Association of cold ambient temperature and cardiovascular markers

Hourly level analysis of the effects of temperature extremes on emergency ambulance calls

Methods

We obtained hourly data on EACs, weather conditions, and air pollutants from Nanjing, a megacity in eastern China, during 2018-21. We first extracted data from the cold and warm seasons to quantify the hourly impact of extreme cold and heat on EACs and potential modifying factors using a distributed lag nonlinear model. Then, we used a random-effects meta-analysis model to pool the estimates of extreme temperatures on EACs from this Nanjing study and from studies identified in the published literature.

Results

The results showed that hourly exposure to extreme cold and heat increased the risk of EACs for all non-accidental causes, with relative risks (RRs) of 1.175 (95% confidence interval (CI) = 1.135, 1.216) at lag seven to 22 hours and 1.096 (95% CI = 1.048, 1.146) at lag zero to 10 hours, respectively. Stronger extreme heat-EAC associations were found between 16:00-24:00. The meta-analysis, which additionally included four prior studies, confirmed a significant association between hourly exposure to temperature extremes and EAC risk (RR = 1.155 for extreme cold and RR = 1.172 for extreme heat).

Conclusions

Our findings indicate that transient exposure to temperature extremes can increase the demand for EACs within a few hours, which may have implications for improving ambulance service efficiency and developing an ambulance early warning system under extreme weather conditions.

Association of cold weather and influenza infection with stroke: a 22-year time-series analysis

Despite the significant adverse health effects and economic burden of stroke inpatients, there has been a paucity of research specifically analyzing and quantifying the association between meteorological factors, air pollutants, influenza infection, and stroke admissions. This study assessed the impact of environmental factors and influenza activity on stroke admissions in Hong Kong from 1998 to 2019, utilizing population-based records. We employed the number of weekly stroke admissions as the primary outcome measure and matched the number with meteorological factors and air pollutant concentrations. Strain-specific influenza-like illness-positive (ILI+) rates were used as a proxy indicator of influenza activity. A quasi-Poisson generalized additive model in combination with a distributed-lag non-linear model (DLNM) was employed to elucidate the relationship of interest. Over the 22-year period, a total of 1,170,882 stroke-related admissions were recorded in Hong Kong. The cumulative adjusted relative risk (ARR) of stroke admission was significantly increased (cumulative ARR = 1.106, 95% CI, 1.069-1.143) at the 5th percentile of temperature (i.e., 15.08 °C) compared with the median reference level. Using zero as the reference value, the cumulative adjusted relative risks of stroke admission were 1.030 (95% CI, 1.018-1.042) at the 95th percentile of ILI + A/H1N1 rate, and 1.022 (95% CI, 1.007-1.038) at the 95th percentile of ILI + total rate. In conclusion, cold weather and influenza infection are risk factors to stroke admissions. Public health strategies for preventing stroke should be considered such as advocating influenza vaccination programmes during winter.

Comorbidities, Tobacco Exposure, and Geography: Added Risk Factors of Heat and Cold Wave-related Mortality among U.S. Veterans with Chronic Obstructive Pulmonary Disease

Rationale: Understanding the health risks associated with extreme weather events is needed to inform policies to protect vulnerable populations. Objectives: To estimate heat and cold wave-related mortality risks in a cohort of veteran patients with chronic obstructive pulmonary disease (COPD) and explore disparities among strata of comorbidities, tobacco exposure, and urbanicity. Methods: We designed a time-stratified case-crossover study among deceased patients with COPD between 2016 and 2021 in the Veterans Health Administration system. Distributed lag models with conditional logistic regression estimated incidence rate ratios of heat and cold wave-associated mortality risk from lag days 0 to 3 for heatwaves and lag days 0 to 7 for cold waves. Attributable risks (ARs) per 100,000 patients were also calculated. Results: Of the 377,545 deceased patients with COPD, the largest heatwave-related mortality risk was in patients with COPD and asthma (AR, 14,016; 95% confidence interval [CI], -326, 30,706) across lag days 0 to 3. The largest cold wave-related mortality burden was in patients with COPD with no other reported comorbidities (AR, 1,704; 95% CI, 759, 2,686) across lag days 0 to 7. Patients residing in urban settings had the greatest heatwave-related (AR, 1,062; 95% CI, 576, 1,559) and cold wave-related (AR, 1,261; 95% CI, 440, 2,105) mortality risk (across lag days 0 to 1 and 0 to 7, respectively). There were no differences in mortality risk by tobacco exposure. Conclusions: Our findings show that individuals with COPD are susceptible to heat and cold waves. This information can inform clinical practice and public health policy about the mortality risk vulnerable populations experience with respect to extreme weather conditions. Furthermore, our results may be used in the development and refinement of future extreme weather warning systems designed for public health purposes.

The effect of ambient temperature on lipid metabolism in children: From a prospective cohort study

BACKGROUND

Dyslipidemia is increasingly recognized as an essential risk factor for cardiovascular diseases. However, few studies illustrated the effects of ambient temperature exposure (TE) on lipid levels in children. The study aimed to examine the association between ambient TE and lipid levels in children.

METHODS

Based on a prospective cohort, a total of 2423 children (with 4466 lipids measure person-time) were collected from 2014 to 2019. The meteorological observation data and adjusted variables were collected. Mixed-effect models and generalized additive mixed model (GAMM) were applied to investigate the association between ambient TE and lipid levels.

RESULTS

A significant negative association was observed between TE and low-density lipoprotein cholesterol (LDL-C) or total cholesterol (TC) levels both in all children [LDL-C, β(95%CI) = -0.350(-0.434,-0.265), P < 0.001; TC, β(95%CI) = -0.274(-0.389,-0.160), P < 0.001] and by different sex group. However, no significant association was found in low-density lipoprotein cholesterol (HDL-C) or triglycerides (TG) levels. The estimated optimal ambient TEs for LDL-C were 18.273 °C and 18.024 °C for girls and boys, respectively. For TC, the optimal ambient TEs were 17.949 °C and 18.024 °C, respectively. With ambient TE decreased, the risk of dyslipidemia increased for both boys [OR = 0.032(0.006,0.179), P < 0.001] and girls [OR = 0.582(0.576,0.587), P < 0.001].

CONCLUSION

This study provided a comprehensive illustration about the associations between ambient TE and lipid levels in different sex and ages from a prospective cohort study. The findings will provide evidence for the government to prevent dyslipidemia in vulnerable children through regulating TE.

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.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

Effects of apparent temperature on cardiovascular disease admissions in rural areas of Linxia Hui Autonomous Prefecture

Cardiovascular disease (CVD) is a major threat to public health worldwide. The relationship between CVD and temperature has been widely reported in developed countries and regions. However, there are few studies of severe CVD in poor rural areas of developing countries. Therefore, this study aimed to explore the relationship between CVD and apparent temperature (AT) in a rural area of Linxia Hui Autonomous Prefecture, China. Daily CVD admission data and meteorological data were collected from Linxia between 2014 and 2015. The media of AT was used as the reference temperature to estimate the cumulative relative risk (RR) of CVD admission. The distributed lag non-linear models were used to examine the association between AT and cumulative RR of CVD admission at lag 0-21 days. In Linxia, high AT (20 °C) had a persistent adverse effect on cumulative RR of CVD admissions, and the RR increased with increasing lag days. Cold (- 10 °C) had a protective effect on the first and later lag days (lag 0-14 and lag 0-21). Adults (aged < 65 years) and females were more susceptible to the effects of heat than males and the elderly (aged ≥ 65 years). In Linxia, China, extremely high AT is an important risk factor for CVD hospitalizations in suburban and rural populations.

Extreme Temperature Exposure and Risks of Preterm Birth Subtypes Based on a Nationwide Survey in China

BACKGROUND

Previous studies have reported that ambient temperature may affect perinatal outcomes. However, whether extreme temperature affects the risk of preterm birth (PTB) remains controversial. Studies on the associations of extreme temperature with PTB subtypes are lacking.

OBJECTIVES

We aimed to investigate the associations of extreme climate events with the risks of PTB and its subtypes, discerning possible modifiers.

METHODS

Data on all singleton deliveries were obtained from the China Labor and Delivery Survey (CLDS), a nationwide investigation implemented in 2015 and 2016. PTB was defined as gestational weeks < 37 and then categorized as early (24-34 wk) and late PTBs (35-36 wk), and clinical subtypes [spontaneous PTB, preterm premature rupture of the fetal membranes (PPROM), iatrogenic PTB]. Ambient temperature data were provided by the China National Weather Data Sharing System. Five heat indexes and five cold indexes were used to define heat waves and cold spells. Generalized linear mixed models with a random term by hospital unit were used to assess the associations of short-term prenatal extreme temperature exposure. The Cox proportional hazard regression model was applied to assess the nonlinear associations of low- or high-temperature exposure at the whole and different trimesters of pregnancy with the risk of PTB. Stratified analyses were conducted to assess the possible modification by geographic region and fetal sex.

