Effect of cold spells and their modifiers on cardiovascular disease events: Evidence from two prospective studies

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

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

The added effects of cold spells on stroke admissions: Differential effects on ischemic and hemorrhagic stroke

BACKGROUND

Epidemiological evidence suggests an association between low ambient temperature and stroke risk, but available data are limited particularly on associations with different stroke subtypes.

AIMS

The aim of this study is to estimate the relationship between cold spells and stroke admissions, including the effect of cold spells on different stroke subtypes (ischemic stroke and intracerebral hemorrhage (ICH)).

METHODS

A total of 144,405 stroke admissions from the Tianjin Centre for Health and Meteorology Multidisciplinary Innovation in China, covering the period from January 2016 to December 2020, were studied, as well as meteorological and air pollutant data. A generalized additive model with a distributed lag nonlinear model was employed to assess the relationship, considering 12 different definitions of a cold spell based on various temperature thresholds and durations. The analysis controlled for lagged and nonlinear effects of temperature. Analyses were performed on all strokes as well as ischemic stroke and ICH.

RESULTS

There was a significant increase in stroke admissions during cold spells. Generally, the increased risk during cold spells increased as the temperature threshold decreased, but was not significantly affected by the duration. The optimal model was obtained using the cold-spell definition based on an average daily temperature below the 10th percentile (0.11°C) for 2 or more consecutive days. According to this model, the effect of cold spells on ischemic stroke admissions had a significant lag effect and was long-lasting, with a single-day effect occurring on lag 7d, peaking on lag 13d (relative risk (RR) = 1.05; 95% confidence interval (CI) = 1.02 to 1.09), and lasting until lag 20d. In contrast, the effect on ICH was immediate and short-lived, with the most significant single-day effect occurring on the current day (RR = 1.17; 95% CI = 1.06 to 1.29) and limited within 3 days. 14.15% of stroke cases could be attributed to cold spells, with ICH exhibiting a higher burden than ischemic stroke except for strict temperature threshold definitions.

CONCLUSION

Cold spells are associated with an increased stroke risk. Different patterns of association were seen for different stroke subtypes. The effect on ischemic stroke had a lag effect and a longer duration, whereas the effect on ICH had an immediate effect and a shorter duration. These findings support the development and improvement of stroke cold-spell early warning systems and highlight the importance of public health interventions to mitigate the adverse health impacts of cold spells.

Cold Spells and the Onset of Acute Myocardial Infarction: A Nationwide Case-Crossover Study in 323 Chinese Cities

BACKGROUND

Few studies have explored the relationships between cold spells and acute myocardial infarction (AMI) using the information of symptom onset.

OBJECTIVES

We assessed the impact of cold spells on AMI onset and the potential effect modifiers.

METHODS

We conducted a time-stratified case-crossover study among 456,051 eligible patients with AMI from 2,054 hospitals in 323 Chinese cities between January 2015 and June 2021 during cold seasons (November to March). Nine definitions of cold spells were used by combining three relative temperature thresholds (i.e., lower than the 7.5th, 5th, and 2.5th percentiles) and three durations of at least 2-4 consecutive d. Conditional logistic regressions with distributed lag models were applied to evaluate the cumulated effects of cold spells on AMI onset over lags 0-6 d, after adjusting for daily mean temperature.

RESULTS

The associations generally appeared on lag 1 d, peaked on lag 3 d, and became nonsignificant approximately on lag 5 d. Cold spells defined by more stringent thresholds of temperature were associated with higher risks of AMI onset. For cold spell days defined by a daily mean temperature of ≤ 7.5 th percentile and durations of ≥ 2 d , ≥ 3 d , and ≥ 4 d , the percentage changes in AMI risk were 4.24% [95% confidence interval (CI): 2.31%, 6.20%], 3.48% (95% CI: 1.62%, 5.38%), and 2.82% (95% CI: 0.98%, 4.70%), respectively. Significant AMI risks associated with cold spells were observed among cases from regions without centralized heating, whereas null or much weaker risks were found among those from regions with centralized heating. Patients ≥ 65 years of age were more susceptible to cold spells.

DISCUSSION

This national case-crossover study presents compelling evidence that cold spells could significantly increase the risk of AMI onset. https://doi.org/10.1289/EHP11841.

Impact of particulate matter on the incidence of atrial fibrillation and the risk of adverse clinical outcomes: A review

BACKGROUND

Atrial fibrillation (AF) is common and increases the risk of stroke and mortality. Previous studies have suggested that air pollution is an important risk factor for new-onset AF. Herein, we review the evidence regarding: 1) the association between exposure to particulate matter (PM) and new-onset AF, and 2) the risk of worse clinical outcomes in patients with pre-existent AF and their relation to PM exposure.

