiovascular disease (CVD) mortality (and its more specific causes) is limited, with inconsistent findings. Existing systematic reviews and meta-analyses of epidemiological studies on heat and CVD mortality have summarized the available evidence. However, the target audience of such reviews is mainly limited to the specific field of environmental epidemiology. This overarching perspective aims to provide health professionals with a comprehensive overview of recent epidemiological evidence of how extreme heat is associated with CVD mortality. The rationale behind this broad perspective is that a better understanding of the effect of extreme heat on CVD mortality will help CVD health professionals optimize their plans to adapt to the changes brought about by climate change and heat events. To policymakers, this perspective would help formulate targeted mitigation, strengthen early warning systems, and develop better adaptation strategies. Despite the heterogeneity in evidence worldwide, due in part to different climatic conditions and population dynamics, there is a clear link between heat and CVD mortality. The risk has often been found to be higher in vulnerable subgroups, including older people, people with preexisting conditions, and the socioeconomically deprived. This perspective also highlights the lack of evidence from low- and middle-income countries and focuses on cause-specific CVD deaths. In addition, the perspective highlights the temporal changes in heat-related CVD deaths as well as the interactive effect of heat with other environmental factors and the potential biological pathways. Importantly, these various aspects of epidemiological studies have never been fully investigated and, therefore, the true extent of the impact of heat on CVD deaths remains largely unknown. Furthermore, this perspective also highlights the research gaps in epidemiological studies and the potential solutions to generate more robust evidence on the future consequences of heat on CVD deaths.

Associations between cold spells of different time types and coronary heart disease severity

Limited evidence showed the association between cold spells and the severity of coronary heart disease (CHD). This study was to investigate the association between cold spells with their different time types and CHD severity. We collected data on CHD patients admitted to the Zhongnan Hospital, Wuhan, China from 2016 to 2021. CHD severity was quantified using the SYNTAX score and transformed into a binomial variable. Daily mean, maximum and minimum temperature were collected during the study period. We first used daily mean temperature to find the optimum definition among multiple thresholds and durations. The daily maximum and minimum temperatures were used to define different types of cold spells (daytime, nighttime and compound) based on the optimum definition. Annual cold spell days were included to assess individual exposure to cold spells. Logistic regression models were performed to fit the association between cold spell days and CHD severity stratified by different tertiles of PM2.5 and NDVI. In this study, 1937 CHD patients were included. The cold spell defined as at least four consecutive days with daily mean temperature below the 5th percentile exhibited the optimum model. We found that a 4-day increase in cold spell days was associated with more severe CHD (OR = 1.170, 95% CI: 1.074, 1.282). Such an association was more pronounced under higher levels of PM2.5 by OR = 1.270 (1.086, 1.494) and lower levels of greenness by OR = 1.240 (1.044, 1.476). Compared with daytime and compound cold spells, nighttime cold spells showed the strongest association with CHD severity by OR = 1.141 (1.026, 1.269). This study showed that exposure to cold spells was positively associated with CHD severity, especially the nighttime cold spells. The association between cold spells and CHD severity was more significant in high levels of PM2.5 and low levels of greenness.

Hourly Heat Exposure and Acute Ischemic Stroke

Importance

Previous studies have demonstrated the associations of daily high temperature with hospitalizations and mortality from ischemic stroke, but the hourly association of ambient heat and acute ischemic stroke (AIS) onset has been rarely examined.

Objectives

To evaluate the association between hourly high ambient temperature and the onset of AIS.

Design, Setting, and Participants

This time-stratified case-crossover study was conducted using a nationwide registry that collects data from more than 200 stroke centers in China. Participants were adult patients with AIS who were hospitalized in the warm seasons between January 1, 2019, and December 31, 2021.

Exposures

Hourly temperature and single-hour temperature exposure lag up to 24 hours before the AIS onset (lag 0 hours to lag 24 hours).

Main Outcomes and Measures

The main outcome was onset of AIS. Associations between hourly mean temperatures and AIS onset were analyzed using conditional logistic regression integrated with the distributed lag nonlinear model. Stratification analyses were applied to examine potential association modifiers. Several sensitivity analyses were conducted to examine the robustness of the results.

