Innovative Approaches Helpful to Enhance Knowledge on Weather-Related Stroke Events Over a Wide Geographical Area and a Large Population

Study on the relationship among typhoon, weather change and acute ischemic stroke in southern Zhejiang Province of China

OBJECTIVE

This study aimed to investigate the relationship between the unique weather change and acute ischemic stroke (AIS) in the southern Zhejiang Province of China and to provide evidence for better predicting and preventing stroke.

METHODS

We retrospectively collected 14,996 ischemic stroke patients data and weather data from January 2019 to December 2021 in the southern Zhejiang Province of China. The correlation and risk between meteorological factors and the number of AIS daily cases were calculated. Wilcoxon rank sum test was used to calculate the difference in the number of cases between typhoon-affected and non-affected periods. A prediction model obeying Poisson regression was established, and the accuracy of the correlation factors in predicting the number of cases was verified.

RESULTS

In southern Zhejiang Province, the number of AIS was the highest in summer and the lowest in spring. Stroke onset is associated with temperature, water vapor pressure and typhoons (P < 0.05). The presence of typhoon (RR 0.882; 95% CI 0.834 to 0.933, P < 0.001) was a protective factor, while maximum temperature (RR 1.021; 95% CI 1.008 to 1.033, P = 0.043) and the water vapor pressure (RR 1.036; 95% CI 1.006 to 1.067, P = 0.036) were risk factors. The occurrence under the influence of typhoons was lower than that without the influence of typhoons (P < 0.05). The prediction model can predict the occurrence of stroke.

CONCLUSION

An association was observed between the occurrence of AIS, temperature, water vapor pressure and typhoon in the southern Zhejiang Province of China. Typhoon occurrence was associated with fewer cases. The predictive model may help high-risk populations prevent diseases early and assist hospitals in allocating resources promptly.

Meteorological factors and risk of ischemic stroke, intracranial hemorrhage, and subarachnoid hemorrhage: A time-stratified case-crossover study

BACKGROUND

Stroke risks associated with rapid climate change remain controversial due to a paucity of evidence.

AIMS

To examine the risk of subarachnoid hemorrhage (SAH), intracranial hemorrhage (ICH), and ischemic stroke (IS) associated with meteorological parameters.

METHODS

In this time-stratified case-crossover study, adult patients hospitalized for their first stroke between 2011 and 2020 from the insurance claims data in Taiwan were identified. The hospitalization day was designated as the case period, and three or four control periods were matched by the same day of the week and month of each case period. Daily mean and 24-h variations in ambient temperature, relative humidity, air pressure, and apparent temperature were measured. Conditional logistic regression models were applied to assess the risk of stroke associated with exposure to weather variables, using the third quintile as a reference, controlling for air pollutant levels.

RESULTS

There were 7161 patients with SAH, 40,426 patients with ICH, and 107,550 patients with IS. There was an inverse linear relationship between mean daily temperature and apparent temperature with ICH. Elevated mean daily atmospheric pressure was associated with an increased risk of ICH. A greater decrease in apparent temperature over a 24-h period was associated with increased risk of ICH but decreased risk of IS (odds ratio (95% confidence interval) for the first vs. third quintile of changes in apparent temperature, 1.141 (1.053-1.237) and 0.946 (0.899-0.996), respectively).

CONCLUSIONS

There were considerable differences in short-term associations between meteorological parameters and three main pathological types of strokes.

DATA ACCESS STATEMENT

The authors have no permission to share the data.

Investigating the impact of weather on stroke in summer

The objective of this study is to explore how changes in weather contribute to an increase in hospital admissions for stroke in summer. We collected 96,509 cases of stroke hospitalization data in Tianjin from 2016 to 2022 summer, along with corresponding meteorological data. The generalized additive model and distributed lag nonlinear model were used to analyze the lag and cumulative effects of temperature on stroke hospitalization. The research results show both the cold effect and the heat effect in summer would increase the risk of hospitalization. The effect of daily maximum temperature on stroke hospitalization was immediate when the temperature was higher, and delayed when the temperature was lower. However, the risk of stroke hospitalization increased more significantly with increasing temperature than with decreasing temperature. In the presence of one or more of the following three weather changes: sharp temperature increase, sharp temperature decrease, continuous high temperature, the daily number of stroke inpatients were higher than the average in the same period. 83% of the Inpatient-heavy events within the study period were caused by a combination of dramatic temperature changes and continuous high temperatures. In 48% of Inpatient-heavy events, continuous high temperature weather above 30℃ for at least 4 consecutive days were observed. And 55% of high temperature weather was accompanied by high humidity. When the daily relative humidity was greater than 70% and the daily maximum temperature was between 26 and 28℃ or more than 34℃, or the daily maximum temperature changes over 10℃ within 48 h, the number of daily inpatients was more than 1.2 times of the average daily inpatients. More attention should be paid to the combined effects of continuous high temperature and sudden temperature changes in summer stroke prevention.

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.

Effect of ambient temperature and other environmental factors on stroke emergency department visits in Beijing: A distributed lag non-linear model

Background

Most studies have focused on the relationship between ambient temperature and stroke mortality, but studies on the relationship between ambient temperature and stroke occurrence are still limited and inconsistent.

Objective

This study aimed to analyze the effect of ambient temperature and other environmental factors on emergency stroke visits in Beijing.

Methods

Our study utilized stroke visit data from the Beijing Red Cross Emergency Medical Center during 2017-2018, and applied a generalized additive model (GAM) as well as a distributed lag non-linear model (DLNM), respectively, regarding the direct, lagged, and cumulative effects of ambient temperature alone and with correction for other environmental factors on stroke occurrence.

Results

With a total of 26,984 emergency stroke patients in 2017-2018, both cold and hot effects were observed and weakened after correction for other environmental factors. Compared to the reference temperature, in the multi-factor model, extreme cold (-10°C) reached a maximum relative risk (RR) of 1.20 [95% Confidence Interval (CI): 1.09, 1.32] at lag 14 days, and extreme hot (30°C) had a maximum RR of 1.07 (95% CI: 1.04, 1.11) at lag 6 days. The cumulative effect of extreme cold reached a maximum of 2.02 (95% CI: 1.11, 3.67) at lag 0-14 days, whereas the cumulative effect of extreme hot temperature is greatest at lag 0-10 days, but no statistically significant effect was found. In addition, ischemic stroke patients, the elderly, and males were more susceptible to the effects of cold temperature.

Conclusions

There is a non-linear relationship between ambient temperature and stroke occurrence, with cold temperature having a greater and longer-lasting impact than hot temperature.

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.

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.

Daily Meteorological Parameters Influence the Risk of Intracerebral Hemorrhage in a Subtropical Monsoon Basin Climate

Background and Purpose

The correlation between meteorological parameters and intracerebral hemorrhage (ICH) occurrence is controversial. Our research explored the effect of daily meteorological parameters on ICH risk in a subtropical monsoon basin climate.