METHODS

A selection of studies between 2000 and 2023 linking PM exposure and AF was performed through searches in PubMed, Scopus, Web of Science, and Google Scholar.

RESULTS

17 studies from different geographical areas demonstrated that exposure to PM was associated with an increased risk of new-onset AF, although the results were heterogeneous regarding the temporal pattern (short- or long-term) ultimately related to AF. Most of the studies concluded that the risk of new-onset AF increased between 2 %-18 % per 10 μg/m³ increment in PM_2.5 or PM₁₀ concentrations, whereas the incidence (percentage of change of incidence) increased between 0.29 %-2.95 % per 10 μg/m³ increment in PM_2.5 or PM₁₀. Evidence about the association between PM and adverse events in patients with pre-existent AF was scarce but 4 studies showed a higher risk of mortality and stroke (between 8 %-64 % in terms of hazard ratio) in patients with pre-existent AF when PM exposure was higher.

CONCLUSIONS

Exposure to PM (both PM_2.5 and PM₁₀) is a risk factor for AF, and a risk factor for mortality and stroke in patients who already suffer from AF. Since the relationship between PM and AF is independent of the region of the world, PM should be considered as a global risk factor for both AF and worse clinical outcomes in AF patients. Specific measures to prevent air pollution exposure need to be adopted.

Associations of cold exposure with hospital admission and mortality due to acute kidney injury: A nationwide time-series study in Korea

BACKGROUND

Emerging evidence supports an association between heat exposure and acute kidney injury (AKI). However, there is a paucity of studies on the association between cold exposure and AKI.

OBJECTIVE

We aimed to investigate the associations of cold exposure with hospital admission and mortality due to AKI and to explore whether these associations were influenced by age and sex.

METHODS

Information on daily counts of hospital admission and mortality due to AKI in 16 regions of Korea during the cold seasons (2010-2019) was obtained from the National Health Insurance Service (a single national insurer providing universal health coverage) and Statistics Korea. Daily mean temperature and relative humidity were calculated from hourly data obtained from 94 monitoring systems operated by the Korean Meteorological Administration. Associations of low temperatures (<10th percentile of daily mean temperature) and cold spells (≥2 consecutive days with <5th percentile of daily mean temperature) up to 21 days with AKI were estimated using quasi-Poisson regression models adjusted for potential confounders (e.g., relative humidity and air pollutants) with distributed lag models and univariate meta-regression models.

RESULTS

Low temperatures were associated with hospital admission due to AKI [relative risk (RR) = 1.12, 95 % confidence interval (CI): 1.09, 1.16]. Cold spells were associated with hospital admission (RR = 1.87, 95 % CI: 1.46, 2.39) and mortality due to AKI (RR = 4.84, 95 % CI: 1.30, 17.98). These associations were stronger among individuals aged ≥65 years than among those aged <65 years.

CONCLUSION

Our results underscore the need for the general population, particularly the elderly, physicians, and other healthcare providers to be more vigilant to cold exposure, given the risk of AKI. Government agencies need to develop specific strategies for the prevention and early detection of cold exposure-related AKI.

Cascading disasters and mental health inequities: Winter Storm Uri, COVID-19 and post-traumatic stress in Texas

Previous research on health effects of extreme weather has emphasized heat events even though cold-attributable mortality exceeds heat-attributable mortality worldwide. Little is known about the mental health effects of cold weather events, which often cascade to produce secondary impacts like power outages, leaving a knowledge gap in context of a changing climate. We address that gap by taking a novel "cascading disaster health inequities" approach to examine winter storm-associated post-traumatic stress (PTS) using survey data (n = 790) collected in eight Texas metro areas following Winter Storm Uri in 2021, which occurred against the backdrop of COVID-19. The incidence of storm-related PTS was 18%. Being Black (odds ratio [OR]: 6.6), Hispanic (OR: 3.5), or of another non-White race (OR: 4.2) was associated with greater odds of PTS compared to being White, which indicates substantial racial/ethnic inequities in mental health impacts (all p < 0.05). Having a disability also increased odds of PTS (OR: 4.4) (p < 0.05). Having piped water outages (OR: 1.9) and being highly impacted by COVID-19 (OR: 3.3) increased odds of PTS (both p < 0.05). When modelling how COVID-19 and outages cascaded, we compared householders to those with no outages and low COVID-19 impacts. PTS was more likely (p < 0.05) if householders had a water or power outage and high COVID-19 impacts (OR: 4.4) and if they had water and power outages and high COVID-19 impacts (OR: 7.7). Findings provide novel evidence of racial/ethnic inequities and cascading effects with regard to extreme cold events amid the COVID-19 pandemic.

