High ambient temperature in summer and risk of stroke or transient ischemic attack: A national study in Israel

Exploring the effect of a sweltering environment on the risk of death from cardiovascular diseases

Background

A substantial body of research has demonstrated a notable impact of hot temperatures on mortality from cardiovascular diseases (CVDs). However, a paucity of studies has addressed the influence of sweltering conditions on CVD mortality.

Objective

To investigate the effect of sweltering conditions on mortality from CVD among permanent residents of Huizhou City, using the temperature-humidity index (THI) as an indicator.

Methods

This study employs descriptive statistics, distributed lag non-linear model (DLNM) and general algebraic modeling system (GAMs) with the THI as an indicator in order to examine the impact of sweltering conditions on the mortality of CVD among permanent residents of Huizhou City.

Results

Sweltering conditions increase the risk of death from CVDs and have a cumulative lag effect. The greater the THI, the more pronounced the increase in mortality, and after a certain range, the mortality rate from CVDs increases significantly, and the effect is gender-specific. The lag effect generally peaks in 2-3 days, and the lag effect of stroke mortality is longer and deeper than that of coronary heart disease (CAD) mortality.

Conclusion

Sweltering increased the mortality of cardiovascular diseases in Huizhou city, so we should pay attention to public health intervention strategies under sweltering.

Medical meteorological forecast for ischemic stroke: random forest regression vs long short-term memory model

Ischemic stroke (IS) is one of the top risk factors for death and disability. Meteorological conditions have an effect on IS attack. In this study, we try to develop models of medical meteorological forecast for IS attack based on machine learning and deep learning algorithms. The medical meteorological forecast would be beneficial to public health in IS events prevention and treatment. We collected data on IS attacks and climatology in each day from 18th September 2016 to 31th December 2020 in Haikou. Data on IS attacks were from the number of hospital admissions due to IS attack among general population. The random forest (RF) regression and long short-term memory (LSTM) algorithms were respectively used to develop the predictive model based on meteorological data. Performance of the model was assessed by mean squared error (MSE) and root mean squared error (RMSE). A total of 42849 IS attacks was included in this study. IS attacks were significantly decreased in winter. The pattern of climatological data was observed the regularity in seasons. For the performance of RF regression model, the MSE is 243, and the RMSE is 15.6. For LSTM model, the MSE is 36, and the RMSE is 6. In conclusion, LSTM model is more accurate than RF regression model to predict IS attacks in general population based on meteorological data. LSTM model showed acceptable accuracy for the prediction and could be used as medical meteorological forecast to predict IS attack among population according to local climate.

Modification effects of immigration status and comorbidities on associations of heat and heatwave with stroke morbidity

BACKGROUND

Heat and heatwave have been associated with stroke morbidity, but it is still unclear whether immigrants from different geographic regions and patients with comorbidity are more vulnerable to heat and heatwave.

METHODS

Time-stratified case-crossover design combined with generalized additive quasi-Poisson models were used to quantify the relative risks (RRs) of heat and heatwave on first-ever stroke morbidity during 0-7 lag days. Attributable fractions (AFs) were estimated to assess the first-ever stroke morbidity burden due to heat and heatwave. Stratified analyses for sex, age, disease subtypes, resident characteristics, and comorbidity type were performed to identify potential modification effects.

RESULTS

Heat and heatwave were associated with first-ever stroke morbidity, with the AF of 2.535% (95% empirical confidence interval (eCI) = 0.748, 4.205) and 2.409% (95% confidence interval (CI) = 1.228, 3.400), respectively. Among northern and southern immigrants, the AF for heat was 2.806% (0.031, 5.069) and 2.798% (0.757, 4.428), respectively, and the AF for heatwave was 2.918% (0.561, 4.618) and 2.387% (1.174, 3.398), respectively, but the effects of both on natives were statistically insignificant. Among patients with hypertension, dyslipidemia, or diabetes, the AF for heat was 3.318% (1.225, 5.007), 4.237% (1.037, 6.770), and 4.860% (1.171, 7.827), respectively, and the AF for heatwave was 2.960% (1.701, 3.993), 2.771% (0.704, 4.308), and 2.652% (0.653, 4.185), respectively. However, the effects of both on patients without comorbidity were statistically insignificant.

CONCLUSION

Heat and heatwave are associated with an increased risk of first-ever stroke morbidity among immigrants and those with comorbid hypertension, dyslipidemia, or diabetes, with the effects primarily due to non-native individuals.

DATA ACCESS STATEMENT

The author(s) are not authorized to share the data.

Climate change and disorders of the nervous system

Anthropogenic climate change is affecting people's health, including those with neurological and psychiatric diseases. Currently, making inferences about the effect of climate change on neurological and psychiatric diseases is challenging because of an overall sparsity of data, differing study methods, paucity of detail regarding disease subtypes, little consideration of the effect of individual and population genetics, and widely differing geographical locations with the potential for regional influences. However, evidence suggests that the incidence, prevalence, and severity of many nervous system conditions (eg, stroke, neurological infections, and some mental health disorders) can be affected by climate change. The data show broad and complex adverse effects, especially of temperature extremes to which people are unaccustomed and wide diurnal temperature fluctuations. Protective measures might be possible through local forecasting. Few studies project the future effects of climate change on brain health, hindering policy developments. Robust studies on the threats from changing climate for people who have, or are at risk of developing, disorders of the nervous system are urgently needed.