Results

A total of 82 455 patients with AIS (mean [SD] age, 65.8 [11.9] years; 52 267 males [63.4%]) were included in the final analysis. A monotonically increasing risk of AIS onset was associated with higher temperatures. The excess AIS risk occurred immediately at lag 0 hours and persisted for 10 hours. Compared with the reference temperature (12.1 °C), the cumulative odds ratio (OR) over lag 0 to 10 hours of AIS onset associated with extremely high temperature (33.3 °C) was 1.88 (95% CI, 1.65-2.13) nationwide. The exposure-response curve was steeper in the north than in the south (OR, 1.80 [95% CI, 1.53-2.11] vs 1.57 [95% CI, 1.31-1.87]). The ORs were greater for males and patients with a history of dyslipidemia or atrial fibrillation, but the differences were not significant.

Conclusions and Relevance

Results of this study suggest that hourly heat exposure is associated with increased risk of AIS onset. This finding may benefit the formulation of public health strategies to reduce cerebrovascular risk associated with high ambient temperature under global warming.

Global burden of non-optimal temperature attributable stroke: The long-term trends, population growth and aging effects

Since the 20th century, the world has undergone climate change, population growth and population aging, which may result in alterations in the epidemiology of non-optimal temperature-associated strokes. We employed multiple methodologies and data from the global burden of disease 2019 to unveil the long-term curvilinear trends in strokes attributed to non-optimal temperature and the impact of aging and population growth on its changing epidemiology. From 1990 to 2019, the age-standardized DALYs rate (ASDR) of strokes attributable to low temperature had been decreasing, but from 2016, the continued downward trend in ASDR disappeared and began to remain stable. On the contrary, the ASDR of strokes attributable to high temperature continued to increase. The high socio-demographic index (SDI) region experienced the fastest decreased trend. The disease burden of stroke attributable to low temperature is increased by aging in 178 countries (87.25%), compared with 130 (63.73%) for high temperature. After excluding aging and population growth, the DALY rate for strokes attributed to high temperature was increasing in 87 countries and territories (42.64%). The disease burden of strokes attributed to low temperature is far greater than that of high temperature in absolute figures. However, globally, there is a significant trend toward an increase in strokes attributed to high temperature. Social development has largely offset the burden of strokes attributed to low temperature, but most regions of the world are equally affected by strokes attributed to high temperature. Simultaneously, in the framework of climate change, aging is also largely hindering stroke prevention efforts.

Associations of long-term exposure to air pollution and green space with reproductive hormones among women undergoing assisted reproductive technology: A longitudinal study

Studies investigating the association between long-term exposure to air pollution (AP)/green space and female reproductive hormones are still limited. Furthermore, their interactive effects remain unclear. Our study sought to explore the separate and interactive impacts of AP/green space on reproductive hormones among women undergoing assisted reproductive technology. We measured estradiol (E2), progesterone (P), testosterone (T), and follicle-stimulating hormone (FSH) from the longitudinal assisted reproduction cohort in Anhui, China. The annual mean concentrations of air pollutants were calculated at the residential level. Normalized Difference Vegetation Index (NDVI) within 500-m represented green space exposure. To assess the effect of AP/green space on hormones, we employed multivariable linear mixed-effect models. Our results showed that each one-interquartile range (IQR) increment in particulate matter (PM2.5 and PM10) and sulfur dioxide (SO2) was associated with -0.03[-0.05, -0.01], -0.03[-0.05, -0.02], and -0.03[-0.05, -0.01] decrease in P. An IQR increase in PM2.5, PM10, SO2, and carbon monoxide (CO) was associated with a -0.16[-0.17, -0.15], -0.15[-0.16, -0.14], -0.15[-0.16, -0.14], and -0.12[-0.13, -0.11] decrease in T and a -0.31[-0.35, -0.27], -0.30[-0.34, -0.26], -0.26[-0.30, -0.22], and -0.21[-0.25, -0.17] decrease in FSH. Conversely, NDVI500-m was associated with higher levels of P, T, and FSH, with β of 0.05[0.02, 0.08], 0.06[0.04, 0.08], and 0.07[0.00, 0.14]. Moreover, we observed the "U" or "J" exposure-response curves between PM2.5, PM10, and SO2 concentrations and E2 and P levels, as well as "inverted-J" curves between NDVI500-m and T and FSH levels. Furthermore, we found statistically significant interactions of SO2 and NDVI500-m on E2 and P as well as CO and NDVI500-m on E2. These findings indicated that green space might mitigate the negative effects of SO2 on E2 and P, as well as the effect of CO on E2. Future research is needed to determine these findings and underlying mechanisms.

