Seasonal and monthly variability in the incidence of venous thromboembolism

Characteristics of In-Flight Medical Emergencies on a Commercial Airline in Mainland China: Retrospective Study

Background

In-flight medical emergencies (IMEs) can have severe outcomes, including the deaths of passengers and aircraft diversions. Information is lacking regarding the incidence rate and characteristics of IMEs in most countries, especially in mainland China.

Objective

The objective of this study was to investigate the incidence, patterns, and associated risk factors of IMEs in mainland China and to provide medical suggestions for the evaluation and management of IMEs.

Methods

This population-based retrospective study examined electronic records for all IME reports between January 1, 2018, and December 31, 2022, from a major airline company in mainland China. Outcome variables included the medical category of the IMEs, the outcomes of first aid, and whether or not the IMEs led to a flight diversion. We calculated the incidence rate and death rate of IMEs based on the number of passengers and flights, respectively. A logistic regression model was used to investigate the factors associated with aircraft diversions.

Results

A total of 199 IMEs and 24 deaths occurred among 447.2 million passengers, yielding an incidence rate of 0.44 (95% CI 0.39-0.51) events per million passengers and 66.56 (95% CI 50.55-86.04) events per million flights, and an all-cause mortality rate of 0.05 (95% CI 0.03-0.07) events per million passengers and 7.50 (95% CI 4.81-11.16) events per million flights. From 2018 to 2022, the highest incidence and mortality rates were observed in 2019 and 2020, respectively, while the lowest were in 2020 and 2021, respectively. Additionally, the highest incidence and mortality rates were observed between 6 PM to 6 AM and noon to 6 PM, respectively. There was a higher incidence rate of IMEs in the winter months. Moreover, the highest case-fatality rates were observed in 2019 (12/74, 16.2%), on flights traveling ≥4000 km (9/43, 20.9%), and on wide-body planes (10/52, 19.2%). Seizures (29/199, 14.6%), cardiac symptoms (25/199, 12.6%), and syncope or presyncope (19/199, 9.6%) were the most common medical problems and main reasons for aircraft diversion. The incidence of aircraft diversion was 42.50 (95% CI 37.02-48.12) events per million flights. Narrow-body planes (odds ratio [OR] 5.69, 95% CI 1.05-30.90), flights ≥4000 km (OR 16.40, 95% CI 1.78-151.29), and the months of December to February (OR 12.70, 95% CI 3.09-52.23), as well as the months of March to May (OR 23.21, 95% CI 3.75-143.43), were significantly associated with a higher risk of diversion.

Conclusions

The occurrence of and deaths associated with IMEs are rare in mainland China, but a temporal trend shows higher incidence rates at night and in winter. The leading IMEs are cardiac symptoms, seizures, and syncope. The establishment of a unified reporting system for IMEs and ground-to-air medical support are of great value for reducing IMEs and deaths in the global community.

Low ambient temperature might trigger the symptom onset of pulmonary embolism: A nationwide case-crossover study at hourly level in China

BACKGROUND

Pulmonary embolism (PE) is an important cause of death and its seasonality has long been observed. Very few epidemiological studies have explored the potential role of ambient temperature in PE symptom onset, especially at the hourly level.

METHODS

We conducted a time-stratified case-crossover study among 17,903 PE patients with hourly onset of symptom from 1590 hospitals across China between January 2015 and September 2020. Conditional logistic regression model combined with distributed lag non-linear models were used to explore the associations between hourly ambient temperature and PE symptom onset. The attributable fractions due to non-optimum temperature were calculated.

RESULTS

The exposure-response relationship curve was inverse and almost linear. Lower temperature was significantly associated with higher risk of PE symptom onset when temperature was below 18 °C. This risk occurred immediately at the same hour, attenuated thereafter, and became nonsignificant at approximately 72 h after exposure. Compared with the referent temperature (P₉₉, 34.1 °C), the odds ratio of PE symptom onset associated with extremely low temperature (P₁, -16.1 °C) over lag 0-72 h was 1.63 (95%CI: 1.23, 2.16). Low temperature may account for 16.19 % of the symptom onset nationally with higher proportion in the south of China. The effects were stronger in older adults, males, and cold seasons.

CONCLUSIONS

We provided the first-hand robust evidence that transient exposure (at the hourly level) to low temperature might trigger the symptom onset of PE and constitute a considerable burden for PE patients. Targeted protections and health education are needed for susceptible populations.

Extensive Lower Limb Deep Vein Thrombosis Provoked by Gastroenteritis-Induced Dehydration: A Case Report for Unusual Precipitating Factor

The incidence of deep vein thrombosis (DVT) has been related to a number of risk factors, including genetic and acquired prothrombotic conditions, infections, inflammatory diseases, hematologic disorders, trauma, and drug use. Dehydration is a known independent risk factor for the development of thrombosis; however possibly insufficient evidence to form a strong association. The purpose of this case report is to present a 30-year-old male with DVT provoked by acute gastroenteritis-induced dehydration. The patient presented to the emergency department (ED) with a recent history of watery diarrhea for four days, for which he was diagnosed with gastroenteritis and managed at an outpatient care facility. The patient visited the ED again with a complaint of a one-day history of progressively worsening continuous pain in his left lower calf associated with swelling. The ultrasound-Doppler/duplex scan for the left lower limb venous system showed negative augmentation signs and non-compressibility of the deep venous system with partial occlusion/echogenic thrombosis extending from the external iliac vein, saphenofemoral junction, superficial femoral vein, popliteal vein, anterior tibial vein, and posterior tibial artery vena comitans. The patient was diagnosed with acute extensive DVT (multiple emboli). Patient care (medical treatment plan/therapeutic anticoagulation) was started in the ED and continued in the Critical Care Unit for close monitoring and care for a couple of days, after which he was transferred to the ward and then discharged in stable condition. He was prescribed a three-month course of appropriate medication regimen. This rare case presentation is a reminder to emergency physicians that dehydration might induce DVT and all patients, regardless of age, diagnosis or comorbidities, should always be risk assessed upon presentation and discharge, and prophylaxis should be provided according to their risk profile.

Seasonal pattern in elderly hospitalized with acute kidney injury: a retrospective nationwide study in Italy

PURPOSE

Acute kidney injury (AKI) frequently complicates hospitalization and is associated with in-hospital mortality (IHM). It has been reported a seasonal trend in different clinical conditions. The aim of this study was to evaluate the possible relationship between seasons of the year and IHM in elderly hospitalized patients with AKI.

METHODS

We selected all admissions complicated by AKI between 2000 and 2015 recorded in the Italian National Hospital Database. ICD-9-CM code 584.xx identified subjects with age ≥ 65 years and age, sex, comorbidity burden, need of dialysis treatment and IHM were compared in hospitalizations recorded during the four seasons. Moreover, we plotted the AKI observed/expected ratio and percentage of mortality during the study period.

RESULTS

We evaluated 759,720 AKI hospitalizations (mean age 80.5 ± 7.8 years, 52.2% males). Patients hospitalized with AKI during winter months had higher age, prevalence of dialysis-dependent AKI, and number of deceased patients. In whole population IHM was higher in winter and lower in summer, while the AKI observed/expected ratio demonstrated two peaks, one in summer and one in winter. Logistic regression analysis demonstrated that parameters such as age, autumn, winter, comorbidity burden were positively associated with IHM.

CONCLUSION

We conclude that a seasonality exists in AKI, however, relationship between seasons and AKI could vary depending on the aspects considered. Both autumn and winter months are independent risk factors for IHM in patients with AKI regardless of age, sex and comorbidity burden. On the contrary, summer time reduces the risk of death during hospitalizations with AKI.