Methods

We retrospectively analyzed patients with ICH in a teaching hospital. Daily meteorological parameters including temperature (TEM), atmospheric pressure (PRE), relative humidity (RHU), and sunshine duration (SSD) were collected, with the diurnal variation (daily maximum minus minimum) and day-to-day variation (average of the day minus the previous day) calculated to represent their fluctuation. We adopted a time-stratified case-crossover approach and selected conditional logistic regression to explore the effect of meteorological parameters on ICH risk. The influence of monthly mean temperature proceeded via stratified analysis. Air pollutants were gathered as covariates.

Results

Our study included 1052 eligible cases with ICH. In a single-factor model, the risk of ICH decreased by 5.9% (P<0.001) for each 1°C higher of the daily mean TEM, and the risk increased by 2.4% (P=0.002) for each 1hPa higher of the daily mean PRE. Prolongation of daily SSD inhibited the risk of ICH, and OR was 0.959 (P=0.007). The risk was raised by 7.5% (P=0.0496) with a 1°C increment of day-to-day variation of TEM. In a two-factor model, the effect of daily mean TEM or daily SSD on ICH risk was still statistically significant after adjusting another factor. The influence of meteorological parameters on ICH risk continued in cold months but disappeared in warm months after stratified analysis.

Conclusion

This research indicates daily TEM and SSD had an inverse correlation to ICH risk in a subtropical monsoon basin climate. They were independent when adjusted by another factor. Daily PRE and day-to-day TEM variation were positively related to ICH risk. The correlation of daily meteorological factors on ICH risk was affected by the monthly thermal background.

The Influence of Selected Meteorological Factors on the Prevalence and Course of Stroke

Background: The objective of this study was to evaluate the impact of weather factors on stroke parameters. Methods: This retrospective study analyzed the records of stroke patients concerning the influence of meteorological conditions and moon phases on stroke parameters. Results: The study group consisted of 402 patients aged between 20 and 102; women constituted 49.8% of the subjects. Ischaemic stroke was diagnosed in 90.5% of patients and hemorrhagic stroke was diagnosed in 9.5% of patients. The highest number of hospitalizations due to stroke was observed in January (48 events); the lowest number was observed in July (23 events). There was no statistically significant correlation between the meteorological parameters on the day of onset and the preceding day of stroke and the neurological status (NIHSS) of patients. Mean air temperature on the day of stroke and the day preceding stroke was significantly lower in the group of patients discharged with a very good functional status (≤2 points in modified Rankin scale (mRS)) compared to the patients with a bad functional status (>2 points in mRS); respectively: 7.98 ± 8.01 vs. 9.63 ± 7.78; p = 0.041 and 8.13 ± 7.72 vs. 9.70 ± 7.50; p = 0.048). Humidity above 75% on the day of stroke was found to be a factor for excellent functional state (RR 1.61; p = 0.016). The total anterior circulation infarcts (in comparison with stroke in the other localization) were more frequent (70%) during a third quarter moon (p = 0.011). The following parameters had a significant influence on the number of stroke cases in relation to autumn having the lowest number of onsets: mean temperature (OR 1.019 95% CI 1.014–1.024, p < 0.000), humidity (OR 1.028, CI 1.023–1.034, p < 0.0001), wind speed (OR 0.923, 95% CI 0.909–0.937, p < 0.0001), insolation (OR 0.885, 95% CI 0.869–0.902, p < 0.0001), precipitation (OR 0.914, 95% CI 0.884–0.946, p < 0.0001). Conclusion: Air humidity and air temperature on the day of stroke onset as well as air temperature on the day preceding stroke are important for the functional status of patients in the acute disease period. A combination of the following meteorological parameters: lowered mean temperature and low sunshine, high humidity and high wind speed all increase the risk of stroke during the winter period. High humidity combined with high precipitation, low wind speed and low sunshine in the autumn period are associated with the lowest stroke incidence risk. A possible relationship between phases of the moon and the incidence requires further investigation.

Weather-related subjective well-being in patients with coronary artery disease

One of the particularly vulnerable groups for adverse weather conditions is people with heart disease. Most of the studies analyzed the association between certain weather conditions and increased mortality, morbidity, hospital admissions, calls, or visits to the emergency department and used as statistical data. This study evaluated associations between daily weather conditions and daily weather-related well-being in patients with coronary artery disease (CAD). From June 2008 to October 2012, a total of 865 consecutive patients with CAD (mean age 60 years; 30% of women) were recruited from the cardiac rehabilitation program at the Hospital Palanga Clinic, Lithuania. To evaluate the well-being, all patients filled in Palanga self-assessment diary for weather sensitivity every day from 8 to 21 days (average 15 ± 3 days) about their well-being (psychological, cardiac, and physical symptoms) on the last day. The weather data was recorded in the database eight times every day with a 3-hour interval using the weather station "Vantage Pro2 Plus" which was located in the same Clinic. The daily averages of the eight time records for weather parameters were calculated and were linked to the same-day diary data. We found that the well-being of patients with CAD was associated with weather parameters; specifically, general well-being was better within the temperature range 9-15 °C and worse on both sides of this range. Worsened general well-being was also associated with higher relative humidity and lower atmospheric pressure. Weather parameters can explain from 3 to 8% of the variance of well-being in patients with CAD.

Seasonal variation of blood pressure in children

Seasonal blood pressure (BP) variation is mostly found between the summer and winter months. Guidelines for diagnosis and treatment of hypertension in children have not considered this variation until recently. This review aims to present an overview of seasonal BP variation in childhood along with potential underlying pathophysiological mechanisms and long-term implications as well as conclusions for future studies. In pediatric cohorts, seven studies investigated seasonal changes in BP. These changes amount to 3.4-5.9 mmHg (or 0.5-1.5 mmHg per - 1 °C difference in environmental temperature) in systolic BP with a peak in fall or winter. Potential mechanisms and mediators of seasonal BP variation include sympathetic activation of the nervous system with an increase of urinary and plasma norepinephrine levels in the winter season. Additionally, the physical activity among children and adolescents was inversely correlated with BP levels. Temperature sensitivity of BP and pediatric BP levels predict future systolic BP and target-organ damage. Therefore, cardiovascular events may even be long-term complications of seasonal BP variation in pediatric hypertensive patients. Overall, these data strongly suggest an important effect of ambient temperature on BP in children. Additional studies in pediatric cohorts are needed to define how best to incorporate such variation into clinical practice.

Exploring stroke risk and prevention in China: insights from an outlier

In contrast to the declining trend in most regions worldwide, the incidence of stroke is increasing in China and is leading to an alarming burden for the national healthcare system. In this review, we have generated new insights from this outlier, and we aim to provide new information that will help decrease the global stroke burden, especially in China and other regions sharing similar problems with China. First of all, several unsolved aspects fundamentally accounting for this discrepancy were promising, including the serious situation of hypertension management, underdiagnosis of atrial fibrillation and underuse of anticoagulants, and unhealthy lifestyles (e.g., heavy smoking). In addition, efforts for further alleviating the incidence of stroke were recommended in certain fields, including targeted antiplatelet regimes and protections from cold wave-related stroke. Furthermore, advanced knowledge about cancer-related strokes, recurrent strokes and the status preceding stroke onset that we called stroke-prone status herein, is required to properly mitigate patient stroke risk, and to provide improved outcomes for patients after a stroke has occurred.