The Green Heart Project: Objectives, Design, and Methods

The Green Heart Project is a community-based trial to evaluate the effects of increasing greenery on urban environment and community health. The study was initiated in 2018 in a low-to-middle-income mixed-race residential area of nearly 28,000 residents in Louisville, KY. The 4 square mile area was surveyed for land use, population characteristics, and greenness, and assigned to 8 paired clusters of demographically- and environmentally matched "target" (T) and adjacent "control" (C), clusters. Ambient levels of ultrafine particles, ozone, oxides of nitrogen, and environmental noise were measured in each cluster. Individual-level data were acquired during in-person exams of 735 participants in Wave 1 (2018-2019) and 545 participants in Wave 2 (2021) to evaluate sociodemographic and psychosocial factors. Blood, urine, nail, and hair samples were collected to evaluate standard cardiovascular risk factors, inflammation, stress, and pollutant exposure. Cardiovascular function was assessed by measuring arterial stiffness and flow-mediated dilation. After completion of Wave 2, more than 8,000 mature, mostly evergreen, trees and shrubs were planted in the T clusters in 2022. Post planting environmental and individual-level data were collected during Wave 3 (2022) from 561 participants. We plan to continue following changes in area characteristics and participant health to evaluate the long-term impact of increasing urban greenery.

Ambient temperatures associated with reduced cognitive function in older adults in China

The cognitive function status of older adults determines the social function and living quality of older adults, which is related to the healthy development and stability of the society. However, the impact of high or low ambient temperature on cognitive function in older adults remains unclear. Based on data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), we comprehensively assessed the impact of ambient temperature on the cognitive function of older adults in this study. The findings exhibited that for each 1 °C ascent in monthly temperature of high temperature, the examination score of global cognitive function of older adults decreased by 0.48 (95% CI 0.21-0.74), which was greater than that of 0.14 (95% CI 0.06-0.25) for each 1 °C reduction in low temperature. Overall, the detrimental effect of high temperature on cognitive function in older adults was more significant than that of low temperature, including on the five sub-cognitive functions involved. Our research provides vital technical guidance and reference for the health protection and prevention of cognitive function of older adults in specific external environmental conditions under the current climatic variation and temperature rise.

Burden of stroke attributable to high ambient temperature from 1990 to 2019: A global analysis

AIMS

To determine the global and regional burden of stroke due to high temperature and the spatiotemporal trends in 204 countries and territories from 1990 to 2019.

METHODS

Based on Global Burden of Disease Study 2019, deaths, disability-adjusted life years (DALYs), and age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) for stroke attributable to high temperature (i.e. a daily mean temperature warmer than the theoretical minimum-risk exposure level (TMREL)) were calculated in global, geographical location, and country and analyzed by age, sex, subtypes, and socio-demographic index (SDI) from 1990 to 2019. The trends in ASMR and ASDR from 1990 to 2019 were estimated by linear regression model. The regression coefficients (β) referred to a mean change of per year for ASMR or ASDR attributable to high temperature.

