Seasonal variation in heart failure hospitalization

Impact of the method of calculating 30-day readmission rate after hospitalization for heart failure. Data from the VancOuver CoastAL Acute Heart Failure (VOCAL-AHF) registry

BACKGROUND

Thirty-day readmission rate after heart failure (HF) hospitalization is widely used to evaluate healthcare quality. Methodology may substantially influence estimated rates. We assessed the impact of different definitions on HF and all-cause readmission rates.

METHODS

Readmission rates were examined in 1835 patients discharged following HF hospitalization using 64 unique definitions derived from five methodological factors: (1) International Classification of Diseases-10 codes (broad vs. narrow), (2) index admission selection (single admission only first-in-year vs. random sample; or multiple admissions in year with vs. without 30-day blanking period), (3) variable denominator (number alive at discharge vs. number alive at 30 days), (4) follow-up period start (discharge date vs. day following discharge), and (5) annual reference period (calendar vs. fiscal). The impact of different factors was assessed using linear regression.

RESULTS

The calculated 30-day readmission rate for HF varied more than two-fold depending solely on the methodological approach (6.5-15.0%). All-cause admission rates exhibited similar variation (18.8-29.9%). The highest rates included all consecutive index admissions (HF 11.1-15.0%, all-cause 24.0-29.9%), and the lowest only one index admission per patient per year (HF 6.5-11.3%, all-cause 18.8-22.7%). When including multiple index admissions and compared with blanking the 30-day post-discharge, not blanking was associated with 2.3% higher readmission rates. Selecting a single admission per year with a first-in-year approach lowered readmission rates by 1.5%, while random-sampling admissions lowered estimates further by 5.2% (P < 0.001).

CONCLUSION

Calculated 30-day readmission rates varied more than two-fold by altering methods. Transparent and consistent methods are needed to ensure reproducible and comparable reporting.

The Icelandic Heart Failure Registry-A nationwide assessment tool for HF care and intervention in HF treatment

INTRODUCTION

The incidence of heart failure (HF) is increasing, largely because populations are both ageing and growing. Most clinical HF treatment trials are conducted on selected cohorts, only a few of which include elderly patients, among whom HF is common. HF registries can include all HF patients, independent of age or comorbidity profile, and thus reflect reality in healthcare management.

METHODS

The Icelandic Heart Failure Registry (IHFR) was created in the autumn of 2019 and has operated since 1 January 2020. Based on the Swedish Heart Failure Registry (SwedeHF), it quickly acquired several extensions. All patients admitted for HF to the Department of Cardiology (DC) at Landspítali - The National University Hospital of Iceland are included. Several variables are collected, including the aetiology of HF, comorbidities, clinical assessment at admission, blood tests, imaging results, treatment given and medical therapy at discharge.

RESULTS

During the 3 years from 2020 to 2022, the DC admitted 1890 patients. As some were readmitted during the study period, the true total was 2384 admissions. Because the IHFR 2023 edition includes 327 variables, automation of many of them is imperative for data collection.

CONCLUSION

HF is a heterogenous disease with numerous underlying factors. HF management differs among HF phenotypes. A registry can serve as an unbiased indicator of care quality and has the potential to be studied in the future to assess the long-term effects of HF treatment. A registry like the IHFR, therefore, can impact the treatment of all patients recorded in it, reduce the rate of readmissions and even optimize HF management costs.

Are there more acute cardiac hospitalizations in winter in patients with systemic sclerosis? An analysis from the National Inpatient Sample

Objective

Cold-induced transient myocardial ischemia has been described in patients with systemic sclerosis. The clinical impact of cold exposure in systemic sclerosis patients with acute cardiac conditions is unknown. We compared the seasonal variation of acute cardiac hospitalizations in patients with and without systemic sclerosis.

Methods

We performed a retrospective cross-sectional study using the National Inpatient Sample from 2016 to 2019. The primary outcome was acute cardiac hospitalization primarily due to heart failure, acute myocardial infarction, or cardiac arrhythmias. We compared the proportion of acute cardiac hospitalizations in each season in patients with and without systemic sclerosis. We also performed a subgroup analysis by US geographic region (Northeast, Midwest, South, West).

Results

There were a total of 10,118,002 acute cardiac hospitalizations over the 4-year study period. Compared to those without systemic sclerosis, patients with systemic sclerosis who were hospitalized for acute cardiac care were younger (mean age 67 ± 13 vs 70 ± 14 years, p < 0.01), a greater proportion were female (82% vs 45%, p < 0.01), and a smaller proportion were Caucasian (68% vs 71%, p < 0.01). There was a lesser proportion of traditional cardiovascular risk factors in systemic sclerosis compared to non-systemic sclerosis patients. There was no significant difference in the proportion of winter admissions between systemic sclerosis and non-systemic sclerosis patients for total acute cardiac hospitalizations (26.4% vs 25.9%, p = 0.51), heart failure (27.0% vs 26.5%, p = 0.64), acute myocardial infarction (26.9% vs 25.5%, p = 0.50), or arrhythmias (24.3% vs 25.0%, p = 0.68). The results were consistent across all four US geographic regions.

Conclusion

Our study did not support that patients with systemic sclerosis had a disproportionally higher risk of acute cardiac hospitalization in winter compared to the general population. We found that systemic sclerosis patients hospitalized for acute cardiac care had a lower burden of traditional cardiovascular risk factors than their non-systemic sclerosis counterparts.

Diabetic Ketoacidosis in Northern Jordan: Seasonal Morbidity and Characteristics of Patients

Purpose

This study aimed to characterize adult patients admitted with diabetic ketoacidosis (DKA) in northern Jordan.

Methods

The study examined medical records of patients diagnosed with DKA from January 2015 to April 2018. Variables analyzed included diabetes type, precipitating illness, admission month, hospital length of stay, and biochemical markers.

Results

Out of 232 admissions with DKA, 70% were diagnosed with type 2 diabetes, and 56% were females. 12% of admissions had a new diagnosis of diabetes, of which 51% had type 2 diabetes. Sepsis (48%), Non-adherence (26%), and diabetic foot infections (18%) were the most encountered precipitating factors for DKA in T1DM. As for T2DM, sepsis (52%), acute coronary syndrome (12%), and pancreatitis (8%) were the most precipitating factors for DKA. High urea levels, high creatinine levels, low phosphorous levels, low hemoglobin levels, and high platelet counts were associated with a longer hospital stay for type 1 diabetes. For type 2 diabetes, low pH on admission, old age, and high Hb A1c within 6 months of admission were factors associated with a prolonged hospital stay. The study found a significant peak of admissions for DKA in both type 1 and type 2 patients in the winter and spring months (Pearson P-value= 0.0013).

Conclusion

The results of the present study highlight the seasonal variation in the frequency of DKA hospitalizations. It also highlights sepsis as the most frequent precipitating factor of DKA in both type 1 and type 2 DM patients.