RESULTS

A total of 70,818 singleton births from 96 hospitals in China were included, among which 4,965 (7.01%) were PTBs. Exposure to extreme cold events 1 wk before delivery was associated with an increased PTB risk, with an adjusted odds ratio (aOR) [95% confidence intervals (CIs)] of 1.07 (95% CI: 1.04, 1.10) and 1.06 (1.04, 1.09) for the total days when the daily average temperature below the fifth percentile (fifth-days) and the 10th percentile (10th-days), 1.18 (1.04, 1.34) for the cold spells when the daily average temperature below the fifth percentile for two consecutive days (fifth-2D), 1.09 (1.03, 1.16) and 1.12 (1.06, 1.19) for the cold spells when the daily average temperature below the 10th percentile for three and two consecutive days (10th-3D and 10th-2D), respectively. Results of extreme temperature exposure during 2 weeks before delivery showed similarly significant associations. The association between cold spells and PTB tended to be stronger for late PTB than for early PTB. Cold spells were mainly associated with spontaneous PTB and late PPROM. A stratified analysis indicated that pregnant women in western and northern regions tended to be more sensitive to cold spells, and pregnant women with a female fetus appeared to be at a higher risk of PTB when exposed to cold spells. Pregnant women in late pregnancy were more susceptible to extreme temperatures. No significant or stable association was found between heat waves and preterm birth.

DISCUSSION

Exposure to cold spells was associated with an increased risk of PTB, especially late, spontaneous PTB and PPROM. The associations appeared to be more pronounced in the north and west regions and in pregnancies with female fetuses. https://doi.org/10.1289/EHP10831.

The role of insurance status in the association between short-term temperature exposure and myocardial infarction hospitalizations in New York State

Myocardial infarction (MI) is a leading cause of morbidity and mortality in the United States and its risk increases with extreme temperatures. Climate change causes variability in weather patterns, including extreme temperature events that disproportionately affect socioeconomically disadvantaged communities. Many studies on the health effects of extreme temperatures have considered community-level socioeconomic disadvantage.

Objectives

To evaluate effect modification of the relationship between short-term ambient temperature and MI, by individual-level insurance status (insured vs. uninsured).

Methods

We identified MI hospitalizations and insurance status across New York State (NYS) hospitals from 1995 to 2015 in the New York Department of Health Statewide Planning and Research Cooperative System database, using International Classification of Diseases codes. We linked short-term ambient temperature (averaging the 6 hours preceding the event [MI hospitalization]) or nonevent control period in patient residential zip codes. We employed a time-stratified case-crossover study design for both insured and uninsured strata, and then compared the group-specific rate ratios.

Results

Over the study period, there were 1,095,051 primary MI admissions, 966,475 (88%) among insured patients. During extremely cold temperatures (<5.8 °C) insured patients experienced reduced rates of MI; this was not observed among the uninsured counterparts. At warmer temperatures starting at the 65th percentile (15.7 °C), uninsured patients had higher rates than insured patients (e.g., for a 6-hour pre-event average temperature increase from the median to the 75th percentile, the rate of MI increased was 2.0% [0.0%-4.0%] higher in uninsured group).

Conclusions

Uninsured individuals may face disproportionate rates of MI hospitalization during extreme temperatures.

Effects of indoor temperature and its fluctuation on blood pressure and its variability

Cardiovascular diseases (CVDs) are the number one health threat globally. Adverse indoor thermal environments are associated with excess mortality caused by CVDs in the cold season. While many studies have focused on the impact of indoor temperature on CVDs, none has considered the fluctuation of indoor temperature. To quantify the effect of indoor temperature on blood pressure and the effect of indoor temperature fluctuation on blood pressure variability (BPV), 172 middle-aged and elderly people in areas that experience both hot summers and cold winters in China completed a household survey regarding their characteristics and living habits. A hierarchical linear model (HLM) was used to analyze the impact of indoor temperature on home blood pressure. A multiple linear model was used to analyze the effect of indoor temperature fluctuation on day-to-day home blood pressure variability. The results showed that there was a significant negative correlation between morning temperature below 18 °C and blood pressure, especially systolic blood pressure (SBP). At the same time, morning temperature fluctuations have an independent influence on BPV, and a deviation of morning temperature fluctuation greater than 1.1 °C significantly increased BPV. Morning temperature and its fluctuation threshold for the rise of SBP and its variability of middle-aged and elderly people were clarified, which can provide a basis for the design, operation, and evaluation of residential thermal environmental health performance for the middle-aged and elderly population in this area, thereby reducing the cardiovascular health risk of the corresponding population.

Association between cold spells and serum lipid levels among the elders: a distributed-lagged effects analysis

Little evidence about the effects of cold spells on serum lipid levels is available. The aim of this study was to explore the association between cold spells and serum lipid levels among the elders in Jinan, China. Data of old adults from health check-up program in Shandong Provincial Qianfoshan Hospital was collected for this study. Linear mixed models combined with distributed lag nonlinear models were used to examine the relationship between cold spells and serum lipid levels, considering the confounding effects of age, sex, blood pressure, body mass index, and other meteorological factors. Subgroup analysis by gender and analysis based on different definitions of cold spells were also conducted. Increased TG levels in lag 0-lag 2 days and decreased TG levels in lag 5-lag 8 days after cold spells were observed among the elders. The largest increase was 0.363 mmol/L (95% CI: 0.184 ~ 0.543) in lag 0 day, while the largest decreased TG levels was 0.083 mmol/L (95% CI: 0.147 ~ 0.019) in lag 6 day. Similar results were obtained in the analysis of different sex and based on different definitions of cold spells. However, no significant association was found between cold spells with TC, LDL-C, and HDL-C. This study indicates that cold spells were significantly associated with serum TG levels in the elders. Effective preventive measures should be implemented around the cold spells to reduce the volatility of serum lipid levels and the occurrence of subsequent cardiovascular diseases.

Abnormal ambient temperature change increases the risk of out-of-hospital cardiac arrest: A systematic review and meta-analysis of exposure types, risk, and vulnerable populations

BACKGROUND

There is growing evidence in support of a short-term association between ambient temperature and cardiac arrest attacks that is a serious manifestation of cardiovascular disease and has a high incidence and low survival rate. However, it remains unrecognized about the hazardous temperature exposure types, exposure risk magnitude, and vulnerable populations.

OBJECTIVES

We comprehensively summarize prior epidemiological studies looking at the short-term associations of out-of-hospital cardiac arrest (OHCA) with various temperature exposures among different populations.

METHODS

We searched PubMed and Web of Science databases from inception to October 2021 for eligible English language. Temperature exposure was categorized into three types: heat (included high temperature, extreme heat, and heatwave), cold (included low temperature and extreme cold), and temperature variation (included diurnal temperature range and temperature change between two adjacent days). Meta-analysis weighted by inverse variance was used to pool effect estimates.

RESULTS

This study included 15 studies from 8 countries, totaling around 1 million OHCA events. Extreme heat and extreme cold were significantly associated with an increased risk of OHCA, and the pooled relative risks (RRs) were 1.071 [95 % confidence interval (CI): 1.019-1.126] and 1.662 (95%CI: 1.138-2.427), respectively. The risk of OHCA was also elevated by heatwaves (RR = 1.248, 95%CI: 1.091-1.427) and more intensive heatwaves had a greater effect. Notably, the elderly and males seemed to be more vulnerable to the effects of heat and cold. However, we did not observe a significant association between temperature variation and the risk of OHCA (1.005, 95%CI: 0.999-1.012).

CONCLUSION

Short-term exposure to heat and cold may be novel risk factors for OHCA. Considering available studies in limited regions, the temperature effect on OHCA should be urgently confirmed in different regions.

Factors affecting outdoor physical activity in extreme temperatures in a sub-tropical Chinese urban population: an exploratory telephone survey

BACKGROUND

Physical activity (PA) can be affected by extreme temperatures, however fewer studies have identified factors impacting this relationship. This study sought to identify factors associated with changes of outdoor PA during extreme cold/heat events in a sub-tropical Chinese urban population, including factors of sociodemographic, health conditions, temperature-related awareness and attitude, and protective behaviours.

METHODS

Two telephone surveys were conducted a week after extreme cold/heat events in 2016 and 2017 among a cohort of Hong Kong residents over age 15. Data was collected on self-reported changes in outdoor PA level during the periods of extreme temperatures, health status, comorbidities, sociodemographic, and temperature-related awareness, and behavioural variables. We conducted multivariable logistic regression analyses to assess predictors of change in outdoor PA over the two extreme temperature events.

RESULTS AND CONCLUSION

Among 435 participants (42.8% response rate), over a third of the participants reported decreased outdoor PA level in extreme temperature events, while 10% reported an increase in extreme heat. Self-reported cardiovascular diseases were associated with decreased PA level in extreme cold, while hypertension was associated with unchanged/increased PA level in extreme heat. These results suggest physical activity to be an important consideration in the understanding of climate change-and-health pathways and meriting further research.

Association between ambient temperature and cardiovascular diseases related hospital admissions in Lanzhou, China

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, ranking first in the global disease burden. Evidence on association between temperature and cardiovascular disease is insufficient and inconsistent in developing countries. In this study, a distributed lag nonlinear model (DLNM) was used to determine the association between daily mean temperature and cardiovascular diseases (CVD) related admission in Lanzhou 2015-2019. We included 41,389 patients with CVD in this study. The relative risk (RR) of CVD admission increased significantly with temperature in lag 5-10 days, and we found harvesting effect of temperature in the study, shown as decreased RR in lag 15-30 days. The maximum RR was 1.15 (95% confidence interval [CI]: 1.03-1.30), corresponding to 24 °C. Both cold and heat effects of temperature could impact the CVD admission. Compared with the 25th percentile of temperature (2 °C), the cumulative relative risk (cumRR) of extreme cold (-5 °C, the 2.5th percentile of the temperature) was 0.69 (95% CI: 0.51-0.94) in lag 0-14, whereas the cumRR of moderate cold (-2 °C, the 10th percentile) was 0.83 (95% CI:0.71-0.97). Compared with the 75th percentile of temperature (20-°C), the cumRR of extreme heat (27 °C, the 97.5th percentile) was 0.93 (95% CI: 0.78-1.10) in lag 0, whereas the cumRR of moderate heat (24 °C, the 90th percentile) was 1.01 (95% CI: 0.94-1.08). In the stratified analysis, cold decreased RR significantly in female and ≥65 years, whereas heat increased it more obviously in male and ≥65 years. Ambient temperature and CVD admissions were positively associated, with the harvesting effect. Our findings demonstrate the adaption of residents in Lanzhou to cold temperature. Public and environmental policies and measures aimed at moderate heat may minimize CVD burden effectively.

