The association between two windchill indices and daily mortality variation in The Netherlands

Is Cold Apparent Temperature Associated With the Hospitalizations for Osteoporotic Fractures in the Central Areas of Wuhan? A Time-Series Study

Osteoporosis is alarming problem due to aggravation of global aging, especially in China. Osteoporotic fracture (OF) is one of the most severe consequents of osteoporosis. Many previous studies found that environmental factors had adverse effects on human health. Cold temperature was associated with OF and bone metabolism in prior observational and experimental researches. However, few studies had been conducted on the acute effect of low temperature and OF. Data on daily meteorological factors and hospitalizations for OF were collected from Wuhan, China, between January 1, 2017 to December 24, 2019. Apparent temperature (AT), comprehensively considered a variety of environmental factors, was calculated by ambient temperature, relative humidity and wind speed. A generalized linear regression model combined with distributed lag non-linear regression model (DLNM) with quasi-Poisson link was used to explore the association between AT and the number of hospitalizations for OF. Subgroup analyses stratified by gender, age and the history of fracture were applied for detecting susceptible people. The exposure-response curve of AT and OF were generally U-shaped with lowest point at 25.8°C. The significant relationship of AT-OF existed only in cold effect (-2.0 vs. 25.8°C) while not in warm effect (37.0 vs. 25.8°C). Statistically significant risks of OF for cold effects were only found in females [RR = 1.12 (95%CI: 1.02, 1.24) at lag 2 day], aged <75 years old [RR = 1.18 (95%CI: 1.04, 1.33) and 1.17 (95%CI: 1.04, 1.33) at lag 2 and 3 days, respectively] and people with history of fracture [RR = 1.39 (95%CI: 1.02, 1.90) and 1.27 (95%CI: 1.05, 1.53) at lag 1 and 2 days, respectively]. The significant associations of AT on OF were only found in cold effect. The females, people aged <75 years and people with history of fracture possibly appeared to be more vulnerable. Public health departments should pay attention to the negative effect of cold AT and take measures in time.

Sex-specific and age-related seasonal variations regarding incidence and in-hospital mortality of pulmonary embolism in Germany

Background

Studies have reported seasonal variations regarding the incidence and the short-term mortality of pulmonary embolism (PE). The aim of this study was to identify sex-specific and age-related differences in seasonal patterns regarding hospitalisations and mortality of PE patients.

Methods

We analysed the impact of seasons on incidence and in-hospital mortality of male and female hospitalised PE patients in Germany (2005-2015) based on the German nationwide inpatient sample.

Results

The German nationwide inpatient sample comprised 885 806 hospitalisations due to PE (2005-2015). Seasonal variations of both incidence (p=0.021) and in-hospital mortality (p<0.001) were of significant magnitude. Quarterly annual incidence (25.5 versus 23.7 of 100 000 citizens per year, p=0.021) and in-hospital mortality (17.0% versus 16.7%, p=0.008) were higher in winter than in summer. Risk of in-hospital mortality in winter was slightly higher (OR 1.03 (95% CI 1.01-1.06), p=0.015) compared to summer, independently of sex, age and comorbidities. Additionally, we observed sex-specific differences during seasons: the highest number of hospitalisations of PE patients of both sexes was during winter, whereas the nadir of male patients was in spring and that of female patients was in summer. Both sexes showed a maximum of in-hospital mortality in spring. Seasonal variation regarding incidence and mortality was pronounced in older patients.

Conclusion

Incidence and the in-hospital mortality of PE patients showed a significant seasonal variation with sex-specific differences. Although it has to be hypothesised that the seasonal variation of PE is multifactorially dependent, variation in each season was not explained by seasonal differences regarding age, sex and the prevalence of important comorbidities.

Effects of Ambient Temperature on Acute Exacerbations of Chronic Obstructive Pulmonary Disease: Results from a Time-Series Analysis of 143318 Hospitalizations

Purpose

To evaluate the associations between acute exacerbations of chronic obstructive pulmonary disease (AECOPD) hospitalizations and daily mean temperature (Tmean) as well as daily apparent temperature (AT), and to explore the practical values of these two indices in policymaking and patient education.