Clinical and hemodynamic features of acute pulmonary embolism patients diagnosed in cold weather predicts adverse clinical outcome

Background

Acute pulmonary embolism (APE) is associated with peak incidence and mortality rate in winter. The present study sought to characterize the clinical and hemodynamic features of cold weather on APE patients.

Methods

All enrolled 224 APE patients underwent clinical and hemodynamic evaluation and baseline parameters were collected. Recruited patients were grouped by weather pattern on admission into cold and warm weather group. The correlation and prognostic values among cold weather and other variables were analyzed.

Results

Compared to warm weather group, patients in cold weather group present with more severe cardiac function, with adverse WHO-functional class (P = 0.032) and higher NT-proBNP concentration [1,853.0 (398.0, 5,237.0) pg/ml vs. 847.5 (56.8, 3,090.5) pg/ml, P = 0.001]. The cold weather group also displayed much critical hemodynamic status and heavier thrombosis load, with higher mPAP (29.1 ± 11.2mmHg vs. 25.6 ± 14.2mmHg, P = 0.045), higher PVR [3.3 (1.7, 6.0) wood units vs. 1.8 (0.9, 3.8) wood units, P < 0.001], higher Miller index (21.4 ± 5.9 vs. 19.1 ± 8.0, P = 0.024), and higher D-dimer levels [2,172.0 (854.5, 3,072.5) mg/L vs. 1,094.5 (210.5, 2,914.5) mg/L, P = 0.008]. Besides, cold weather showed well correlation with the above variables. Survival analysis showed APE patients in cold weather had significantly higher clinical worsening event rate (P = 0.010) and could be an independent predictor of adverse clinical outcome in the multivariate analysis (HR 2.629; 95% CI 1.127, 6.135; P = 0.025).

Conclusion

APE patients in cold weather were associated with thrombus overload, cardiac dysfunction, hemodynamic collapse and higher clinical worsening event rate. Cold weather proves to be an independent predictor of adverse clinical outcome.

Correlation of Air Pollution and Prevalence of Acute Pulmonary Embolism in Northern Thailand

BACKGROUND

The relationship between the level of air pollution and acute pulmonary embolism (APE) has had inconsistent results.

OBJECTIVE

This study aimed to analyze the relationship between the high level of air pollution exposure and APE.

METHODS

A ten-year retrospective cohort, single-center study was performed on patients diagnosed with APE from October 2010 to December 2020. The association between air pollution and monthly APE case diagnosis was analyzed.

RESULTS

A total number of 696 patients was included. The effect of every 10 µg/m³ increment of particulate matters with an aerodynamic diameter < 10 µm (PM₁₀) on total monthly APE cases (unprovoked PE and provoked PE) was increased significantly at lag 4, 5 and 6 months with adjusted RR (95% CI) of 1.06 (1.01, 1.12), p = 0.011, 1.07 (1.01, 1.13), p = 0.021 and 1.06 (1.01, 1.12), p = 0.030, respectively. Adjusted RR for APE was significantly increased for PM₁₀ in the second tertile ((adjusted RR (95% CI) 1.76 (1.12, 2.77)), p = 0.014.

CONCLUSIONS

We conclude that PM₁₀ is associated with an increased prevalence of APE cases. The policy for tighter control of air pollution in our country is needed to reduce the impact of air pollutants on people's health.

Differences in thrombin and plasmin generation potential between East African and Western European adults: The role of genetic and non-genetic factors

BACKGROUND

Geographic variability in coagulation across populations and their determinants are poorly understood.

OBJECTIVE

To compare thrombin (TG) and plasmin (PG) generation parameters between healthy Tanzanian and Dutch individuals, and to study associations with inflammation and different genetic, host and environmental factors.

METHODS

TG and PG parameters were measured in 313 Tanzanians of African descent living in Tanzania and 392 Dutch of European descent living in the Netherlands and related to results of a dietary questionnaire, circulating inflammatory markers, genotyping, and plasma metabolomics.

RESULTS

Tanzanians exhibited an enhanced TG and PG capacity, compared to Dutch participants. A higher proportion of Tanzanians had a TG value in the upper quartile with a PG value in the lower/middle quartile, suggesting a relative pro-coagulant state. Tanzanians also displayed an increased normalized thrombomodulin sensitivity ratio, suggesting reduced sensitivity to protein C. In Tanzanians, PG parameters (lag time and TTP) were associated with seasonality and food-derived plasma metabolites. The Tanzanians had higher concentrations of pro-inflammatory cytokines, which correlated strongly with TG and PG parameters. There was limited overlap in genetic variation associated with TG and PG parameters between the two cohorts. Pathway analysis of genetic variants in the Tanzanian cohort revealed multiple immune pathways that were enriched with TG and PG traits, confirming the importance of co-regulation between coagulation and inflammation.

CONCLUSIONS

Tanzanians have an enhanced TG and PG potential compared to Dutch individuals, which may relate to differences in inflammation, genetics and diet. These observations highlight the importance of better understanding of the geographic variability in coagulation across populations.

Association between air temperature, air pollution and hospital admissions for pulmonary embolism and venous thrombosis in Italy

BACKGROUND

Previous studies reported a link between short-term exposure to environmental stressors (air pollution and air temperature) and atherothrombotic cardiovascular diseases. However, only few of them reported consistent associations with venous thromboembolism (VTE). Our aim was to estimate the association between daily air temperature and particulate matter (PM) air pollution with hospital admissions for pulmonary embolism (PE) and venous thrombosis (VT) at national level in Italy.

METHODS

We collected daily hospital PE and VT admissions from the Italian Ministry of Health during 2006-2015 in all the 8,084 municipalities of Italy, and we merged them with air temperature and daily PM10 concentrations estimated by satellite-based spatiotemporal models. First, we applied multivariate Poisson regression models at province level. Then, we obtained national overall effects by random-effects meta-analysis.

RESULTS

This analysis was conducted on 219,952 PE and 275,506 VT hospitalizations. Meta-analytical results showed weak associations between the two exposures and the study outcomes in the full year analysis. During autumn and winter, PE hospital admissions increased by 1.07% (95% confidence intervals [CI]: 0.21%; 1.92%) and 0.96% (95% CI: 0.07%; 1.83%) respectively, per 1 °C decrement of air temperature in the previous 10 days (lag 0-10). In summer we observed adverse effects at high temperatures, with a 1% (95% CI: 0.10%; 1.91%) increasing risk per 1 °C increment. We found no association between VT and cold temperatures.

CONCLUSION

Results show a significant effect of air temperature on PE hospitalizations in the cold seasons and summer. No effect of particulate matter was detected.

Effects of Short-Term Air Pollution Exposure on Venous Thromboembolism: A Case-Crossover Study

RATIONALE

Exposure to outdoor air pollution is associated with increased cardiovascular disease, respiratory illness, and mortality. The effect of air pollution on venous thromboembolism (VTE) is less certain.

OBJECTIVES

To test for associations between short-term exposure to air pollution and VTE.

METHODS

Retrospective case-crossover study of adult patients with an objectively confirmed VTE event. Exposure to mean and maximum PM2.5 and ozone were estimated with inverse distance squared weighting from multiple stationary air quality monitors. Conditional logistic regression with a 7-day individual lag model estimated the odds ratio of VTE occurrence during the case period relative to the referent period. Prespecified subgroup analysis was performed to further test associations in higher risk patients.

RESULTS

A total of 2,803 VTE events met inclusion criteria for analysis. Deep vein thrombosis was identified in 1,966 (70.1%) and pulmonary embolism in 915 (32.6%) subjects. Median age was 57 years. Small negative associations were observed for maximum PM2.5 exposure at 1 day (odds ratio [95% confidence interval]; OR=0.992 [0.986-0.997]) and mean PM2.5 exposure at 1 day (OR=0.982 [0.97-0.994]), 5 days (OR=0.987 [0.975-0.999]), 6 days (OR=0.984 [0.972-0.996]), 7 days (OR=0.982 [0.971-0.994]), prior to VTE diagnosis. Similar negative associations were observed for 8-hour mean (OR=0.989 [0.981-0.997]) and 8-hour maximum (OR=0.992 [0.985-0.999]) ozone exposure 4 days prior to VTE diagnosis. Positive relationships (ORs~1.02) between 8-hour mean and maximum ozone exposure 6-7 days preceding VTE diagnosis were observed in a recently hospitalized subgroup.