Relationship between birth weight and ambient temperature during pregnancy in a cross-sectional study of the residents of Suzhou, China

Objective

The association between birth weight and ambient temperature during pregnancy remains inconclusive, and data from Chinese populations are scarce. We conducted a cross-sectional study to investigate the association between birth weight and ambient temperature during pregnancy among the residents of Suzhou Industrial Park, Suzhou, China.

Methods

Information regarding 10,903 infants born between January 2018 and December 2018 who were born at the hospitals in Suzhou Industrial Park, Jiangsu province was obtained via public birth records.

Results

This study found that the ambient temperature during the first trimester of pregnancy was negatively correlated with birth weight, suggesting that elevated temperature may be related to lower birth weight. However, the ambient temperatures during the second and third trimesters of pregnancy were positively correlated with birth weight. Moreover, when the ambient temperature was below 15°C during the second trimester of pregnancy, the birth weight increased with temperature. However, when the temperature was higher than 15°C, the birth weight decreased with temperature. The relationship between ambient temperature in the third trimester and birth weight presented an inverted "U" curve. When the ambient temperature was lower than 20°C, the birth weight increased with ambient temperature, but when the ambient temperature was higher than 20°C, the increase of ambient temperature showed no significant relationship with the increase of birth weight.

Conclusion

The ambient temperature was correlated with birth weight. The ambient temperature during the first trimester of pregnancy was negatively correlated with birth weight. The relationship between ambient temperature in the third trimester and birth weight presented an inverted "U" curve.

Increased emergency cases for out-of-hospital cardiac arrest due to cold spells in Shenzhen, China

Cold spells have been associated with specific diseases. However, there is insufficient scientific evidence on the effects of cold spells on out-of-hospital cardiac arrest (OHCA). Data on OHCA cases and on meteorological factors and air pollutants were collected between 2013 and 2020. We adopted a quasi-Poisson generalized additive model with a distributed lag nonlinear model (DLNM) to estimate the effect of cold spells on daily OHCA incidence. Backward attributable risk within the DLNM framework was calculated to quantify the disease burden. We compared the effects and OHCA burden of cold spells using nine definitions. The risks of different cold spells on OHCA increased at higher intensities and longer durations. Based on Akaike's information criterion for the quasi-Poisson regression model and the attributable risk, the optimal cold spell was defined as a period in the cold month when the daily mean temperature was below the 10th percentile of the temperature distribution in the study period for at least 2 days. The single-day effect of the optimal cold spell on OHCA occurred immediately and lasted for approximately 1 week. The maximum single-day effect was 1.052 (95% CI: 1.018-1.087) at lag0, while the maximum cumulative effect was 1.433 (95% CI:1.148-1.788) after a 14-day lag. Men were more susceptible to cold spells. Young and middle-aged people were affected by cold spells similar to the elderly. Cold spells can increase the risk of OHCA with an approximately 1-week lag effect. Health regulators should take more targeted measures to protect susceptible populations during cold weather.

Ambient temperature and hospital admissions for non-ST segment elevation myocardial infarction in the tropics

BACKGROUND

Myocardial infarction is an important cause of cardiovascular mortality and can be precipitated by climatic factors. The temperature dependence of myocardial infarction risk has been well examined in temperate settings. Fewer studies have investigated this in the tropics where thermal amplitudes are narrower. This study investigated how ambient temperature influenced the risk of non-ST segment elevation myocardial infarction (NSTEMI), an increasingly common type of myocardial infarction, in the tropical city-state of Singapore.

METHODS

All nationally reported NSTEMI cases from 2009 to 2018 were included and assessed for its short-term association with ambient temperature using conditional Poisson regression models that comprised a three-way interaction term with year, month and day of the week and adjusted for relative humidity. The Distributed Lag Non-Linear Modelling (DLNM) was used to account for the immediate and lagged effects of environmental exposures. Stratified analysis by sex and age groups was undertaken to assess potential effect modification.

RESULTS

There were 60,643 reports of NSTEMI. Temperature decline (cool effect) was associated with a delayed cumulative, non-linear increase in NSTEMI risk over 10 days post exposure [Relative Risk (RR_{lag0-10, 10th percentile}: 1.12, 95%CI: 1.02-1.24)]. Those aged 65 years and above were potentially more susceptible (RR _{lag0-10, 10th percentile}: 1.19, 95 % CI: 1.06-1.33) to the cool effect compared to those below that age (RR_{lag0-10, 10th percentile}: 1.00, 95 % CI: 0.85-1.18) (p-value for difference = 0.087).

CONCLUSION

Short-term temperature fluctuations were independently associated with NSTEMI incidence in the tropics, with age as a potential effect modifier of this association. An increase in the frequency of climate change driven temperature events may trigger more instances of NSTEMI in tropical cosmopolitan cities.

Association between Indoor Temperature in Winter and Serum Cholesterol: A Cross-Sectional Analysis of the Smart Wellness Housing Survey in Japan

AIM

Issuance of the WHO Housing and health guidelines has paralleled growing interest in the housing environment. Despite accumulating evidence of an association between outdoor temperature and serum cholesterol, indoor temperature has not been well investigated. This study examined the association between indoor temperature and serum cholesterol.

METHODS

We collected valid health checkup data of 2004 participants (1333 households), measured the indoor temperature for 2 weeks in winter, and divided participants according to whether they lived in a warm (average bedroom temperature ≥ 18℃), slightly cold (12-18℃) or cold house (＜12˚C). The relationship between bedroom temperature and serum cholesterol was analyzed using multivariate logistic regression models, adjusting for demographics, lifestyle habits and the season in which the health checkup was conducted, with a random effect of climate areas in Japan.

RESULTS

The sample sizes for warm, slightly cold, and cold houses were 206, 940, and 858, respectively. Compared to those in warm houses, the odds ratio of total cholesterol exceeding 220 mg/dL was 1.83 (95%CI: 1.23-2.71, p=0.003) for participants in slightly cold houses and 1.87 (95%CI: 1.25-2.80, p=0.002) in cold houses. Similarly, the odds ratio of LDL/non-HDL cholesterol exceeding the standard range was 1.49 (p=0.056)/1.67 (p=0.035) for those in slightly cold houses and 1.64 (p=0.020)/1.77 (p=0.021) in cold houses. HDL cholesterol and triglycerides were not significantly associated with bedroom temperature.

CONCLUSION

Besides lifestyle modification, improving indoor thermal environment through strategies such as installing high thermal insulation and appropriate use of heating devices may contribute to better serum cholesterol condition.

Temperature, cardiovascular mortality, and the role of hypertension and renin-angiotensin-aldosterone axis in seasonal adversity: a narrative review

Environmental temperature is now well known to have a U-shaped relationship with cardiovascular (CV) and all-cause mortality. Both heat and cold above and below an optimum temperature, respectively, are associated with adverse outcomes. However, cold in general and moderate cold specifically is predominantly responsible for much of temperature-attributable adversity. Importantly, hypertension-the most important CV risk factor-has seasonal variation such that BP is significantly higher in winter. Besides worsening BP control in established hypertensives, cold-induced BP increase also contributes to long-term BP variability among normotensive and pre-hypertensive patients, also a known CV risk factor. Disappointingly, despite the now well-stablished impact of temperature on BP and on CV mortality separately, direct linkage between seasonal BP change and CV outcomes remains preliminary. Proving or disproving this link is of immense clinical and public health importance because if seasonal BP variation contributes to seasonal adversity, this should be a modifiable risk. Mechanistically, existing evidence strongly suggests a central role of the sympathetic nervous system (SNS), and secondarily, the renin-angiotensin-aldosterone axis (RAAS) in mediating cold-induced BP increase. Though numerous other inflammatory, metabolic, and vascular perturbations likely also contribute, these may also well be secondary to cold-induced SNS/RAAS activation. This review aims to summarize the current evidence linking temperature, BP and CV outcomes. We also examine underlying mechanisms especially in regard to the SNS/RAAS axis, and highlight possible mitigation measures for clinicians.

Association between El Niño-Southern Oscillation events and stroke: a case-crossover study in Kaunas city, Lithuania, 2000-2015

The aim of this study was to determine the association between the daily number of cases of ischemic stroke (IS) and hemorrhagic stroke (HS) in patients aged 25-64 years and the El Niño-Southern Oscillation (ENSO) events during 2000-2015. As an indicator of the effect of the ENSO, the monthly NIÑO 3.4 index (Equatorial Pacific Sea Surface Temperature) was used. During the 5844-day study period, 5600 cases of stroke (3170 (56.61%) in men and 2430 (43.39%) in women) were analyzed. Of these, 4354 (77.8%) cases were IS, and 1041 (18.6%) cases were HS. In 3496 (62.2%) cases, stroke occurred in the age group of 55-64 years. In the analysis, we used the following categories of the ENSO events: strong La Niña, moderate La Niña, moderate El Niño, and strong El Niño. The effect of the ENSO was examined by using the multivariate Poisson regression adjusting for weather variables. The highest risk of both strokes (BS) was observed on days of strong and moderate La Niña (rate ratio (RR) 1.27, 95% CI 1.13-1.42) and RR = 1.15 (1.07-1.23), respectively), while the risk for IS was the highest on days of moderate El Niño (RR = 1.11(1.02-1.20)). A lower risk for BS was found on days of strong El Niño (RR = 0.77(0.62-0.97)). We found that ENSO events affected the occurrence of BS and IS in all age groups, and the strongest effect was observed among females. The results of this study provide new evidence that ENSO events may affect the risk of stroke, especially the risk of IS.