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.

Association between stroke occurrence and changes in atmospheric circulation

Background

The impact of weather on morbidity from stroke has been analysed in previous studies. As the risk of stroke was mostly associated with changing weather, the changes in the daily stroke occurrence may be associated with changes in atmospheric circulation. The aim of our study was to detect and evaluate the association between daily numbers of ischaemic strokes (ISs) and haemorrhagic strokes (HSs) and the teleconnection pattern.

Methods

The study was performed in Kaunas, Lithuania, from 2000 to 2010. The daily numbers of ISs, subarachnoid haemorrhages (SAHs), and intracerebral haemorrhages (ICHs) were obtained from the Kaunas Stroke Register. We evaluated the association between these types of stroke and the teleconnection pattern by applying Poisson regression and adjusting for the linear trend, month, and other weather variables.

Results

During the study period, we analysed 4038 cases (2226 men and 1812 women) of stroke. Of these, 3245 (80.4%) cases were ISs, 533 (13.2%) cases were ICHs, and 260 (6.4%) cases were SAHs. An increased risk of SAH was associated with a change in mean daily atmospheric pressure over 3.9 hPa (RR = 1.49, 95% CI 1.14–1.96), and a stronger El Niño event had a protective effect against SAHs (RR = 0.34, 95% CI 0.16–0.69). The risk of HS was positively associated with East Atlantic/West Russia indices (RR = 1.13, 95% CI 1.04–1.23). The risk of IS was negatively associated with the Arctic Oscillation index on the same day and on the previous day (RR = 0.97, p < 0.033). During November–March, the risk of HS was associated with a positive North Atlantic Oscillation (NAO) (RR = 1.29, 95% CI 1.03–1.62), and the risk of IS was negatively associated with the NAO index (RR = 0.92, 95% CI 0.85–0.99).

Conclusions

The results of our study provide new evidence that the North Atlantic Oscillation, Arctic Oscillation, East Atlantic/West Russia, and El Niño-Southern Oscillation pattern may affect the risk of stroke. The impact of these teleconnections is not identical for various types of stroke. Emergency services should be aware that specific weather conditions are more likely to prompt calls for more severe strokes.

Optimal Antihypertensive Medication Adherence Reduces the Effect of Ambient Temperature on Intracerebral Hemorrhage Occurrence: A Case-Crossover Study

BACKGROUND AND PURPOSE

The role of antihypertensive medication adherence in reducing the effect of ambient temperature (TEM) on intracerebral hemorrhage (ICH) pathogenesis is unclear. We aimed to study the influence of ambient TEM on the ICH occurrence in hypertensive patients with different medication adherence.

METHODS

We enrolled consecutive ICH patients with a definite history of hypertension in a teaching hospital over a period of six years. Medication adherence was calculated using the proportion of prescription days covered (PDC) to antihypertensive mediation in the last month before the ICH attack. Optimal medication adherence (OMA) was the PDC > 80%, and non-optimal medication adherence (non-OMA) was ≤80%. Daily ambient TEM and its variation were collected as the explanatory variables, and dominant air pollutants were gathered as covariates. We adopted a time-stratified case-crossover approach to minimize individual confounders. Conditional logistic regression was conducted to calculate the odds ratio (OR) of daily ambient TEM on ICH occurrence.

RESULTS

We recruited a total of 474 patients in this study. The number of participants with OMA and non-OMA was 249 and 225. Daily mean and max TEM in lag0 to lag2, as well as daily min TEM in lag0 to lag1, were significantly related to ICH onset in all enrolled patients and non-OMA cases. However, only daily TEM in lag0 was meaningfully associated with ICH onset in the OMA cases. The risk of ICH in OMA patients, respectively, changed by 7.9% (OR = 0.921, [0.861, 0.985]) or 6.3% (OR = 0.937, [0.882, 0.995]) when daily mean or max TEM was altered by 1°C in lag0, but the change raised by 10.4% (OR = 0.896, [0.836, 0.960]) or 7.5% (OR = 0.925, [0.868, 0.986]) in non-OMA patients. And the risk varied (OR = 0.933, [0.882, 0.988]) only in non-OMA patients when daily min TEM was altered by 1°C in lag1.

CONCLUSION

Our results indicate that OMA to antihypertensive drugs reduces the influence of ambient TEM on ICH occurrence in hypertensive patients.

Impact of Extreme Temperatures on Ambulance Dispatches Due to Cardiovascular Causes in North-West Spain

Introduction and objectives. The increase in mortality and hospital admissions associated with high and low temperatures is well established. However, less is known about the influence of extreme ambient temperature conditions on cardiovascular ambulance dispatches. This study seeks to evaluate the effects of minimum and maximum daily temperatures on cardiovascular morbidity in the cities of Vigo and A Coruña in North-West Spain, using emergency medical calls during the period 2005–2017. Methods. For the purposes of analysis, we employed a quasi-Poisson time series regression model, within a distributed non-linear lag model by exposure variable and city. The relative risks of cold- and heat-related calls were estimated for each city and temperature model. Results. A total of 70,537 calls were evaluated, most of which were associated with low maximum and minimum temperatures on cold days in both cities. At maximum temperatures, significant cold-related effects were observed at lags of 3–6 days in Vigo and 5–11 days in A Coruña. At minimum temperatures, cold-related effects registered a similar pattern in both cities, with significant relative risks at lags of 4 to 12 days in A Coruña. Heat-related effects did not display a clearly significant pattern. Conclusions. An increase in cardiovascular morbidity is observed with moderately low temperatures without extremes being required to establish an effect. Public health prevention plans and warning systems should consider including moderate temperature range in the prevention of cardiovascular morbidity.

Potential Impacts of Meteorological Variables on Acute Ischemic Stroke Onset

Purpose

The effects of meteorological parameters on stroke occurrence remain debated. The aim of the study was to assess the association between meteorological parameters and ischemic stroke onset in cold seasons in Tianjin.

Patients and Methods

Patients with acute ischemic stroke (946) were identified by standard sampling from one stroke unit in the Second Hospital of Tianjin Medical University, Tianjin, China, from 10/1/2014 to 4/30/2019. Generalized linear Poisson regression models were used to explore the effect of meteorological parameters (air temperature, barometric pressure, and relative humidity) on daily ischemic stroke onset after adjusting for air pollutants, day of week, and public holiday.

Results

The results showed that ischemic stroke onset was positively associated with the diurnal variation of temperature (β coefficient: 0.020, 95% CI [0.001, 0.038] p<0.05). Significant positive correlation between ischemic stroke onset and barometric pressure (mean, minimum) was found (β coefficient: 0.010, 95% CI [0.001,0.019] p<0.05; 0.010, 95% CI [0.001,0.019] p<0.05). The subgroup analysis considering age and gender difference showed that the older and the female were more vulnerable to weather conditions.