Short-Term Effect of Ambient Temperature in Acute Ischemic Stroke with Endovascular Treatment Due to Large Vessel Occlusion

Purpose

Acute ischemic stroke (AIS) stands as the primary cause of mortality and extended disability globally. While prior studies have examined the connection between stroke and local weather, they have produced conflicting results. Our goal was to examine the correlation between temperature and functional prognosis in patients with large vessel occlusion (LVO) undergoing endovascular therapy (EVT).

Patients and methods

This study included a total of 1809 patients. Temperatures from stroke onset to groin puncture were categorized into Cold (10th percentile of temperature), Cool (10th-50th percentile of temperature), Warm (50th-90th percentile of temperature), and Hot (90th percentile of temperature) groups. The primary efficacy result was the modified Rankin Scale (mRS) score at 90 days. Safety outcomes included mortality, symptomatic intracranial hemorrhage (sICH) and complications after cerebral infarction.

Results

The primary efficacy results demonstrated a statistical enhancement in functional outcomes at 90 days for patients in the Warm group compared to the Cold group (adjusted common odds ratio [OR]: 1.386; 95% confidence interval [CI]: 1.024-1.878, P=0.035). Secondary efficacy results showed that temperature was associated with a higher rate of 90-day functional independence (adjusted OR: 1.016; 95% CI: 1.004-1.029; P=0.009), which was higher in the Warm group compared with patients in the Cold group (adjusted OR: 1.646; 95% CI: 1.107-2.448, P=0.014). There were no significant differences between groups in terms of sICH, 90-day mortality, and post-infarction complications.

Conclusion

Compared with Cold temperature, Warm temperature is associated with better functional outcomes and reduced mortality risk without increasing the risk of sICH.

Projection of future heat-related morbidity in three metropolitan prefectures of Japan based on large ensemble simulations of climate change under 2 °C global warming scenarios

Recently, global warming has become a prominent topic, including its impacts on human health. The number of heat illness cases requiring ambulance transport has been strongly linked to increasing temperature and the frequency of heat waves. Thus, a potential increase in the number of cases in the future is a concern for medical resource management. In this study, we estimated the number of heat illness cases in three prefectures of Japan under 2 °C global warming scenarios, approximately corresponding to the 2040s. Based on the population composition, a regression model was used to estimate the number of heat illness cases with an input parameter of time-dependent meteorological ambient temperature or computed thermophysiological response of test subjects in large-scale computation. We generated 504 weather patterns using 2 °C global warming scenarios. The large-scale computational results show that daily amount of sweating increased twice and the core temperature increased by maximum 0.168 °C, suggesting significant heat strain. According to the regression model, the estimated number of heat illness cases in the 2040s of the three prefectures was 1.90 (95%CI: 1.35-2.38) times higher than that in the 2010s. These computational results suggest the need to manage ambulance services and medical resource allocation, including intervention for public awareness of heat illnesses. This issue will be important in other aging societies in near future.

Bidirectional modification effects on nonlinear associations of summer temperature and air pollution with first-ever stroke morbidity

High temperature and air pollution may induce stroke morbidity. However, whether associations between high temperature and air pollution with stroke morbidity are modified by each other is still unclear. Data on 23,578 first-ever stroke patients in Shenzhen, China, during the summers of 2014-2018 were collected. Distributed lag nonlinear models were used to assess the modifying effects of air pollution stratified by the median for the associations between summer temperature and stroke morbidity at 0-3 lag days; modifying effects of temperature stratified by the minimum morbidity temperature on the associations between air pollution and stroke morbidity at the same lags were also estimated. The attributable risks of high temperature and high pollution on stroke morbidity were quantified. Stratified analyses of gender, age, migration type, and complication type were conducted to assess vulnerable population characteristics. Summer high temperature may induce stroke morbidity at high-level PM2.5, PM10, O3, SO2, and NO2 conditions, with attributable fraction (AF) of 2.982% (95% empirical confidence interval [eCI]: 0.943, 4.929), 3.113% (0.948, 5.200), 2.841% (0.943, 4.620), 3.617% (1.539, 5.470), and 2.048% (0.279, 3.637), respectively. High-temperature effects were statistically insignificant at corresponding low-level air pollution conditions. High-level PM2.5, PM10, and O3 may induce stroke morbidity at high-temperature conditions, with AF of 3.664% (0.036, 7.196), 4.129% (0.076, 7.963), and 4.574% (1.009, 7.762), respectively. High-level PM2.5, PM10, and O3 were not associated with stroke morbidity at low-temperature conditions. The effects of high temperature and high pollution on stroke morbidity were statistically significant among immigrants and patients with hypertension, dyslipidemia, or diabetes but insignificant among natives and patients without complications. The associations of summer temperature and air pollution with first-ever stroke morbidity may be enhanced bidirectionally. Publicity on the health risks of combined high temperature and high pollution events should be strengthened to raise protection awareness of relevant vulnerable populations.

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.

Association between ambient temperature and stroke risk in high-risk populations: a systematic review

Background

Significant associations exist between ambient temperature and stroke risk, but results in high cardiovascular risk populations are lacking. This systemic review summarised current evidence on ambient temperature and overall stroke risk in a high cardiovascular risk population.