RESULTS

The global burden of stroke attributable to high temperature had an increase trend from 1990 to 2019 (β = 0.005, 95% uncertainty interval (UI) = 0.003-0.007 for ASMR and β = 0.104, 95% UI = 0.066-0.142 for ASDR, respectively). Globally, in 2019, an estimated 0.048 million deaths and 1.01 million DALYs of stroke were attributable to high temperature, and the global ASMR and ASDR of stroke attributable to high temperature were 0.60 (95% UI = 0.07-1.30) and 13.31 (1.40-28.97) per 100,000 population, respectively. The largest burden occurred in Western Sub-Saharan Africa, followed by South Asia, Southeast Asia, and North Africa and the Middle East. ASMR and ASDR increased with age and were higher in males and for intracerebral hemorrhage, and were the highest in the low SDI regions. In 2019, the region with the largest percentage increase in ASMR and ASDR attributable to high temperature was Eastern Sub-Saharan Africa from 1990 to 2019.

CONCLUSIONS

Stroke burden due to high temperature has been increasing, and a higher burden was observed in people aged 65-75 years, males, and countries with a low SDI. Stroke burden attributable to high temperature constitutes a major global public health concern in the context of global warming.

Association Between Long-Term Exposure to Fine Particulate Matter Constituents and Progression of Cerebral Blood Flow Velocity in Beijing: Modifying Effect of Greenness

Few studies have explored the effects of fine particulate matter (PM_2.5) and its constituents on the progression of cerebral blood flow velocity (BFV) and the potential modifying role of greenness. In this study, we investigated the association of PM_2.5 and its constituents, including sulfate (SO₄ ^2-), nitrate (NO₃ ^-), ammonium (NH₄ ⁺), organic matter (OM), and black carbon (BC), with the progression of BFV in the middle cerebral artery. Participants from the Beijing Health Management Cohort who underwent at least two transcranial Doppler sonography examinations during 2015-2020 were recruited. BFV change and BFV change rate were used to define the progression of cerebral BFV. Linear mixed effects models were employed to analyze the data, and the weighted quantile sum regression assessed the contribution of PM_2.5 constituents. Additionally, greenness was examined as a modifier. Among the examined constituents, OM exhibited the strongest association with BFV progression. An interquartile range increase in PM_2.5 and OM exposure concentrations was associated with a decrease of -16.519 cm/s (95% CI: -17.837, -15.201) and -15.403 cm/s (95% CI: -16.681, -14.126) in BFV change, and -10.369 cm/s/year (95% CI: -11.387, -9.352) and -9.615 cm/s/year (95% CI: -10.599, -8.632) in BFV change rate, respectively. Furthermore, stronger associations between PM_2.5 and BFV progression were observed in individuals working in areas with lower greenness, those aged under 45 years, and females. In conclusion, reducing PM_2.5 levels in the air, particularly the OM constituent, and enhancing greenness could potentially contribute to the protection of cerebrovascular health.

Potential role of ambient temperature as a trigger for intracerebral hemorrhage: a time-stratified case-crossover study in Tianjin, China

The adverse effects of ambient temperature on human health are receiving increasing attention, yet evidence of its impact on intracerebral hemorrhage (ICH) onset is limited. Here, the relationship between ambient temperature and ICH was evaluated. A time-stratified case-crossover analysis was performed based on 4051 ICH patients admitted to five stroke units in Tianjin between January 2014 and December 2020. Conditional logistic regression was applied to evaluate the associations between the daily mean temperature (Tm) or daily temperature range (DTR) and ICH onset. We found a negative association between Tm and ICH onset (OR = 0.977, 95% CI 0.968-0.987) but not between DTR and ICH onset. In stratified analyses, men and individuals aged ≥ 60 years were more susceptible to low-ambient temperature effects; corresponding adjusted ORs were 0.970 (95% CI 0.956-0.983) and 0.969 (95% CI 0.957-0.982), respectively. Tm significantly affected patients with deep ICH (OR = 0.976, 95% CI 0.965-0.988), but had no effect on lobar ICH. There was also seasonal heterogeneity in the effect of Tm on ICH onset, with Tm being negatively associated with ICH onset only in the warm season (OR = 0.961, 95% CI 0.941-0.982). Results suggest that the low-ambient temperature might trigger ICH onset, especially for the male and elderly population, providing important health guidance to prevent cold exposure-induced ICH.