Climate change and cardiovascular disease: implications for global health

Climate change is the greatest existential challenge to planetary and human health and is dictated by a shift in the Earth's weather and air conditions owing to anthropogenic activity. Climate change has resulted not only in extreme temperatures, but also in an increase in the frequency of droughts, wildfires, dust storms, coastal flooding, storm surges and hurricanes, as well as multiple compound and cascading events. The interactions between climate change and health outcomes are diverse and complex and include several exposure pathways that might promote the development of non-communicable diseases such as cardiovascular disease. A collaborative approach is needed to solve this climate crisis, whereby medical professionals, scientific researchers, public health officials and policymakers should work together to mitigate and limit the consequences of global warming. In this Review, we aim to provide an overview of the consequences of climate change on cardiovascular health, which result from direct exposure pathways, such as shifts in ambient temperature, air pollution, forest fires, desert (dust and sand) storms and extreme weather events. We also describe the populations that are most susceptible to the health effects caused by climate change and propose potential mitigation strategies, with an emphasis on collaboration at the scientific, governmental and policy levels.

Health risks and economic losses from cold spells in China

BACKGROUND

Cold significantly increases the risk of mortality. However, the health risks associated with cold spells, persistent and extreme cold temperature events, have yet to be investigated in detail.

METHODS

Meteorological and mortality data was collated from 280 counties in China from 2013 through 2019. GLM (Generalized Linear Models) was used to calculate county-level exposure-response relationships for nine different cold spell definitions. Next, we estimated the exposure-response associations between cold spells and mortality in national, Southern, and Northern China. Based on exposure-response relationships, along with the population and mortality data, we then calculated the number of excess deaths due to the cold spell of 2839 counties across China in 2018. Then, we calculated the loss of VSL (value of a statistical life) in each province.

RESULTS

We identified that P5day7 was the cold spell definition that was associated with the highest health in China. Compared with non-cold spell days, the risk of non-accidental mortality, circulatory mortality, and respiratory mortality, on cold spell days increased by 17.4% (95% confidence interval [CI]: 15.8%, 19.0%), 20.8% (95%CI: 18.8%, 23.0%), and 22.7% (95%CI: 19.5%, 25.9%) respectively at lag 7 day in the South. In the North, the risk increased by 13.0% (95% CI: 11.0%, 15.0%), 13.8% (95% CI: 11.4%, 16.2%), and 21.0% (95% CI: 16.6%, 25.6%), respectively. The number of related deaths in China were 57,783, 29,827, and 10,922. The corresponding VSLs were 229,195, 118,322, and 43,315 million CNY (Chinese Yuan), thus accounting for 0.25%, 0.13%, and 0.05% of national GDP (Gross Domestic Product).

CONCLUSION

Cold spells have caused a severe epidemiological and economic burden in China. South China should pay more attention to the health risks associated with cold spells.

Association between Cold Spells and Mortality Risk and Burden: A Nationwide Study in China

BACKGROUND

Few multicity studies have evaluated the association between cold spells and mortality risk and burden.

OBJECTIVES

We aimed to estimate the association between cold spells and cause-specific mortality and to evaluate the mortality burden in China.

METHODS

We conducted a time-series analysis with a nationally representative Disease Surveillance Points System database during the cool seasons spanning from 2013 to 2015 in 272 Chinese cities. We used 12 cold-spell definitions and overdispersed generalized additive models with distributed lag models to estimate the city-specific cumulative association of cold spells over lags of 0-28 d. We controlled for the nonlinear and lagged effects of cold temperature over 0-28 d to evaluate the added effect estimates of cold spell. We also quantified the nationwide mortality burden and pooled the estimated association at national and different climatic levels with meta-regression models.

RESULTS

For the cold-spell definition of daily mean temperatures of ≤5th percentile of city-specific daily mean temperature and duration of ≥4 consecutive d, the relative risks (i.e., risk ratios) associated with cold spells were 1.39 [95% confidence interval (CI): 1.15, 1.69] for non-accidental mortality, 1.66 (95% CI: 1.20, 2.31) for coronary heart disease mortality, 1.49 (95% CI: 1.12, 1.97) for stroke mortality, and 1.26 (95% CI: 0.85, 1.87) for chronic obstructive pulmonary disease mortality. Cold spells showed a maximal lagged association of 28 d with the risks peaked at 10-15 d. A statistically significant attributable fraction (AF) of non-accidental mortality [2.10% (95% CI: 0.94%, 3.04%)] was estimated. The risks were higher in the temperate continental and the temperate monsoon zones than in the subtropical monsoon zone. The elderly population was especially vulnerable to cold spells.