Methods

We performed a systematic literature search across MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, and GEOBASE, from inception to 3 July 2023, to identify all population-based studies. Eligible studies screened by independent reviewers recruited individuals aged 18 years and over, where minimum 80% of participants had a high cerebral vascular disease (CVD) risk profile. The primary outcomes are stroke morbidity and mortality, while the secondary outcomes are morbidity and mortality of ischaemic stroke (IS), intracranial cerebral haemorrhage (ICH), and subarachnoid haemorrhage (SH).

Results

The database searches identified 9,025 articles. After removing duplicates, 7,647 articles were screened in title and abstract to identify 380 articles for full-text screening. After the full-text screening of 380 articles by two independent reviewers, 23 articles were included in the review.

Conclusion

The evidence for an association between ambient temperature and stroke incidence is that lower temperatures were more likely to increase morbidity and mortality risk of both haemorrhagic and ischaemic stroke in older people. Conversely, higher ambient temperature is significantly associated with intracranial haemorrhage risk, but decreased risk with IS. Higher and lower ambient temperatures consistently increase stroke risks in patients with comorbidities of congestive heart failure and dyslipidaemia. This evidence implies the need to establish clinical guidelines for preventive intervention in patients with high stroke risks during extreme ambient temperatures.

Risk and attributable fraction estimation for the impact of exposure to compound drought and hot events on daily stroke admissions

BACKGROUND

The projection indicates that compound drought and hot events (CDHEs) will intensify, posing risks to cardiovascular health by potentially increasing stroke incidents. However, epidemiological evidence on this topic remains scarce. This study investigates the association between exposure to CDHEs and the risk of daily stroke admissions, specifically examining the effects on various stroke categories such as Subarachnoid Hemorrhage (SAH), Intracerebral Hemorrhage (ICH), Ischemic Stroke (IS), Transient Ischemic Attack (TIA), and other types of stroke.

METHODS

Data on daily stroke admissions from 2010 to 2015 were obtained from the Urban Employee Basic Medical Insurance (UEBMI) and Urban Resident Basic Medical Insurance (URBMI) claims databases in Guangzhou, China. Hot events were identified as days when the daily mean temperature exceeded the 75th percentile during the warm season (May to October) over the study period. The Standardized Precipitation Evapotranspiration Index (SPEI) was utilized to identify drought conditions, with thresholds set at -1 and -1.5 for low-severity and high-severity drought events, respectively. Through a generalized additive model (GAM), we analyzed the cumulative effects of CDHE exposure on daily stroke admissions and calculated the Attributable Fraction (AF) related to CDHEs.

RESULTS

The analysis included 179,963 stroke admission records. We observed a significant increase in stroke admission risks due to exposure to hot events coupled with high-severity drought conditions (RR = 1.18, 95%CI: 1.01-1.38), with IS being the most affected category (RR = 1.20, 95%CI: 1.03-1.40). The AF of total stroke admission attributed to hot events in conjunction with high-severity drought conditions was 24.40% (95%CI: 1.86%-50.20%).

CONCLUSION

The combination of hot events with high-severity drought conditions is likely linked to an increased risk of stroke and IS admissions, which providing new insights into the impact of temperature and climate-related hazards on cardiovascular health.

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.

The effects of heatwave on cognitive impairment among older adults: Exploring the combined effects of air pollution and green space

The association between heatwaves and cognitive impairment in older adults, especially the joint effect of air pollution and green space on this association, remains unknown. The present cohort study used data from waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) from 2008 to 2018. Heatwaves were defined as having daily maximum temperature ≥ 92.5th, 95th and 97.5th percentile that continued at least two, three and four days, measured as the one-year heatwave days prior to the participants' incident cognitive impairment. Data on the annual average air pollutant concentrations of fine particulate matter (PM2.5) and ozone (O3) as well as green space exposure (according to the Normalized Difference Vegetation Index (NDVI)) were collected. Time-varying Cox proportional hazards models were constructed to examine the independent effect of heatwaves on cognitive impairment and the combined effect of heatwaves, air pollution, and green space on cognitive impairment. Potential multiplicative interactions were examined by adding a product term of air pollutants and NDVI with heatwaves in the models. The relative excess risk due to interaction (RERI) was calculated to reflect additive interactions. We found that heatwave exposure was associated with higher risks of cognitive impairment, with hazard ratios (HRs) and 95 % confidence intervals (CIs) ranging from 1.035 (95 % CI: 1.016-1.055) to 1.058 (95 % CI: 1.040-1.075). We observed a positive interaction of PM2.5 concentrations, O3 concentrations, lack of green space, and heatwave exposure on a multiplicative scale (HRs for product terms >1). Furthermore, we found a synergistic interaction of PM2.5 concentrations, O3, lack of green space, and heatwave exposure on an additive scale, with RERIs >0. These results suggest that extreme heat exposure may be a potential risk factor for cognitive impairment in older adults. Additionally, coexposure to air pollution and lack of green space exacerbated the adverse effects of heatwaves on cognitive function.

A Long Way from Steubenville: Environmental Epidemiology in a Rapidly Changing World

This commentary focuses on research that has long been at the core of environmental epidemiology: studies of the health effects of air pollution. It highlights publications in the American Journal of Epidemiology going back more than 50 years that have contributed to the debate about the validity of this research and its meaning for public policy. Technological advances have greatly expanded the toolbox of environmental epidemiologists in terms of measuring and analyzing complex exposures in large populations. Yet, discussions about biases in estimating air pollution health effects have always been and remain intense. Epidemiologists have brought new methodologies and concepts to this research, alleviating some but not all concerns. Here, the focus is on seminal epidemiologic work that established valid links between air pollution exposures and health outcomes and generated data for environmental policies and prevention. With this commentary, I hope to inspire epidemiologists to address many more of the burning environmental health questions-wildfires included-with a similar scientific doggedness. The rapidly changing conditions of our planet are challenging us to innovate and offer solutions, albeit perhaps a little bit faster this time around.