Low ambient temperature as a novel risk factor of oral diseases: A time-series study

BACKGROUND

The seasonal variation of oral diseases has been observed in life, but the influences of oral diseases associated with non-optimal ambient temperature were unknown.

OBJECTIVE

To examine whether non-optimum ambient temperature is associated with increased risks of oral diseases.

METHODS

We conducted a time series study based on outpatient data from the Shanghai Health Information Center, containing all public hospitals in Shanghai from 2016 to 2019. Generalized additive models with distributed lagged nonlinear models were applied to fit the data.

RESULT

A total of 3,882,636 outpatient cases of oral diseases were collected. Low temperature (<7 °C) posed increased risks for oral diseases. Daily temperature above 7 °C had no effect on oral diseases. The excess risks were present on the lag 1 day and lasted till lag 7 day. Relative to referent temperatures, the cumulative risks of total oral diseases, pulpitis, periodontitis, gum pain, stomatitis, and glossitis at extreme low temperature (-3 °C, 1st percentile) over lag 0-7 day were 1.92 (95% confidence interval, CI: 1.40, 2.63), 2.40 (95% CI: 1.78, 3.25), 1.62 (95% CI: 1.15, 2.29), 1.75 (95% CI: 1.08, 2.83), 1.81 (95% CI: 1.30, 2.53), and 2.22 (95% CI: 1.23, 3.99). These associations were larger in patients who were above age 60.

CONCLUSION

This study provided novel epidemiological evidence that low ambient temperature may increase the risks of oral diseases. The temperature thresholds for eight oral diseases range from 3 to 7 °C. The excess risks could last for 7 days and were larger in older patients.

Associations of combined exposures to ambient temperature, air pollution, and green space with hypertension in rural areas of Anhui Province, China: A cross-sectional study

Hypertension (HTN) was a major preventable cause of cardiovascular disease (CVD), contributing to a huge disease burden. Ambient temperature, air pollution and green space were important influencing factors of HTN, and few studies have assessed the effects and interactions of ambient temperature, air pollution and green space on HTN in rural areas. In this study, we selected 8400 individuals randomly in rural areas of Anhui Province by a multi-stage stratified cluster sampling. A total of 8383 individuals were included in the final analysis. We collected particulate pollutants and meteorological data from the local air quality monitoring stations and National Center for Meteorological Science from January 1 to December 31, 2020, respectively. The normalized differential vegetation index (NDVI) of Anhui Province in 2020 was produced and processed by remote sensing inversion on the basis of medium resolution satellite images. The average annual mean exposure concentrations of air pollution, meteorological factors, and NDVI were calculated for each individual based on the geocoded residential address. HTN was defined according the Chinese Guidelines for Prevention and Treatment of HTN. The effects and interactions of ambient temperature, air pollution and green space on HTN were evaluated by generalized linear model and interaction model, respectively. In this study, the prevalence of HTN was 24.14%. The adjusted odd ratio of HTN for each 1 μg/m³ increasing in PM_2.5 and PM₁₀, 1 °C of ambient temperature, and 0.1 of NDVI were:1.276 (1.013, 1.043), 1.012 (1.006, 1.018), 0.862 (0.862, 0.981) and 0.669 (0.611, 0.733), respectively. The results showed that air pollutants were positively correlated with HTN, while ambient temperature and green space were negatively correlated with HTN. Meanwhile, the negative associations of green space on HTN could decrease with the increasing concentrations of air pollution, but increase with the rising of ambient temperature.

Impact of ambient temperature on life loss per death from cardiovascular diseases: a multicenter study in central China

BACKGROUND

In the context of global climate change, studies have focused on the ambient temperature and mortality of cardiovascular diseases (CVDs). However, little is known about the effect of ambient temperature on year of life lost (YLL), especially the life loss per death caused by ambient temperature. In this study, we aimed to assess the relationship between ambient temperature and life loss and estimate the impact of ambient temperature on life loss per death.

METHODS

We collected daily time series of mortality and meteorological data from 70 locations in Hunan province, central China, in periods ranging from Jan. 1, 2013, to Dec. 31, 2017. Crude rates of YLL were calculated per 100,000 people per year (YLL/100,000 population) for each location. A distributed lag nonlinear model and multivariate meta-regression were used to estimate the associations between ambient temperature and YLL rates. Then, the average life loss per death attributable to ambient temperature was calculated.

RESULTS

There were 711,484 CVD deaths recorded within the study period. The exposure-response curve between ambient temperature and YLL rates was inverted J or U-shaped. Relative to the minimum YLL rate temperature, the life loss risk of extreme cold temperature lasted for 10 to 12 days, whereas the risk of extreme hot temperature appeared immediately and lasted for 3 days. On average, the life loss per death attributable to non-optimum ambient temperatures was 1.89 (95% CI, 1.21-2.56) years. Life loss was mainly caused by cold temperature (1.13, 95% CI, 0.89‑1.37), particularly moderate cold (1.00, 95% CI, 0.78‑1.23). For demographic characteristics, the mean life loss per death was relatively higher for males (2.07, 95% CI, 1.44‑2.68) and younger populations (3.72, 95% CI, 2.06‑5.46) than for females (1.88, 95% CI, 1.21-2.57) and elderly people (1.69, 95% CI, 1.28-2.10), respectively.

CONCLUSIONS

We found that both cold and hot temperatures significantly aggravated premature death from CVDs. Our results indicated that the whole range of effects of ambient temperature on CVDs should be given attention.

Electrocardiogram abnormalities in residents in cold homes: a cross-sectional analysis of the nationwide Smart Wellness Housing survey in Japan

Background

Excess winter mortality caused by cardiovascular disease is particularly profound in cold houses. Consistent with this, accumulating evidence indicates that low indoor temperatures at home increase blood pressure. However, it remains unclear whether low indoor temperatures affect other cardiovascular biomarkers. In its latest list of priority medical devices for management of cardiovascular diseases, the World Health Organization (WHO) included electrocardiography systems as capital medical devices. We therefore examined the association between indoor temperature and electrocardiogram findings.

Methods

We collected electrocardiogram data from 1480 participants during health checkups. We also measured the indoor temperature in the living room and bedroom for 2 weeks in winter, and divided participants into those living in warm houses (average exposure temperature ≥ 18 °C), slightly cold houses (12–18 °C), and cold houses (< 12 °C) in accordance with guidelines issued by the WHO and United Kingdom. The association between indoor temperature (warm vs. slightly cold vs. cold houses) and electrocardiogram findings was analyzed using multivariate logistic regression models, with adjustment for confounders such as demographics (e.g., age, sex, body mass index, household income), lifestyle (e.g., eating habit, exercise, smoking, alcohol drinking), and region.

Results

The average temperature at home was 14.7 °C, and 238, 924, and 318 participants lived in warm, slightly cold, and cold houses, respectively. Electrocardiogram abnormalities were observed in 17.6%, 25.4%, and 30.2% of participants living in warm, slightly cold, and cold houses, respectively (p = 0.003, chi-squared test). Compared to participants living in warm houses, the odds ratio of having electrocardiogram abnormalities was 1.79 (95% confidence interval: 1.14–2.81, p = 0.011) for those living in slightly cold houses and 2.18 (95% confidence interval: 1.27–3.75, p = 0.005) for those living in cold houses.

Conclusions

In addition to blood pressure, living in cold houses may have adverse effects on electrocardiogram. Conversely, keeping the indoor thermal environment within an appropriate range through a combination of living in highly thermal insulated houses and appropriate use of heating devices may contribute to good cardiovascular health.

Trial registration

The trial was retrospectively registered on 27 Dec 2017 to the University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR, https://www.umin.ac.jp/ctr/, registration identifier number UMIN000030601).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-021-01024-1.

Effects of cold and hot temperature on metabolic indicators in adults from a prospective cohort study

BACKGROUND

Previous studies have found that exposed to low and high outdoor temperature was associated with cardiovascular diseases morbidity and mortality. The risk factors for cardiovascular disease include high blood lipid, high uric acid (UA) and high fasting plasma glucose (FPG). However, few studies have explored the effects of low and high temperature on these metabolic indicators.

OBJECTIVE

To explore the effect of low and high temperature on metabolic indicators in adults from northwest of China.

METHODS

Based on a prospective cohort study, a total of 30,759 individuals who participated in both baseline and first follow-up from 2011 to 2015 were selected in this study. The meteorological observation data and environmental monitoring data were collected in the same period. Associations between cold and hot temperature and blood lipid (total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDL-C), and high density lipoprotein-cholesterol (HDL-C)), UA and FPG were conducted with mixed effect models after adjusting for confounding factors.