DISCUSSION

Our study provides evidence for the significant relative risks of non-accidental, cardiovascular, and respiratory mortality associated with cold spells. The findings on vulnerable populations and differential risks in different climatic zones may help establish region-specific forecasting systems against the hazardous impact of cold spells. https://doi.org/10.1289/EHP9284.

The effects of submaximal exercise and cold exposure on blood coagulation parameters in coronary artery disease patients

BACKGROUND

Both exercise and cold exposure increase blood coagulation potential but their combined effects are not known. The purpose of the present study was to assess blood coagulation factors in response to submaximal exercise in the cold environment among patients with stable coronary artery disease (CAD).

METHODS

Sixteen men (61.1 ± 7.1 years) with stable CAD participated in three 30-min experimental conditions (seated rest in - 15 °C and exercise in both + 22 °C and - 15 °C) in random order. The employed exercise consisted of brisk walking (66-69% of maximal heart rate). Factor VII (FVII), fibrinogen, D-dimer and von Willebrand factor (vWF) were analyzed from blood samples obtained before, immediately and one hour after each experiment.

RESULTS

On average, FVII activity (95% confidence interval, CI) was 123 (108-143) %, 123 (106-140) %, 121 (103-139) % (baseline, recovery 1, recovery 2), fibrinogen concentration (95% CI) 3.81 (3.49-4.12) g/l, 3.71 (3.34-4.08) g/l, 3.65 (3.26-4.05) g/l, D-dimer concentration (95% CI) 0.42 (0.28-0.56) µg/ml, 0.42 (0.29-.55) µg/ml and 0.39 (0.29-0.49) µg/ml, and vWF activity (95% CI) 184 (135-232) %, 170 (128-212) % and 173 (129-217) % after exercise in the cold. Average FVII activity varied from 122 to 123%, fibrinogen concentration from 3.71 to 3.75 g/l, D-dimer concentration from 0.35 to 0.51 µg/ml and von Willebrand factor activity from 168 to 175% immediately after each three experimental condition.

CONCLUSIONS

Our findings suggest that submaximal lower body exercise carried out in a cold environment does not significantly affect blood coagulation parameters among patients with stable CAD.

Extreme weather events in europe and their health consequences - A systematic review

BACKGROUND

Due to climate change, the frequency, intensity and severity of extreme weather events, such as heat waves, cold waves, storms, heavy precipitation causing wildfires, floods, and droughts are increasing, which could adversely affect human health. The purpose of this systematic review is therefore to assess the current literature about the association between these extreme weather events and their impact on the health of the European population.

METHODS

Observational studies published from January 1, 2007 to May 17, 2020 on health effects of extreme weather events in Europe were searched systematically in Medline, Embase and Cochrane Central Register of Controlled Trials. The exposures of interest included extreme temperature, heat waves, cold waves, droughts, floods, storms and wildfires. The health impacts included total mortality, cardiovascular mortality and morbidity, respiratory mortality and morbidity, and mental health. We conducted the systematic review following PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis). The quality of the included studies was assessed using the NICE quality appraisal checklist (National Institute for Health and Care Excellence).

RESULTS

The search yielded 1472 articles, of which 35 met the inclusion criteria and were included in our review. Studies regarding five extreme weather events (extreme heat events, extreme cold events, wildfires, floods, droughts) were found. A positive association between extreme heat/cold events and overall, cardiovascular and respiratory mortality was reported from most studies. Wildfires are likely to increase the overall and cardiovascular mortality. Floods might be associated with the deterioration of mental health instead of mortality. Depending on their length, droughts could have an influence on both respiratory and cardiovascular mortality. Contradictory evidence was found in heat-associated morbidity and wildfire-associated respiratory mortality. The associations are inconclusive due to the heterogeneous study designs, study quality, exposure and outcome assessment.

CONCLUSIONS

Evidence from most of the included studies showed that extreme heat and cold events, droughts, wildfires and floods in Europe have negative impacts on human health including mental health, although some of the associations are not conclusive. Additional high-quality studies are needed to confirm our results and further studies regarding the effects of other extreme weather events in Europe are to be expected.