Effects of weather conditions on endovascular treatment case volume for patients with ischemic stroke

BACKGROUND

Weather conditions have been shown to influence the occurrence of cardiovascular events. We tested the hypothesis that weather parameters may be associated with variations of case volume of endovascular treatment (EVT) for acute ischemic stroke.

METHODS

Individual data from the ETIS (Endovascular Treatment in Ischemic Stroke) French national registry were matched to local weather stations. Meteorological parameters (rainfall, humidity, atmospheric pressure, air temperature) were gathered from national online resources. Weather readings and EVT case volumes were annually standardized per weather station and EVT center, and their associations tested with non-parametric univariable and generalized linear statistical models.

RESULTS

Between 2015 and 2021, 9913 EVT procedures addressed by 135 primary stroke units were matched to weather conditions. The mean daily case volume per center was 0.41 [StDev 0.33], and there was a median of 0.84 procedures daily linked to a weather station [StDev 0.47]. We found lower atmospheric pressure (β estimate -0.04; 95%CI[-0.07;-0.03], p<0.001), higher humidity (β estimate 0.07; 95%CI [0.05;0.09], p<0.001) and lower temperatures (β estimate -0.08; 95%CI[-0.10;-0.06], p<0.001) to be associated with higher standardized EVT daily case volumes. These associations were stable when testing them across strata of binned EVT standardized case volumes.

CONCLUSIONS

Our study suggests that lower ambient temperature, lower atmospheric pressure, and higher air humidity are associated with significantly more daily EVT cases in a European temperate country. These results may provide insight into both system of care optimization at times of climate change and intracranial LVO pathophysiology. REGISTRATION-URL: https://clinicaltrials.gov/ct2/show/NCT03776877.

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.

Impacts of exposure to ambient temperature and altitude on the burden of stroke

OBJECTIVE

To evaluate the impact of ambient temperature and altitude exposure on the burden of stroke in a Chinese cohort.

METHODS

This study was conducted using data from the National Stroke High-Risk Population Screening System 2020, which assess the overall prevalence, incidence, and mortality rate of stroke in China. For this study, we obtained the annual mean ambient temperature, diurnal temperature range, and altitude for each city. Body mass index (BMI) of participants were calculated.

RESULT

The sample comprised 676,394 adults aged 40 years or older from 170 cities in 31 provinces in China. A negative linear relationship between mean ambient temperature and stroke risk (incidence and prevalence) as well as a negative association between mean ambient temperature and stroke mortality had been found. A nonlinear relationship with decreased risk in both high and low diurnal temperature range is observed for stroke burden (incidence, prevalence, and mortality). There is no significant correlation between city altitude and stroke burden. The U-shaped relationships of BMI with the incidence and prevalence of stroke indicate that the lowest incidence and prevalence are observed when BMI is approximately 20.

CONCLUSION

Overall, our study provides important insights into the environmental and individual factors that contribute to the burden of stroke in China, and may inform public health interventions aimed at reducing this burden.

Heat-related first cardiovascular event incidence in the city of Madrid (Spain): Vulnerability assessment by demographic, socioeconomic, and health indicators

While climate change and population ageing are expected to increase the exposure and vulnerability to extreme heat events, there is emerging evidence suggesting that social inequalities would additionally magnify the projected health impacts. However, limited evidence exists on how social determinants modify heat-related cardiovascular morbidity. This study aims to explore the association between heat and the incidence of first acute cardiovascular event (CVE) in adults in Madrid between 2015 and 2018, and to assess how social context and other individual characteristics modify the estimated association. We performed a case-crossover study using the individual information collected from electronic medical records of 6514 adults aged 40-75 living in Madrid city that suffered a first CVE during summer (June-September) between 2015 and 2018. We applied conditional logistic regression with a distributed lag non-linear model to analyse the heat-CVE association. Estimates were expressed as Odds Ratio (OR) for extreme heat (at 97.5th percentile of daily maximum temperature distribution), compared to the minimum risk temperature. We performed stratified analyses by specific diagnosis, sex, age (40-64, 65-75), country of origin, area-level deprivation, and presence of comorbidities. Overall, the risk of suffering CVE increased by 15.3% (OR: 1.153 [95%CI 1.010-1.317]) during extreme heat. Males were particularly more affected (1.248, [1.059-1.471]), vs 1.039 [0.810-1.331] in females), and non-Spanish population (1.869 [1.28-2.728]), vs 1.084 [0.940-1.250] in Spanish). Similar estimates were found by age groups. We observed a dose-response pattern across deprivation levels, with larger risks in populations with higher deprivation (1.228 [1.031-1.462]) and almost null association in the lowest deprivation group (1.062 [0.836-1.349]). No clear patterns of larger vulnerability were found by presence of comorbidity. We found that heat unequally increased the risk of suffering CVE in adults in Madrid, affecting mainly males and deprived populations. Local measures should pay special attention to vulnerable populations.