Conclusion

Our study demonstrated that there was a measurable effect of weather parameters on daily ischemic stroke onset in colder seasons, suggesting that meteorological variables may, at least in part, play as risk factors for ischemic stroke onset, especially for the aging and female population.

Temperature and Precipitation Associate With Ischemic Stroke Outcomes in the United States

Background

There is disagreement in the literature about the relationship between strokes and seasonal conditions. We sought to (1) describe seasonal patterns of stroke in the United States, and (2) determine the relationship between weather variables and stroke outcomes.

Methods and Results

We performed a cross‐sectional study using Get With The Guidelines‐Stroke data from 896 hospitals across the continental United States. We examined effects of season, climate region, and climate variables on stroke outcomes. We identified 457 638 patients admitted from 2011 to 2015 with ischemic stroke. There was a higher frequency of admissions in winter (116 862 in winter versus 113 689 in spring, 113 569 in summer, and 113 518 in fall; P<0.0001). Winter was associated with higher odds of in‐hospital mortality (odds ratio [OR] 1.08 relative to spring, confidence interval [CI] 1.04–1.13, P=0.0004) and lower odds of discharge home (OR 0.92, CI 0.91–0.94, P<0.0001) or independent ambulation at discharge (OR 0.96, CI 0.94–0.98, P=0.0006). These differences were attenuated after adjusting for climate region and case mix and became inconsistent after controlling for weather variables. Temperature and precipitation were independently associated with outcome after multivariable analysis, with increases in temperature and precipitation associated with lower odds of mortality (OR 0.95, CI 0.93–0.97, P<0.0001 and OR 0.95, CI 0.90–1.00, P=0.035, respectively).

Conclusions

Admissions for ischemic stroke were more frequent in the winter. Warmer and wetter weather conditions were independently associated with better outcomes. Further studies should aim to identify sensitive populations and inform public health measures aimed at resource allocation, readiness, and adaptive strategies.

Effects of heat on first-ever strokes and the effect modification of atmospheric pressure: A time-series study in Shenzhen, China

BACKGROUND

Stroke is a leading cause of death globally. Extreme temperatures may induce stroke, but evidence on the effects of heat on first-ever strokes is not clear. Low air pressure can lead to depression and an increase in blood pressure, and it may exacerbate the health impact of heat. In this study, we aimed to evaluate the effects of heat on first-ever strokes, the possible sensitive populations, and the effect of modification of atmospheric pressure.

METHODS

We collected data on 142,569 first-ever strokes during 2005-2016 in Shenzhen, a coastal city in southern China, with subtropical oceanic monsoon climate. We fitted a time-series Poisson model in our study, estimating the association between daily mean temperature and first-ever strokes in hot months, with a distributed lag non-linear model with 7 days of lag. We calculated strokes attributable to heat in various gender, age groups, household register types, stroke subtypes, and atmospheric pressure levels.

RESULTS

Heat had a significant cumulative association with first-ever strokes, and the risk of strokes increased with the rise in temperature after it was higher than 30 °C (the 85th percentile). In total, 1.95% (95% empirical CI 0.63-3.20%) of first-ever strokes were attributable to high temperature. The attributable fraction and attributable number of heat were statistically significant in male, female, middle-aged and old patients, immigrant patients, and CBI patients. The fraction attributable to heat was 3.33% in the low atmospheric pressure group, and the number of estimated daily attributable strokes at low atmospheric pressure levels was higher than that of medium and high atmospheric pressure levels (p < 0.01).

CONCLUSIONS

High temperatures in hot months may trigger first-ever strokes, and low atmospheric pressure may exacerbate the effect. We mainly found associations between heat and first-ever strokes for intracerebral hemorrhage, middle-aged and old patients, as well as immigrant patients.

The effect characteristics of temperature on stroke mortality in Inner Mongolia and globally

The current study investigated the correlation between stroke mortality and temperature. Monthly and seasonal variations in stroke mortality were plotted and daily stroke-related deaths were calculated. The lag times were calculated using the time series analysis. The correlation between stroke incidence and the diurnal temperature range (DTR) was analyzed using case-crossover analysis. Global stroke mortality was described in five latitudes. In the eastern region of Inner Mongolia, the stroke mortality was 174.18/105, about twice of that of the midwestern regions (87.07/105), and temperature was negatively correlated with stroke mortality. Mortality peaked in the winter and troughed in the summer (χ² = 13.634, P < 0.001). The days in which stroke-related deaths were greater than ten occurred between late October and early April. The effect of temperature on stroke incidence occurred during a lag time of 1 (P = 0.024) or 2 months (P = 0.039). A DTR over 13 °C was positively correlated (r = 0.95, P = 0.004) with stroke with a lag time of 1 day. The effect of temperature on stroke was shown to be the same for various populations. As the latitude increases, stroke mortality also increases with latitudes > 40°; the highest mortality was 188.05/105 at the highest latitude. Only in relatively cold regions as the temperature decreases does stroke mortality increase for various populations. Differences in the time lag as well as in the DTR lag and DTR critical point vary for both the temperature and region.

Differences of hemorrhagic and ischemic strokes in age spectra and responses to climatic thermal conditions

The risks of emergency room (ER) visits for cerebral infarction (CI) and intracerebral hemorrhage (ICH) is found to differ in different age groups under different climatic thermal environments. Based on CI and ICH related ER-visit records from three major hospitals in Beijing, China, from 2008 to 2012, the advanced Universal Thermal Climate Index (UTCI), was adopted in this study to assess the climatic thermal environment. Particularly, daily mean UTCI was used as a predictor for the risk of ER visits for CI and ICH. A generalized quasi-Poisson additive model combined with a distributed lag non-linear model was performed to quantify their association. The results indicated that (i) the highest growth rate of ER visits for ICH occurred in age 38 to 48, whereas an increasing ER admissions for CI maintained at age 38 to 78. (ii) The frequency distribution of UTCI in Beijing peaked at -8 and 30 °C, corresponding to moderate cold stress and moderate heat stress, respectively. (iii) Correlation analysis indicated that ICH morbidity was negatively correlated with UTCI, whereas occurrence of CI showed no significant association with UTCI. (iv) The estimated relative risk of ER visits corresponding to 1 °C change in UTCI, which was then stratified by age and gender, indicated that all sub-groups of ICH patients responded similarly to thermal stress. Namely, there is an immediate ICH risk (UTCI = -13 °C, RR = 1.35, 95% CIs: 1.11-1.63) from cold stress on the onset day, but non-significant impact from heat stress. As for CI occurrences, no effect from cold stress was identified, except for only those aged 45 to 65 were threatened by heat stress (UTCI = 38 °C, RR = 1.64, 95% CIs: 1.10-2.44) on lag 0-2 d.