Cardiovascular diseases display etiological and seasonal trend in human population: Evidence from seasonal cardiovascular comorbid diseases (SCCD) index

Seasonal changes in the human cardiovascular system are known to play an important role in the onset of many diseases. Confounding variables include behavioral and environmental factors; failing to address such variables makes measuring the true temporal impact of these diseases difficult. On the other hand, numerous clinical studies imply that only specific groups of people are more seasonal sensitive and that their maladaptation might contribute to various illnesses. As a result, it is critical to evaluate the etiological and seasonal sensitive patterns of cardiovascular diseases (CVD), which impact the majority of the human population. The hypothesis for this study formulated that cardiovascular and associated illnesses had substantial connections with seasonal and etiological variations. Thus in the present study, 4519 systematic screen-eligible studies were analyzed using data mining to uncover 852 disease association relationships between cardiovascular and associated disorders. A disease ontology-based semantic similarity network (DSN) analysis was performed to narrow down the identified CVDs. Further, topological analysis was used to predict the seven CVDs, including myocardial infarction (MI), in three clusters. Following that, Mann-Kendall and Cox-Stuart analyses were used to investigate the seasonal sensitivity and temporal relationship of these seven CVDs. Finally, temporal relationships were confirmed using LOESS and TBATS, as well as seasonal breakdown utilizing autocorrelation and fast Fourier transform results. The study provides indirect evidence of a severe etiological association among the three cardiovascular diseases, including MI, atrial fibrillation, and atherosclerosis, which are winter season sensitive in most of the world population. Hypertension has two seasonal falls and peaks due to its seasonal nature, that is, summer and winter hypertension. While, heart failure was also identified, with minor temporal trends. Hence, all five diseases could be classified as seasonal cardiovascular comorbid diseases (SCCD). Furthermore, these diseases could be studied for potential common risk factors such as biochemical, genetic, and physiological factors.

Visits to Sexually Transmitted Infection Clinics in Italy from January 2016 to November 2021: A Multicenter, Retrospective Study

There is no evidence of seasonal variation in visits to clinics dedicated to sexually transmitted infections (STIs) in Italy, nor of changes after the advent of the COVID-19 pandemic. An observational, retrospective, multicentric study was conducted to record and analyze all the visits to the STI clinics of the Dermatology Units of the University Hospitals of Ferrara and Bologna and of the Infectious Disease Unit of Ferrara, Italy, between January 2016 and November 2021. Overall, 11.733 visits were registered over a 70-month study period (63.7% males, mean age 34.5 ± 12.8 yrs). The mean number of monthly visits significantly decreased from the advent of the pandemic (136) compared to before (177). In the pre-pandemic period, visits to STI clinics increased in the autumn/winter months when compared to spring/summer, while the trend was the opposite in the pandemic period. Thus, during the pandemic, both an overall significant reduction in visits to STI clinics and a reversal in their seasonality were observed. These trends affected males and females equally. The marked decrease, mostly found in the pandemic winter months, can be linked to the "lockdown"/self-isolation ordinances and social distancing measures during the colder months, coinciding with the spread of the COVID-19 infection, which limited the opportunities for meeting and socializing.

Seasonal variation in in-hospital outcomes of Takotsubo-syndrome-related admissions: A National Inpatient Analysis, 2019

Takotsubo syndrome (TTS) is a transitory stress-related cardiomyopathy characterized by acute but reversible left ventricular failure. The disease most commonly affects postmenopausal women following a traumatic experience, often presenting as an acute myocardial infarction (MI), and its prevalence is increasing globally. Cardiovascular events such as Acute Coronary Syndrome (ACS) and stroke have well-defined seasonal variations and are most common in the winter [[8], [9], [10]]. However, there is insufficient data on the impact of such climatic variations on the etiopathogenesis and outcomes of TTS-related hospitalization in the United States.

Seasonal changes in proportion of cardiac surgeries associated with diabetes, smoking and elderly age

Background

Seasonal variations in the ambient temperature may affect the exacerbation of cardiovascular diseases. Our primary objective was to evaluate the seasonality of the monthly proportion of cardiac surgeries associated with diabetes, smoking and/or elderly age at a tertiary-care university hospital in East-Central Europe with a temperate climate zone. As a secondary objective, we also assessed whether additional factors affecting small blood vessels (smoking, aging, obesity) modulate the seasonal variability of diabetes.

Methods

Medical records were analyzed for 9838 consecutive adult patients who underwent cardiac surgery in 2007–2018. Individual seasonal variations of diabetes, smoking, and elderly patients were analyzed monthly, along with the potential risk factors for cardiovascular complication. We also characterized whether pairwise coexistence of diabetes, smoking, and elderly age augments or blunts the seasonal variations.

Results

Seasonal variations in the monthly proportion of cardiac surgeries associated with diabetes, smoking and/or elderly age were observed. The proportion of cardiac surgeries of non-elderly and smoking patients with diabetes peaked in winter (amplitude of change as [peak-nadir]/nadir: 19.2%, p<0.02), which was associated with increases in systolic (6.1%, p<0.001) and diastolic blood pressures (4.4%, p<0.05) and serum triglyceride levels (27.1%, p<0.005). However, heart surgery in elderly patients without diabetes and smoking was most frequently required in summer (52.1%, p<0.001). Concomitant occurrence of diabetes and smoking had an additive effect on the requirement for cardiac surgery (107%, p<0.001), while the simultaneous presence of older age and diabetes or smoking eliminated seasonal variations.

Conclusions

Scheduling regular cardiovascular control in accordance with periodicities in diabetes, elderly, and smoking patients more than once a year may improve patient health and social consequences.

Trial registration

NCT03967639.

Effect of environment and season on acute decompensated heart failure: data from low-to middle-income country

Objectives

The environmental effect in heart failure (HF) patients is well established. However, the data is limited from low-to middle-income countries like India. This study determined the impact of environment on acute decompensated HF (ADHF) admissions and mortality in India.

Methods

Retrospectively, the data of all HF patients admitted between April 2017 and March 2019 was accessed through electronic hospital records. Simultaneously, the environmental-related data was collected from the central pollution control board.

Results

The study included 4561 patients of ADHF. The peak of monthly ADHF events (admission and mortality) was observed during the chilly month (January) while the lowest rates were observed in summer months (May–June). The most significant factor correlating inversely with the monthly ADHF admission (r = −0.78, p = 0.003) and mortality (r = −0.65, p = 0.004) was the maximum air temperature, and it was found to be the independent predictor for both ADHF mortality [t = −2.78, β = −0.84; 95%CI(-6.0 to −0.6), p = 0.021] and admission [t = −4.83, β = −0.91; 95%CI(-19.8 to −6.9), p = 0.001]. The above correlation was better seen in the elderly subset and male gender. Humidity and the air pollution attributes did not have a significant correlation with ADHF admission or mortality.