CONCLUSIONS

Short-term exposure to PM2.5 and ozone does not appear to be associated with an overall increased risk of VTE. Further well-designed studies are needed to test whether previously reported associations between VTE and air pollution exist.

Time series analysis of the in-hospital diagnostic process in suspected pulmonary embolism evaluated by computed tomography: An explorative study

PURPOSE

This retrospective study aims to analyze the distribution of demand and the duration of the diagnostic workup of suspected pulmonary embolism (PE) using computed tomography pulmonary angiography (CTPA).

METHODS

Time data from physical examination to report creation were identified for each CTPA in 2013 and 2018 at a tertiary hospital. Multivariable multinomial logistic and linear regression models were used to evaluate differences between 3 time intervals (I1: 6am-2pm, I2: 2pm-10pm, I3: 10pm-6am). A cosinor model was applied to analyze the amount of CTPA per hour.

RESULTS

The relative demand for CTPA from the emergency room was lower in l1 compared to l2 and l3 (I1/I2: odds ratio (OR) 0.84, 95 % confidence interval (CI) 0.78-0.91; I1/I3: OR 0.80, 95 % CI 0.72-0.89; peak 4:23 pm). Requests for in-patients displayed a tendency towards I1 (I1/2: OR 1.15, 95 % CI 1.06-1.24; l1/l3: OR 1.19, 95 % CI 1.07-1.33; peak 1:54 pm). The time from CTPA request to study was shorter in I3 compared to I1 and I2 in 2013 (I1/I3: ratio 5.23, 95 % CI 3.38-8.10; I2/I3: ratio 3.50, 95 % CI 2.24-5.45) and 2018 (I1/I3: ratio 2.27, 95 % CI 1.60-3.22; I2/I3: ratio 2.11, 95 % CI 1.50-2.97). This applied similarly to fatal cases (I1/I3: ratio 2.91, 95 % CI 1.78-4.75; I2/I3: ratio 2.45, 95 % CI1.52-3.95).

CONCLUSIONS

The temporal distribution of demand for CTPA depends on the sector of patient care and the processing time differs substantially during the day. Time series analysis can reveal such coherences and may help to optimize workflows in radiology departments.

Seasonal association between ambient fine particulate matter and venous thromboembolism in Beijing, China: a time-series study

Little is known about the influence of ambient fine particulate matter (PM2.5) on the incidence of venous thromboembolism in areas with heavy air pollution. We examined seasonal associations between airborne concentrations of fine particulate matter and outpatient visits for venous thromboembolism in Beijing using a city-wide time-series design that covered a period of 30 months (January 1, 2010 to June 30, 2012). Generalized additive models were used to investigate the associations with adjustment of temperature for various time lags (lag 0 for the warm season and lag 0-10 for the cold season). Overall, 92,435 outpatient visits were recorded by the Beijing Medical Claim Data for Employees database during the study period. We found a significant association between PM2.5 levels and outpatient visits for venous thromboembolism. A 10-μg/m3 increase in PM2.5 concentrations on lag days 0-2 corresponded to a 0.64% (95% confidence interval: 0.55-0.73%; P < 0.001) increase in outpatient visits for venous thromboembolism during the cold season, and a 10-μg/m3 increase in PM2.5 concentrations on lag days 0-3 corresponded to a 0.82% (95% confidence interval: 0.67-0.96%; P < 0.001) increase in outpatient visits for venous thromboembolism during the warm season. Our findings suggest that PM2.5 exposure is associated with outpatient visits for venous thromboembolism in Beijing, and a more pronounced association was observed during the warm season. We propose that various temperature-adjustment strategies should be used when investigating seasonal associations.

Increased incidence of venous thromboembolism following hip or knee arthroplasty in winter

BACKGROUND

Deep vein thrombosis (DVT) and pulmonary embolism (PE) cause significant morbidity and mortality following arthroplasty. A seasonal variation in the rate of PE in arthroplasty patients in the northern hemisphere has been reported. We hypothesized that there would be a similar seasonal variation in arthroplasty patients in Australia.

METHODS

We performed a retrospective review of all patients who received primary and/or revision arthroplasty of the hip or knee over a 15-year period (2000-2015) across Western Australia. We identified all patients who were diagnosed with DVT and/or PE according to International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Australian Modification codes. The incidence of venous thromboembolic (VTE) disease was calculated as the proportion of operations that led to this complication per 3-month seasonal period.

RESULTS

A total of 12,507 total hip arthroplasties (THAs) and 8899 total knee arthroplasties (TKAs) were recorded during the study period. There was a total of 274 DVT and/or PE among the combined total of 21,406 hip and knee arthroplasties performed between 2000 and 2015. There was a significantly higher rate of VTE for females than males (odds ratio (OR): 1.33, 95% confidence interval (CI): 1.03-1.71, p = 0.0293), for TKA than THA (OR: 1.60, 95% CI:1.26-2.03, p < 0.0001) and in winter than other seasons (OR: 1.51, 95% CI: 1.14-2.01, p = 0.0047).

CONCLUSION

There is a statistically significant increase in the incidence of VTE in arthroplasty patients during the winter months in Western Australia. This finding is the first of its kind for patients in the southern hemisphere and corroborates previous studies in the northern hemisphere.

Correlation between climatic and biochemical parameters in etiopathogenesis of unprovoked deep vein thrombosis of the lower limbs

AIM

Beside the intention of early detection and optimal treatment of deep venous thrombosis (DVT), the aim of this study was to investigate the influence of chronobiological rhythms on the etiopathogenesis of unprovoked deep vein thrombosis of the lower limbs with monitoring of seasonal variations in biochemical parameters.

PATIENTS AND METHODOLOGY

The prospective clinical trial included all consecutive hospitalized patients and outpatients diagnosed with DVT at the Vascular Surgery Clinic of the Clinical Center in Niš, starting from January 2013 to December 2014.

RESULTS

There was no statistically significant difference in correlation between the distribution of the incidence of DVT of the lower limbs (p = 0.582), sex (p = 0.350), age (p = 0.385) and localization (p = 0.886) and the seasons. Creatinine levels were significantly higher in patients who developed DVT in spring than in those who developed DVT in winter (p < 0.05), while LDL cholesterol levels were significantly higher in patients diagnosed with DVT in winter than in those diagnosed with DVT in autumn (p < 0.05).

CONCLUSION

According to the results of the study, it can be concluded that in the territory of South Serbia, the seasons are not significantly related to the incidence, sex, age and localization of unprovoked DVT of the lower limbs. Creatinine levels were significantly higher in patients who developed DVT in spring than in those who developed DVT in winter, while LDL cholesterol levels were significantly higher in patients during winter than during autumn.