Daylight saving time, circadian rhythms, and cardiovascular health

Very recently, the European Parliament, called to decide on possible abolition of the Daylight Saving Time (DST), approved a resolution calling the scientific community to conduct a more in-depth evaluation. The question is based on disruption of body's circadian rhythms. We review here the relationship between DST and cardiovascular health. The available evidence suggests the existence of an association between DST and a modest increase of occurrence of acute myocardial infarction, especially in the first week after the spring shift. Possible mechanisms include sleep deprivation, circadian misalignment and environmental conditions. The role of gender and individual preference in circadian rhythms (chronotype) will need further assessment.

Mean air temperature as a risk factor for stroke mortality in São Paulo, Brazil

In Brazil, chronic diseases account for the largest percentage of all deaths among men and women. Among the cardiovascular diseases, stroke is the leading cause of death, accounting for 10% of all deaths. We evaluated associations between stroke and mean air temperature using recorded mortality data and meteorological station data from 2002 to 2011. A time series analysis was applied to 55,633 mortality cases. Ischemic and hemorrhagic strokes (IS and HS, respectively) were divided to test different impact on which subgroup. Poisson regression with distributed lag non-linear model was used and adjusted for seasonality, pollutants, humidity, and days of the week. HS mortality was associated with low mean temperatures for men relative risk (RR) = 2.43 (95% CI, 1.12-5.28) and women RR = 1.39 (95% CI, 1.03-1.86). RR of IS mortality was not significant using a 21-day lag window. Analyzing the lag response separately, we observed that the effect of temperature is acute in stroke mortality (higher risk among lags 0-5). However, for IS, higher mean temperatures were significant for this subtype with more than 15-day lag. Our findings showed that mean air temperature is associated with stroke mortality in the city of São Paulo for men and women and IS and HS may have different triggers. Further studies are needed to evaluate physiologic differences between these two subtypes of stroke.

Effects of Barometric Pressure and Temperature on Acute Ischemic Stroke Hospitalization in Augusta, GA

Several studies worldwide have demonstrated significant relationships between meteorological parameters and stroke events. However, authors often reported discordant effects of both barometric pressure and air temperature on stroke occurrence. The present study investigated whether there was an association between weather parameters (barometric pressure and temperature) and ischemic stroke hospitalization. The aim of the study was to find out whether daily barometric pressure may be used as a prognostic variable to evaluate the workload change of a neurological intensive care unit. We conducted a retrospective review study in which we collected the independent (barometric pressure and temperature) and dependent variables (stroke hospitalization) every 24 h for the periods 10/1/2016-4/30/2017 at Augusta University Medical Center of Augusta, GA. We analyzed the data with zero-inflated Poisson model to assess the relationship between the barometric pressure, temperature, and daily stroke hospitalization. The results showed that there was a significantly correlation between daily barometric pressure variation and daily stroke hospitalization, especially on elder male patients (≥ 65). Stroke events were more likely to occur in the patients with risk factors than in those without risk factors when exposed to barometric pressure and temperature changes. Decreased barometric pressure and increased temperature were associated with increased daily stroke hospitalization. Furthermore, there was a potential delayed effect of increased stroke events after cold temperature exposure. Barometric pressure and temperature changes over the preceding 24 h are associated with daily stroke hospitalization. These findings may enhance our understanding of relationship between stroke and weather and maybe used in the development of public health strategies to minimize the weather-related stroke risk.

Echoes from Gaea, Poseidon, Hephaestus, and Prometheus: environmental risk factors for high blood pressure

High blood pressure (BP) affects over one billion people and is the leading risk factor for global mortality. While many lifestyle and genetic risk factors are well-accepted to increase BP, the role of the external environment is typically overlooked. Mounting evidence now supports that numerous environmental factors can promote an elevation in BP. Broadly speaking these include aspects of the natural environment (e.g., cold temperatures, higher altitude, and winter season), natural disasters (e.g., earthquakes, volcanic eruptions), and man-made exposures (e.g., noise, air pollutants, and toxins/chemicals). This is important for health care providers to recognize as one (or several) of these environmental factors could be playing a clinically meaningful role in elevating BP or disrupting hypertension control among their patients. At the population level, certain environmental exposures may even be contributing to the growing pandemic of hypertension. Here we provide an updated review of the literature linking environment exposures with high BP and outline practical recommendations for clinicians.

Impact of Ambient Temperature on Incidence of Acute Lower Limb Ischemia

BACKGROUND

This was a retrospective study to explore the possible association between atmospheric temperatures with the occurrence of acute leg ischemia (ALI).

METHODS

A linear regression analysis was performed for a period of 10 years on the impact of ambient temperature on the incidence of ALI. Mean ambient temperature on a daily basis was retrieved electronically from our observatory, and the daily incidence of ALI was retrieved from the Clinical Data Analysis and Reporting (CDAR) system. CDAR system could retrieve clinical data from all 42 public hospitals in our region, which provided almost 90% inpatient care of the population. Daily incidence was defined as total number of emergency admissions from all 42 pubic hospitals due to ALI from 00:00 till 23:59 hr of that day.

RESULTS

For the 10-year period, spanning from January 2005 to December 2014, there were a total of 634 recorded ALI with revascularization, 608 (95.9%) of which underwent emergency femoral embolectomy, 15 (2.4%) underwent thrombolysis, and 11 (1.7%) underwent thrombolysis and embolectomy. ALIs with primary amputation or conservative management were excluded from the study. The average daily incidence of ALI was 0.170. A linear regression model was built using mean ambient temperature as independent variable and incidence of ALI as dependent variables. The line of best fit was drawn through the data points. The daily incidence of ALI could be predicted by ambient temperature (in °C) with the equation: incidence = 0.274-0.004 × temperature (linear regression; r = -0.053, r² = 0.003, F = 10.42, and P = 0.001). In other words, daily incidence was 0.274 at 0°C; and for every 10°C increase, the incidence would drop by 0.040. At 30°C, daily incidence of ALI was 0.154.

CONCLUSIONS

This study showed an association of cold temperature and ALI in our population. Measures to protect the susceptible population from cold temperatures should be considered.

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.

Modulation of blood pressure in response to low ambient temperature: The role of DNA methylation of zinc finger genes

BACKGROUND

Blood pressure rises with a drop in external temperature, but the role of DNA methylation in such blood pressure modulation has not been studied in detail. We evaluated blood pressure and DNA methylation of vascular disease-related genes in association with low temperature.

METHODS

To examine changes in blood pressure and DNA methylation associated with low temperature, we conducted repeated measures analysis among 50 participants over 3 repeated visits, and validated the association among another 52 participants. In addition, the mean of methylation changes in the identified CpG sites was evaluated with changes in blood pressure. Mediation analyses were also conducted to model the indirect association between low ambient temperature and blood pressure through changes in DNA methylation.