Conclusion

In conclusion, even in low-to middle-income country like India, a periodic effect of season was demonstrated for ADHF mortality and admission, with a peak in ADHF events noted during winter months especially in the regions having extremes of seasons. Air pollution could not affect the ADHF outcome for which further studies are needed.

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.

Impact of the COVID-19 Pandemic on Patients Without COVID-19 With Acute Myocardial Infarction and Heart Failure

Background Excess mortality from cardiovascular disease during the COVID-19 pandemic has been reported. The mechanism is unclear but may include delay or deferral of care, or differential treatment during hospitalization because of strains on hospital capacity. Methods and Results We used emergency department and inpatient data from a 12-hospital health system to examine changes in volume, patient age and comorbidities, treatment (right- and left-heart catheterization), and outcomes for patients with acute myocardial infarction (AMI) and heart failure (HF) during the COVID-19 pandemic compared with pre-COVID-19 (2018 and 2019), controlling for seasonal variation. We analyzed 27 427 emergency department visits or hospitalizations. Patient volume decreased during COVID-19 for both HF and AMI, but age, race, sex, and medical comorbidities were similar before and during COVID-19 for both groups. Acuity increased for AMI as measured by the proportion of patients with ST-segment elevation. There were no differences in right-heart catheterization for patients with HF or in left heart catheterization for patients with AMI. In-hospital mortality increased for AMI during COVID-19 (odds ratio [OR], 1.46; 95% CI, 1.21-1.76), particularly among the ST-segment-elevation myocardial infarction subgroup (OR, 2.57; 95% CI, 2.24-2.96), but was unchanged for HF (OR, 1.02; 95% CI, 0.89-1.16). Conclusions Cardiovascular volume decreased during COVID-19. Despite similar patient age and comorbidities and in-hospital treatments during COVID-19, mortality increased for patients with AMI but not patients with HF. Given that AMI is a time-sensitive condition, delay or deferral of care rather than changes in hospital care delivery may have led to worse cardiovascular outcomes during COVID-19.

Does the “July effect” of new trainees at teaching hospitals impact outcomes for patients hospitalized with heart failure? Real-world analyses of more than half a million US admissions

Introduction:

The “July effect” refers to the potential of adverse clinical outcomes related to the annual turnover of trainees. We investigated whether this impacts inpatient heart failure (HF) outcomes.

Methods:

Data from all adults (≥18 years) admitted with a primary diagnosis of HF at US teaching hospitals from the 2012–2014 National Inpatient Sample were analyzed. Non-teaching hospital admissions were excluded. The primary outcome was in-hospital mortality. Secondary metrics included hospital length of stay (LOS) and total cost adjusted for inflation. Logistic and linear regression models were used to adjust for confounders. Admissions were classified into 4 quarters (Q1–Q4), based on the academic calendar. Q1 and Q4 were designated to assess the effect of novice (July effect) versus experienced trainees, respectively.

Results:

There were 699,675 HF admissions during Q1 and Q4 in the study period. Mean age was 71 ± 15 years and 48% were females. There were 20,270 in-hospital deaths, with no difference between Q1 and Q4; crude odds ratio (OR) 1.00, 95% confidence interval (CI) 0.94–1.07, p = 0.95. After risk adjustment, there was no in-hospital mortality difference between Q1 and Q4 admissions; adjusted OR 0.96, 95% CI 0.89–1.03, p = 0.23. There was no difference in hospital LOS or total cost; 5.8 versus 5.8 days, p = 0.66 and $13,755 versus $13,586, p = 0.46, in Q1 and Q4, respectively.

Conclusions:

In this nationally representative sample, there was no evidence of a “July effect” on inpatient HF outcomes in the US. This suggests that HF patients should not delay seeking care during trainee transitions at teaching hospitals.

Impact of COVID-19 pandemic restrictions on the cardio-respiratory health of New Zealanders

BACKGROUND AND OBJECTIVE

The COVID-19 pandemic has caused disruption to health, social interaction, travel and economies worldwide. In New Zealand, the government closed the border to non-residents and required all arrivals to quarantine for 14 days. They also implemented a strict contact-restriction system to eliminate COVID-19 from the community. These measures also reduced the circulation of other respiratory viruses such as influenza and respiratory syncytial virus. We assessed the impact of these measures on hospital admissions for respiratory and cardiac diseases.

METHODS

National data on hospital admissions for each week of 2020 were compared to admissions for the previous 5 years. Analyses were curtailed after week 33, when a COVID-19 outbreak in Auckland led to different levels of pandemic restrictions making national data difficult to interpret.

RESULTS

The numbers of acute infectious respiratory admissions were similar to previous years before the introduction of COVID-19 restrictions, but then fell lower and remained low after the pandemic restrictions were eased. The usual winter peak in respiratory admissions was not seen in 2020. Other than small reductions during the period of the strictest contact restrictions, non-infectious respiratory and cardiac admissions were similar to previous years and the usual winter peak in heart failure admissions was observed.

CONCLUSION

The observed patterns of hospital admissions in 2020 are compatible with the hypothesis that circulating respiratory viruses drive the normal seasonal trends in respiratory admissions. By contrast, these findings suggest that respiratory viruses do not drive the winter peak in heart failure.

Social and environmental risks as contributors to the clinical course of heart failure

Heart failure is a major contributor to healthcare expenditures. Many clinical risk factors for the development and exacerbation of heart failure had been reported, including diabetes, renal dysfunction, and respiratory disease. In addition to these clinical parameters, the effects of social factors, such as occupation or lifestyle, and environmental factors may have a great impact on disease development and progression of heart failure. However, the current understanding of social and environmental factors as contributors to the clinical course of heart failure is insufficient. To present the knowledge of these factors to date, this comprehensive review of the literature sought to identify the major contributors to heart failure within this context. Social factors for the risk of heart failure included occupation and lifestyle, specifically in terms of the effects of specific occupations, occupational exposure to toxicities, work style, and sleep deprivation. Socioeconomic factors focused on income and education level, social status, the neighborhood environment, and marital status. Environmental factors included traffic and noise, air pollution, and other climate factors. In addition, psychological stress and behavior traits were investigated. The development of heart failure may be closely related to these factors; therefore, these data should be summarized for the context to improve their effects on patients with heart failure. The present study reviews the literature to summarize these influences.

The Impact of Environmental Factors on the Mortality of Patients With Chronic Heart Failure

Outcomes of acute heart failure hospitalizations are worse during the winter than the rest of the year. Seasonality data are more limited for outcomes in chronic heart failure and the effect of environmental variables is unknown. In this population-level study, we merged 20-year data for 555,324 patients with heart failure from the national Veterans Administration database with data on climate from the National Oceanic and Atmospheric Administration and air pollutants by the Environmental Protection Agency. The outcome was the all-cause mortality rate, stratified by geographical location and each month. The impact of environmental factors was assessed through Pearson's correlation and multiple regression with a family-wise α = 0.05. The monthly all-cause mortality was 13.9% higher in the winter than the summer, regardless of gender, age group, and heart failure etiology. Winter season, lower temperatures, and higher concentrations of nitrogen dioxide were associated with a higher mortality rate in multivariate analysis of the overall population. Different environmental factors were associated in regions with similar patterns of temperature and precipitation. The only environmental factor associated with the mortality rate of patients dwelling in large urban centers was the air quality index. In conclusion, the mortality in chronic heart failure exhibits a seasonal pattern, regardless of latitude or climate. In this group of patients, particularly those of male gender, a higher mortality was associated with environmental factors and incorporating these factors in treatment plans and recommendations could have a favorable cost-benefit ratio.