Influence of weather and air pollution on the occurrence of idiopathic pulmonary embolism in the region of Sousse (Tunisia)

Pulmonary embolism (PE) is the most serious manifestation of thromboembolic conditions. Its incidence varies considerably between countries, suggesting its interaction with the external environment. To analyze the influence of climate and air pollution on the occurrence of idiopathic PE in the region of Sousse (Tunisia). A total of 142 patients with idiopathic PE at two academic hospitals in Sousse (Tunisia) were enrolled in the study over a 7-year period. An analysis of two time series (environmental data and PE cases) was performed. Climatic data were collected from the National Institute of Meteorology. Air pollution data were obtained from the modeling platform of the National Agency for Protection of the Environment. The year 2015 was marked by the occurrence of the highest number of cases (24.6%). A statistically significant decrease in PE risk of 41.9% was observed during the summer with an OR of 0.59 (95% CI [0.36-0.94] and p = 0.026), compared with other seasons. Poisson GLM regression showed a significant increased risk of PE of 3.3% for each 1 °C temperature drop. After multiple binary logistic regression, the elevation of PM₁₀ concentration was independently associated with an increased risk of PE (p < 10^-3, OR 79.55, 95% CI [42.28-149.6]). Some environmental parameters may predispose to the onset of idiopathic PE. Understanding their accurate influence may have preventive and curative implications.

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.

Prominent seasonal variation in pulmonary embolism than deep vein thrombosis incidence: a Korean venous thrombosis epidemiology study

BACKGROUND/AIMS

Seasonal variation is an environmental factor proposed to affect the incidence of venous thromboembolism (VTE). However, VTE seasonal variation is not well studied in Asian populations, which have different genetic determinants of VTE compared to Westerners. The present study aimed at investigating seasonal variation of VTE occurrence and the effect of various demographic factors (i.e., age, sex, and co-morbidities) on variation.

METHODS

VTE seasonal variation was evaluated in 59,626 index cases (from January 2009 to December 2013) in the Korean Health Insurance Review and Assessment Service database. We quantified and compared VTE occurrence across four seasons, and additionally assessed monthly through a chronobiological analysis.

RESULTS

VTE incidence varied both seasonally and monthly, with new cases peaking in the winter (January and February) and the lowest incidence in the summer (August and September). After adjusting for sex, age, type of VTE, and combined cancer diagnosis, winter remained a significant independent factor driving VTE incidence. Additionally, seasonal variation was prominent in patients aged 60 years or older and in patients with pulmonary embolism, but not so prominent in patients of aged less than 60 years and patients with deep vein thrombosis.

CONCLUSION

Seasonal variation was a weak but independent contributor to VTE incidence in a Korean population diagnosed from 2009 to 2013, especially in those individuals with old age or suffering from a pulmonary embolism.

Seasonal variation in the frequency of venous thromboembolism: An updated result of a meta-analysis and systemic review

Objective

Venous thromboembolism, including deep vein thrombosis and pulmonary embolism, is likely to cause the death of both medical and surgical patients. Despite some evidence of seasonal variation in the incidence of venous thromboembolism, the existing studies obtain contradictory results. A temporal pattern for pulmonary embolism is known, but data on deep vein thrombosis are inconclusive. The purpose of this study is to make a meta-analysis and systematically review the literature about seasonal variations of pulmonary embolism and/or deep vein thrombosis in order to objectively diagnose venous thromboembolism.

Methods

According to dichotomous data, risk ratios (RRs) and 95% confidence intervals (CIs) were used to compare the incidence of venous thromboembolism in different seasons. The research was classified according to pulmonary embolism mortality, pulmonary embolism/deep vein thrombosis incidence, latitude/elevation/climatic types, and monthly incidence for four subgroup comparisons. There were a total of 23 eligible studies, in which 40,309 patients with venous thromboembolism were compared.

Results

The pooled total venous thromboembolism incidence was 27.2% in winter, 23.1% in spring, 24.6% in summer, and 25.1% in autumn. According to the results of pooled analysis, the incidence of venous thromboembolism in winter was much higher than that in summer (RR = 1.12, 95% CI: 1.01–1.24, adjusted P = .04), especially deep vein thrombosis. Moreover, the incidence of venous thromboembolism in summer and autumn was lower than that in winter in low-latitude (<200 m) areas and median low-latitude (0–50°-N) areas. Interestingly, the frequency of pulmonary embolism mortality was the largest in spring and smallest in summer (spring > winter ≈ autumn > summer). For monthly data, a statistically significantly lower incidence of venous thromboembolism was observed in May and July than in October.

Conclusions

The study revealed a significantly higher incidence of venous thromboembolism and deep vein thrombosis in winter than in summer. Pulmonary embolism mortality occurred more frequently in spring than during other seasons. A statistically significantly lower incidence of venous thromboembolism was observed in May and July compared with that in October.

Achilles tendon ruptures during summer show the lowest incidence, but exhibit an increased risk of re-rupture

PURPOSE

Achilles tendon rupture (ATR) is a common injury. The knowledge of seasonal factors´ impact is incomplete, but may provide means for preventive approaches for Achilles tendon related morbidity. The aim of this study was to investigate seasonal variations in ATR incidence in relation to injury mechanism, adverse events including risk of re-rupture, and patient-reported outcome in adults in Stockholm, Sweden.

METHODS

In total, 349 patients with unilateral acute Achilles tendon rupture, prospectively treated with standardized surgical techniques, were retrospectively assessed. Date of injury was assigned to one of the four internationally defined meteorological seasons in the northern hemisphere. Injury mechanism and the rate of adverse events; deep venous thrombosis, infection and re-rupture in relation to per-operative complications. Patient-reported outcome at 1 year was assessed with the validated Achilles tendon Total Rupture Score.

RESULTS

ATR incidence was significantly highest during winter and spring, and lowest during summer (p < 0.05). The most common sporting activities associated with ATR were badminton, floorball and soccer (> 50%). The rate of soccer-related ATR was highest during summer (p < 0.05). Patients sustaining an ATR during summer, compared to other seasons, exhibited more per-operative complications (p < 0.05), a significantly higher risk of re-rupture (p < 0.05) and a lower rate of good outcome (n.s.). The risk of other adverse events after ATR did not differ between the seasons.

CONCLUSION

Winter and spring are the high risk seasons for sports-related ATR and the risk sports are badminton, soccer and floorball. The reason for the higher risk of re-rupture after ATR repair during summer should be further investigated.

LEVEL OF EVIDENCE

III.

Chronologic and Climatic Factors of Acute Aortic Dissection: Study of 1642 Patients in Two Continents

BACKGROUND

The purpose of this study was to examine whether chronologic and climatic factors and lunar phases affect the onset of acute aortic dissection (AAD).

METHODS

The frequencies of AAD were analyzed with regard to the chronologic and climatic factors and lunar phases on the day when AAD occurred for 1642 patients with AAD from two aortic referral centers in the United States and China.

RESULTS

Mean age of patients was 51.6 ± 13.1 years, and 1260 (76.7%) were men. Dissection was type A in 1125 patients (68.5%) and type B in 517 (31.5%). Early mortality rate was 11.6% (190 of 1642), including 89 aortic ruptures before operation and 101 operative deaths. There was a winter peak in occurrence (33.6%, P < .01) with a relative risk of 1.519. In a week, the frequency was highest on Wednesday (15.5%) and Monday (15.2%), and lowest on Sunday (12.8%). Month-specific incidence was significantly inversely correlated to the mean temperature (rho = -0.650, P = .022) and directly correlated to the atmospheric pressure (rho = 0.706, P = .001). The proportion of type A dissection was significantly higher in the full moon phase compared with type B dissection (73.7% vs 66.9%, P = .012).

CONCLUSIONS

Acute aortic dissection exhibits significant chronologic variation in the frequency of occurrence, with a peak in winter and on Wednesdays, and nadir in summer and on Sundays. The incidence is significantly correlated to the mean temperature and atmospheric pressure. The proportion of type A dissection is higher in the full moon phase. These results are important for understanding the mechanisms involved in triggering AAD events and helpful for improving disease prevention and patient care.