RESULTS

With a 1°C decrease in temperature, increases of 0.6mmHg (standard error (SE), 0.2) in SBP and 0.3mmHg (SE, 0.1) in DBP occurred (P<0.05). Of 24,490 CpG sites in vascular genes, 2 CpG sites of zinc finger (ZNF) genes were significantly associated with temperature after Bonferroni's correction in discovery and replication data. A 10% increase in methylation expression in 2 CpG sites in ZNF genes was associated with a 4-mmHg elevation in DBP (SE, 1.8; P=0.0236). The hypermethylation was attributable to the association of ambient temperature with DBP (proportion of mediation=11.8-20.4%).

CONCLUSIONS

Methylation changes in ZNF genes might be involved in the elevation of blood pressure when the body is exposed to cold temperature.

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.

Ambient Temperature and Stroke Occurrence: A Systematic Review and Meta-Analysis

Biologically plausible associations exist between climatic conditions and stroke risk, but study results are inconsistent. We aimed to summarize current evidence on ambient temperature and overall stroke occurrence, and by age, sex, and variation of temperature. We performed a systematic literature search across MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, and GEOBASE, from inception to 16 October 2015 to identify all population-based observational studies. Where possible, data were pooled for meta-analysis with Odds ratios (OR) and corresponding 95% confidence intervals (CI) by means of the random effects meta-analysis. We included 21 studies with a total of 476,511 patients. The data were varied as indicated by significant heterogeneity across studies for both ischemic stroke (IS) and intracerebral hemorrhage (ICH). Pooled OR (95% CI) in every 1 degree Celsius increase in ambient temperature was significant for ICH 0.97 (0.94–1.00), but not for IS 1.00 (0.99–1.01) and subarachnoid hemorrhage (SAH) 1.00 (0.98–1.01). Meta-analysis was not possible for the pre-specified subgroup analyses by age, sex, and variation of temperature. Change in temperature over the previous 24 h appeared to be more important than absolute temperature in relation to the risk of stroke, especially in relation to the risk of ICH. Older age appeared to increase vulnerability to low temperature for both IS and ICH. To conclude, this review shows that lower mean ambient temperature is significantly associated with the risk of ICH, but not with IS and SAH. Larger temperature changes were associated with higher stroke rates in the elderly.

Air Pressure, Humidity and Stroke Occurrence: A Systematic Review and Meta-Analysis

Background/Aims: An influence of climate upon stroke risk is biologically plausible and supported by epidemiological evidence. We aimed to determine whether air pressure (AP) and humidity are associated with hospital stroke admission. Methods: We searched MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, and GEOBASE, from inception to 16 October 2015 to identify relevant population-based observational studies. Where possible, data were pooled for meta-analysis with odds ratios (OR) and corresponding 95% confidence intervals (CI) by means of the random-effect method. Results: We included 11 studies with a total of 314,385 patients. The effect of AP was varied across studies for ischemic stroke (IS) and subarachnoid haemorrhage (SAH). Pooled ORs (95%CI) associated with 1 hPa increase in AP for the risk of IS, intracerebral hemorrhage (ICH) and SAH were 1.00 (0.99–1.01), 1.01 (0.99–1.02) and 1.02 (0.97–1.07) respectively. The pooled ORs (95%CI) associated with 1 percent increase in humidity for the risk of IS and ICH were 1.00 (1.00–1.01) and 1.00 (0.99–1.01) respectively. Conclusion: This review shows that there is no evidence of a relationship between AP or humidity and the occurrence of hospital admission for stroke. Further research is needed to clarify the extent and nature of any relationship between AP, humidity and stroke in different geographical areas.

Influence of meteorological factors on acute aortic events in a subtropical territory

BACKGROUND/OBJECTIVE

This study aims to examine the relationship between weather changes and acute aortic events in a subtropical territory.

METHODS

A linear regression analysis was performed in a pan-territory epidemiological survey for a period of 10 years on the impacts of meteorological factors (ambient temperature, atmospheric pressure, relative humidity, amount of cloud, rainfall, number of lightning strikes, presence of typhoon, and thunderstorm warning) on the daily incidences of acute aortic dissections and ruptured aortic aneurysms. Meteorological variables were retrieved on a daily basis from a well-established observatory, and the daily incidences of aortic dissections and rupture of aortic aneurysms were retrieved from the Clinical Data Analysis and Reporting System.

RESULTS

During the study period (January 2005 to December 2014), 3878 patients were identified as having acute aortic dissections, and 1174 patients had ruptured aortic aneurysms. Corresponding averaged daily incidences were 1.06 and 0.32, respectively. The incidences of aortic dissection and ruptured aortic aneurysm in a day could be predicted by ambient temperature in degrees Celsius using the following linear regression models: (1) incidence of aortic dissection = 1.548 - 0.021 × temperature; (2) incidence of ruptured aortic aneurysm = 0.564 - 0.010 × temperature. In addition, both high atmospheric pressure and absence of thunderstorm warning are positively associated with more aortic dissections. For rupture of aortic aneurysms, high atmospheric pressure and low relative humidity were positive predictors. In multiple regression analysis, however, ambient temperature was the only significant predictor for both acute aortic dissections and ruptured aortic aneurysms.

CONCLUSION

This is the first pan-territory study to show an attributable effect of ambient temperature on acute aortic events. This paper confirms that even in a subtropical country, meteorological variables were important factors influencing acute aortic events.

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.

Effect of seasonal and monthly variation in weather and air pollution factors on stroke incidence in Seoul, Korea

BACKGROUND AND PURPOSE

The purpose of the present study was to determine whether seasonal and monthly variations in stroke incidence exist and whether they are related to meteorologic and air pollution parameters under similar weather and environmental conditions in selected areas of Seongdong district, Seoul, South Korea.

METHODS

From January 1, 2004, to December 31, 2013, 3001 consecutive stroke events were registered in residents of selected areas of Seongdong district, Seoul, South Korea. The authors calculated the stroke attack rate per 100,000 people per month and the relative risk of stroke incidence associated with meteorologic and air pollution parameters. We also analyzed odds ratios with a 95% confidence interval for seasonal and monthly stroke incidence.

RESULTS

The incidence of stroke in September was significantly higher (odds ratio, 1.233; 95% confidence interval, 1.042-1.468) compared with January. The seasonal ischemic stroke incidence in summer (odds ratio, 1.183; 95% confidence interval, 1.056-1.345) was significantly higher than in winter, whereas the seasonal incidence of intracerebral hemorrhage relative to winter was not significant. The mean temperature was positively correlated with ischemic stroke (relative risk, 1.006; P=0.003), and nitrogen dioxide (relative risk, 1.262; P=0.001) showed a strong positive correlation with intracerebral hemorrhage incidence among the older age group.

CONCLUSIONS

We demonstrated distinct patterns of seasonal and monthly variation in the incidence of stroke and its subtypes through consideration of the meteorologic and air pollution parameters. We therefore expect that these findings may enhance our understanding of the relationships between stroke and weather and pollutants.