Particulate Matter and Temperature: Increased Risk of Adverse Clinical Outcomes in Patients With Atrial Fibrillation

OBJECTIVE

To test the hypothesis that particulate matter with an aerodynamic diameter of less than 10 μm (PM₁₀) and temperature are associated with an increased risk of adverse clinical outcomes in patients with atrial fibrillation (AF) taking vitamin K antagonists (VKAs).

PATIENTS AND METHODS

We included patients with AF whose condition was stable while taking VKAs (international normalized ratio, 2.0 to 3.0) for 6 months seen in a tertiary hospital (recruitment from May 1, 2007, to December 1, 2007). During a median follow-up of 6.5 years (interquartile range, 4.3 to 7.9 years), ischemic strokes, major bleeding, adverse cardiovascular events, and mortality were recorded. From 2007 to 2016, data on average temperature and PM₁₀ were compared with clinical outcomes.

RESULTS

The study group included 1361 patients (663 [48.7%] male; median age, 76 years [interquartile range, 71 to 81 years]). High PM₁₀ and low temperatures were associated with higher risk of major bleeding (adjusted hazard ratio [aHR], 1.44; 95% CI, 1.22 to 1.70 and aHR, 1.03; 95% CI, 1.01 to 1.05, respectively) and mortality (aHR, 1.50; 95% CI, 1.34 to 1.69 and aHR, 1.04; 95% CI, 1.02 to 1.06, respectively); PM₁₀ was also associated with ischemic stroke and temperature with cardiovascular events. The relative risk (RR) for cardiovascular events and mortality increased in months in the lower quartile of temperature (RR, 1.12; 95% CI, 1.04 to 1.21 and RR, 1.41; 95% CI, 1.15 to 1.74, respectively). Comparing seasons, there were higher risks of cardiovascular events in spring, autumn, and winter than in summer, whereas the risk of mortality increased only in winter.

CONCLUSION

In patients with AF taking VKAs, high PM₁₀ and low temperature were associated with increased risk of ischemic stroke and cardiovascular events, respectively. Both factors increased major bleeding and mortality risks, which were higher during colder months and seasons.

Short-term effects of extreme temperatures on cause specific cardiovascular admissions in Beijing, China

Extreme temperature-related cardiovascular diseases (CVDs) have become a growing public health concern. However, the impact of temperature on the cause of specific CVDs has not been well studied in the study area. The objective of this study was to assess the impact of temperature on cause-specific cardiovascular hospital admissions in Beijing, China. We obtained data from 172 large general hospitals from the Beijing Public Health Information Center Cardiovascular Case Database and China. Meteorological Administration covering 16 districts in Beijing from 2013 to 2017. We used a time-stratified case crossover design with a distributed lag nonlinear model (DLNM) to derive the impact of temperature on CVD in hospitals back to 27 days on CVD admissions. The temperature data were stratified as cold (extreme and moderate ) and hot (moderate and extreme ). Within five years (January 2013-December 2017), a total of 460,938 (male 54.9% and female 45.1%) CVD admission cases were reported. The exposure-response relationship for hospitalization was described by a "J" shape for the total and cause-specific. An increase in the six-day moving average temperature from moderate hot (30.2 °C) to extreme hot (36.9 °C) resulted in a significant increase in CVD admissions of 16.1%(95% CI = 12.8%-28.9%). However, the effect of cold temperature exposure on CVD admissions over a lag time of 0-27 days was found to be non significant, with a relative risk of 0.45 (95% CI = 0.378-0.55) for extreme cold (-8.5 °C)and 0.53 (95% CI = 0.47-0.60) for moderate cold (-5.6 °C). The results of this study indicate that exposure to extremely high temperatures is highly associated with an increase in cause-specific CVD admissions. These finding may guide to create and raise awareness of the general population, government and private sectors regarding on the effects of current weather conditions on CVD.

Meteorological rhythms of respiratory and circulatory diseases revealed by Harmonic Analysis

The intricately fluctuating onset of respiratory and circulatory diseases displays rhythms of multi-scaled meteorological conditions due to their sensitivity to weather changes. The intrinsic meteorological rhythms of these diseases are revealed in this bio-meteorological study via Fourier decomposition and harmonic analysis. Daily emergency room (ER) visit data for respiratory and circulatory diseases from three comprehensive hospitals in Haidian district of Beijing, China were used in the analysis. Meteorological data included three temperature metrics, relative humidity, sunshine duration, daily mean air pressure, and wind speed. The Fourier decomposition and harmonic analysis on ER visits and meteorological variables involve frequency, period, and power of all harmonics. The results indicated that: i) for respiratory morbidity, a strong climatic annual rhythm responding to annual temperature change was firstly revealed; its ratio of spectral density was 16-33%. Moreover, significant correlations existed between the high-frequency fluctuations (<30 d) of morbidity and short-term harmonics of humidity and solar duration. High-frequency harmonics of temperature and pressure showed no statistically significant effect. ii) With regard to all types of circulatory morbidity, their annual periodicity was weaker than that of respiratory diseases, whose harmonic energy took a ratio less than 8%. Besides, the power of all high-frequency harmonics of circulatory morbidity accounted for up to 70-90% in the original sequences, and their relationship to many short-term meteorological factors were significant, including the mean and maximum temperatures, wind speed, and solar duration. iii) The weekly rhythm appeared in respiratory ER visits with 15% of harmonic variance but not prominent in circulatory morbidity. In summary, by decomposing the sequence of respiratory and circulatory diseases as well as recognizing their meteorological rhythms, different responses to meteorological conditions on various time scales were identified.