Temperature and socioeconomic vulnerability: associations with cardiac event-induced posttraumatic stress symptoms

Background

Posttraumatic stress symptoms (PTSS) are common after acute coronary syndrome (ACS) and predict increased morbidity and mortality. Climate change contributes to worse mental and cardiovascular health outcomes, thus, PTSS represent a potential mechanism linking climate change to adverse cardiovascular outcomes. Because people living in areas with lower socioeconomic status (SES) experience greater climate vulnerability, have worse cardiovascular health, and may be more susceptible to PTSS, any effect of temperature on PTSS could be amplified in this population.

Methods

Spatial regression models were estimated to test the association of temperature and temperature variability (within-day variability, directed change over time, and absolute change over time), census tract-level SES, and their interaction with PTSS 1 month post-hospital discharge in a longitudinal cohort study comprising 956 patients evaluated for ACS at an urban U.S. academic medical center between November 2013-May 2017. PTSS were self-reported in relation to the ACS event that brought the patient to the hospital. Census tract-level was computed as a composite score from the CDC Social Vulnerability Index, with higher values indicating lower SES.

Results

No temperature or temperature variability metrics were associated with PTSS. Lower census tract-level SES was associated with greater PTSS at 1 month. There was a marginally significant interaction of SES with ACS status, such that we only observed evidence of an association among those with ACS.

Conclusion

Temperature exposures were not associated with acute CVD-induced PTSS, which could be a result of a small sample size, mismatched timescale, or lack of a true effect. Conversely, lower census tract-level SES was associated with developing worse PTSS 1 month after evaluation for an ACS. This association appeared stronger in individuals with a true ACS. Early interventions to prevent PTSS could promote better mental and CVD outcomes in this at-risk population.

Explainable prediction of daily hospitalizations for cerebrovascular disease using stacked ensemble learning

BACKGROUND

With the prevalence of cerebrovascular disease (CD) and the increasing strain on healthcare resources, forecasting the healthcare demands of cerebrovascular patients has significant implications for optimizing medical resources.

METHODS

In this study, a stacking ensemble model comprised of four base learners (ridge regression, random forest, gradient boosting decision tree, and artificial neural network) and a meta learner (elastic net) was proposed for predicting the daily number of hospital admissions (HAs) for CD using the historical HAs data, air quality data, and meteorological data in Chengdu, China from 2015 to 2018. To solve the label imbalance problem, a re-weighting method based on label distribution smoothing was integrated into the meta learner. We trained the model using the data from 2015 to 2017 and evaluated its predictive ability using the data in 2018 based on four metrics, including mean absolute error (MAE), root mean square error (RMSE), mean absolute percentage error (MAPE), and coefficient of determination (R²). In addition, the SHapley Additive exPlanations (SHAP) framework was applied to provide explanation for the prediction of our stacking model.

RESULTS

Our proposed model outperformed all the base learners and long short-term memory (LSTM) on two datasets. Particularly, compared with the optimal results obtained by individual models, the MAE, RMSE, and MAPE of the stacking model decreased by 13.9%, 12.7%, and 5.8%, respectively, and the R² improved by 6.8% on CD dataset. The model explanation demonstrated that environmental features played a role in further improving the model performance and identified that high temperature and high concentrations of gaseous air pollutants might strongly associate with an increased risk of CD.

CONCLUSIONS

Our stacking model considering environmental exposure is efficient in predicting daily HAs for CD and has practical value in early warning and healthcare resource allocation.

Urban-rural disparity in heatwave effects on diabetes mortality in eastern China: A case-crossover analysis in 2016-2019

Diabetics are sensitive to high ambient temperature due to impaired thermoregulation. However, available evidence on the impact of prolonged high temperature (i.e., heatwave) on diabetes deaths is limited and whether urban and rural areas differ in heatwave vulnerability remains unknown so far. A time-stratified case-crossover analysis was employed to estimate the association between heatwaves and diabetes deaths in 1486 districts (509 urban and 977 rural areas) of eastern China (Jiangsu Province), 2016-2019. For each decedent, residential heatwave exposure was measured by matching daily mean temperatures to the geocoded residential address. We adopted nine-tiered heatwave definitions incorporating intensity and duration. Stratified analyses by decedents' characteristics (gender, age, and education) were also conducted. During the study period, there were 18,685 deaths from diabetes (urban proportion: 36.95 %, p-value for urban-rural difference < 0.05). Heatwaves were associated with an increased risk of diabetes deaths, with greater and longer-lasting effects in rural areas than urban areas [e.g., rural odds ratio (OR): 1.19 (95 % confidence interval (CI): 1.14, 1.25) vs. urban OR: 1.09 (95 % CI: 1.05, 1.12)]. Risk of diabetes deaths increased with the intensity of heatwaves in rural areas (p-value for trend <0.01), but not in urban areas. Stratified analyses in rural areas suggested that females and less-educated people were more vulnerable to heatwave-related diabetes deaths. Our findings revealed the urban-rural disparity in the risk of diabetes deaths associated with heatwaves. Rural diabetics should be made aware of the increased death risk posed by heatwaves in the context of warming climate.

Global Burden of Ischemic Stroke in Young Adults in 204 Countries and Territories

BACKGROUND AND OBJECTIVES

To estimate the rates of incidence, death, and disability-adjusted life years (DALYs) of ischemic stroke in young adults aged 15-49 years and the relevant risk factors by sex, age group, and sociodemographic index (SDI) in 204 countries and territories.

METHODS

Data from the Global Burden of Diseases, Injuries, and Risk Factors (GBD) 2019 study were used. The estimated annual percentage changes (EAPCs) were calculated to evaluate the temporal trends from 1990 to 2019. We also estimated the risk factors contributing to DALYs resulting from ischemic stroke.