RESULTS

A nonlinear relationship between outdoor temperature and metabolic indicators was found. For the cold effects, each 5 °C decrease of mean temperature was associated with an increase of 5.07% (95% CI: 3.52%, 6.63%) in TG and 2.85% (95% CI: 2.18%, 3.53%) in UA, While a decrease of 3.38% (95% CI: 2.67%, 4.09%) in HDL-C and 1.26% (95% CI: 0.48%, 2.04%) in LDL-C. For the heat effects, each 5 °C increase in mean temperature was associated with 1.82% (95% CI: 0.89%, 2.76%), 0.56% (95% CI: 0.11%, 1.00%), 5.82% (95% CI: 4.58%, 7.06%), 9.02% (95% CI: 7.17%, 10.87%), 0.20% (95% CI: 0.01%, 0.40%), and 1.22% (95% CI: 0.19%, 2.24%) decrease in TC, TG, HDL-C, LDL-C, UA and FPG. Age, smoking, drinking, high-oil diet and hyperlipidemia might modify the association between mean temperature and metabolic indicators.

CONCLUSION

There was a significant effect of cold and hot temperature on metabolic indicators in a high altitude area of northwestern China. These results provide a basis for understanding the underlying mechanism of the influence of temperature on metabolic diseases.

Ambient temperatures, heatwaves and out-of-hospital cardiac arrest in Brisbane, Australia

BACKGROUND

The health impacts of temperatures are gaining attention in Australia and worldwide. While a number of studies have investigated the association of temperatures with the risk of cardiovascular diseases, few examined out-of-hospital cardiac arrest (OHCA) and none have done so in Australia. This study examined the exposure-response relationship between temperatures, including heatwaves and OHCA in Brisbane, Australia.

METHODS

A quasi-Poisson regression model coupled with a distributed lag non-linear model was employed, using OHCA and meteorological data between 1 January 2007 and 31 December 2019. Reference temperature was chosen to be the temperature of minimum risk (21.4°C). Heatwaves were defined as daily average temperatures at or above a heat threshold (90th, 95th, 98th, 99th percentile of the yearly temperature distribution) for at least two consecutive days.

RESULTS

The effect of any temperature above the reference temperature was not statistically significant; whereas low temperatures (below reference temperature) increased OHCA risk. The effect of low temperatures was delayed for 1 day, sustained up to 3 days, peaking at 2 days following exposures. Heatwaves significantly increased OHCA risk across the operational definitions. When a threshold of 95th percentile of yearly temperature distribution was used to define heatwaves, OHCA risk increased 1.25 (95% CI 1.04 to 1.50) times. When the heat threshold for defining heatwaves increased to 99th percentile, the relative risk increased to 1.48 (1.11 to 1.96).

CONCLUSIONS

Low temperatures and defined heatwaves increase OHCA risk. The findings of this study have important public health implications for mitigating strategies aimed at minimising temperature-related OHCA.

Air temperature variability and high-sensitivity C reactive protein in a general population of China

BACKGROUND

Along with global climate change, the relationship between temperature variability (TV) and cardiovascular hospitalization and deaths have been well established. However, limited studies were conducted to reveal the underlying mechanism for TV-related cardiovascular diseases.

OBJECTIVES

In the current study, a novel TV calculation, taking account for both interday and intraday TV as well as lag effects, was used to investigate the effect of short-term TV on the level of high-sensitivity C reactive protein (hs-CRP), which is a crucial preclinical predictor for cardiovascular disease (CVD).

RESULTS

Among the 11,623 Chinese population (46.0% male; mean age 49.8 years), the average hs-CRP was 1.4 mg/ L (standard deviation 1.6 mg/L). Statistical significance between TV and hs-CRP was observed for different TV exposure days (TV01-TV07) in adjusted model, with highest effect for TV06. Specifically, per 1 °C increase in TV06 led to 2.241% (95%CI: 1.552%-2.935%) increase in hs-CRP. Female, obesity and elderly population were more susceptible to TV. The largest mediator for the association of TV and hs-CRP was lipoprotein(a), accounting for 8.68%, followed by smoking status (4.78%), alcohol use (3.95%) and systolic BP (3.20%).

CONCLUSION

Short-term TV will significantly increase the level of hs-CRP, suggesting hs-CRP to be the potential biologic mechanisms underlying the cardiovascular effects of TV. And more attention should be paid to unstable weather in the global climate change context. Further developing efficient public health policies on climate change may benefit for global heath.

Seasonality of stroke: Winter admissions and mortality excess: A Thailand National Stroke population database study

OBJECTIVES

We examined the existence and potential burden of seasonality of stroke admissions and mortality within a tropical climate using cohort data collected between 1 st November 2003 and 31 st October 2012.

PATIENTS AND METHODS

In a prospective cohort of hospitalised stroke patients from the catchment of ∼75 % of the Thai population (n = 569,307; mean SD age = 64(14.5)), incident stroke admissions, in-hospital mortality, prolonged hospitalisations, and stroke related complications by season were determined. Rates of incident stroke admissions by month and season were plotted. Winter excess indexes for study outcomes expressed as a percentage were calculated. Using logistic regression we examined the association between winter admission and in-hospital mortality (non-winter admission as reference) adjusting for age, sex, stroke type, year of admission, and presence of pre-existing comorbidities.

RESULTS

We observed a winter excess in mortality during hospitalisation (+10.3 %) and prolonged length of stay (+7.3 %). Respective winter excess indexes for dyslipidaemias, arrhythmias, anaemia, and alcohol related disorders in patients that died during hospitalisation were +1.4 %, +6.2 %, +0.2 %, +1.5 %. In these patients, respective winter excess indexes for post-stroke complications of pneumonia and sepsis were +6.7 % and +3.2 %. In fully adjusted analyses, winter admission (compared to non-winter admission) was associated with increased odds of in-hospital mortality (OR (95 % CI) = 1.023 (1.006-1.040)).

CONCLUSIONS

We provide robust evidence for the existence of an excess in winter stroke admissions and subsequent in-hospital deaths within a tropical region.

Can ultra short-term changes in ambient temperature trigger myocardial infarction?

BACKGROUND

Climate change is increasing global average temperatures, as well as the frequency of extreme weather events. Both low and high ambient temperatures have been associated with elevated mortality; however, little is known about the cardiovascular impacts of hourly temperature.

METHODS

We assessed the association between hourly ambient temperature and risk of myocardial infarction (MI) across adult residents of New York State (NYS). We identified cases across NYS hospitals from 2000 to 2015 in the New York Department of Health Statewide Planning and Research Cooperative System dataset, using ICD codes. Hourly ambient temperature was assessed at each patient's residential ZIP code, up to 48 hours prior to MI. We employed a time-stratified case-crossover study design matching case to control periods on hour of day, day of week, month and year.

RESULTS

Of the 791,695 primary MI hospital admissions, 45% were female, the mean (standard deviation; SD) age was 70 (15) years, and 49% of cases occurred among New York City residents. The observed temperature range was -29 °C to 39 °C, with a mean of 10.8 °C (10.5 °C). Temperature in the 6 h preceding the MI was positively associated with risk of MI, across the range of observed temperatures, with null or nearly null associations for earlier hours. We estimated a cumulative percent increase in hourly myocardial infarction rate of 7.9% (95% confidence interval [CI]: 5.2%, 10.6%) for an 11 °C (median) to 27 °C (95th percentile) temperature increase for lag hours 0-5. Men, Medicare-ineligible individuals (age < 65), and those experiencing their first MI were most sensitive.

CONCLUSION

Our study provides evidence that increases in hourly ambient temperature can trigger myocardial infarction. Health-based definitions of extreme heat events may better capture the deleterious effects of heat by accounting for hourly temperature. Our findings can inform the design of more effective preparedness strategies for the increasingly frequent extreme heat events.

Term birthweight and critical windows of prenatal exposure to average meteorological conditions and meteorological variability

BACKGROUND

Heat stress during pregnancy may limit fetal growth, with ramifications throughout the life course. However, critical exposure windows are unknown, and effects of meteorological variability have not been investigated.

OBJECTIVES

We aimed to identify sensitive windows for the associations of mean and variability of temperature and humidity with term birthweight.

METHODS

We analyzed data from two French mother-child cohorts, EDEN and PELAGIE (n = 4771), recruited in 2002-2006. Temperature exposure was assessed using a satellite-based model with daily 1-km² resolution, and relative humidity exposure data were obtained from Météo France monitors. Distributed lag models were constructed using weekly means and standard deviation (SD, to quantify variability) from the first 37 gestational weeks. Analyses were then stratified by sex. Results for each exposure were adjusted for the other exposures, gestational age at birth, season and year of conception, cohort and recruitment center, and individual confounders.

RESULTS

There was no evidence of association between term birthweight and mean temperature. We identified a critical window in weeks 6-20 for temperature variability (cumulative change in term birthweight of -54.2 g [95% CI: -102, -6] for a 1 °C increase in SD of temperature for each week in that window). Upon stratification by sex of the infant, the relationship remained for boys (weeks 1-21, cumulative change: -125 g [95% CI: -228, -21]). For mean humidity, there was a critical window in weeks 26-37, with a cumulative change of -28 g (95% CI: -49, -7) associated with a 5% increase in humidity for each week. The critical window was longer and had a stronger association in boys (weeks 29-37; -37 g, 95% CI: -63, -11) than girls (week 14; -1.8 g, 95% CI: -3.6, -0.1).

DISCUSSION

Weekly temperature variability and mean humidity during critical exposure windows were associated with decreased term birthweight, especially in boys.

The association between ambient temperature and clinical visits for inflammation-related diseases in rural areas in China

BACKGROUND

The association between temperature and mortality has been widely reported. However, it remains largely unclear whether inflammation-related diseases, caused by excessive or inappropriate inflammatory reaction, may be affected by ambient temperature, particularly in low-income areas.

OBJECTIVES

To explore the association between ambient temperature and clinical visits for inflammation-related diseases in rural villages in the Ningxia Hui Autonomous Region, China, during 2012─2015.