Methods

Daily AECOPD hospitalizations and Meteorological data in Beijing were obtained between 2013 and 2016. Distributed lag non-linear model was adopted to investigate the association between daily ambient temperature and AECOPD hospitalizations. The cumulative effects of cold/hot temperature were abstracted. For the extreme and moderate low-temperature effect estimates, we, respectively, computed the RR of AECOPD hospitalizations at the 1st and 10th percentiles of temperature in comparison with that at the 25th percentile of temperature. For the extreme and moderate high temperature effect estimates, we, respectively, computed the RR of AECOPD hospitalizations at the 99th and 90th percentiles of temperature in comparison with that at the 75th percentile of temperature.

Results

During the study period, 143, 318 AECOPD hospitalizations were collected. A reverse J-shape relationship was found between temperature and AECOPD hospitalizations. When comparing the effect of Tmean, higher RRs were associated with increases in AT on AECOPD hospitalizations but a lower value of Akaike’s Information Criterion for quasi-Poisson (Q-AIC). The RR of extremely low temperature of Tmean and AT were 1.55 (95% CI: 1.21,2.00) and 2.08 (95% CI: 1.44,3.01), respectively. Moderate low temperature also had an adverse impact on AECOPD hospitalizations. No associations were found between high temperature and AECOPD risk. We found the females and those aged <65 years to be more susceptible to temperature change.

Conclusion

Lower temperature is associated with a higher risk for AECOPD hospitalizations. Ambient temperature is probably a better predictor in terms of quantifying risk than mean temperature when studying temperature impact on health.

Effects of urbanization on winter wind chill conditions over China

Human-perceived wind chill describes the combined effects of wind velocity and low temperature, strongly related to human health and natural environment. Although long-term trends in the air or ambient temperature over China under global warming have been well studied in the literature, the changes in human-perceived wind chill conditions, especially under possible urbanization effects, are still not completely known. This paper investigates the changes of wind chill over China and quantifies the associated urbanization effect by examining nearly 2000 meteorological stations during 1961-2014 using the generalized additive model (GAM). Results show that the winter wind chill temperature (WCT) in China exhibits more prominent raising trends than the air temperature, i.e., 0.623 and 0.349 °C per decade, respectively. The wind speed (V) and wind chill days (WCD) decreased by 0.149 m/s and 1.970 days per decade, respectively. These trends become more substantial in densely populated and highly urbanized areas such as the North China Plain. The expansion of urban built-up area induces additional warming (reducing) to the increase (decrease) in WCT (WCD). On average, an increase from 0% to 100% in the urban fraction induced 0.290 ± 0.067 °C higher WCT (± denotes the 95% confidence interval), along with a reduction in V and WCD by 0.052 ± 0.014 m/s and 3.513 ± 0.387 days, respectively; whereas, the presence of the grassland and forest significantly diminishes the WCT and increases the WCD and surface V. It is expected that wind chill over China tends to be weakened under glocal warming and local urbanization in the near future. Our results have important implications for climate change mitigation, urban planning, landscape design, and air pollution abatement.

Examining the association between apparent temperature and admissions for schizophrenia in Hefei, China, 2005-2014: A time-series analysis

BACKGROUND

Many studies have investigated the association between schizophrenia and daily mean temperature, but the conclusions were not consistent. Apparent temperature (AT), a comprehensive indicator of temperature and humidity, reflected human thermal sensation more objectively than temperature. We aimed to investigate the relationship between high/low AT and schizophrenia hospitalizations in Hefei, China, and further to identify vulnerable subpopulations.

METHODS

Poisson generalized linear regression model combined with distributed lag non-linear model (DLNM) was applied to quantify the relationship between AT and schizophrenia hospitalizations, compared with the AT of minimum admissions (3.3 °C). Stratified analysis was conducted by sex, marital status and age. Separate models for AT and temperature were compared as well.

RESULTS

The high AT (90th, 28.3 °C) exerted the greatest effect at lag0, with RR = 1.062 (95%CI, 1.019-1.106). The effect of the low AT (10th, -4.7 °C) was first observed at lag3 (RR = 1.007, 95%CI: 1.000-1.015), and increased to the maximum at lag7 (RR = 1.018, 95%CI: 1.009-1.027). The male patients, the married patients and patients aged 41-60 years appeared to be more vulnerable to both high and low ATs. The values of Akaike Information Criterion and mean squared error (MSE) in model with AT were smaller than that with temperature.

CONCLUSIONS

Both high and low ATs were associated with increase in schizophrenia hospitalizations. More protective measures should be taken to avoid adverse AT exposure in susceptible groups.