Impact of COVID-19 Pandemic Lockdown in Decompensated Heart Failure Hospitalizations

Background and Objectives

Coronavirus disease 2019 (COVID-19) pandemic lockdown may have collaterally affected the care of patients with acute decompensated heart failure (ADHF). We aimed to evaluate the impact of lockdown pandemic on hospitalizations for ADHF.

Methods

We conducted a single-center study, performing a retrospective analysis of prospectively collected data. We included consecutive adult patients with a primary diagnosis of ADHF admitted to a cardiovascular disease specialized hospital. We compared those patients admitted between March–June of 2019 (before COVID-19 [BC]) and 2020 (after COVID-19 [AC]), during mandatory lockdown.

Results

A total 79 corresponding to BC period and 60 to AC period were included, representing a decrease of 25% (interquartile range [IQR], 11–33). During the BC period, 31.6% of patients were referred from other centers compared to 15% during the pandemic (p=0.02). In the AC period patients were older (median age, 81[IQR, 73–87] years vs. 77 [IQR, 64–84] years, p=0.014). The etiology of HF, cause of decompensation, left ventricular function, and laboratory parameters were similar in both periods. The use of mechanical ventilation (13.9% vs. 3.3%, p=0.03) and circulatory support (7.6% vs. 0%, p=0.02) was higher in the BC period. During the BC period, 5 emergency heart transplants were performed, and none in AC, (p=0.004). In-hospital mortality was similar in both periods (3.8% vs. 3.3%; p=0.80).

Conclusions

We observed a reduction in the number of hospitalizations and referral of patients for ADHF during COVID-19 pandemic.

Winter LVAD implantation is associated with adverse clinical outcomes

BACKGROUND

The seasonal variation of incidence and severity of heart failure is well known. However, the impact of seasonal variation on clinical outcomes following left ventricular assist device (LVAD) implantation remains unknown.

METHODS

We retrospectively reviewed consecutive patients who received LVAD implantation between January 2014 and December 2016 along with their first year of post-implant outcomes. Clinical outcomes were compared between those with winter LVAD implantation (between October and March) and those with non-winter LVAD implantation.

RESULTS

168 patients with a median age of 57 years and 130 males were included. There was no seasonal difference in the number of LVAD implantations. One-year survival free from major adverse events was significantly lower in the winter implant group (n = 88) compared to the non-winter group (n = 80) (44% vs 61%) with an adjusted hazard ratio of 1.81 (95% confidence interval 1.11-2.90, p = 0.014), largely due to a higher rate of heart failure readmission in the winter implant patients (incidence rate ratio 2.29, 95% confidence interval 0.89-5.84).

CONCLUSION

Patients who underwent LVAD implantation during the winter season had a higher heart failure readmission rate. A detailed mechanism and therapeutic strategy given our findings warrant further investigation.

Effect of temperature variation on hospital admissions and outcomes in dogs with myxomatous mitral valve disease and new onset pulmonary edema

The effect of seasonal variation on hospital admissions and outcomes in humans with cardiovascular disease and congestive heart failure (CHF) has been described. This study evaluates the effect of temperature variation on admissions and outcomes in dogs with myxomatous mitral valve disease (MMVD) and first onset CHF. Ninety-three client-owned dogs with MMVD and a first occurrence of pulmonary edema were included in this retrospective clinical cohort study. Recorded clinical and echocardiographic variables were accumulated and analyzed with dogs allocated into groups in a temperature-wise manner that considered the mean of the average (Tave) and maximum ambient temperature (Tmax) of the 14 days preceding hospital admission. A survival analysis was also performed. No difference was found in the percentage of dogs decompensating in three different temperature periods (i.e., cold, intermediate, and hot temperature) according to both Tave and Tmax. Dogs developing CHF during the intermediate temperatures according to Tmax died earlier from cardiac-related causes (median survival time 280 days, 95% CI = 147–486 days) compared to those decompensating during hot temperatures (median survival time 518 days, 95% CI = 344–819 days, P = 0.039). However, an effect of the ambient temperature on survival was not confirmed by Cox proportional hazard analysis. In conclusion, this study failed to show that ambient temperature has an effect on the first occurrence of CHF and outcomes in dogs with MMVD.

Seasonality in Mortality in a Cardiology Department: A Five-Year Analysis in 500 Patients

BACKGROUND

Previous studies have indicated that cardiovascular mortality follows a seasonal trend. The aim of this work was to determine the evolution of mortality throughout the year in a cardiology department.

METHODS

All admissions and deaths occurring in our Cardiology Department over a 5-year period (2013-2017) were recorded retrospectively.

RESULTS

From a total of 17,829 hospital admissions, 500 patients died (2.8%, 0.3 patients/day). The mean age of deceased patients was 74.2 ± 13.1 years, and 186 (37.2%) were women. Mortality ranged from 0.17 deaths/day in August to 0.40 deaths/day in February (p = 0.03), and from 0.20 deaths/day in summer to 0.36 deaths/day in winter (p = 0.001). There was also a trend towards a variation in hospitalizations, with a peak in January (10.5 admissions/day) and the lowest figure in August (7.0 admissions/day), p = 0.047. We found no significant seasonal trend regarding mortality rate with respect to the number of hospital admissions (p = 0.89). The most common cause of death was refractory heart failure (267 patients [65.8%]). A noncardiac cause of death was observed in 134 patients (26.8%).

CONCLUSIONS

In a cardiology department, there are twice as many deaths in winter as in summer. Hospitalizations also tend to be more frequent in winter than in summer.

Seasonality of the Cardiac Biomarker Troponin in the Eastern Croatian Population

Background: The seasonality of acute myocardial infarction and progressive heart failure has been well established so far. Cardiac troponins (cTns) are organ-specific, not disease-specific, biomarkers. The seasonality of cTns has not been reported before. Methods: Data were collected from the emergency admission unit of a community hospital in eastern Croatia for each month of the year 2014 covering the number of patients whose doctors requested high-sensitivity cTn I (hs-cTn I) testing, the number of positive test results and hospital admissions. Results: The proportion of patients with positive test results was 15.75% (350 patients out of 2221 patients referred to testing), with the males being outnumbered by the females (F: 57.15%, M: 42.85%) (p = 0.069). The month with the highest number of patients with positive test results was December, whereas the month with the lowest number of those patients was January (p < 0.001). The highest numbers of patients referred to testing (30.9%) and of those with positive test results (50.8%) were found in the oldest age group (76+). Conclusion: Tracking the results of cTns testing during patient admissions to emergency departments would be a more effective approach from a public health perspective than tracking the number of patients diagnosed with a particular cardiovascular (CV) disease and could be used as a research approach to guide a search for precipitating factors for CV disease specific to a local community.