METHODS

Daily data on inflammation-related diseases and weather conditions were collected from 258 villages in Haiyuan (161 villages) and Yanchi (97 villages) counties during 2012─2015. A Quasi-Poisson regression with distributed lag non-linear model was used to examine the association between temperature and clinical visits for inflammation-related diseases. Stratified analyses were performed by types of diseases including arthritis, gastroenteritis, and gynecological inflammations.

RESULTS

During the study period, there were 724,788 and 288,965 clinical visits for inflammation-related diseases in Haiyuan and Yanchi, respectively. Both exposure to low (RR: 2.045, 95% CI: 1.690, 2.474) and high temperatures (RR: 1.244, 95% CI: 1.107, 1.399) were associated with increased risk of total inflammation-related visits in Haiyuan county. Low temperatures were associated with increased risks of all types of inflammation-related diseases in Yanchi county (RR: 4.344, 95% CI: 2.887, 6.535), while high temperatures only affected gastroenteritis (RR: 1.274, 95% CI: 1.040, 1.561). Moderate temperatures explained approximately 26% and 33% of clinical visits due to inflammation-related diseases in Haiyuan and Yanchi, respectively, with the burden attributable to cold exposure higher than hot exposure. The reference temperature values ranged from 17 to 19 in Haiyuan, and 12 to 14 in Yanchi for all types of clinical visits.

CONCLUSIONS

Our findings add additional evidence for the adverse effect of suboptimal ambient temperature and provide useful information for public health programs targeting people living in rural villages.

The Impact of Non-optimum Ambient Temperature on Years of Life Lost: A Multi-county Observational Study in Hunan, China

The ambient temperature–health relationship is of growing interest as the climate changes. Previous studies have examined the association between ambient temperature and mortality or morbidity, however, there is little literature available on the ambient temperature effects on year of life lost (YLL). Thus, we aimed to quantify the YLL attributable to non-optimum ambient temperature. We obtained data from 1 January 2013 to 31 December 2017 of 70 counties in Hunan, China. In order to combine the effects of each county, we used YLL rate as a health outcome indicator. The YLL rate was equal to the total YLL divided by the population of each county, and multiplied by 100,000. We estimated the associations between ambient temperature and YLL with a distributed lag non-linear model (DNLM) in a single county, and then pooled them in a multivariate meta-regression. The daily mean YLL rates were 22.62 y/(p·100,000), 10.14 y/(p·100,000) and 2.33 y/(p·100,000) within the study period for non-accidental, cardiovascular, and respiratory disease death. Ambient temperature was responsible for advancing a substantial fraction of YLL, with attributable fractions of 10.73% (4.36–17.09%) and 16.44% (9.09–23.79%) for non-accidental and cardiovascular disease death, respectively. However, the ambient temperature effect was not significantly for respiratory disease death, corresponding to 5.47% (−2.65–13.60%). Most of the YLL burden was caused by a cold temperature than the optimum temperature, with an overall estimate of 10.27% (4.52–16.03%) and 15.94% (8.82–23.05%) for non-accidental and cardiovascular disease death, respectively. Cold and heat temperature-related YLLs were higher in the elderly and females than the young and males. Extreme cold temperature had an effect on all age groups in different kinds of disease-caused death. This study highlights that general preventative measures could be important for moderate temperatures, whereas quick and effective measures should be provided for extreme temperatures.

The nonlinear association between outdoor temperature and cholesterol levels, with modifying effect of individual characteristics and behaviors

Few studies have been conducted to investigate the underlying mechanisms of the effect of temperature on cardiovascular disease at population level, especially among Chinese population. A total of 56,039 participants were recruited from Kailuan cohort study, China. The lipoprotein profile indicators, including triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein, were collected. Non-linear associations between temperature and the lipoprotein profile indicators were examined using a nonlinear function for temperature. Stratified analyses were performed in groups by individual characteristics (age, gender, and body mass index) and individual behaviors (physical activities and smoking habits). Generally, a non-linear relationship was found between cholesterol levels and temperature. A 1 °C decrease in temperature below the threshold was related with 0.004 mmol/L (95% CI 0.0004, 0.008), 0.022 mmol/L (95% CI 0.020, 0.025), and 0.009 mmol/L (95% CI 0.008, 0.011) increase in TG, LDL, and HDL, respectively; a 1 °C increase in temperature above the threshold was associated with 0.005 mmol/L (95% CI 0.003, 0.007), 0.012 mmol/L (95% CI 0.009, 0.015), and 0.002 mmol/L (95% CI 0.001, 0.004) increase in TG, LDL, and HDL, respectively. Stratified analyses showed that effect estimates on TG and LDL were larger among females, subjects with higher BMI, and those with smoking habits, while effect estimates on HDL were smaller among these subjects (expect for female). Our results suggest both cold and hot effect of temperature on cholesterol. Furthermore, females, and people with higher BMI or smoking habit may be more susceptible to outdoor temperature.

Clinical blood pressure responses to daily ambient temperature exposure in China: An analysis based on a representative nationwide population

BACKGROUND

Limited evidence is available regarding the potential heterogeneity of ambient temperature on blood pressure (BP) in various climate zones.

OBJECTIVES

To explore the effect of daily ambient temperature on BP in various climate zones across 31 provinces in China.

METHODS

A representative population sample (n = 451,770) were obtained from the China Hypertension Survey study (CHS) from October 2012 to December 2015. Survey seasons were divided into warm and cold seasons. Survey sites were divided into three climate zones as subtropical, temperate monsoon and temperate continental zones.

RESULTS

After adjustment for confounders, an overall 10 °C decrease in ambient temperature was statistically associated 0.74 mmHg (95% CI: 0.69, 0.79) and 0.60 mmHg (95% CI: -0.63, -0.57) rise for SBP and DBP, respectively. In the warm season, U-shaped exposure-response curves were observed between ambient temperature and BP in temperate monsoon and continental zones, and liner curves in other zones. A greater SBP change due to a lower temperature was observed in subtropical zones, so did DBP in temperate continental zones, especially for cold season. Female, rural and elderly populations were more susceptible to cold weather than their counterparts.

DISCUSSION

There is a geographical disparity between temperature and BP across different climate zones, which should been taken into consideration when maintaining stable blood pressure levels.

UTCI as a bio-meteorological tool in the assessment of cold-induced stress as a risk factor for hypertension

BACKGROUND

Hypertension (HT) affects >1/3 of adult populations in developed countries. Several studies reported periodic changes in blood pressure (BP) values depending on atmospheric conditions, and analyzed the impact of outdoor temperature, atmospheric pressure, relative humidity and other meteorological parameters. The Universal Thermal Climate Index (UTCI) is a bio-meteorological index derived from an analysis of human thermal balance that comprehensively describes the impact of meteorological factors, including both cold stress and heat stress and their physiological consequences.

AIM

Our aim was to assess the relationship between UTCI values and the number of consultations for HT within the framework of the healthcare system.

METHODS

This work presents a retrospective epidemiological study of data collected in Olsztyn (Poland), characterized by cold climate type. The analytical material comprised 5578 consultations in emergency departments (EDs) due to HT.

RESULTS

Seasonal differences in the numbers of HT consultations with a significant increase in winter months were noticed, especially as regards women. Under cold stress conditions, the relative risk (RR) related to consultations for HT was 2-fold higher for women as compared to thermoneutral conditions (p < 0.001). For men these differences were also statistically significant, though at a much smaller level (p = 0.03). The increased RR of HT due to cold stress was found among younger and older women contrary to the women at the perimenopausal age.

CONCLUSIONS

Cold stress should be considered as a significant risk factor among patients, particularly women, diagnosed with cardiovascular diseases. The UTCI is an adequate bio-meteorological tool for the assessment of relationships between atmospheric conditions and occurrence of cardiac symptoms.

Acute effects of ambient temperature on hypotension hospital visits: A time-series analysis in seven metropolitan cities of Korea from 2011 to 2015

BACKGROUND

Although blood pressure decreases in response to high ambient temperature, little is known about whether the ambient temperature can induce clinical hypotension events. Therefore, we conducted a time-series analysis to evaluate the association between hypotension hospital visits and ambient temperature in seven metropolitan cities of Korea.

METHODS

We used the National Health Insurance Database, which contains the complete hospital visit data of the entire Korean population. We collected hospital visit data of seven metropolitan cities and linked the number of daily hypotension hospital visits to city-level ambient temperature, relative humidity, and air pollution levels from 2011 to 2015. Time-series analysis using the Poisson generalized additive model was conducted for each metropolitan city and we meta-analyzed the time-series results using the random effect model.

RESULTS

There were 132,097 hospital visits for hypotension during our study period. A 1 degree Celsius (°C) increase in ambient temperature was associated with 1.1% increase in hospital visits for hypotension on lag day 0. Effects of ambient temperature lasted for 7 days, showing greater effects in shorter lag days. Subgroup analysis by sex and income groups showed similar results, but effects of ambient temperature on hypotension hospital visits was higher in the younger age group compared to older age group (aged over 65 years old). The results were unchanged when we applied cumulative lags, different case definitions, degrees of freedom per year, and multi-pollutant model adjusting for air pollutants.

CONCLUSIONS

Hospital visits for hypotension were positively associated with ambient temperature. Increased hypotension events in response to increased ambient temperature might explain the high cardiovascular mortality on hot days.

Effects of cold temperature and snowfall on stroke mortality: A case-crossover analysis

BACKGROUND

We sought to determine if cold temperature and snowfall are independently associated with stroke mortality, and whether effects differ between hemorrhagic and ischemic stroke.