RESULTS

From 1990 to 2019, the global age-standardized incidence (EAPC = -0.97), death (EAPC = -0.11), and DALYs rates (EAPC = -0.55) of ischemic stroke in young adults decreased. The largest increases in age-standardized incidence, death, and DALYs rates were observed in the low and low-middle SDI quintiles. At the regional level, North Africa and the Middle East and Southeast Asia showed the largest increases in the age-standardized incidence, death, and DALYs rates of ischemic stroke. The age-standardized incidence rate was higher among young women than among young men in 2019. Globally, a high environmental temperature, high body mass index (BMI), and a high fasting plasma glucose contributed to the largest increases in age-standardized DALYs rates between 1990 and 2019. In the same period, the largest increases in the age-standardized DALYs rates in high-SDI and low-SDI regions were attributable to high environmental temperatures and alcohol use, respectively.

DISCUSSION

The burden of ischemic stroke in young adults continues to increase in low-SDI regions such as North Africa and the Middle East and Southeast Asia. There were differences in the primary risk factors related to the burden of ischemic stroke in different SDI regions. Targeted implementation of cost-effective policies and interventions is an urgent need to reduce the burden of ischemic stroke in young adults.

The joint and interaction effect of high temperature and humidity on mortality in China

BACKGROUND

Although many studies have reported the mortality effect of temperature, there were few studies on the mortality risk of humidity, let alone the joint effect of temperature and humidity. This study aimed to investigate the joint and interaction effect of high temperature and relative humidity on mortality in China, which will deepen understanding the health risk of mixture climate exposure.

METHODS

The mortality and meteorological data were collected from 353 locations in China (2013-2017 in Jilin, Hunan, Guangdong and Yunnan provinces, 2009-2017 in Zhejiang province, and 2006-2011 in other Provinces). We defined location-specific daily mean temperature ≥ 75th percentile of distribution as high temperature, while minimum mortality relative humidity as the threshold of high relative humidity. A time-series model with a distributed lag non-linear model was first employed to estimate the location-specific associations between humid-hot events and mortality, then we conducted meta-analysis to pool the mortality effect of humid-hot events. Finally, an additive interaction model was used to examine the interactive effect between high temperature and relative humidity.

RESULTS

The excess rate (ER) of non-accidental mortality attributed to dry-hot events was 10.18% (95% confidence interval (CI): 8.93%, 11.45%), which was higher than that of wet-hot events (ER = 3.21%, 95% CI: 0.59%, 5.89%). The attributable fraction (AF) of mortality attributed to dry-hot events was 10.00% (95% CI: 9.50%, 10.72%) with higher burden for females, older people, central China, cardiovascular diseases and urban city. While for wet-hot events, AF was much lower (3.31%, 95% CI: 2.60%, 4.30%). We also found that high temperature and low relative humidity had synergistic additive interaction on mortality risk.

CONCLUSION

Dry-hot events may have a higher risk of mortality than wet-hot events, and the joint effect of high temperature and low relative humidity may be greater than the sum of their individual effects.

Short-term effects of exposure to ambient PM1, PM2.5, and PM10 on ischemic and hemorrhagic stroke incidence in Shandong Province, China

BACKGROUND

Short-term exposure to ambient PM_2.5 and PM₁₀ is associated with increased risk of mortality and hospital admissions for stroke. However, there is less evidence regarding the effect of exposure to PM₁ on stroke incidence. We estimated the incidence risk of stroke and the attributable fractions related to short-term exposure to ambient PM₁, PM_2.5 and PM₁₀ in China.

METHODS

County-specific incidence of stroke was obtained from health statistics in years 2014-2019. We linked county-level mean daily concentrations of PM₁, PM_2.5 and PM₁₀ with stroke incidence. We used the time stratified case-crossover design to estimate the associations between stroke incidence and exposure to PM₁, PM_2.5 and PM₁₀. We also estimated the disease burden fractions attributable to PM₁, PM_2.5, and PM₁₀.

RESULTS

The study included a total of 2,193,954 stroke, from which 1,861,331 were ischemic and 332,623 were hemorrhagic stroke. PM₁, PM_2.5, and PM₁₀ levels were associated with increased risks of total stroke and ischemic stroke at when assessing the associations in exposure at lag0-4 days. The increase of 10 μg/m³ in PM₁, PM_2.5, and PM₁₀ was associated with total stroke, and the relative risks were 1.012 (95% confidence interval: 1.008, 1.015), 1.006 (1.004, 1.007) and 1.003 (1.002, 1.004), while the associations with ischemic stroke were 1.013 (1.010, 1.017), 1.006 (1.005, 1.008) and 1.003 (1.002, 1.004), respectively. There was no significant association between PM and risk of hemorrhagic stroke. The attributable fractions of total stroke were 6.9% (5.1%, 8.5%), 5.6% (4.2%, 6.8%) and 5.6% (3.9%, 7.1%) for PM₁, PM_2.5, and PM₁₀, respectively.

CONCLUSIONS

PM₁ showed a stronger association with stroke, with a larger attributable fraction of outcomes, than PM_2.5 and PM₁₀. Clean air policies should target the whole scope of PM, including PM₁.