Excess winter mortality and morbidity before, during, and after the Great Recession: the Portuguese case

Although winter mortality and morbidity are phenomena common to most European countries, their magnitude varies significantly from country to country. The geographical disparities among regions with similar climates are the result of several social, economic, demographic, and biological conditions that influence an individual's vulnerability to winter conditions. The impact of poor socioeconomic conditions may be of such magnitude that an economic recession may aggravate the seasonal mortality pattern. This paper aims to measure the seasonal winter mortality, morbidity, and their related costs during the Great Recession (2009-2012) in mainland Portugal and its Regional Health Administrations (RHAs) and to compare it with the periods preceding and following it. Monthly mortality and morbidity data were collected and clustered into three periods: Great Recession (2009-2012), Pre-Recession (2005-2008), and Post-Recession (2013-2016). The impact of seasonal winter mortality and morbidity during the Great Recession in Portugal and its Regional Health Administrations was measured through the assessment of age-standardized excess winter (EW) death and hospital admissions rate and index, expected life expectancy gains without EW deaths, EW rate of potential years of life lost, and EW rate of emergency hospital admission costs. Important increases of winter deaths and hospital admissions were identified, resulting in an important number of potential years of life lost (87 years of life lost per 100,000 inhabitants in 2009-2012), life expectancy loss (1 year in 2009-2012), and National Health Service costs with explicit temporal and spatial variations. These human and economic costs have decreased consistently during the analyzed periods, while no significant increase was found during the Great Recession. Despite its reduction, the winter excess morbidity and mortality highlight that Portugal still faces substantial challenges related to a highly vulnerable population, calling for investments in better social and health protection.

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

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

The short-term effects of cold spells on pediatric outpatient admission for allergic rhinitis in Hefei, China

BACKGROUND

Some studies have reported that cold weather is associated with the development of allergic rhinitis (AR), but the study of extreme cold temperatures and AR is scarced. This study was conducted to find out the optimal definition of the cold spells in Hefei and to explore the relationship between cold spells and childhood AR, further to identify potential susceptible populations.

METHODS

Data of daily AR, meteorological variables and air pollutants from January 1, 2014 to December 31, 2016 were collected in Hefei. Poisson generalized linear regression with a distributed-lag nonlinear model (DLNM) was used to explore the relationship between cold spells and daily pediatric outpatient with allergic rhinitis, by comparing the number of the admission during the cold spells with those during non-cold spells in cold seasons (December to April), after adjusting for relative humidity, air pollutants, seasonality, long-term trends, calendar month, holiday and day of the week (DOW).

RESULTS

All definitions of cold spells both had a certain impact on children with allergic rhinitis, and the trend of their effects was similar. The optimal cold spells was defined as the daily average temperature for below 10th with two consecutive days during the study period, and the greatest impact of cold spells was at lag0, with a 12.5% (95%CI: 6.3%-19.1%) increase of AR than non-cold spell days, and its impact could last for 2 days. Male children, children aged 5-18 years and non-scattered children were considered to be more vulnerable to AR in cold spell days.

CONCLUSIONS

There was evidence showed that the cold spells may significantly increase the pediatric outpatient admission for allergic rhinitis, especially for male children, children aged 5-18 years and non-scattered children. For the serious threat posed by cold spells, caregivers and health practitioners should strengthen their awareness of the prevention of vulnerable people.

Use of primary care data to predict those most vulnerable to cold weather: a case-crossover analysis

Background

The National Institute for Health and Care Excellence (NICE) recommends that GPs use routinely available data to identify patients most at risk of death and ill health from living in cold homes.

Aim

To investigate whether sociodemographic characteristics, clinical factors, and house energy efficiency characteristics could predict cold-related mortality.