MATERIALS AND METHODS

We conducted a case-crossover study of 13,201 stroke deaths utilizing weather records between the months of November and April for Quebec, Canada from 1981 to 2015. We compared exposure to cold temperature and snowfall with controls days when stroke death did not occur. We computed odds ratios (OR) and 95% confidence intervals (CI) for the association of minimum temperature and duration of snowfall with stroke, adjusted for change in barometric pressure and relative humidity.

RESULTS

The likelihood of mortality the day following exposure to cold temperature was elevated for hemorrhagic stroke in men, independent of snowfall. Relative to 0 °C, a temperature of -20 °C was associated with 1.17 times the odds of hemorrhagic stroke death (95% CI 1.04-1.32). An independent effect of snowfall was also present in men, with 12 h of snowfall associated with 1.12 times the odds of hemorrhagic stroke death (95% CI 1.00-1.24) compared with no snowfall. There was no evidence of an increased risk in women. Cold temperature and snowfall were not associated with ischemic stroke death in either men or women.

CONCLUSION

Our results suggest that cold temperature and snowfall are independent risk factors for death from hemorrhagic stroke in men. These findings imply that interventions to prevent fatal hemorrhagic stroke during winter should include both cold temperature exposure and snowfall in men.

The effect of the Winter Fuel Payment on household temperature and health: a regression discontinuity design study

Background

The Winter Fuel Payment (WFP) is a non-NHS population-level policy intervention that aims to reduce cold exposure and enhance the health and well-being of older adults. Labelling this cash transfer as ‘winter fuel’ has been shown to lead to increased household energy expenditure, but it is not known if this expenditure produces warmer homes or health benefits.

Objectives

First, the association between indoor temperature and health was established to identify the outcome measures most likely to be affected by the WFP. Then, whether or not receiving the WFP is associated with raised household temperature levels and/or improved health was assessed.

Design

Random and fixed effects regression models were used to estimate the link between ambient indoor temperature and health. A regression discontinuity (RD) design analysis exploiting the sharp eligibility criteria for the WFP was employed to estimate the potential impact of the payment.

Setting

The sample was drawn from the English Longitudinal Study of Ageing (ELSA), an observational study of community-dwelling individuals aged ≥ 50 years in England.

Participants

Analyses examining the association between household temperature and health had a maximum sample of 12,210 adults aged 50–90 years. The RD analyses drew on a maximum of 5902 observations.

Intervention

The WFP provides households with a member who is aged > 60 years (up to 2010, from which point the minimum age increased) in the qualifying week with a lump sum annual payment, typically in November or December.

Main outcome measures

Differences in indoor temperature were examined, and, following an extensive literature review of relevant participant-reported health indicators and objectively recorded biomarkers likely to be affected by indoor temperature, a series of key measures were selected: blood pressure, inflammation, lung function, the presence of chest infections, subjective health and depressive symptom ratings.

Data sources

The first six waves of the ELSA were drawn from, accessible through the UK Data Service (SN:5050 English Longitudinal Study of Ageing: Waves 0–7, 1998–2015).

Results

Results from both random and fixed-effects multilevel regression models showed that low levels of indoor temperature were associated with raised systolic and diastolic blood pressure levels and raised fibrinogen levels. However, across the RD models, no evidence was found that the WFP was consistently associated with differences in either household temperature or the health of qualifying (vs. non-qualifying) households.

Limitations

The presence of small effects cannot be ruled out, not detectable because of the sample size in the current study.

Conclusions

This study capitalised on the sharp assignment rules regarding WFP eligibility to estimate the potential effect of the WFP on household temperature and health in a national sample of English adults. The RD design employed did not identify evidence linking the WFP to warmer homes or potential health and well-being effects.

Future work

Further research should utilise larger samples of participants close to the WFP eligibility cut-off point examined during particularly cold weather in order to identify whether or not the WFP is linked to health benefits not detected in the current study, which may have implications for population health and the evaluation of the effectiveness of the WFP.

Funding

The National Institute for Health Research Public Health Research programme.

Are the current thresholds, indicators, and time window for cold warning effective enough to protect cardiovascular health?

More extreme cold weather and larger weather variations have raised concerns regarding their effects on public health. Although prior studies assessed the effects of cold air temperature on health, especially mortality, limited studies evaluated wind chill temperatures on morbidity, and health effects under the current cold warning threshold. This study identified the thresholds, lag periods, and best indicators of extreme cold on cardiovascular disease (CVD) by comparing effects of wind chill temperatures and cold air temperatures on CVD emergency department (ED) visits in winter and winter transition months. Information was collected on 662,625 CVD ED visits from statewide hospital discharge dataset in New York State. Meteorological factors, including air temperature, wind speed, and barometric pressure were collected from National Oceanic and Atmospheric Administration. A case-crossover approach was used to assess the extreme cold-CVD relationship in winter (December-February) and transition months (November and March) after controlling for PM_2.5. Conditional logistic regression models were employed to analyze the association between cold weather factors and CVD ED visits. We observed CVD effects occurred when wind chill temperatures were as high as -3.8 °C (25 °F), warmer than current wind chill warning standard (≤-28.8 °C or ≤-20 °F). Wind chill temperature was a more sensitive indicator of CVD ED visits during winter with temperatures ≤ -3.8 °C (25 °F) with delay effect (lag 6); however, air temperature was better during transition months for temperatures ≤ 7.2 °C (45 °F) at earlier lag days (1-3). Among all CVD subtypes, hypertension ED visit had the strongest negative association with both wind chill temperature and air temperature. This study recommends modifying the current cold warning temperature threshold given larger proportions of CVD cases are occurring at considerably higher temperatures than the current criteria. We also recommend issuing cold warnings in winter transitional months.

Short-term association between ambient temperature and acute myocardial infarction hospitalizations for diabetes mellitus patients: A time series study

BACKGROUND

Acute myocardial infarction (AMI) is the leading cause of death among people with diabetes mellitus (DM) and has been found to occur more frequently with extreme temperatures. With the increasing prevalence of DM and the rising global mean temperature, the number of heat-related AMI cases among DM patients may increase. This study compares excess risk of AMI during periods of extreme temperatures between patients with DM and without DM.

METHODS

Distributed lag nonlinear models (DLNMs) were used to estimate the short-term association between daily mean temperature and AMI admissions (International Classification of Diseases 9th revision [ICD-9] code: 410.00-410.99), stratified by DM status (ICD-9: 250.00-250.99), to all public hospitals in Hong Kong from 2002 to 2011, adjusting for other meteorological variables and air pollutants. Analyses were also stratified by season, age group, gender, and admission type (first admissions and readmissions). The admissions data and meteorological data were obtained from the Hong Kong Hospital Authority (HA) and the Hong Kong Observatory (HKO).

FINDINGS

A total of 53,769 AMI admissions were included in the study. AMI admissions among DM patients were linearly and negatively associated with temperature in the cold season (cumulative relative risk [cumRR] [95% confidence interval] in lag 0-22 days (12 °C versus 24 °C) = 2.10 [1.62-2.72]), while those among patients without DM only started increasing when temperatures dropped below 22 °C with a weaker association (cumRR = 1.43 [1.21-1.69]). In the hot season, AMI hospitalizations among DM patients started increasing when the temperature dropped below or rose above 28.8 °C (cumRR in lag 0-4 days [30.4 versus 28.8 °C] = 1.14 [1.00-1.31]), while those among patients without DM showed no association with temperature. The differences in sensitivity to temperature between patients with DM and without DM were most apparent in the group <75 years old and among first-admission cases in the cold season. The main limitation of this study was the unavailability of data on individual exposure to ambient temperature.

CONCLUSIONS

DM patients had a higher increased risk of AMI admissions than non-DM patients during extreme temperatures. AMI admissions risks among DM patients rise sharply in both high and low temperatures, with a stronger effect in low temperatures, while AMI risk among non-DM patients only increased mildly in low temperatures. Targeted health protection guidelines should be provided to warn DM patients and physicians about the dangers of extreme temperatures. Further studies to project the impacts of AMI risks on DM patients by climate change are warranted.

Acute Associations Between Outdoor Temperature and Premature Rupture of Membranes

BACKGROUND

Extreme ambient temperatures have been linked to preterm birth. Preterm premature rupture of membranes is a common precursor to preterm birth but is rarely studied in relation to temperature.

METHODS

We linked 15,381 singleton pregnancies with premature rupture of membranes from a nationwide US obstetrics cohort (2002-2008) to local temperature. Case-crossover analyses compared daily temperature during the week preceding delivery and the day of delivery to 2 control periods, before and after the case period. Conditional logistic regression models calculated the odds ratio (OR) and 95% confidence intervals (CIs) of preterm and term premature rupture of membranes for a 1°C increase in temperature during the warm (May-September) and cold (October-April) season separately after adjusting for humidity, barometric pressure, ozone, and particulate matter.

RESULTS

During the warm season, 1°C increase during the week before delivery was associated with a 5% (95% CI, 3%, 6%) increased preterm premature rupture of membranes risk, and a 4% (95% CI, 3%, 5%) increased term premature rupture of membranes risk. During the cold season, 1°C increase was associated with a 2% decreased risk for both preterm (95% CI, 1%, 3%) and term premature rupture of membranes (95% CI, 1%, 3%). The day-specific associations for the week before delivery were similar, but somewhat stronger for days closer to delivery.

CONCLUSIONS

Relatively small ambient temperature changes were associated with the risk of both preterm and term premature of membranes. Given the adverse consequences of premature rupture of membranes and concerns over global climate change, these findings merit further investigation. See video abstract at, http://links.lww.com/EDE/B312.