Associations between ambient air pollution, meteorology, and daily hospital admissions for ischemic stroke: a time-stratified case-crossover study in Beijing

Air pollution and ischemic stroke (IS) are both vital factors affecting the health of Beijing citizens. This study aims at exploring the associations between air pollution, meteorology, and the hospital admission of IS (IS HA). Information on 476,659 IS inpatients in secondary and higher hospitals in Beijing from 2013 to 2018 were collected. A time-stratified case-crossover design with the generalized additive model and the distributed lag nonlinear model were used. In the single-pollutant models, an inter-quartile range increase in O_3, SO₂, CO, and NO₂ resulted in a significant highest increase in IS HA by 2.23% (95% CI: 1.56%, 2.90%), 1.53% (95% CI: 1.12%, 1.95%), 1.05% (95% CI: 0.70%, 1.40%), and 0.51% (95% CI: 0.24%, 0.79%) on the day of pollution, so did PM_2.5 and PM₁₀ by 1.13% (95% CI: 0.68%, 1.59%) and 1.19% (95% CI: 0.74%, 1.64%) at a lag of 0-5 days. There was a nonlinear relationship between meteorology and IS HA. In the multivariate model, the cumulative relative risks with a maximum lag time of 21 days of PM_2.5 and NO₂ were 1.11 (95% CI: 1.04, 1.19) and 0.88 (95% CI: 0.82, 0.94), while the effects of SO₂, O₃, and meteorology were insignificant. The findings suggested that particulate pollutants could increase the risk of IS, and the elderly were more sensitive to it, while the results of gaseous pollutants are still discordant. The control of air pollution and the protection of susceptible populations should receive higher attention from policymakers.

Materials with Tunable Optical Properties for Wearable Epidermal Sensing in Health Monitoring

Advances in wearable epidermal sensors have revolutionized the way that physiological signals are captured and measured for health monitoring. One major challenge is to convert physiological signals to easily readable signals in a convenient way. One possibility for wearable epidermal sensors is based on visible readouts. There are a range of materials whose optical properties can be tuned by parameters such as temperature, pH, light, and electric fields. Herein, this review covers and highlights a set of materials with tunable optical properties and their integration into wearable epidermal sensors for health monitoring. Specifically, the recent progress, fabrication, and applications of these materials for wearable epidermal sensors are summarized and discussed. Finally, the challenges and perspectives for the next generation wearable devices are proposed.

Can weather help explain 'why now?': The potential role of hourly temperature as a stroke trigger

BACKGROUND

While evidence suggests that daily ambient temperature exposure influences stroke risk, little is known about the potential triggering role of ultra short-term temperature.

METHODS

We examined the association between hourly temperature and ischemic and hemorrhagic stroke, separately, and identified any relevant lags of exposure among adult New York State residents from 2000 to 2015. Cases were identified via ICD-9 codes from the New York Department of Health Statewide Planning and Reearch Cooperative System. We estimated ambient temperature up to 36 h prior to estimated stroke onset based on patient residential ZIP Code. We applied a time-stratified case-crossover study design; control periods were matched to case periods by year, month, day of week, and hour of day. Additionally, we assessed effect modification by leading stroke risk factors hypertension and atrial fibrillation.

RESULTS

We observed 578,181 ischemic and 164,755 hemorrhagic strokes. Among ischemic and hemorrhagic strokes respectively, the mean (standard deviation; SD) patient age was 71.8 (14.6) and 66.8 (17.4) years, with 55% and 49% female. Temperature ranged from -29.5 °C to 39.2 °C, with mean (SD) 10.9 °C (10.3 °C). We found linear relationships for both stroke types. Higher temperature was associated with ischemic stroke over the 7 h following exposure; a 10 °C increase over 7 h was associated with 5.1% (95% Confidence Interval [CI]: 3.8, 6.4%) increase in hourly stroke rate. In contrast, temperature was negatively associated with hemorrhagic stroke over 5 h, with a 5-h cumulative association of -6.2% (95% CI: 8.6, -3.7%). We observed suggestive evidence of a larger association with hemorrhagic stroke among patients with hypertension and a smaller association with ischemic stroke among those with atrial fibrillation.

CONCLUSION

Hourly temperature was positively associated with ischemic stroke and negatively associated with hemorrhagic stroke. Our results suggest that ultra short-term weather influences stroke risk and hypertension may confer vulnerability.

Relationship between diurnal temperature range and emergency ambulance dispatches due to stroke in Guangzhou, China

BACKGROUND

The evidence between diurnal temperature range (DTR) and stroke remains controversial and sparse. We aimed to assess the relationship between DTR and emergency ambulance dispatches (EADs) due to stroke, and to explore whether there were effect modifications to the relationship.

METHODS

A Quasi-Poisson generalized linear regression combined with a distributed lag non-linear model was used to examine the relationship between DTR and EADs for stroke between January 1st 2011 and June 30th 2018 in Guangzhou, China. We estimated the effects of the low DTR and high DTR (defined as DTR below and above 10 °C respectively) on EADs. The effects of minimum, maximum, 5th, 25th, 50th, 75th, and 95th percentiles of DTR compared with the DTR of 10 °C were also analyzed.

RESULTS

A total of 20,275 EADs for stroke were included for analyses, among which 17,556 EADs were used in the model further adjusted for age and sex. A quasi-U-shaped relationship between DTR and EADs over lag0-2 days was observed. For the low DTR, per 1 °C decrease in DTR was significantly associated with an increase of 2.64% (RR = 1.03, 95% CI: 1.01-1.04) for EADs, while per 1 °C increase for the high DTR was non-significantly related with an increased risk of EADs (RR = 1.01, 95% CI: 0.90-1.13). Significant effects of the 5th and 25th percentiles of DTR on EADs were found when compared with the DTR of 10 °C. No significant effect modifications by age, sex or season were found to the association between DTR and EADs.