Association between extreme temperature and acute myocardial infarction hospital admissions in Beijing, China: 2013-2016

Over the past few decades, a growing body of epidemiological studies found the effects of temperature on cardiovascular disease, including the risk for acute myocardial infarction (AMI). Our study aimed to investigate whether there is an association between extremely temperature and acute myocardial infarction hospital admission in Beijng, China. We obtained 81029 AMI cases and daily temperature data from January 1, 2013 to December 31, 2016. We employed a time series design and modeled distributed lag nonlinear model (DLNM) to analyze effects of temperature on daily AMI cases. Compared with the 10th percentile temperature measured by daily mean temperature (Tmean), daily minimum temperature (Tmin) and daily minimum apparent temperature (ATmin), the cumulative relative risks (CRR) at 1st percentile of Tmean, Tmin and ATmin for AMI hospitalization were 1.15(95% CI: 1.02, 1.30), 1.24(95% CI: 1.11, 1.38) and 1.41(95% CI: 1.18, 1.68), respectively. Moderate low temperature (10th vs 25th) also had adverse impact on AMI events. The susceptive groups were males and people 65 years and older. No associations were found between high temperature and AMI risk. The main limitation of the study is temperature exposure was not individualized. These findings on cold-associated AMI hospitalization helps characterize the public health burden of cold and target interventions to reduce temperature induced AMI occurrence.

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.

The association between wind-related variables and stroke symptom onset: A case-crossover study on Jeju Island

BACKGROUND

Although several studies have investigated the effects of ambient temperature on the risk of stroke, few studies have examined the relationship between other meteorological conditions and stroke. Therefore, the aim of this study was to analyze the association between wind-related variables and stroke symptoms onset.

METHODS

Data regarding the onset of stroke symptoms occurring between January 1, 2006, and December 31, 2007 on Jeju Island were collected from the Jeju National University Hospital stroke registry. A fixed-strata case-crossover analysis based on time of onset and adjusted for ambient temperature, relative humidity, air pressure, and pollutants was used to analyze the effects of wind speed, the daily wind speed range (DWR), and the wind chill index on stroke symptom onset using varied lag terms. Models examining the modification effects by age, sex, smoking status, season, and type of stroke were also analyzed.

RESULTS

A total of 409 stroke events (381 ischemic and 28 hemorrhagic) were registered between 2006 and 2007. The odds ratios (ORs) for wind speed, DWR, and wind chill among the total sample at lag 0-8 were 1.18 (95% confidence interval (CI): 1.06-1.31), 1.08 (95% CI: 1.02-1.14), and 1.22 (95% CI: 1.07-1.39) respectively. The ORs for wind speed, DWR, and wind chill for ischemic stroke patients were slightly greater than for patients in the total sample (OR=1.20, 95% CI: 1.08-1.34; OR=1.09, 95% CI: 1.03-1.15; and OR=1.22, 95% CI: 1.07-1.39, respectively). Statistically significant season-specific effects were found for spring and winter, and various delayed effects were observed. In addition, age, sex, and smoking status modified the effect size of wind speed, DWR, and wind chill.

CONCLUSIONS

Our analyses showed that the risk of stroke symptoms onset was associated with wind speed, DWR, and wind chill on Jeju Island.

Effects of weather conditions on emergency ambulance calls for acute coronary syndromes

The aim of this study was to evaluate the relationship between weather conditions and daily emergency ambulance calls for acute coronary syndromes (ACS). The study included data on 3631 patients who called the ambulance for chest pain and were admitted to the department of cardiology as patients with ACS. We investigated the effect of daily air temperature (T), barometric pressure (BP), relative humidity, and wind speed (WS) to detect the risk areas for low and high daily volume (DV) of emergency calls. We used the classification and regression tree method as well as cluster analysis. The clusters were created by applying the k-means cluster algorithm using the standardized daily weather variables. The analysis was performed separately during cold (October-April) and warm (May-September) seasons. During the cold period, the greatest DV was observed on days of low T during the 3-day sequence, on cold and windy days, and on days of low BP and high WS during the 3-day sequence; low DV was associated with high BP and decreased WS on the previous day. During June-September, a lower DV was associated with low BP, windless days, and high BP and low WS during the 3-day sequence. During the warm period, the greatest DV was associated with increased BP and changing WS during the 3-day sequence. These results suggest that daily T, BP, and WS on the day of the ambulance call and on the two previous days may be prognostic variables for the risk of ACS.