Effect of Seasonal Variation on Clinical Outcome in Patients with Chronic Conditions: Analysis of the Commonwealth Scientific and Industrial Research Organization (CSIRO) National Telehealth Trial

BACKGROUND

Seasonal variation has an impact on the hospitalization rate of patients with a range of cardiovascular diseases, including myocardial infarction and angina. This paper presents findings on the influence of seasonal variation on the results of a recently completed national trial of home telemonitoring of patients with chronic conditions, carried out at five locations along the east coast of Australia.

OBJECTIVE

The aim is to evaluate the effect of the seasonal timing of hospital admission and length of stay on clinical outcome of a home telemonitoring trial involving patients (age: mean 72.2, SD 9.4 years) with chronic conditions (chronic obstructive pulmonary disease coronary artery disease, hypertensive diseases, congestive heart failure, diabetes, or asthma) and to explore methods of minimizing the influence of seasonal variations in the analysis of the effect of at-home telemonitoring on the number of hospital admissions and length of stay (LOS).

METHODS

Patients were selected from a hospital list of eligible patients living with a range of chronic conditions. Each test patient was case matched with at least one control patient. A total of 114 test patients and 173 control patients were available in this trial. However, of the 287 patients, we only considered patients who had one or more admissions in the years from 2010 to 2012. Three different groups were analyzed separately because of substantially different climates: (1) Queensland, (2) Australian Capital Territory and Victoria, and (3) Tasmania. Time series data were analyzed using linear regression for a period of 3 years before the intervention to obtain an average seasonal variation pattern. A novel method that can reduce the impact of seasonal variation on the rate of hospitalization and LOS was used in the analysis of the outcome variables of the at-home telemonitoring trial.

RESULTS

Test patients were monitored for a mean 481 (SD 77) days with 87% (53/61) of patients monitored for more than 12 months. Trends in seasonal variations were obtained from 3 years' of hospitalization data before intervention for the Queensland, Tasmania, and Australian Capital Territory and Victoria subgroups, respectively. The maximum deviation from baseline trends for LOS was 101.7% (SD 42.2%), 60.6% (SD 36.4%), and 158.3% (SD 68.1%). However, by synchronizing outcomes to the start date of intervention, the impact of seasonal variations was minimized to a maximum of 9.5% (SD 7.7%), thus improving the accuracy of the clinical outcomes reported.

CONCLUSIONS

Seasonal variations have a significant effect on the rate of hospital admission and LOS in patients with chronic conditions. However, the impact of seasonal variation on clinical outcomes (rate of admissions, number of hospital admissions, and LOS) of at-home telemonitoring can be attenuated by synchronizing the analysis of outcomes to the commencement dates for the telemonitoring of vital signs.

TRIAL REGISTRATION

Australian New Zealand Clinical Trial Registry ACTRN12613000635763; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=364030&isReview=true (Archived by WebCite at http://www.webcitation.org/ 6xLPv9QDb).

Increased hospitalizations for decompensated heart failure and acute myocardial infarction during mild winters: A seven-year experience in the public health system of the largest city in Latin America

BACKGROUND

In high-income temperate countries, the number of hospitalizations for heart failure (HF) and acute myocardial infarction (AMI) increases during the winter. This finding has not been fully investigated in low- and middle-income countries with tropical and subtropical climates. We investigated the seasonality of hospitalizations for HF and AMI in Sao Paulo (Brazil), the largest city in Latin America.

METHODS

This was a retrospective study using data for 76,474 hospitalizations for HF and 54,561 hospitalizations for AMI obtained from public hospitals, from January 2008 to April 2015. The average number of hospitalizations for HF and AMI per month during winter was compared to each of the other seasons. The autoregressive integrated moving average (ARIMA) model was used to test the association between temperature and hospitalization rates.

FINDINGS

The highest average number of hospital admissions for HF and AMI per month occurred during winter, with an increase of up to 30% for HF and 16% for AMI when compared to summer, the season with lowest figures for both diseases (respectively, HF: 996 vs. 767 per month, p<0.001; and AMI: 678 vs. 586 per month, p<0.001). Monthly average temperatures were moderately lower during winter than other seasons and they were not associated with hospitalizations for HF and AMI.

INTERPRETATION

The winter season was associated with a greater number of hospitalizations for both HF and AMI. This increase was not associated with seasonal oscillations in temperature, which were modest. Our study suggests that the prevention of cardiovascular disease decompensation should be emphasized during winter even in low to middle-income countries with tropical and subtropical climates.

Seasonal variability of NT-proBNP in Swedish primary care patients

The aim of this study was to determine if there is a seasonal variation in the widely used heart failure marker NT-proBNP. The study included all primary care requests for NT-proBNP in the county of Uppsala, Sweden, between January 2007 and December 2015. For seasonal variation, the NT-proBNP results for individual months were compared. The NT-proBNP values were highest in July to September, but there was also a minor peak in December-January. In conclusion, a seasonal periodicity for NT-proBNP was demonstrated in primary care patients. The data could be useful for practitioners for evaluation of NT-proBNP results and monitoring of patients with heart failure.

Effects of climate and fine particulate matter on hospitalizations and deaths for heart failure in elderly: A population-based cohort study

BACKGROUND

There are limited data on the effects of climate and air pollutant exposure on heart failure (HF) within taking into account individual and contextual variables.

OBJECTIVES

We measured the lag effects of temperature, relative humidity, atmospheric pressure and fine particulate matter (PM_2.5) on hospitalizations and deaths for HF in elderly diagnosed with this disease on a 10-year period in the province of Quebec, Canada.

METHODS

Our population-based cohort study included 112,793 elderly diagnosed with HF between 2001 and 2011. Time dependent Cox regression models approximated with pooled logistic regressions were used to evaluate the 3- and 7-day lag effects of daily temperature, relative humidity, atmospheric pressure and PM_2.5 exposure on HF morbidity and mortality controlling for several individual and contextual covariates.

RESULTS

Overall, 18,309 elderly were hospitalized and 4297 died for the main cause of HF. We observed an increased risk of hospitalizations and deaths for HF with a decrease in the average temperature of the 3 and 7days before the event. An increase in atmospheric pressure in the previous 7days was also associated with a higher risk of having a HF negative outcome, but no effect was observed in the 3-day lag model. No association was found with relative humidity and with PM_2.5 regardless of the lag period.

CONCLUSIONS

Lag effects of temperature and other meteorological parameters on HF events were limited but present. Nonetheless, preventive measures should be issued for elderly diagnosed with HF considering the burden and the expensive costs associated with the management of this disease.