Novel evidence for a greater burden of ambient air pollution on cardiovascular disease

Ambient and household air pollution is a major health problem worldwide, contributing annually to approximately seven million of all-cause avoidable deaths, shorter life expectancy, and significant direct and indirect costs for the community. Air pollution is a complex mixture of gaseous and particulate materials that vary depending on their source and physicochemical features. Each material has detrimental effects on human health, but a number of experimental and clinical studies have shown a strong impact for fine particulate matter (PM_2.5). In particular, there is more and more evidence that PM_2.5 exerts adverse effects particularly on the cardiovascular system, contributing substantially (mainly through mechanisms of atherosclerosis, thrombosis and inflammation) to coronary artery and cerebrovascular disease, but also to heart failure, hypertension, diabetes and cardiac arrhythmias. In this review, we summarize knowledge on the mechanisms and magnitude of the cardiovascular adverse effects of short-and long-term exposure to ambient air pollution, particularly for the PM_2.5 size fraction. We also emphasize that very recent data indicate that the global mortality and morbidity burden of cardiovascular disease associated with this air pollutant is dramatically greater than what has been thought up to now.

Atmospheric fronts as minor cardiovascular risk factors, a new approach to preventive cardiology

BACKGROUND

Cardiovascular diseases are the number one cause of death globally and represent 31% of all global deaths. The aim of our study was to determine the influence of front effects on acute cardiovascular diseases (ACVDs).

METHODS

We obtained all ACVD admissions in a Central-European region, Hungary, Budapest. A time-series analysis was applied to 6499 morbidity cases during a five-year period (2009-2013). Poisson-regression model was used and adjusted for air temperature, pressure, humidity, wind velocity, their interactions and seasonality to assess the association of fronts and ACVDs.

RESULTS

There is a positive significant association between ACVDs and a cold front effect lagged by one day (p=0.018) with a relative risk (RR) of 1.095 [95% CI (1.021,1.181)]. Our findings show that among patient subgroups with major cardiovascular risk factors (hypertension, diabetes, hyperlipidemia, history of CVDs) the patterns are similar, but occluded fronts also have a significant effect.

CONCLUSION

Atmospheric fronts could play an important role in the pathogenesis of ACVDs. Our findings might help to provide a better understanding about fronts as minor cardiovascular risk factors and to organize medical prevention more effectively. Our research project may become a basis of a new field of preventive cardiovascular medicine in the future.

Venous Thromboembolism in Denmark: Seasonality in Occurrence and Mortality

Background  Many cardiovascular conditions exhibit seasonality in occurrence and mortality, but little is known about the seasonality of venous thromboembolism.

Methods  Using Danish registries, we identified all patients with deep vein thrombosis, pulmonary embolism, splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis during 1977–2016. We tallied monthly deaths occurring within 90 days of the venous thromboembolism diagnosis. We estimated peak-to-trough ratios and timing of the peak of both diagnoses and deaths summed over all years of the study period. The departure from 1.0 of the peak-to-trough ratio measures the intensity of any seasonal pattern.

Results  We estimated a peak-to-trough ratio of 1.09 (95% confidence interval: 1.07–1.11) for deep vein thrombosis and 1.22 (1.19–1.24) for pulmonary embolism occurrence. The peak-to-trough ratios for splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis occurrence were 1.10 (1.01–1.20), 1.19 (1.00–1.40), and 1.12 (1.07–1.17), respectively. The occurrence of all conditions peaked during winter or fall. In time trend analyses, the peak-to-trough ratio increased considerably for splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis occurrence. In associated mortality, the peak-to-trough ratio for deep vein thrombosis was larger (1.15, 1.07–1.23) than that for pulmonary embolism (1.04, 1.01–1.08).

Discussion  Excess winter risks were modest, but more marked for pulmonary embolism occurrence than for deep vein thrombosis occurrence. The seasonal pattern intensified throughout the study period for splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis. The winter peak in mortality following pulmonary embolism was smaller than that for deep vein thrombosis.

Daylight Saving Time and Acute Myocardial Infarction: A Meta-Analysis

BACKGROUND

The available evidence on the effects of daylight saving time (DST) transitions on major cardiovascular diseases is limited and conflicting. We carried out the first meta-analysis aimed at evaluating the risk of acute myocardial infarction (AMI) following DST transitions.

METHODS

We searched cohort or case-control studies evaluating the incidence of AMI, among adults (≥18 y), during the weeks following spring and/or autumn DST shifts, versus control periods. The search was made in MedLine and Scopus, up to 31 December 2018, with no language restriction. A summary odds ratio of AMI was computed after: (1) spring, (2) autumn or (3) both transitions considered together. Meta-analyses were also stratified by gender and age. Data were combined using a generic inverse-variance approach.

RESULTS

Seven studies (>115,000 subjects) were included in the analyses. A significantly higher risk of AMI (Odds Ratio: 1.03; 95% CI: 1.01⁻1.06) was observed during the two weeks following spring or autumn DST transitions. However, although AMI risk increased significantly after the spring shift (OR: 1.05; 1.02⁻1.07), the incidence of AMI during the week after winter DST transition was comparable with control periods (OR 1.01; 0.98⁻1.04). No substantial differences were observed when the analyses were stratified by age or gender.

CONCLUSION

The risk of AMI increases modestly but significantly after DST transitions, supporting the proposal of DST shifts discontinuation. Additional studies that fully adjust for potential confounders are required to confirm the present findings.

Health effects of seasonal variation in cardiovascular hemodynamics among workers in forest environments

Seasonal variation in cardiovascular functions (CVFs) associated with climatic changes is an important emerging public health issue. The objectives of this study were to demonstrate seasonal variation in CVFs by comparing intra-individual differences between winter and summer among people working in a forest environment and to discuss the possible mechanisms accounting for the health effects of seasonal variation in cardiovascular hemodynamics. A total of 72 staff members of the Experimental Forest of National Taiwan University were recruited for continuous health monitoring during two seasons to investigate the intra-individual seasonal variation in CVFs, complete blood counts, and biochemical examinations. CVFs were assessed by measuring the arterial pressure waveform by a cuff sphygmomanometer using an oscillometric blood pressure device, and aortic stiffness was measured by brachial-ankle pulse wave velocity (baPWV). The results showed that cholesterol levels, white and red blood cell counts, and platelet counts were higher in winter than in summer. Subjects showed not only higher vascular stress, as indicated by higher levels of brachial systolic and diastolic blood pressure (SBP and DBP), central end-SBP and DBP, systemic vascular resistance (SVR), and baPWV, but also lower cardiac activities, including lower levels of heart rate, left ventricular contractility, and cardiac output in winter than in summer. The central and brachial BP, cardiac output, SVR, and baPWV were significantly associated with temperature changes in seasonal variation after controlling related confounding factors. This study provides evidence of higher vascular stress and susceptibility to atherothrombosis during winter compared with summer.

A incidência regional do tromboembolismo venoso no Brasil

Contexto

Vários estudos realizados em climas temperados sugerem que há uma variação na incidência de tromboembolismo venoso (TEV) de acordo com as estações climáticas. Entretanto, nenhum estudo foi feito comparando áreas de clima semiárido com áreas de clima temperado.

Objetivos

Analisar se existe correlação entre a incidência do TEV em áreas de clima semiárido e de clima temperado no Brasil.

Métodos

Foi feito um levantamento de dados retrospectivos de pacientes com diagnóstico de TEV no Sistema Único de Saúde de janeiro de 2011 a dezembro de 2014 provenientes dos seguintes estados com clima semiáridos: Alagoas, Ceará, Maranhão, Paraíba, Pernambuco, Piauí e Rio Grande do Norte, localizados na Região Nordeste do Brasil; e dos seguintes estados com clima temperado: Paraná, Santa Catarina e Rio Grande do Sul, localizados na Região Sul do Brasil. Os dados de variação climática foram obtidos do Instituto Nacional de Meteorologia e os dados populacionais do Instituto Brasileiro de Geografia e Estatística.