Altitude and cold weather: are they vascular risks?

PURPOSE OF REVIEW

The relationship of altitude and cold to cardiovascular risk is complex. Cold is hard to separate from altitude. This review highlights the latest information on cardiovascular disease associated with high altitude and cold; both represent unique clinical situations.

RECENT FINDINGS

Evolution and genetics are relevant to high altitude, with much new information available. Specific physiology explains some congenital heart disease at altitude. New reports of hematological changes associated with altitude and cold help clarify thrombosis, which is relevant to reports of very late in-stent thrombosis at altitude. Multiple cardiovascular risk factors are affected by altitude and cold, and an increased incidence of myocardial infarction occurs. There is new research on acute mountain sickness associated with inflammation with relevance for clinical study of pulmonary edema. Socioeconomics plays a part in altitude and cold effects on cardiovascular disease. In addition to acute disease, high altitude involves chronic mountain sickness with new knowledge of associated cardiovascular endothelial abnormalities.

SUMMARY

High altitude and cold involve acute disease, chronic disease, and public health issues. Continued research is essential to enable the best clinical management in this era of rapid worldwide travel.

Relationships between cold-temperature indices and all causes and cardiopulmonary morbidity and mortality in a subtropical island

This study aimed to identify optimal cold-temperature indices that are associated with the elevated risks of mortality from, and outpatient visits for all causes and cardiopulmonary diseases during the cold seasons (November to April) from 2000 to 2008 in Northern, Central and Southern Taiwan. Eight cold-temperature indices, average, maximum, and minimum temperatures, and the temperature humidity index, wind chill index, apparent temperature, effective temperature (ET), and net effective temperature and their standardized Z scores were applied to distributed lag non-linear models. Index-specific cumulative 26-day (lag 0-25) mortality risk, cumulative 8-day (lag 0-7) outpatient visit risk, and their 95% confidence intervals were estimated at 1 and 2 standardized deviations below the median temperature, comparing with the Z score of the lowest risks for mortality and outpatient visits. The average temperature was adequate to evaluate the mortality risk from all causes and circulatory diseases. Excess all-cause mortality increased for 17-24% when average temperature was at Z=-1, and for 27-41% at Z=-2 among study areas. The cold-temperature indices were inconsistent in estimating risk of outpatient visits. Average temperature and THI were appropriate indices for measuring risk for all-cause outpatient visits. Relative risk of all-cause outpatient visits increased slightly by 2-7% when average temperature was at Z=-1, but no significant risk at Z=-2. Minimum temperature estimated the strongest risk associated with outpatient visits of respiratory diseases. In conclusion, the relationships between cold temperatures and health varied among study areas, types of health event, and the cold-temperature indices applied. Mortality from all causes and circulatory diseases and outpatient visits of respiratory diseases has a strong association with cold temperatures in the subtropical island, Taiwan.

Apparent temperature and air pollution vs. elderly population mortality in Metro Vancouver

Background

Meteorological conditions and air pollution in urban environments have been associated with general population and elderly mortality, showing seasonal variation.

Objectives

This study is designed to evaluate the relationship between apparent temperature (AT) and air pollution (PM_2.5) vs. mortality in elderly population of Metro Vancouver.

Methods

Statistical analyses are performed on moving sum daily mortality rates vs. moving average AT and PM_2.5 in 1-, 2-, 3-, 5-, and 7-day models for all seasons, warm temperatures above 15°C, and cold temperatures below 10°C.

Results

Approximately 37% of the variation in all-season mortality from circulatory and respiratory causes can be explained by the variation in 7-day moving average apparent temperature (r² = 0.37, p<0.001). Although the analytical results from air pollution models show increasingly better prediction ability of longer time-intervals (r² = 0.012, p<0.001 in a 7-day model), a very weak negative association between elderly mortality and air pollution is observed.

Conclusions

Apparent temperature is associated with mortality from respiratory and circulatory causes in elderly population of Metro Vancouver. In a changing climate, one may anticipate to observe potential health impacts from the projected high- and particularly from the low-temperature extremes.

The effect of various temperature indicators on different mortality categories in a subtropical city of Brisbane, Australia

BACKGROUND

The relationship between temperature and mortality has been explored for decades and many temperature indicators have been applied separately. However, few data are available to show how the effects of different temperature indicators on different mortality categories, particularly in a typical subtropical climate.