Seasonal Periodicity of Ischemic Heart Disease and Heart Failure

Seasonal variation for ischemic heart disease and heart failure is known. The interplay of environmental, biological, and physiologic changes is fascinating. This article highlights the seasonal periodicity of ischemic heart disease and heart failure and examines some of the potential reasons for these unique observations.

Discovery of temporal and disease association patterns in condition-specific hospital utilization rates

Identifying temporal variation in hospitalization rates may provide insights about disease patterns and thereby inform research, policy, and clinical care. However, the majority of medical conditions have not been studied for their potential seasonal variation. The objective of this study was to apply a data-driven approach to characterize temporal variation in condition-specific hospitalizations. Using a dataset of 34 million inpatient discharges gathered from hospitals in New York State from 2008-2011, we grouped all discharges into 263 clinical conditions based on the principal discharge diagnosis using Clinical Classification Software in order to mitigate the limitation that administrative claims data reflect clinical conditions to varying specificity. After applying Seasonal-Trend Decomposition by LOESS, we estimated the periodicity of the seasonal component using spectral analysis and applied harmonic regression to calculate the amplitude and phase of the condition's seasonal utilization pattern. We also introduced four new indices of temporal variation: mean oscillation width, seasonal coefficient, trend coefficient, and linearity of the trend. Finally, K-means clustering was used to group conditions across these four indices to identify common temporal variation patterns. Of all 263 clinical conditions considered, 164 demonstrated statistically significant seasonality. Notably, we identified conditions for which seasonal variation has not been previously described such as ovarian cancer, tuberculosis, and schizophrenia. Clustering analysis yielded three distinct groups of conditions based on multiple measures of seasonal variation. Our study was limited to New York State and results may not directly apply to other regions with distinct climates and health burden. A substantial proportion of medical conditions, larger than previously described, exhibit seasonal variation in hospital utilization. Moreover, the application of clustering tools yields groups of clinically heterogeneous conditions with similar seasonal phenotypes. Further investigation is necessary to uncover common etiologies underlying these shared seasonal phenotypes.

Temporal variation of diabetic ketoacidosis and hypoglycemia in adults with type 1 diabetes: A nationwide cohort study

BACKGROUND

Seasonality in health outcomes has long been recognized for conditions such as colds and flus. The aim of the present study was to determine whether hospitalizations for acute complications of type 1 diabetes (T1D) vary by month and season.

METHODS

An observational study was performed of national administrative health data. Hospitalizations for acute complications in adults (aged ≥18 years) with T1D were identified using ICD-10 (Canadian revision) codes between 2004 and 2010. Monthly and seasonal counts per year were determined for the study period. For each acute complication, the ratio of the number of observed hospitalizations/expected number of hospitalizations was calculated for each month and season per year, adjusting for varied lengths of month, season, and year.

RESULTS

In all, there were 21 568 hospitalizations for diabetic ketoacidosis (DKA) and 5349 hospitalizations for hypoglycemia during the study period. December had higher than expected hospitalizations for DKA and March had higher than expected hospitalizations for hypoglycemia. There did not appear to be variation for either DKA or hypoglycemia hospitalizations by season.

CONCLUSIONS

The results of the present study suggest temporal variation in hospitalizations for DKA and hypoglycemia, and therefore signal important times of patient vulnerability. Potential mechanisms underlying this pattern warrant further examination. Prevention strategies and resources for patients with T1D may need to be increased at specific times during the year.

Relationships of physiologically equivalent temperature and hospital admissions due to I30-I51 other forms of heart disease in Germany in 2009-2011

We aimed to understand relationships of the weather as biometeorological and hospital admissions due to other forms of heart disease by subtypes, which have been paid less attention, in a national setting in recent years. This is an ecological study. Ten percent of daily hospital admissions of the included hospitals (n = 1618) across Germany that were available between 1 January 2009 and 31 December 2011 (n = 5,235,600) were extracted from Statistisches Bundesamt, Germany. We identified I30-I51 other forms of heart disease by the International Classification of Diseases version 10 as the study outcomes. Daily weather data from 64 weather stations that have covered 13 German states, including air temperature, humidity, wind speed, cloud cover, radiation flux and vapour pressure, were obtained and generated into physiologically equivalent temperature (PET). Admissions due to other diseases of pericardium, nonrheumatic mitral valve disorders, nonrheumatic aortic valve disorders, cardiomyopathy, atrioventricular and left bundle-branch block, other conduction disorders, atrial fibrillation and flutter, and other cardiac arrhythmias peaked when PET was between 0 and 10 °C. Complications and ill-defined descriptions of heart disease admissions peaked at PET 0 °C. Cardiac arrest and heart failure admissions peaked when PET was between 0 and -10 °C while the rest did not vary significantly. A common drop of admissions was found when PET was above 10 °C. More medical resources could have been needed for heart health on days when PETs were <10 °C than on other days. Adaptation to such weather change for medical professionals and the general public would seem to be imperative.

Relation of Total and Cardiovascular Death Rates to Climate System, Temperature, Barometric Pressure, and Respiratory Infection

A distinct seasonal pattern in total and cardiovascular death rates has been reported. The factors contributing to this pattern have not been fully explored. Seven locations (average total population 71,354,000) were selected where data were available including relatively warm, cold, and moderate temperatures. Over the period 2004 to 2009, there were 2,526,123 all-cause deaths, 838,264 circulatory deaths, 255,273 coronary heart disease deaths, and 135,801 ST-elevation myocardial infarction (STEMI) deaths. We used time series and multivariate regression modeling to explore the association between death rates and climatic factors (temperature, dew point, precipitation, barometric pressure), influenza levels, air pollution levels, hours of daylight, and day of week. Average seasonal patterns for all-cause and cardiovascular deaths were very similar across the 7 locations despite differences in climate. After adjusting for multiple covariates and potential confounders, there was a 0.49% increase in all-cause death rate for every 1°C decrease. In general, all-cause, circulatory, coronary heart disease and STEMI death rates increased linearly with decreasing temperatures. The temperature effect varied by location, including temperature's linear slope, cubic fit, positional shift on the temperature axis, and the presence of circulatory death increases in locally hot temperatures. The variable effect of temperature by location suggests that people acclimatize to local temperature cycles. All-cause and circulatory death rates also demonstrated sizable associations with influenza levels, dew point temperature, and barometric pressure. A greater understanding of how climate, temperature, and barometric pressure influence cardiovascular responses would enhance our understanding of circulatory and STEMI deaths.

[Do weather and seasons influence our heart?]

There are numerous publications about impact of meteo, seasons and pollution on cardiovascular diseases. Cardiovascular diseases, in particular myocardial infarction and heart failure, have been consistently more frequent during winter in the northern and southern hemisphere. Chronic exposure to air pollution influences the development of atherosclerosis and increases the risk for coronary artery disease. There is a positive association between short-term increase in gaseous components with the risk of hospitalization or death from congestive heart failure. The considerable impact on health care service warrants a comprehensive approach to cardiovascular disease management.