Design and setting

A case-crossover analysis was conducted on 34 777 patients aged ≥65 years from the Clinical Practice Research Datalink who died between April 2012 and March 2014. The average temperature of date of death and 3 days previously were calculated from Met Office data. The average 3-day temperature for the 28th day before/after date of death were calculated, and comparisons were made between these temperatures and those experienced around the date of death.

Method

Conditional logistic regression was applied to estimate the odds ratio (OR) of death associated with temperature and interactions between temperature and sociodemographic characteristics, clinical factors, and house energy efficiency characteristics, expressed as relative odds ratios (RORs).

Results

Lower 3-day temperature was associated with higher risk of death (OR 1.011 per 1°C fall; 95% CI = 1.007 to 1.015; P<0.001). No modifying effects were observed for sociodemographic characteristics, clinical factors, and house energy efficiency characteristics. Analysis of winter deaths for causes typically associated with excess winter mortality (N = 7710) showed some evidence of a weaker effect of lower 3-day temperature for females (ROR 0.980 per 1°C, 95% CI = 0.959 to 1.002, P = 0.082), and a stronger effect for patients living in northern England (ROR 1.040 per 1°C, 95% CI = 1.013 to 1.066, P = 0.002).

Conclusion

It is unlikely that GPs can identify older patients at highest risk of cold-related death using routinely available data, and NICE may need to refine its guidance.

Health effects of milder winters: a review of evidence from the United Kingdom

Cold-related mortality and morbidity remains an important public health problem in the UK and elsewhere. Health burdens have often reported to be higher in the UK compared to other countries with colder climates, however such assessments are usually based on comparison of excess winter mortality indices, which are subject to biases. Daily time-series regression or case-crossover studies provide the best evidence of the acute effects of cold exposure. Such studies report a 6% increase in all-cause deaths in England & Wales for every 1 °C fall in daily mean temperature within the top 5% of the coldest days. In major Scottish cities, a 1 °C reduction in mean temperature below 11 °C was associated with an increase in mortality of 2.9%, 3.4%, 4.8% and 1.7% from all-causes, cardiovascular, respiratory, and non-cardio-respiratory causes respectively. In Northern Ireland, a 1 °C fall during winter months led to increases of 4.5%, 3.9% and 11.2% for all-cause, cardiovascular and respiratory deaths respectively among adults. Raised risks are also observed with morbidity outcomes. Hip fractures among the elderly are only weakly associated with snow and ice conditions in the UK, with the majority of cases occurring indoors. A person's susceptibility to cold weather is affected by both individual- and contextual-level risk factors. Variations in the distributions of health, demographic, socio-economic and built-environment characteristics are likely to explain most differences in cold risk observed between UK regions. Although cold-related health impacts reduced throughout much of the previous century in UK populations, there is little evidence on the contribution that milder winters due to climate change may have made to reductions in more recent decades. Intervention measures designed to minimise cold exposure and reduce fuel poverty will likely play a key role in determining current and future health burdens associated with cold weather.

Associations of time of day with cardiovascular disease risk factors measured in older men: results from the British Regional Heart Study

OBJECTIVE

We estimated associations of time of day with cardiovascular disease (CVD) risk factors measured in older men.

METHODS

CVD risk factors (markers of inflammation and haemostasis, and cardiac markers) were measured on one occasion between 08:00 and 19:00 hours in 4252 men aged 60-79 years from the British Regional Heart Study. Linear models were used to estimate associations between time of day and risk factors. When an association was found, we examined whether the relationship between risk factors and cardiovascular mortality was affected by the adjustment for time of day using survival analyses.

RESULTS

N-terminal pro-brain natriuretic peptide (NT-proBNP) levels increased by 3.3% per hour (95% CI 1.9% to 4.8%), interleukin-6 (IL-6) increased by 2.6% per hour (95% CI 1.8% to 3.4%), while tissue plasminogen activator (t-PA) decreased by 3.3% per hour (95% CI 3.7% to 2.9%); these associations were unaffected by adjustment for possible confounding factors. The percentages of variation in these risk factors attributable to time of day were less than 2%. In survival analyses, the association of IL-6, NT-proBNP and t-PA with cardiovascular mortality was not affected by the adjustment for time of day. C reactive protein, fibrinogen, D-dimer, von Willebrand factor and cardiac troponin T showed no associations with time of day.

CONCLUSIONS

In older men, markers of inflammation (IL-6), haemostasis (t-PA) and a cardiac marker (NT-proBNP) varied by time of day. The contribution of time of day to variations in these markers was small and did not appear to be relevant for the CVD risk prediction.

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.