OBJECTIVE

To assess the associations between various temperature indicators and different mortality categories in Brisbane, Australia during 1996-2004.

METHODS

We applied two methods to assess the threshold and temperature indicator for each age and death groups: mean temperature and the threshold assessed from all cause mortality was used for all mortality categories; the specific temperature indicator and the threshold for each mortality category were identified separately according to the minimisation of AIC. We conducted polynomial distributed lag non-linear model to identify effect estimates in mortality with one degree of temperature increase (or decrease) above (or below) the threshold on current days and lagged effects using both methods.

RESULTS

Akaike's Information Criterion was minimized when mean temperature was used for all non-external deaths and deaths from 75 to 84 years; when minimum temperature was used for deaths from 0 to 64 years, 65-74 years, ≥ 85 years, and from the respiratory diseases; when maximum temperature was used for deaths from cardiovascular diseases. The effect estimates using certain temperature indicators were similar as mean temperature both for current day and lag effects.

CONCLUSION

Different age groups and death categories were sensitive to different temperature indicators. However, the effect estimates from certain temperature indicators did not significantly differ from those of mean temperature.

Seasonal Variation in Occurrence of Pulmonary Embolism: Analysis of the Database of the Emilia‐Romagna Region, Italy

Seasonal variation in the occurrence of cardiovascular and cerebrovascular events, including pulmonary embolism (PE), has been reported; however, recent large-scale, population-based studies conducted in the United States did not confirm such seasonality. The aim of this large-scale population study was to determine whether a temporal pattern in the occurrence of PE exists. The analysis considered all consecutive cases of PE in the database of all hospital admissions of the Emilia Romagna region in Italy at the Center for Health Statistics between January 1998 and December 2005. PE cases were first grouped according to season of occurrence, and the data were analyzed by the chi(2) test for goodness of fit. Then, inferential chronobiologic (cosinor and partial Fourier) analysis was applied to monthly data, and the best-fitting curve for the annual variation was derived. The total sample consisted of 19,245 patients (8,143 male, mean age 71.6+/-14.1 yrs; 11,102 female, mean age 76.1+/-13.7 yrs). Of these, 2,484 were <65 yrs, 5,443 were between 65 and 74, and 11,318 were > or = 75 yrs. There were 4,486 (23.3%) fatal-case outcomes. PE occurred least frequently in spring (n=4,442 or 23.1%) and most frequent in winter (n=5,236 or 27.2%, goodness of fit chi(2)=75.75, p<0.001). Similar results were obtained for subgroups formed by gender, age, fatal/non-fatal outcome, presence/absence of major underlying co-morbid conditions, and specific risk factors. Inferential chronobiological analysis identified a significant annual pattern in PE, with the peak between November and December for the total sample of cases (p<0.001), males (p<0.001), females (p=0.002), fatal and non-fatal cases (p<0.001 for both), and subgroups formed by age (<65 yrs, p=0.012; 65-74 yrs, p<0.001; > or = 75 yrs, p=0.012). This pattern was independent of the presence/absence of hypertension (p=0.003 and p<0.001, respectively), pulmonary disease (p<0.001 and p<0.001, respectively), stroke (p<0.001 and p=0.004, respectively), neoplasms (p=0.005 and p=0.001, respectively), heart failure (p=0.022 and p<0.001, respectively), and deep vein thrombosis (p=0.002 and p<0.001, respectively). However, only a non-statistically significant trend was found for subgroups formed by cases of diabetes mellitus, infections, renal failure, and trauma.

Manual performance deterioration in the cold estimated using the wind chill equivalent temperature

Manual performance during work in cold and windy climates is severely hampered by decreased dexterity, but valid dexterity decrease predictors based on climatic factors are scarce. Therefore, this study investigated the decrease in finger- and hand dexterity and grip force for nine combinations of ambient temperature (-20, -10 and 0 degrees C) and wind speeds (0.2, 4 and 8 m x s(2)), controlled in a climatic chamber. Finger dexterity was determined by the Purdue pegboard test, hand dexterity by the Minnesota manual dexterity test and grip force by a hand dynamometer. Twelve subjects with average to low fat percentage were exposed to cold air for one hour with and without extra insulation by a parka. The subjects were clothed in standard work clothing of the Royal Netherlands Air Force for cold conditions. Extra insulation did affect cold sensation but not manual performance. The deterioration in manual performance appeared to be strongly dependent upon Wind Chill Equivalent Temperature (WCET) and the square root of exposure time (r=0.93 for group average). These simple models may be valuable to assess problems with work in the cold, but more work should be done to determine critical values in dexterity for a wide variety of operational tasks.