Clinical scenario 1 is associated with winter onset of acute heart failure

BACKGROUND

Several reports have evaluated the association between seasonal variation and acute heart failure (AHF) onset. Cold weather may induce AHF, but the clinical characteristics of patients susceptible to AHF during winter have not been established. Clinical Scenario (CS) is used in the early clinical management of AHF, so we investigated the relationship between CS classification and winter onset of AHF in Japan.

METHODS AND RESULTS

We enrolled 582 patients hospitalized for AHF and compared the frequency of AHF among the 4 seasons in each CS group to clarify the clinical characteristics of the winter onset group. Significant increase of AHF during winter was seen in CS1 (systolic blood pressure [SBP] (>140 mmHg) (P=0.01) but not in CS2 (SBP ≥ 100 and ≤ 140 mmHg) or CS3 (SBP <100 mmHg). CS1 patients were divided into winter and other season admission groups. In multivariate analysis, only lack of loop diuretic use was associated with winter admission of CS1 patients (odds ratio 0.562, 95% confidence interval: 0.256-0.798, P=0.006).

CONCLUSIONS

Winter predominance of AHF was seen only in CS1, and lack of loop diuretic use was a risk factor for winter onset. Future studies are necessary to confirm whether loop diuretics are useful in preventing AHF with CS1 in winter.

Variation of heart transplant rates in the United States during holidays

BACKGROUND

Some cardiac transplant programs may upgrade listed patients to United Network for Organ Sharing (UNOS) 1A-status during the holidays. Whether more transplants actually occur during holidays is unknown.

METHODS

We assessed rates of single-organ heart transplantation from 2001 to 2010 for recipients age ≥18 yr using the UNOS database. Patients were stratified by transplantation during holiday (±3 d, n = 2375) and non-holiday periods (n = 16 112). Holidays included Easter/Spring break, Memorial Day, July 4th, Labor Day, Thanksgiving, and Christmas/New Years (winter holidays). Secondary analysis assessing transplant rates across seasons was also completed.

RESULTS

Donor and recipient characteristics were similar between groups. Compared with non-holidays, July 4th had higher transplant rates (5.69 vs. 5.09 transplants/d, p = 0.03) while the winter holiday had lower transplant rates (4.50 vs. 5.09 transplants/d, p < 0.01). There was a trend toward lower transplant rates for all holidays compared with non-holidays (p = 0.06). Transplant rates were significantly different across seasons with greater rates in spring and summer (p < 0.01).

CONCLUSION

Heart transplant rates were higher during the July 4th and lower during the winter holidays. Although there was a higher likelihood of transplantation during the spring and summer seasons, upgrading patients to 1A status during most holidays may not improve their chances for transplantation.

Cardiac repolarization and autonomic regulation during short-term cold exposure in hypertensive men: an experimental study

OBJECTIVES

The aim of our study was to assess the effect of short-term cold exposure, typical in subarctic climate, on cardiac electrical function among untreated middle-aged hypertensive men.

METHODS

We conducted a population-based recruitment of 51 hypertensive men and a control group of 32 men without hypertension (age 55-65 years) who underwent whole-body cold exposure (15 min exposure to temperature -10°C, wind 3 m/s, winter clothes). Conduction times and amplitudes, vectorcardiography, arrhythmias, and heart rate variability (autonomic nervous function) were assessed.

RESULTS

Short-term cold exposure increased T-peak to T-end interval from 67 to 72 ms (p<0.001) and 71 to 75 ms (p<0.001) and T-wave amplitude from 0.12 to 0.14 mV (p<0.001) and from 0.17 to 0.21 mV (p<0.001), while QTc interval was shortened from 408 to 398 ms (p<0.001) and from 410 to 401 ms (p<0.001) among hypertensive men and controls, respectively. Cold exposure increased both low (from 390 to 630 ms2 (p<0.001) and 380 to 700 ms2 (p<0.001), respectively) and high frequency heart rate variability (from 90 to 190 ms2 (p<0.001) and 150 to 300 ms2 (p<0.001), respectively), while low-to-high frequency-ratio was reduced. In addition, the frequency of ventricular ectopic beats increased slightly during cold exposure. The cold induced changes were similar between untreated hypertensive men and controls.

CONCLUSIONS

Short-term cold exposure with moderate facial and mild whole body cooling resulted in prolongation of T-peak to T-end interval and higher T-wave amplitude while QTc interval was shortened. These changes of ventricular repolarization may have resulted from altered cardiac autonomic regulation and were unaffected by untreated hypertension.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02007031.

Effect of seasonal variation on hospital admission due to cardiovascular disease - findings from an observational study in a divisional hospital in Bangladesh

BACKGROUND

Seasonal variation in the hospital admission due to cardiovascular disease (CVDs) has been widely reported. However, very limited data on Bangladesh is available regarding this matter. The aim of the current study was to investigate the effect of seasonal variation on hospital admission due to CVDs in a leading hospital of Bangladesh.

METHODS

Over a period of two years (from May 2010 to April 2012), the number of patients hospitalized due to various CVDs and number of death among these hospitalized patients were recorded on a day-to-day basis. The data were recorded according to the chief reason of hospital admission such as myocardial infarction or MI (acute, old and non-ST elevation), unstable angina (UA), exaggeration of stable angina, acute left ventricular failure (LVF), cardiomyopathy (ischemic and dilated) or heart failure, syncope and arrhythmia. The data were cumulated and analyzed on month-wise and season-wise manner.

RESULTS

A total of 8371 patients were admitted over the study period (5909 male and 2462 female; M/F ratio - 2.4:1). The highest number of patients were admitted during winter (n = 2839, 33.9%) and lowest during summer (n = 1648, 19.7%). The hospital admission was also significantly higher in winter compared to other seasons (p-value versus summer, autumn and spring was 0.018, 0.020 and 0.023 respectively). Acute MI (n = 2374), Acute LVF (n = 1582) and UA (n = 1277) were the top three reasons for hospitalization. Number of death also significantly higher in winter compared to other seasons (p-value versus summer, winter and spring was 0.044, 0.050 and 0.014 respectively).

CONCLUSION

A seasonal variation in the hospital admission due to CVDs with a peak in winter was clearly demonstrated in the study. These data could be useful to improve causative prevention measures, therapeutic management, and educational strategies.

Data-driven discovery of seasonally linked diseases from an Electronic Health Records system

BACKGROUND

Patterns of disease incidence can identify new risk factors for the disease or provide insight into the etiology. For example, allergies and infectious diseases have been shown to follow periodic temporal patterns due to seasonal changes in environmental or infectious agents. Previous work searching for seasonal or other temporal patterns in disease diagnosis rates has been limited both in the scope of the diseases examined and in the ability to distinguish unexpected seasonal patterns. Electronic Health Records (EHR) compile extensive longitudinal clinical information, constituting a unique source for discovery of trends in occurrence of disease. However, the data suffer from inherent biases that preclude an identification of temporal trends.