Ambient temperature and risk of cardiovascular events at labor and delivery: A case-crossover study

BACKGROUND

Extreme ambient temperatures are linked to cardiac events in the general population, but this relationship is unclear among pregnant women. We estimated the associations and attributable risk between ambient temperature and the risk of cardiovascular event at labor/delivery, and investigated whether these associations vary by maternal race/ethnicity.

METHODS

We identified 680 women with singleton deliveries affected by cardiovascular events across 12 US sites (2002-2008). Average daily temperature during the week before, delivery day, and each of the seven days before delivery was estimated for each woman. In a case-crossover analysis, exposures during these hazard periods were compared to two control periods before and after delivery using conditional logistic regression adjusted for other environmental factors.

RESULTS

During the cold season (October-April), 1°C lower during the week prior to delivery was associated with a 4% (95% CI: 1-7%) increased risk of having a labor/delivery affected by cardiovascular events including cardiac arrest and stroke. During the warm season (May-September), 1°C higher during the week prior was associated with a 7% (95% CI: 3-12%) increased risk. These risks translated to 13.4 and 23.9 excess events per 100,000 singleton deliveries during the cold and warm season, respectively. During the warm season, the risks were more pronounced on days closer to delivery and Black women appeared to be more susceptible to the same temperature increase.

CONCLUSION

Small changes in temperature appear to affect the risk of having cardiovascular events at labor/delivery. Black women had a differentially higher warm season risk. These findings merit further investigation.

What drives cold-related excess mortality in a south Asian tropical monsoon climate-season vs. temperatures and diurnal temperature changes

Despite the tropical climate which is characterized by generally high temperatures and persistent mild temperatures during the winter season, Bangladesh, along with many other tropical countries, experiences strong winter and cold-related excess mortality. The objective of this paper was to analyse the nature of these cold effects and understand the role of season vs. temperature and diurnal changes in temperature. For approaching these questions, we applied different Poisson regression models. Temperature as well as diurnal temperature range (DTR) were considered as predictor variables. Different approaches to seasonality adjustment were evaluated and special consideration was given to seasonal differences in atmospheric effects. Our findings show that while seasonality adjustment affected the magnitude of cold effects, cold-related mortality persisted regardless the adjustment approach. Strongest effects of low temperatures were observed at the same day (lag 1) with an increase of 1.7% (95% CI = 0.86-2.54%) per 1 °C decrease in temperature during the winter season. Diurnal temperature affected mortality with increasing levels at higher ranges. Mortality increased with 0.97% (95% CI = 0.17-1.75%) when looking at the entire season, but effects of DTR were not significant during winter when running a seasonal model. Different from effects observed in the mid-latitudes, cold effects in Bangladesh occurred on a very short time scale highlighting the role of temperature versus season. Insufficient adaptation with regard to housing and clothing might lead to such cold-related increases in mortality despite rather moderate temperature values. Although the study did not demonstrate an effect of DTR during the cold season, the strong correlation with (minimum) temperature might cause a multicollinearity problem and effects are difficult to attribute to one driver.

Spatiotemporal variations of extreme low temperature for emergency transport: a nationwide observational study

Although recent studies have investigated the effect of extreme heat on emergency transport, few have investigated the spatiotemporal variations of extreme low temperature for emergency transport on a national scale. Data pertaining to emergency ambulance transport and weather variation in the 47 prefectures of Japan between 2007 and 2010 were obtained. Nonlinear and delayed relationships between temperature and morbidity were assessed using a two-stage analysis. First, a Poisson regression analysis allowing for overdispersion in a distributed lag nonlinear model was used to estimate the prefecture-specific effects of temperature on morbidity. Second, a multivariate meta-analysis was applied to pool estimates on a national level. Of 15,868,086 emergency transports over the study period, 5,375,621 emergency transports were reported during the winter months (November through February). The overall cumulative relative risk (RR) at the first percentile vs. the minimum morbidity percentile was 1.24 (95 % CI = 1.15-1.34) for all causes, 1.50 (95 % CI = 1.30-1.74) for cardiovascular diseases, and 1.59 (95 % CI = 1.33-1.89) for respiratory diseases. There were differences in the temporal variations between extreme low temperature and respiratory disease morbidity. Spatial variation between prefectures was observed for all causes (Cochran Q test, p < 0.001; I ² = 34.0 %) and respiratory diseases (Cochran Q test, p = 0.026; I ² = 18.2 %); however, there was no significant spatial heterogeneity for cardiovascular diseases (Cochran Q test, p = 0.413; I ² = 2.0 %). Our findings indicated that there were differences in the spatiotemporal variations of extreme low temperatures for emergency transport during winter in Japan. Our findings highlight the importance of further investigating to identify social and environmental factors, which can be responsible for spatial heterogeneity between prefectures.

Spatiotemporal variation in heat-related out-of-hospital cardiac arrest during the summer in Japan

BACKGROUND

Although several studies have reported the impacts of extremely high temperature on cardiovascular diseases, few studies have investigated the spatiotemporal variation in the incidence of out-of-hospital cardiac arrest (OHCA) due to extremely high temperature in Japan.

METHODS

Daily OHCA data from 2005 to 2014 were acquired from all 47 prefectures of Japan. We used time-series Poisson regression analysis combined with a distributed lag non-linear model to assess the temporal variability in the effects of extremely high temperature on OHCA incidence in each prefecture, adjusted for time trends. Spatial variability in the relationships between extremely high temperature and OHCA between prefectures was estimated using a multivariate random-effects meta-analysis.

RESULTS

We analyzed 166,496 OHCA cases of presumed cardiac origin occurring during the summer (June to September) that met the inclusion criteria. The minimum morbidity percentile (MMP) was the 51st percentile of temperature during the summer in Japan. The overall cumulative relative risk at the 99th percentile vs. the MMP over lags 0-10days was 1.21 (95% CI: 1.12-1.31). There was also a strong low temperature effect during the summer periods. No substantial difference in spatial or temporal variability was observed over the study period.

CONCLUSIONS

Our study demonstrated spatiotemporal homogeneity in the risk of OHCA during periods of extremely high temperature between 2005 and 2014 in Japan. Our findings suggest that public health strategies for OHCA due to extremely high temperatures should be finely adjusted and should particularly account for the unchanging risk during the summer.

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.

Estimating the associations of apparent temperature and inflammatory, hemostatic, and lipid markers in a cohort of midlife women

Associations between temperature and cardiovascular (CVD) mortality have been reported, but the underlying biological mechanisms remain uncertain. We explored the association between apparent temperature and serum biomarkers for CVD. Using linear mixed effects models, we examined the relationships between residence-proximate apparent temperature (same day and 1, 7, and 30 days prior) and several inflammatory, hemostatic, and lipid biomarkers for midlife women from 1999 through 2004. Our study population consisted of 2,306 women with mean age of 51 years (± 3 years) enrolled in Study of Women's Health Across the Nation (SWAN) in Chicago, Illinois; Detroit, Michigan; Los Angeles and Oakland, California; Newark, New Jersey; and Pittsburgh, Pennsylvania. Mean daily apparent temperature was calculated using temperature and relative humidity data provided by the National Climatic Data Center and the US Environmental Protection Agency, while daily data for fine particles, ozone, carbon monoxide, and nitrogen dioxide from the US Environmental Protection Agency Air Quality Data Mart were considered as confounders. All analyses were stratified by warm and cold seasons. More significant (p < 0.10) negative associations were found during the warm season for various lag times, including hs-CRP, fibrinogen, tissue plasminogen activator antigen (tPA-ag), tissue plasminogen activator antigen (PAI-1), Factor VIIc, high-density lipoprotein (HDL), and total cholesterol. During the cold season, significant negative associations for fibrinogen and HDL, but significant positive associations for tPA-ag, PAI-1, and triglycerides were observed for various lag times. With the exception of ozone, pollutants did not confound these associations. Apparent temperature was associated with several serum biomarkers of CVD risk in midlife women, shedding light on potential mechanisms.

Extreme temperature and out-of-hospital cardiac arrest in Japan: A nationwide, retrospective, observational study

BACKGROUND

Although several studies have estimated the effect of extreme temperatures on out-of-hospital cardiac arrest (OHCA) in a single city or region, few have investigated variations in this association on a national level in Japan.

METHODS

Daily data on OHCAs and weather variations were obtained from the 47 prefectures of Japan between 2005 and 2014. A time-series Poisson regression model with a distributed lag non-linear model was used to estimate the prefecture-specific effects. A multivariate meta-analysis was applied to pooled estimates on a national level.

RESULTS

A total of 659,752 OHCA cases of presumed-cardiac origin met the inclusion criteria. The minimum morbidity percentile (MMP) was identified as the 84th percentile for temperature, ranging from 20.8°C in Hokkaido to 28.8°C in Okinawa. The overall pooled relative risk versus the MMP was 2.10 (95% CI: 1.84, 2.40) at extremely low temperatures (1st percentile) and 1.06 (95% CI: 1.01, 1.12) at extremely high temperatures (99th percentile). The effects of extremely high temperatures were acute and disappeared after a few days, while those of extremely low temperatures were also acute, but persisted for several days. The multivariate Cochran's Q test indicated no heterogeneity between prefectures (p=0.699; I²=1.0%).

CONCLUSIONS

Extreme temperatures are associated with an increased risk of OHCA. Timely prevention strategies might reduce the risk of OHCA during extreme temperatures. Several days prevention should be also implemented for extremely low temperatures.