Are fuel poverty reduction schemes associated with decreased excess winter mortality in elders? A case study from London, U.K

The London Borough of Newham, London piloted the Warm Zone, a government-led fuel poverty reduction scheme. Fuel poverty is often cited as a factor in excess winter mortality (EWM) in the U.K. This study reported in this paper assessed whether EWM decreased for people aged > or =65 years in Newham as compared to all London, employing data from before and throughout the duration of the Warm Zone project. The paper also discusses the difficulties surrounding the measurement and interpretation of health impact relating to fuel poverty. We calculated and compared the yearly EWM indices for people aged > or =65 years for all of London, and for Newham over 12 years (1993-2005). The yearly EWM ratio for Newham in relation to all London was then calculated and compared. No definitive evidence to support the effect of the War Zone on EMW were noted. Relationships between EWM and fewer poverty reduction schemes are difficult to interpret, as many factors are entangled. These include cold strain and biological, genetic, gender, physiological, thermoregulation, environmental, meteorological, socio-economic, healthcare provision/expenditure, lifestyle and co-morbidity aspects, besides the challenges of sample sizes and whether other fuel poverty reduction schemes were simultaneously in operation. Those in privately owned housing might be ;masked' (underestimated) in their vulnerability to fuel poverty. Redefining the specific criteria for eligibility for fuel poverty grants and tackling heat inefficiency in privately owned homes not eligible for home heating improvement despite fulfilling other criteria for vulnerability requires attention. The implications are discussed.

Seasonal variation in the occurrence of venous thromboembolism: data from the MASTER Registry

Many studies showed that the occurrence of cardiovascular and cerebrovascular events exhibits a seasonal variation. As for venous thromboembolism (VTE), not univocal results are available, and studies are mainly retrospective. We aimed to confirm the existence of a seasonal pattern in the occurrence of VTE on a large prospective population. The analysis considered consecutive cases of VTE enrolled into the MASTER Registry in 25 Italian hospitals, between January 2002 and November 2004. The total population consisted of 2119 subjects (1056 men, mean age 59 +/- 18 years). The total sample was divided into subgroups by gender, age (<40, 41-60, 61-80, > or = 80 years), type of event (first episode; proximal or distal; upper or lower limb; idiopathic or secondary deep vein thrombosis or pulmonary embolism, or both), and underlying risk factors, eg, cancer, previous VTE, estroprogestinic therapy, lack of prophylaxis, immobilization, surgery, pregnancy or puerperium, and medical diseases. Cases were grouped according to season and month of occurrence, and the data were analyzed by either the chi(2) test for goodness of fit and chronobiological analysis. VTE was most frequent in Autumn and less frequent in Spring (32.9% vs 19%, respectively, chi(2) = 90.62; P < .001). This pattern was shown for most subgroups. Chronobiological analysis identified a significant rhythmic annual pattern, with a main September-October peak for several subgroups (men, age 41-60 and 61-80 years, secondary event, previous VTE, immobilization), and a trend for most of the others. It is possible that subjects at increased risk could perhaps deserve appropriate or potentiated VTE prophylaxis in certain periods of the year.

Heat-related and cold-related deaths in England and Wales: who is at risk?

BACKGROUND

Despite the high burden from exposure to both hot and cold weather each year in England and Wales, there has been relatively little investigation on who is most at risk, resulting in uncertainties in informing government interventions.

OBJECTIVE

To determine the subgroups of the population that are most vulnerable to heat-related and cold-related mortality.

METHODS

Ecological time-series study of daily mortality in all regions of England and Wales between 1993 and 2003, with postcode linkage of individual deaths to a UK database of all care and nursing homes, and 2001 UK census small-area indicators.