CONCLUSIONS

We found a quasi-U-shaped relationship between DTR and EADs due to stroke in this study, while age, sex or season did not significantly modify the association between DTR and EADs. More high-quality evidence is needed to further explore and validate the relationship between DTR and stroke.

Long-term exposure to ambient PM2.5 and stroke mortality among urban residents in northern China

Evidence is still limited for the role of long-term PM_2.5 exposure in cerebrovascular diseases among residents in high pollution regions. The study is aimed to investigate the long-term effects of PM_2.5 exposure on stroke mortality, and further explore the effect modification of temperature variation on the PM_2.5-mortality association in northern China. Based on a cohort data with an average follow-up of 9.8 years among 38,435 urban adults, high-resolution estimates of PM_2.5 derived from a satellite-based model were assigned to each participant. A Cox regression model with time-varying exposures and strata of geographic regions was employed to assess the risks of stroke mortality associated with PM_2.5, after adjusting for individual risk factors. The cross-product term of PM_2.5 exposure and annual temperature range was further added into the regression model to test whether the long-term temperature variation would modify the association of PM_2.5 with stroke mortality. Among the study participants, the annual mean level of PM_2.5 concentration was 66.3 μg/m³ ranging from 39.0 μg/m³ to 100.6 μg/m³. For each 10 μg/m³ increment in PM_2.5, the hazard ratio (HR) was 1.31 (95% CI: 1.04-1.65) for stroke mortality after multivariable adjustment. In addition, the HRs of PM_2.5 decreased gradually as the increase of annual temperature range with the HRs of 1.95 (95% CI: 1.36-2.81), 1.53 (95% CI: 1.06-2.22), and 1.11 (95% CI: 0.75-1.63) in the low, middle, and high group of annual temperature range, respectively. The findings provided further evidence of long-term PM_2.5 exposure on stroke mortality in high-exposure settings such as northern China, and also highlighted the view that assessing the adverse health effects of air pollution might not ignore the role of temperature variations in the context of climate change.

The Effect of Minimum and Maximum Air Temperatures in the Summer on Heat Stroke in Japan: A Time-Stratified Case-Crossover Study

An increase in the global surface temperature and changes in urban morphologies are associated with increased heat stress especially in urban areas. This can be one of the contributing factors underlying an increase in heat strokes. We examined the impact of summer minimum air temperatures, which often represent nighttime temperatures, as well as a maximum temperature on a heat stroke. We collected data from the records of daily ambulance transports for heat strokes and meteorological data for July and August of 2017–2019 in the Tottori Prefecture, Japan. A time-stratified case-crossover design was used to determine the association of maximum/minimum air temperatures and the incidence of heat strokes. We used a logistic regression to identify factors associated with the severity of heat strokes. A total of 1108 cases were identified with 373 (33.7%) calls originating in the home (of these, 59.8% were the age of ≥ 75). A total of 65.8% of cases under the age of 18 were related to exercise. Days with a minimum temperature ≥ 25 °C had an odds ratio (95% confidence interval) of 3.77 (2.19, 6.51) for the incidence of an exercise-related heat stroke (reference: days with a minimum temperature < 23 °C). The odds ratio for a heat stroke occurring at home or for calls for an ambulance to the home was 6.75 (4.47, 10.20). The severity of the heat stroke was associated with older age but not with air temperature. Minimum and maximum air temperatures may be associated with the incidence of heat strokes and in particular the former with non-exertional heat strokes.

A time series analysis of the relationship between ambient temperature and ischaemic stroke in the Ljubljana area: immediate, delayed and cumulative effects

BACKGROUND

Stroke is a major health problem around the world. Several studies have examine the influence of ambient temperature on incidence of stoke, but they reported different results for different types of stroke and different geographical regions. Hence, effect of ambient temperature is still much of interest, when focusing on ischemic stroke (IS) in regions that have not been examined yet. The aim of our study is to analyse association between IS incidences and short, delayed and cumulative effect of average daily ambient temperature, humidity and pressure in central Europe. To the best of our knowledge, this is the first IS study conducted between 45° and 50° latitude where large part of Central European population resides.

METHODS

We linked daily hospitals' admission data for whole population and separately for two specific age groups with ambient temperature data. We considered patients coming from Ljubljana basin and its immediate surrounding. Data were gathered daily from January 2012 to December 2017. To measure the effect of average ambient temperature, humidity and pressure we used generalized linear model with a log-link-function and a Poisson distribution.

RESULTS

The results of our study show a statistically significant immediate, delayed and cumulative effects of ambient temperatures on IS incidence for the whole population and the population older than 65 years. Specifically, 1 °C reduction in ambient temperature on a given day (Lag 0) increases the IS risk for approximately 5‰ (all population) or 6‰ (population older than 65 years). Similar effects were found for lags from 1 to 6. Analysis of time windows from 0 to 1 days up to 0-28 days also show statistically significant cumulative effect for the same two age groups. IS incidence was not found to be significantly related to pressure or humidity in any group.

CONCLUSION

The findings of this study may help healthcare authorities in central Europe improve existing stroke prevention measures and raise public awareness.