Effects of extreme temperatures on cardiovascular emergency hospitalizations in a Mediterranean region: a self-controlled case series study

BACKGROUND

Cold spells and heatwaves increase mortality. However little is known about the effect of heatwaves or cold spells on cardiovascular morbidity. This study aims to assess the effect of cold spells and heatwaves on cardiovascular diseases in a Mediterranean region (Catalonia, Southern Europe).

METHODS

We conducted a population-based retrospective study. Data were obtained from the System for the Development of Research in Primary Care and from the Catalan Meteorological Service. The outcome was first emergency hospitalizations due to coronary heart disease, stroke, or heart failure. Exposures were: cold spells; cold spells and 3 or 7 subsequent days; and heatwaves. Incidence rate ratios (IRR) and 95% confidence intervals were calculated using the self-controlled case series method. We accounted for age, time trends, and air pollutants; results were shown by age groups, gender or cardiovascular event type.

RESULTS

There were 22,611 cardiovascular hospitalizations in winter and 17,017 in summer between 2006 and 2013. The overall incidence of cardiovascular hospitalizations significantly increased during cold spells (IRR = 1.120; CI 95%: 1.10-1.30) and the effect was even stronger in the 7 days subsequent to the cold spell (IRR = 1.29; CI 95%: 1.22-1.36). Conversely, cardiovascular hospitalizations did not increase during heatwaves, neither in the overall nor in the stratified analysis.

CONCLUSIONS

Cold spells but not heatwaves, increased the incidence of emergency cardiovascular hospitalizations in Catalonia. The effect of cold spells was greater when including the 7 subsequent days. Such knowledge might be useful to develop strategies to reduce the impact of extreme temperature episodes on human health.

Association of Maximum Temperature With Sedentary Time in Older British Men

Background

Sedentary behavior is very common in older adults and a risk factor for mortality. Understanding determinants of sedentary behavior may help in defining strategies aimed to reduce the time spent sedentary. The degree of difference in sedentary time attributable to varying temperatures has not been yet estimated in older men.

Methods

Men aged 71 to 91 years participating in an established UK population-based cohort study were invited to wear an Actigraph GT3X accelerometer for 1 week in 2010–12. Outcome was sedentary time (<1.5 Metabolic Equivalent of Task) in minutes per day. Associations between daily outdoor maximum temperature and accelerometer-measured sedentary time were estimated using multilevel models.

Results

43% (1361/3137) of invited men participated in the study and provided adequate data. Men spent on average 615 minutes in sedentary time per day (72% of the total accelerometer-wear time). After adjusting for covariates, men spent 26 minutes more per day (P < .001) in sedentary time when temperatures were in the lowest (–3.5; 9.2°C) versus highest quintile (19.1; 29.5°C).

Conclusions

Sedentary time in older adults is highest at lowest temperatures, typically recorded in winter. Findings are relevant for guidelines: interventions may consider targeting older men in winter providing recommendations for minimizing sedentariness on daily basis.

Relationship between outdoor temperature and cardiovascular disease risk factors in older people

Background Previous studies demonstrated that lower outdoor temperatures increase the levels of established cardiovascular disease risk factors, such as blood pressure and lipids. Whether or not low temperatures increase novel cardiovascular disease risk factors levels is not well studied. The aim was to investigate associations of outdoor temperature with a comprehensive range of established and novel cardiovascular disease risk factors in two large Northern European studies of older adults, in whom cardiovascular disease risk is increased. Design and methods Data came from the British Regional Heart Study (4252 men aged 60-79 years) and the Prospective Study of Pravastatin in the Elderly at Risk (5804 men and women aged 70-82 years). Associations between outdoor temperature and cardiovascular disease risk factors were quantified in each study and then pooled using a random effects model. Results With a 5℃ lower mean temperature, total cholesterol was 0.04 mmol/l (95% confidence interval (CI) 0.02-0.07) higher, low density lipoprotein cholesterol was 0.02 mmol/l (95% CI 0.01-0.05) higher and SBP was 1.12 mm Hg (95% CI 0.60-1.64) higher. Among novel cardiovascular disease risk factors, C-reactive protein was 3.3% (95% CI 1.0-5.6%) higher, interleukin-6 was 2.7% (95% CI 1.1-4.3%) higher, and vitamin D was 11.2% (95% CI 1.0-20.4%) lower. Conclusions Lower outdoor temperature was associated with adverse effects on cholesterol, blood pressure, circulating inflammatory markers, and vitamin D in two older populations. Public health approaches to protect the elderly against low temperatures could help in reducing the levels of several cardiovascular disease risk factors.