RESULTS

A risk of mortality was observed for both heat and cold exposure in all regions, with the strongest heat effects in London and strongest cold effects in the Eastern region. For all regions, a mean relative risk of 1.03 (95% confidence interval (CI) 1.02 to 1.03) was estimated per degree increase above the heat threshold, defined as the 95th centile of the temperature distribution in each region, and 1.06 (95% CI 1.05 to 1.06) per degree decrease below the cold threshold (set at the 5th centile). Elderly people, particularly those in nursing and care homes, were most vulnerable. The greatest risk of heat mortality was observed for respiratory and external causes, and in women, which remained after control for age. Vulnerability to either heat or cold was not modified by deprivation, except in rural populations where cold effects were slightly stronger in more deprived areas.

CONCLUSIONS

Interventions to reduce vulnerability to both hot and cold weather should target all elderly people. Specific interventions should also be developed for people in nursing and care homes as heat illness is easily preventable.

The impact of ambient temperature on mortality among the urban population in Skopje, Macedonia during the period 1996-2000

Background

This study assesses the relationship between daily numbers of deaths and variations in ambient temperature within the city of Skopje, R. Macedonia.

Methods

The daily number of deaths from all causes, during the period 1996–2000, as well as those deaths from cardiovascular diseases, occurring within the city of Skopje were related to the average daily temperature on the same day using Multiple Regression statistical analyses. Temperature was measured within the regression model as two complementary variables: 'Warm' and 'Cold'. Excess winter mortality was calculated as winter deaths (deaths occurring in December to March) minus the average of non-winter deaths (April to July of the current year and August to November of the previous year).

Results

In this study the average daily total of deaths was 7% and 13% greater in the cold when compared to the whole period and warm period respectively. The same relationship was noticed for deaths caused by cardiovascular diseases. The Regression Beta Coefficient (b = -0.19) for the total mortality as a function of the temperature in Skopje during the period 1996–2000 was statistically significant with negative connotation as was the circulatory mortality due to average temperature (statistically significant regression Beta coefficient (b = -0.24)). A measure of this increase is provided, on an annual basis, in the form of the excess winter mortality figure.

Conclusion

Mortality with in the city of Skopje displayed a marked seasonality, with peaks in the winter and relative troughs in the summer.

The lagged effect of cold temperature and wind chill on cardiorespiratory mortality in Scotland

AIMS

To investigate the lagged effects of cold temperature on cardiorespiratory mortality and to determine whether "wind chill" is a better predictor of these effects than "dry bulb" temperature.

METHODS

Generalised linear Poisson regression models were used to investigate the relation between mortality and "dry bulb" and "wind chill" temperatures in the three largest Scottish cities (Glasgow, Edinburgh, and Aberdeen) between January 1981 and December 2001. Effects of temperature on mortality (lags up to one month) were quantified. Analyses were conducted for the whole year and by season (cool and warm seasons).

MAIN RESULTS

Temperature was a significant predictor of mortality with the strongest association observed between temperature and respiratory mortality. There was a non-linear association between mortality and temperature. Mortality increased as temperatures fell throughout the range, but the rate of increase was steeper at temperatures below 11 degrees C. The association between temperature and mortality persisted at lag periods beyond two weeks but the effect size generally decreased with increasing lag. For temperatures below 11 degrees C, a 1 degrees C drop in the daytime mean temperature on any one day was associated with an increase in mortality of 2.9% (95% CI 2.5 to 3.4), 3.4% (95% CI 2.6 to 4.1), 4.8% (95% CI 3.5 to 6.2) and 1.7% (95% CI 1.0 to 2.4) over the following month for all cause, cardiovascular, respiratory, and "other" cause mortality respectively. The effect of temperature on mortality was not observed to be significantly modified by season. There was little indication that "wind chill" temperature was a better predictor of mortality than "dry bulb" temperature.

CONCLUSIONS

Exposure to cold temperature is an important public health problem in Scotland, particularly for those dying from respiratory disease.

Cold periods and coronary events: an analysis of populations worldwide

STUDY OBJECTIVE

To investigate the association between cold periods and coronary events, and the extent to which climate, sex, age, and previous cardiac history increase risk during cold weather.

DESIGN

A hierarchical analyses of populations from the World Health Organisation's MONICA project.

SETTING

Twenty four populations from the WHO's MONICA project, a 21 country register made between 1980 and 1995.

PATIENTS

People aged 35-64 years who had a coronary event.