Resultados

Houve correlação significativa na incidência de casos de TEV em regiões de temperaturas mais baixas (p < 0,001). A Região Sul apresentou temperaturas significativamente menores que as da Região Nordeste (p < 0,001) e apresentou número significativamente maior de casos de TEV do que a Região Nordeste (p < 0,001).

Conclusão

Há mais casos de TEV em regiões de clima temperado, onde as temperaturas são mais baixas. No entanto, pouco ainda é conhecido na literatura sobre a flutuação sazonal e a incidência de TEV. Sendo assim, mais estudos são necessários nessa área.

Weekend Versus Weekday Admission and In-Hospital Mortality for Pulmonary Embolism: A 14-Year Retrospective Study on the National Hospital Database of Italy

We assessed the association between weekday (WD) or weekend (WE) admission and mortality for patients hospitalized with acute pulmonary embolism (PE). Weekend included holidays. We analyzed hospital administrative data of all patients discharged with a diagnosis of PE extracted from the Italian Health Ministry database (January 2001 to December 2014). A total of 265 035 hospitalizations with a diagnosis of PE were retrieved, in which PE was the primary diagnosis in 198 565 (74.9%); 200 166 (75.5%) patients were admitted on WD and 64 869 (24.5%) on WE. Admissions for PE were more frequent on Mondays (41 917 admissions, 15.8% of all events) and less frequent on Saturdays (32 295 admissions, 12.2%) and Sundays (32 574 admissions, 12.3%). Patients admitted on WE were on average 1 year older, presented more frequently with respiratory failure, and had more common comorbidities. After adjustment for age, gender, comorbidities, and presence of respiratory failure, in-hospital mortality for patients admitted on WE was greater (odds ratio: 1.15, 95% confidence interval: 1.13-1.18; P < .001). This study supports that, in Italy, hospitalization for PE on WE is associated with a significantly higher mortality rate than on WD.

Seasonal variations in exacerbations and deaths in patients with COPD during the TIOSPIR® trial

Background

Although COPD exacerbations are known to occur more frequently in winter, there is little information on hospitalizations and cause-specific mortality. This study aimed to examine seasonal variations in mortality and exacerbations in patients with COPD during the TIOtropium Safety and Performance In Respimat^® (TIOSPIR^®) trial.

Patients and methods

TIOSPIR was a large-scale, multicenter trial, which assessed the safety and efficacy of tiotropium delivered via HandiHaler^® (18 μg once daily) or Respimat^® Soft Mist™ (2.5 or 5 μg once daily) inhaler in patients with COPD. Patients were aged ≥40 years, with a smoking history ≥10 pack-years, and post-bronchodilator forced expiratory volume in 1 second ≤70% and forced expiratory volume in 1 second/forced vital capacity ≤0.70. COPD exacerbations and deaths were monitored throughout the trial. The data were pooled to examine seasonal patterns. Southern hemisphere data were shifted by 6 months to align with northern hemisphere seasons.

Results

TIOSPIR was conducted in 43 northern (n=15,968) and 7 southern (n=1,148) hemisphere (n=1,148) countries. The median duration of treatment was 835 days, with a mean follow-up of 2.3 years. Among 19,494 exacerbations, there were clear seasonal differences (winter, 6,646 [34.1%]; spring, 4,515 [23.2%]; summer, 3,198 [16.4%]; autumn, 5,135 [26.3%]). Exacerbations peaked in early winter (December in the northern hemisphere and June in the southern hemisphere), respiratory hospitalizations in midwinter, and respiratory deaths in early spring.

Conclusion

Although winter poses a 2-fold hazard for COPD exacerbations vs summer, respiratory deaths peak in early spring. These data suggest that seasonal intensification of preventive treatments may impact COPD morbidity and mortality.

Trial registration number

NCT01126437.

Emotional states and future risk of venous thromboembolism

Emotional states of depression and loneliness are reported to be associated with higher risk and optimism with lower risk of arterial cardiovascular disease (CVD) and death. The relation between emotional states and risk of venous thromboembolism (VTE) has not been explored previously. We aimed to investigate the associations between self-reported emotional states and risk of incident VTE in a population-based, prospective study. The frequency of feeling depressed, lonely and happy/optimistic were registered by self-administered questionnaires, along with major co-morbidities and lifestyle habits, in 25,964 subjects aged 25–96 years, enrolled in the Tromsø Study in 1994–1995. Incident VTE-events were registered from the date of inclusion until September 1, 2007. There were 440 incident VTE-events during a median of 12.4 years of follow-up. Subjects who often felt depressed had 1.6-fold (95% CI:1.02–2.50) higher risk of VTE compared to those not depressed in analyses adjusted for other risk factors (age, sex , body mass index, oes-trogens), lifestyle (smoking, alcohol consumption, educational level) and co-morbidities (diabetes, CVD, and cancer). Often feeling lonely was not associated with VTE. However, the incidence rate of VTE in subjects who concurrently felt often lonely and depressed was higher than for depression alone (age-and sex-adjusted incidence rate: 3.27 vs. 2.21). Oppositely, subjects who often felt happy/optimistic had 40% reduced risk of VTE (HR 0.60, 95% CI: 0.41–0.87). Our findings suggest that self-reported emotional states are associated with risk of VTE. Depressive feelings were associated with increased risk, while happiness/ optimism was associated with reduced risk of VTE.

Serum levels of vitamin D are not associated with future risk of venous thromboembolism

Previous studies have provided indirect evidence for a possible association between vitamin D status and risk of venous thromboembolism (VTE). However, no study has so far investigated the association between serum levels of 25-hydroxyvitamin D (25(OH)D), the biomarker of vitamin D status, and risk of VTE. The aim of our study was to investigate whether high levels of 25(OH)D were associated with decreased risk of VTE in a prospective population-based study. Serum levels of 25(OH)D were measured in 6,021 men and women, aged 25–84 years, who participated in the Tromsø Study in 1994–1995. Incident VTE-events were registered from date of inclusion through the end of follow-up, September 1, 2007. Cox-regression models were used to calculate hazard ratios (HR) with 95% confidence interval (CI) for VTE. There were 201 incident VTE-events during a median of 10.7 years of follow-up. The risk of VTE did not decrease per one standard deviation (SD) (19.8 nmol/l) increase in serum 25(OH)D (multivariable HR 1.02; 95% CI 0.91–1.22). Moreover, subjects with serum 25(OH)D ≥ 70 nmol/l (upper quartile) did not have decreased risk of VTE compared to those ≤ 44 nmol/l (lower quartile) in age- and sex-adjusted analysis (HR 0.91, 95% CI: 0.60–1.37, p for trend across quartiles 0.9) or multivariable analysis adjusted for age, sex, body mass index, smoking, and physical activity (HR 0.76, 95% CI: 0.45–1.28, p for trend across quartiles 0.9). Subgroup analyses showed no associations between serum levels of 25(OH)D and unprovoked or provoked VTE. In conclusion, in our study, normal serum levels of 25(OH)D were not associated with future risk of VTE, suggesting that vitamin D status does not play an important role in the pathogenesis of VTE. However, our findings did not apply to subjects with vitamin D deficiency (< 30 nmol/l) due to lack of statistical power among these subjects.

The calendar of cytokines: Seasonal variation of circulating cytokines in chronic venous insufficiency

Objectives

To assess if in chronic venous insufficiency, there is a seasonal variation of cytokines levels which could explain the typical worsening of symptoms during Spring and Summer.

Participants

From 193 chronic venous insufficiency patients, we selected 32 patients in clinical stage C2–C3 of the Clinical–Etiology–Anatomy–Pathophysiology classification.

Design

A prospective, comparative and blinded cytokines assessment in two different seasons.

Setting

We sorted patients by two homogenous groups, 17 Autumn Group and 15 Spring Group. A complete clinical and haemodynamic assessment and laboratory analysis of 22 circulating cytokines were performed on each patient.