Meteorological Variables Associated with Stroke

To elucidate relationships between meteorological variables and incidence of stroke, we studied patients diagnosed with stroke after presenting to the emergency department (May 1, 2010–August 8, 2011). Patient demographics and medical data were reviewed retrospectively with regional meteorological data. Across 467 days, 134 stroke events were recorded on 114 days. On stroke days, maximum temperature (max T) and atmospheric pressure (AP) combined were a significant predictor of stroke (max T odds ratio (OR) = 1.014, 95% confidence interval (CI) = 1.003–1.026, and P = 0.04; AP: OR = 1.033, 95% CI = 0.997–1.071, and P = 0.02). When the patient could identify the hour of the stroke, average temperature (avg T) was significantly higher than nonstroke hours (18.2°C versus 16.16°C, P = 0.04). Daily fluctuations in AP and avg T also had significant effects on stroke incidence (AP: OR = 0.629, 95% CI = 0.512–0.773, and P = 0.0001; avg T OR = 1.1399, 95% CI = 1.218–606, and P = 0.0001). Patient age, stroke history, body mass index, ethnicity, and sex were further contributors to stroke risk. Temperature, atmospheric pressure, and certain physiological conditions likely play roles in weather-related stroke susceptibility. The mechanisms driving these associations are not fully understood.

Identification of potential biomarkers for artificial cold exposure-induced hypertensive stroke by proteomic analysis

BACKGROUND

The effect of changing temperature on an individual's cerebrovascular risk is both biologically plausible and supported by epidemiologic evidence. We used a global proteomic-based approach to analyze the expression alterations of proteins in artificial cold exposure (ACE)-induced hypertensive stroke in renovascular hypertensive rats (RHR) and to identify the biomarker of ACE-induced hypertensive stroke.

METHODS

The RHR models were established by 2 kidney 2 clip methods. ACE treatment was achieved using an intelligent artificial climate cabinet. Blood pressure and neurologic symptoms were observed before and after ACE treatment. Hemorrhagic condition and infarction survey were examined using 2,3,5-triphenyltetrazolium chloride staining. The total number of proteins derived from the cerebral tissue of the RHR models were analyzed with 2-dimensional gel electrophoresis (2-DE), ImageMaster 2D Platinum software, and mass spectrometry. Significantly regulated proteins selected for further functional studies using the Search Tool for the Retrieval of Interacting Genes/Proteins system were verified by Western blot.

RESULTS

ACE-induced stroke in the RHR group (31.25%, 25 of 80 vs. 16.25%, 13 of 80; P < .05) but not in the sham-operated group. Following ACE treatment, we identified 37 differentially expressed proteins and 28 were unique. Two of the upregulated proteins, Syt1 and Idh3a, were obtained by bioinformatics analysis and verified by Western blot.

CONCLUSIONS

The rate of morbidity as a result of stroke in RHR was obviously elevated after ACE treatment. ACE might affect protein expression profile in cerebral tissues of RHR. Syt1 and Idh3a may play a vital role in ACE-induced hypertensive stroke.

Age and meteorological factors in the occurrence of spontaneous intracerebral hemorrhage in a metropolitan city

Objective

The aim of this study was to investigate the correlation between meteorological factors and occurrence of spontaneous intracerebral hemorrhage (ICH) according to age.

Materials and Methods

We retrospectively analyzed the records of 735 ICH patients in a metropolitan hospital-based population. Observed and expected numbers of ICH patients were obtained at 5℃ intervals of ambient temperature and a ratio of observed to expected frequency was then calculated. Changes in ambient temperature from the day before ICH onset day were observed. The Wilcoxon-Mann-Whitney test was used to test differences in meteorological variables between the onset and non-onset days. The Kruskal-Wallis test was used for comparison of meteorological variables across gender and age.

Results

ICH was observed more frequently (observed/expected ratio ≥ 1) at lower mean, minimum, and maximum ambient temperature (p = 0.0002, 0.0003, and 0.0002, respectively). Significantly lower mean, minimum, and maximum ambient temperature, dew point temperature, wind speed, and atmospheric pressure (p = 0.0003, 0.0005, 0.0001, 0.0013, 0.0431, and 0.0453, respectively) was observed for days on which spontaneous ICH occurred. In the subgroup analysis, the ICH onset day showed significantly lower mean, minimum, and maximum ambient temperature, dew point temperature, relative humidity, and higher atmospheric pressure in the older (≥ 65 years) female group (p = 0.0093, 0.0077, 0.0165, 0.0028, 0.0055, and 0.0205, respectively).

Conclusion

Occurrence of spontaneous ICH is closely associated with meteorological factors and older females are more susceptible to lower ambient temperature.

Air temperature exposure and outdoor occupational injuries: a significant cold effect in Central Italy

OBJECTIVE

To investigate the short-term effect of air temperature on outdoor occupational injuries (out_OI) in Central Italy, also by taking different geographical factors and employment sectors of workers into account.

METHODS

Out_OI for all of Tuscany (Central Italy), from 2003 to 2010 (n=162,399), were provided by the National Institute of Insurance for Occupational Illness and Injury. Representative daily meteorological data of the geographical area under study were obtained from the European Reanalysis-interim climatological reanalysis archive. Relationships between short-term changes in air temperature and out_OI were studied through Generalised Additive Models.

RESULTS

The exposure-response curves of out_OI and short-term changes in air temperature generally showed significant out_OI increases when cold conditions occurred. The air temperature breakpoint corresponded to the 10th centile (-0.8°C) of the air temperature time series used in this study: a 1°C decrease in temperature below the 10th centile corresponded to a 2.3% (CI 1.3% to 3.3%) increase of out_OI throughout all of Tuscany. The cold effect was strongest in plain areas, especially when out_OI occurred in vehicles other than cars. No relationships of injuries with temperature extremes were observed in workers who generally spend half or most of their time outdoors, such as construction, land and forestry workers. However, these latter outdoor workers showed significant linear associations of injuries with typical (far-from-extreme) temperatures.

CONCLUSIONS

This large population-based study highlights the significant and independent effects of short-term air temperature changes (especially cold) in triggering out_OI. These findings represent the first step towards developing a geographically differentiated, operative outdoor-temperature-occupational-health warning system aimed at preventing outdoor work injuries.

The influence of meteorological and geomagnetic factors on acute myocardial infarction and brain stroke in Moscow, Russia

Evidence of the impact of air temperature and pressure on cardiovascular morbidity is still quite limited and controversial, and even less is known about the potential influence of geomagnetic activity. The objective of this study was to assess impacts of air temperature, barometric pressure and geomagnetic activity on hospitalizations with myocardial infarctions and brain strokes. We studied 2,833 myocardial infarctions and 1,096 brain strokes registered in two Moscow hospitals between 1992 and 2005. Daily event rates were linked with meteorological and geomagnetic conditions, using generalized linear model with controls for day of the week, seasonal and long-term trends. The number of myocardial infarctions decreased with temperature, displayed a U-shaped relationship with pressure and variations in pressure, and increased with geomagnetic activity. The number of strokes increased with temperature, daily temperature range and geomagnetic activity. Detrimental effects on strokes of low pressure and falling pressure were observed. Relative risks of infarctions and strokes during geomagnetic storms were 1.29 (95% CI 1.19-1.40) and 1.25 (1.10-1.42), respectively. The number of strokes doubled during cold spells. The influence of barometric pressure on hospitalizations was relatively greater than the influence of geomagnetic activity, and the influence of temperature was greater than the influence of pressure. Brain strokes were more sensitive to inclement weather than myocardial infarctions. This paper provides quantitative estimates of the expected increases in hospital admissions on the worst days and can help to develop preventive health plans for cardiovascular diseases.