MAIN RESULTS

Daily rates of coronary events were correlated with the average temperature over the current and previous three days. In cold periods, coronary event rates increased more in populations living in warm climates than in populations living in cold climates, where the increases were slight. The increase was greater in women than in men, especially in warm climates. On average, the odds for women having an event in the cold periods were 1.07 higher than the odds for men (95% posterior interval: 1.03 to 1.11). The effects of cold periods were similar in those with and without a history of a previous myocardial infarction.

CONCLUSIONS

Rates of coronary events increased during comparatively cold periods, especially in warm climates. The smaller increases in colder climates suggest that some events in warmer climates are preventable. It is suggested that people living in warm climates, particularly women, should keep warm on cold days.

Seasonal variation in cause-specific mortality: are there high-risk groups? 25-year follow-up of civil servants from the first Whitehall study

OBJECTIVES

To determine the seasonal effect on all-cause and cause-specific mortality and to identify high-risk groups.

METHODS

A 25-year follow-up of 19,019 male civil servants aged 40-69 years.

RESULTS

All-cause mortality was seasonal (ratio of highest mortality rate during winter versus lowest rate during summer 1.22, 95% CI : 1.1-1.3), largely due to the seasonal nature of ischaemic heart disease. Participants at high risk based on age, employment grade, blood pressure, cholesterol, forced expiratory volume, smoking and diabetes did not have higher seasonal mortality, although participants with ischaemic heart disease at baseline did have a higher seasonality effect (1.38, 95% CI : 1.2-1.6) than those without (1.18, 95% CI : 1.1-1.3) (P = 0.03).

CONCLUSIONS

Seasonal mortality differences were greater among those with prevalent ischaemic heart disease and at older ages, but were not greater in individuals of lower socioeconomic status or with a high multivariate risk score. Since seasonal differences showed no evidence of declining over time, elucidating their causes and preventive strategies remains a public health challenge.

Urban air pollution and cardiopulmonary ill health: a 14.5 year time series study

OBJECTIVES

To examine possible associations between daily concentrations of urban air pollutants and hospital emergency admissions and mortality due to cardiac and pulmonary disease.

METHODS

A time series study was conducted in the City of Edinburgh, which has a population of about 450,000. Poisson log linear regression models were used to investigate the relation of the daily event rate with daily air pollution concentrations of sulphur dioxide (SO2) and black smoke from 1981 to 1995, and of nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and particulate matter (PM10) from 1992 to 1995. Adjustments were made for seasonal and weekday variation, daily temperature, and wind speed.

RESULTS

The most significant findings were positive associations over the period 1981-95 between black smoke as a mean of the previous three days and daily all cause mortality in people aged > or = 65, and respiratory mortality also in this age group (3.9% increase in mortality for a 10 micrograms/m3 increment in black smoke). For hospital emergency admissions between 1992 and 1995 the two most significant findings (p < 0.05) were for cardiovascular admissions of people aged > or = 65 which showed a positive association with PM10 as a mean of the 3 previous days, and a negative association with O3 as a mean of the previous three days. Analyses of outcomes based on linkage with previous cardiorespiratory emergency admissions did not show substantially different results.

CONCLUSION

These data suggest that in the City of Edinburgh, after correction for confounders, there was a small but significant association between concentrations of black smoke and respiratory mortality in the older age group, probably attributable to higher pollution levels in the early part of the study period. There were also generally weak and variable associations between day to day changes in concentrations of urban air pollutants at a single central point and emergency hospital admission rates from cardiac and respiratory disease.

[The effect of atmospheric variables on mortality due to respiratory and cardiovascular diseases in those over 65 in the Community of Madrid]

OBJECTIVE

To investigate the influence of environmental variables on daily mortality, due to respiratory and cardiovascular diseases, in the C.M. from 1986 to 1991.

METHODOLOGY

The environmental and mortality variables are correlated between cold and heat effects, checking the possible coincidence of models between temperature and mortality by Box-Jenkins models. The filtered mortality is correlated to the daily average temperatures, for 0-15 lags.

RESULTS

The minimum daily mortality is produced in an average temperature of 23.9 degrees. There exists a correlation (p < 0.001) between cold temperature and all the mortality causes in the 15 analysed lags. A correlation (p < 0.01) to vascular diseases appears with hot temperature and, among them, with cerebrovascular accidents (ACVA) in women for 0-3 lags.

CONCLUSIONS

Cold temperatures increase the mortality for all the analysed lags and causes. The heat produces immediate effects on the mortality by ACVA in women.