Main outcome measures

Circulating cytokines levels assessment.

Results

The two groups resulted homogenous for age, gender, clinical class, and haemodynamic parameters. Comparing cytokines expressions in Autumn Group vs. Spring Group, we found a significant difference of 11 out of 22 circulating cytokines (p < 0.05). Particularly Eotaxin, Interleukin-8, Monocyte Chemoattractant Protein-1, Tumour Necrosis Factor-α and Vascular Endothelial Growth Factor were increased in Autumn compared to the Control Group (p < 0.001); while significantly reduced in Spring, within the normal range (p, not significant).

Conclusions

Symptoms of chronic venous insufficiency are self-reported by patients more intense during warm seasons. Surprisingly, in our study, cytokines levels were significantly higher during Autumn and downregulated in Spring. These variations show for the first time the presence of a ‘Calendar of Cytokines’ in chronic venous insufficiency, which needs to be further investigated.

Better documentation in electronic medical records would lead to an increased use of lower extremity venous ultrasound in the inpatient setting: a retrospective study

Aim

We hypothesized that the quality of the assessment of abnormal laboratory data in the emergency department (ED) could affect the hospital-attending physicians' decision-making after a patient's hospitalization. To test this hypothesis, we investigated how patients with a positive D-dimer result were reported by ED physicians in electronic medical records, and measured whether lower extremity venous ultrasonography examination was undertaken during hospitalization by the hospital-attending physicians.

Methods

In an urban tertiary acute care general hospital in Japan, between January 2012 and December 2013, we included patients hospitalized after a positive D-dimer measurement (≥1.0 μg/mL) that was taken in the emergency department. We retrospectively measured the quality of ED physician assessments. Then we examined whether that affected the decisions of attending physicians to order lower extremity venous ultrasonography examinations during hospitalization. The exposure variable was the quality of the ED physicians' assessment of patients with positive D-dimer results. The outcome was whether a lower extremity venous ultrasonography examination was ordered by the attending physician during hospitalization.

Results

When assessments were described by ED physicians for patients with positive D-dimer results, the attending physicians frequently ordered lower extremity venous ultrasonography (odds ratio, 10.74; 95% confidence interval, 5.92-19.50), even if the assessments only contained "copied and pasted" laboratory data (odds ratio, 1.68; 95% confidence interval, 2.10-2.40).

Conclusions

Better documentation by ED physicians, regarding patients with positive D-dimer results, strongly affected the decisions made by attending physicians to order lower extremity venous ultrasonography examination.

Chronobiology of Acute Aortic Dissection in the Marfan Syndrome (from the National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions and the International Registry of Acute Aortic Dissection)

Marfan syndrome (MFS) is an autosomal dominant connective tissue disease associated with acute aortic dissection (AAD). We used 2 large registries that include patients with MFS to investigate possible trends in the chronobiology of AAD in MFS. We queried the International Registry of Acute Aortic Dissection (IRAD) and the Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions (GenTAC) registry to extract data on all patients with MFS who had suffered an AAD. The group included 257 patients with MFS who suffered an AAD from 1980 to 2012. The chi-square tests were used for statistical testing. Mean subject age at time of AAD was 38 years, and 61% of subjects were men. AAD was more likely in the winter/spring season (November to April) than the other half of the year (57% vs 43%, p = 0.05). Dissections were significantly more likely to occur during the daytime hours, with 65% of dissections occurring from 6 a.m. to 6 p.m. (p = 0.001). Men were more likely to dissect during the daytime hours (6 a.m. to 6 p.m.) than women (74% vs 51%, p = 0.01). These insights offer a glimpse of the times of greatest vulnerability for patients with MFS who suffer from this catastrophic event. In conclusion, the chronobiology of AAD in MFS reflects that of AAD in the general population.

Pulmonary embolism: Does the seasonal effect depend on age? A 12-year nationwide analysis of hospitalization and mortality

BACKGROUND

Circannual variations in the incidence and mortality of pulmonary embolism (PE) have been previously described although conflicting observations have been reported. However, the association between age and seasonal variations of incidence and mortality rates is not established. This nationwide study aimed to assess the seasonal pattern in hospitalizations and mortality for PE along with the effect of age.

METHODS

Comprehensive records from the French hospital discharge databases between 2002 and 2013 and death certificates between 2000 and 2010 were used. For each outcome and separately for each sex, monthly event counts were analyzed using quasi-Poisson models with tensor-products of regression splines, including a seasonal component and controlling for the underlying time trend, age of patients and population size changes.

RESULTS

During the period studied, 599,432 patients with PE were hospitalized and 150,404 death certificates mentioned a PE. Compared with summer months, the winter peak was associated with 25% increasing rates in hospitalizations and mortality. The rates ratio of hospitalizations between the winter peak and the summer trough increased with age. The winter excess of incidence raised from 10%, IC 95% [5-16] in 30-year-old men to 33% [31-35] in 75year-old men. In the same way, the incidences at the peak time was 13% [9-18] and 34% [31-36] higher in 30 and 75-year-old women respectively.

CONCLUSION

Based on large nationwide study, our study showed a clear seasonal pattern both on PE incidence and mortality. In addition, our data supported an association of age on the PE seasonal variations.

Chronobiology of Takotsubo Syndrome and Myocardial Infarction: Analogies and Differences

Several pathophysiologic factors, not harmful if taken alone, are capable of triggering unfavorable events when presenting together within the same temporal window (chronorisk), and the occurrence of many cardiovascular events is not evenly distributed in time. Both acute myocardial infarction and takotsubo syndrome seem to exhibit a temporal preference in their onset, characterized by variations according to time of day, day of the week, and month of the year, although with both analogies and differences.

Analysis of environmental risk factors for pulmonary embolism: A case-crossover study (2001-2013)

BACKGROUND

The relationship between environmental factors and pulmonary embolism (PE) has received little attention. The aim of this study was to estimate the influence of climatological factors and air pollution levels on PE in Spain from 2001 to 2013.

METHODS

We carried out a retrospective study. Data were collected from the Minimum Basic Data Set (MBDS) and the State Meteorological Agency (AEMET) of Spain. A case-crossover analysis was applied to identify environmental risk factors related to hospitalizations and deaths. For each patient, climatic and pollutant factors were assigned using data from the meteorological station closest to his/her postal code.

RESULTS

A seasonal effect for PE hospital admission was observed, with more frequent admissions noted during Spain's colder seasons with peaks in autumn and winter. Lower temperatures as well as higher concentrations of NO2 and O3 at the time of admission (when 2weeks and 3weeks respectively were used as controls) were significant risk factors for hospital admissions with PE.

CONCLUSIONS

Pulmonary embolism epidemiology was adversely influenced by colder climatological factors (absolute temperature, and seasonality) and higher concentrations of ambient air pollution (NO2, O3).

Dehydration as a Possible Cause of Monthly Variation in the Incidence of Venous Thromboembolism

BACKGROUND

Monthly or seasonal changes in the incidence of venous thromboembolism (VTE) were previously reported; however, the mechanism of such variability is not completely understood.

METHODS

In the present retrospective single-center analysis, consecutive patients with proximal deep vein thrombosis and/or pulmonary embolism (PE) diagnosed between January 2009 and December 2013 were evaluated.