Season, temperature and blood pressure: a complex interaction

An increase in blood pressure values measured during winter either in the office, at home, or at ambulatory blood pressure monitoring was consistently observed. Besides potentially contributing to increase the risk for cardiovascular events during the cold season, long term blood pressure variations can influence results of clinical trials, epidemiological surveys, and require personalized management of antihypertensive medications in the single patient. Those variations are often considered as an effect of climate, due to the close correlation observed in various countries and in different settings between temperature and blood pressure among children, adults, and specially the elderly. However, obtaining true measurements of exposition is a main problem when investigating the effects of climate on human health especially when the aim is to disentangle the effects of climate from those of seasonality. The aim of the present note is not to provide a complete review of the literature demonstrating the implications of seasonal blood pressure changes in the clinical and experimental setting; rather it is to consider methodological aspects useful to investigate the interaction between seasonality and temperature on blood pressure and to make health care providers aware of the implications of environmental factors on blood pressure in clinical and research settings.

Association of global weather changes with acute coronary syndromes: gaining insights from clinical trials data

The aim of this study was to develop a method for the identification of global weather parameters and patient characteristics associated with a type of heart attack in which there is a sudden partial blockage of a coronary artery. This type of heart attack does not demonstrate an elevation of the ST segment on an electrocardiogram and is defined as a non-ST elevation acute coronary syndrome (NSTE-ACS). Data from the Global Summary of the Day database was linked with the enrollment and baseline data for a phase III international clinical trial in NSTE-ACS in four 48-h time periods covering the week prior to the clinical event that prompted enrollment in the study. Meteorological events were determined by standardizing the weather data from enrollment dates against an empirical distribution from the month prior. These meteorological events were then linked to the patients' geographic region, demographics and comorbidities to identify potential susceptible populations. After standardization, changes in temperature and humidity demonstrated an association with the enrollment event. Additionally there appeared to be an association with gender, region and a history of stroke. This methodology may provide a useful global insight into assessing the biometeorologic component of diseases from international data.

Seasonal blood pressure changes: an independent relationship with temperature and daylight hours

Seasonal blood pressure (BP) changes have been found to be related to either outdoor or indoor temperature. No information regarding the independent effects of temperature measured proximally to the patient, the personal-level environmental temperature (PET), is available. Inclusion of daylight hours in multivariate analysis might allow exploring the independent interaction of BP with seasonality. To investigate whether ambulatory BP monitoring is affected by PET or by seasonality, 1897 patients referred to our hypertension units underwent ambulatory BP monitoring with a battery-powered temperature data logger fitted to the carrying pouch of the monitor. Predictors of 24-hour daytime and nighttime BP and of morning BP surge were investigated with a multivariate stepwise regression model, including age, sex, body mass index, antihypertensive treatment, office BP, ambulatory heart rate, PET, relative humidity, atmospheric pressure, and daylight hours as independent variables. At adjusted regression analysis, daytime systolic BP was negatively related to PET (-0.14; 95% confidence interval, -0.25 to -0.02); nighttime BP was positively related to daylight hours (0.63; 0.37-0.90); and morning BP surge was negatively related to daylight hours (-0.54; -0.87 to -0.21). These results provide new evidence that PET and seasonality (daylight hours) are 2 independent predictors of ambulatory BP monitoring.

Variation in mortality of ischemic and hemorrhagic strokes in relation to high temperature

Outdoor temperature has been reported to have a significant influence on the seasonal variations of stroke mortality, but few studies have investigated the effect of high temperature on the mortality of ischemic and hemorrhagic strokes. The main study goal was to examine the effect of temperature, particularly high temperature, on ischemic and hemorrhagic strokes. We investigated the association between outdoor temperature and stroke mortality in four metropolitan cities in Korea during 1992-2007. We used time series analysis of the age-adjusted mortality rate for ischemic and hemorrhagic stroke deaths by using generalized additive and generalized linear models, and estimated the percentage change of mortality rate associated with a 1°C increase of mean temperature. The temperature-responses for the hemorrhagic and ischemic stroke mortality differed, particularly in the range of high temperature. The estimated percentage change of ischemic stroke mortality above a threshold temperature was 5.4 % (95 % CI, 3.9-6.9 %) in Seoul, 4.1 % (95 % CI, 1.6-6.6 %) in Incheon, 2.3 % (-0.2 to 5.0 %) in Daegu and 3.6 % (0.7-6.6 %) in Busan, after controlling for daily mean humidity, mean air pressure, day of the week, season, and year. Additional adjustment of air pollution concentrations in the model did not change the effects. Hemorrhagic stroke mortality risk significantly decreased with increasing temperature without a threshold in the four cities after adjusting for confounders. These findings suggest that the mortality of hemorrhagic and ischemic strokes show different patterns in relation to outdoor temperature. High temperature was harmful for ischemic stroke but not for hemorrhagic stroke. The risk of high temperature to ischemic stroke did not differ by age or gender.

Air temperature-related human health outcomes: current impact and estimations of future risks in Central Italy

The association between air temperature and human health is described in detail in a large amount of literature. However, scientific publications estimating how climate change will affect the population's health are much less extensive. In this study current evaluations and future predictions of the impact of temperature on human health in different geographical areas have been carried out. Non-accidental mortality and hospitalizations, and daily average air temperatures have been obtained for the 1999-2008 period for the ten main cities in Tuscany (Central Italy). High-resolution city-specific climatologic A1B scenarios centered on 2020 and 2040 have been assessed. Generalized additive and distributed lag models have been used to identify the relationships between temperature and health outcomes stratified by age: general adults (<65), elderly (aged 65-74) and very elderly (≥75). The cumulative impact (over a lag-period of 30 days) of the effects of cold and especially heat, was mainly significant for mortality in the very elderly, with a higher impact on coastal plain than inland cities: 1 °C decrease/increase in temperature below/above the threshold was associated with a 2.27% (95% CI: 0.17-4.93) and 15.97% (95% CI: 7.43-24.51) change in mortality respectively in the coastal plain cities. A slight unexpected increase in short-term cold-related mortality in the very elderly, with respect to the baseline period, is predicted for the following years in half of the cities considered. Most cities also showed an extensive predicted increase in short-term heat-related mortality and a general increase in the annual temperature-related elderly mortality rate. These findings should encourage efforts to implement adaptation actions conducive to policy-making decisions, especially for planning short- and long-term health intervention strategies and mitigation aimed at preventing and minimizing the consequences of climate change on human health.