RESULTS

The study population included 1496 patients, 48% men, mean age 63 ± 18 years. Most (82%) cases with VTE were provoked and 39% of patients had active cancer. Four months of peak incidence (3, 7, 10 and 11) were compared with 4 months of the lowest incidence (4, 5, 6, and 12), showing a significant difference in VTE numbers (597 vs 405 cases/year, P = 0.001). In all subgroup analyses, including gender, provoked or unprovoked event and presence or absence of cancer, significant differences between the months of peak and lowest incidence remained. Blood urea nitrogen (BUN)-creatinine ratio was significantly higher in all cases in the peak incidence group compared to the lowest incidence group (24 ± 1.5 vs 21 ± 1.6, P = 0.03). In patients with unprovoked VTE (n = 269), levels of BUN and hematocrit were significantly increased in the peak incidence group compared to lowest incidence group (19.5 ± 0.8 mg/dL vs 16 ± 1.1 mg/dL, P = 0.03; 39.2 ± 0.3% vs 37.4 ± 0.5%, P = 0.01, respectively).

CONCLUSIONS

The current study demonstrates that occurrence of VTE exhibits monthly variation also existing in patients with provoked events and even in those with cancer. Dehydration is suggested as a potential explanation to the month-related variation in incidence of VTE.

Evaluation of meteorological and epidemiological characteristics of fatal pulmonary embolism

The objective of the present study was to identify risk factors among epidemiological factors and meteorological conditions in connection with fatal pulmonary embolism. Information was collected from forensic autopsy records in sudden unexpected death cases where pulmonary embolism was the exact cause of death between 2001 and 2010 in Budapest. Meteorological parameters were detected during the investigated period. Gender, age, manner of death, cause of death, place of death, post-mortem pathomorphological changes and daily meteorological conditions (i.e. daily mean temperature and atmospheric pressure) were examined. We detected that the number of registered pulmonary embolism (No 467, 211 male) follows power law in time regardless of the manner of death. We first described that the number of registered fatal pulmonary embolism up to the nth day can be expressed as Y(n) = α ⋅ n (β) where Y denotes the number of fatal pulmonary embolisms up to the nth day and α > 0 and β > 1 are model parameters. We found that there is a definite link between the cold temperature and the increasing incidence of fatal pulmonary embolism. Cold temperature and the change of air pressure appear to be predisposing factors for fatal pulmonary embolism. Meteorological parameters should have provided additional information about the predisposing factors of thromboembolism.

"Timing" of arrival and in-hospital mortality in a cohort of patients under anticoagulant therapy presenting to the emergency departments with cerebral hemorrhage: A multicenter chronobiological study in Italy

Therapy with oral anticoagulants (OACs) is a risk factor for cerebral hemorrhage (CH). Although different studies have been undertaken to investigate the timing of the onset of major cardiovascular events, no data exist on temporal patterns of the onset of CH in subjects treated with OACs. The aim of this study is to evaluate the timing of CH in patients treated with OACs. All patients who developed CH under OACs therapy and admitted to 28 Italian Emergency Departments (EDs) between September 2011 and July 2013 were enrolled. Age, sex, time and location of the hemorrhagic lesion, type of the bleeding events (idiopathic or post-traumatic), anticoagulant therapy (warfarin or new oral anticoagulants - NOAs) and time of ED admission (i.e., hour, day, month and season) were recorded. Five hundred and seventeen patients (63.2% male aged 80 ± 7.9 yrs) with CH were involved. Warfarin was taken by 494 patients (95.6%), and NOAs by 23 (4.4%). In-hospital mortality (IHM) was recorded in 208 cases (40.2%). Cosinor analysis showed a peak of CH arrival between 12:00 and 14:00 h both in the whole population (PR 73.9%, p = 0.002) and the male subgroup (PR 65.2%, p = 0.009), whereas females showed an anticipated morning peak between 08:00 and 10:00 h (PR 65.7%, p = 0.008). A further analysis between idiopathic and post-traumatic CH confirmed the presence of a 24 h pattern with a peak between 12:00 and 14:00 h (PR 58.5%, p = 0.019) and between 08:00 and 10:00 h (PR80.1%, p < 0.001) for idiopathic events and post-traumatic hemorrhages, respectively. Moreover, a seasonal winter peak was identified for idiopathic forms (PR 74%, p = 0.035), and a summer peak for post-traumatic forms (PR 77%, p = 0.025). The present study suggests the presence of a temporal pattern of ED arrivals in CH patients treated with OACs.

Association between particulate air pollution and venous thromboembolism: A systematic literature review

Air pollution is a leading global problem for public health. A number of ambient pollutants have been involved, including carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3) and particulate matter (PM). Although exposure to PM has been linked to a wide array of cardiovascular and respiratory disorders, its effect on venous thrombotic disorders is still uncertain. To elucidate this issue, we have performed a systematic review on the existing literature on the association between PM and venous thromboembolism (VTE), using MEDLINE, EMBASE and Cochrane electronic databases. Of the 158 reviewed studies, 11 of them (3 case-crossover studies, 2 time-series studies, 2 case-control studies, 2 prospective cohort studies, 2 retrospective studies) involving more than 500,000 events fulfilled the inclusion criteria and results are presented here. Because there was substantial heterogeneity in study design, duration of follow-up, statistical measure of effects, clinical outcomes and threshold, we refrained to perform a quantitative analysis of the available data and carried out only a systematic review. Overall, the literature data suggest a link between PM and VTE, but further trials on larger populations of patients with homogeneous study designs and outcomes are warranted.

Seasonal Changes in Hospital Admissions for Pulmonary Embolism in Metropolitan Areas of Tokyo (from the Tokyo Cardiovascular Care Unit Network)

Although several studies have shown the relation between temperature/atmospheric pressure and pulmonary embolism (PE), their results are inconsistent. Furthermore, diurnal temperature range (DTR) and diurnal pressure range (DPR) were not fully evaluated for their associations with hospital admissions for PE. Study subjects comprised cases of 1,148 PE treated at institutions belonging to the Tokyo Cardiovascular Care Unit Network from January 2005 to December 2012. Patient data were combined with a variety of daily local climate parameters obtained from the Japan Meteorological Agency. Every 1°C increase in the DTR at lag0 corresponded to an increased relative risk of hospital admission for PE (odds ratio [OR] 1.036, 95% confidence interval [CI] 1.003 to 1.070). In the cooler season (November to April), an increase of 1 hPa (barometric pressure) in the DPR at lag4 and lag5 was associated with an increased relative risk of hospital admission for PE (OR 1.042, 95% CI 1.007 to 1.077 and OR 0.952, 95% CI 0.914 to 0.992, respectively). An increase in the PE hospitalization rate was seen only in the cool season. Using a metropolitan database, we showed that DTR and DPR have different impacts on hospital admissions for PE. In conclusion, we found that an increase in the DTR increases the PE hospitalization rate, especially during the cooler season. The impact of DTR and DPR on PE incidence and related hospitalizations needs to be further evaluated.

Serum levels of 25(OH)D are not associated with venous thromboembolism in the elderly population. A case-control study

The prevalence of both vitamin D deficiency and venous thromboembolism (VTE) is important in the elderly. Previous studies have provided evidence for a possible association between vitamin D status and the risk of VTE. Thus, we aimed to investigate the association between vitamin D levels and VTE in the population aged 75 and over included in the EDITH case-control study. The association between vitamin D status and VTE was analysed. We also analysed the monthly and seasonal variations of VTE and vitamin D. Between May 2000 and December 2009, 340 elderly patients (mean age 81.5 years, 32% men) with unprovoked VTE and their controls were included. The univariate and multivariate analysis found no significant association between serum levels of vitamin D and the risk of unprovoked VTE. In the unadjusted analysis, a higher BMI was statistically associated with an increased risk of VTE (OR 1.09; 95% CI 1.05-1.13) whereas a better walking capacity and living at home were associated with a decreased rate of VTE: OR 0.57; 95% CI 0.36-0.90 and 0.40; 95% CI 0.25-0.66, respectively. Although not significant, more VTE events occurred during winter (p=0.09). No seasonal variations of vitamin D levels were found (p=0.11). In conclusion, in contrast with previous reports our findings suggest that vitamin D is not associated with VTE in the elderly population.