METHODS

Motivated by observation of the biases in this data source, we developed a method (Lomb-Scargle periodograms in detrended data, LSP-detrend) to find periodic patterns by adjusting the temporal information for broad trends in incidence, as well as seasonal changes in total hospitalizations. LSP-detrend can sensitively uncover periodic temporal patterns in the corrected data and identify the significance of the trend. We apply LSP-detrend to a compilation of records from 1.5 million patients encoded by ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification), including 2,805 disorders with more than 500 occurrences across a 12 year period, recorded from 1.5 million patients.

RESULTS AND CONCLUSIONS

Although EHR data, and ICD-9 coded records in particular, were not created with the intention of aggregated use for research, these data can in fact be mined for periodic patterns in incidence of disease, if confounders are properly removed. Of all diagnoses, around 10% are identified as seasonal by LSP-detrend, including many known phenomena. We robustly reproduce previous findings, even for relatively rare diseases. For instance, Kawasaki disease, a rare childhood disease that has been associated with weather patterns, is detected as strongly linked with winter months. Among the novel results, we find a bi-annual increase in exacerbations of myasthenia gravis, a potentially life threatening complication of an autoimmune disease. We dissect the causes of this seasonal incidence and propose that factors predisposing patients to this event vary through the year.

Structured approach in improving weekend handovers in a medical high dependency unit

Weekend admissions to hospital have been associated with adverse patient outcomes, including higher morbidity and mortality risk in general medicine and surgery. The reasons behind this are likely to be multifactorial and include reduced senior clinician-led care, decreased overall workforce, and ineffective or incomplete handover. With the advent of shift-work patterns, robust handover between medical teams is of paramount importance, particularly before weekends. This has been reflected in recent publications by Royal College of Physicians (acute care toolkit 1: handover, May 2011), that identified handover as an error-prone process and issued guidelines designed to optimise its effectiveness.

The aim of this project was to evaluate weekend patient mortality and success of handover on the medical high dependency unit of a large teaching hospital in the United Kingdom, before and after introduction of a structured handover tool on Friday afternoons during May 2013. This unit is registrar-led at weekends. Weekend mortality decreased from 43% in March 2013 to 22% in May 2013 (odds ratio 0.37, 95% CI 0.19–0.68, p=0.07). Documentation of resuscitation status and escalation plans increased from 75% in March 2013 to 93% in May 2013. There was universal positive feedback from registrars involved with the handover tool, who provided senior cover during the weekends in May 2013. It is hoped that structured, written handover will ultimately become commonplace in this unit and will improve patient safety at weekends.

Association of low body temperature and poor outcomes in patients admitted with worsening heart failure: a substudy of the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study with Tolvaptan (EVEREST) trial

AIMS

Risk stratification in patients admitted with worsening heart failure (HF) is essential for tailoring therapy and counselling. Risk models are available but rarely used, in part because many require laboratory and imaging results that are not routinely available. Body temperature is associated with prognosis in other illnesses, and we hypothesized that low body temperature would be associated with worse outcomes in patients admitted with worsening HF.

METHODS AND RESULTS

The Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study with Tolvaptan (EVEREST) trial was an event-driven, randomized, double-blind, placebo-controlled study of tolvaptan in 4133 patients hospitalized for worsening HF with an EF <40%. Co-primary endpoints were all-cause mortality and cardiovascular (CV) death or HF rehospitalization. Body temperature was measured orally at randomization and entered in analyses both as a continuous variable and categorized into three groups (<36 °C, 36-36.5 °C, and >36.5 °C) using Cox regression models. The composite of CV death or HF rehospitalization occurred in 1544 patients within 1 year. For every 1 °C decrease in body temperature, the risk of adverse outcomes increased by 16% [hazard raio (HR) 1.16, 95% confidence interval (CI) 1.04-1.28], after adjustment for age, gender, race, systolic blood pressure, EF, blood urea nitrogen, and serum sodium. In fully adjusted analysis, the risk of adverse outcomes in the lowest body temperature group (<36 °C) was 51% higher than that of the index group (>36.5 °C) (HR 1.35, 95% CI 1.15-1.58).

CONCLUSIONS

Low body temperature is an independent marker of poor cardiovascular outcomes in patients admitted with worsening HF and reduced EF.

Cold-related cardiorespiratory symptoms among subjects with and without hypertension: the National FINRISK Study 2002

BACKGROUND

Exposure to cold weather increases blood pressure (BP) and may aggravate the symptoms and influence the prognosis of subjects with a diagnosis of hypertension. We tested the hypothesis that subjects with hypertension alone or in combination with another cardiovascular disease (CVD) experience cold-related cardiorespiratory symptoms more commonly than persons without hypertension. This information is relevant for proper treatment and could serve as an indicator for predicting wintertime morbidity and mortality.

METHODS

A self-administered questionnaire inquiring of cold-related symptoms was obtained from 6591 men and women aged 25-74 yrs of the FINRISK Study 2002 population. BP was measured in association with clinical examinations. Symptom prevalence was compared between subjects with diagnosed hypertensive disease with (n = 395) or without (n = 764) another CVD, untreated diagnosed hypertension (n = 1308), measured high BP (n = 1070) and a reference group (n = 2728) with normal BP.

RESULTS

Hypertension in combination with another CVD was associated with increased cold-related dyspnoea (men: adjusted odds ratio 3.94, 95% confidence interval 2.57-6.02)/women: 4.41, 2.84-6.86), cough (2.64, 1.62-4.32/4.26, 2.60-6.99), wheezing (2.51, 1.42-4.43/;3.73, 2.08-6.69), mucus excretion (1.90, 1.24-2.91/2.53, 1.54-4.16), chest pain (22.5, 9.81-51.7/17.7, 8.37-37.5) and arrhythmias (43.4, 8.91-211/8.99, 3.99-20.2), compared with the reference group. Both diagnosed treated hypertension and untreated hypertension and measured high BP resulted in increased cardiorespiratory symptoms during the cold season.

CONCLUSION

Hypertension alone and together with another CVD is strongly associated with cold-related cardiorespiratory symptoms. As these symptoms may predict adverse health events, hypertensive patients need customized care and advice on how to cope with cold weather.

Winter cardiovascular diseases phenomenon

This paper review seasonal patterns across twelve cardiovascular diseases: Deep venous thrombosis, pulmonary embolism, aortic dissection and rupture, stroke, intracerebral hemorrhage, hypertension, heart failure, angina pectoris, myocardial infarction, sudden cardiac death, venricular arrythmia and atrial fibrillation, and discuss a possible cause of the occurrence of these diseases. There is a clear seasonal trend of cardiovascular diseases, with the highest incidence occurring during the colder winter months, which have been described in many countries. This phenomenon likely contributes to the numbers of deaths occurring in winter. The implications of this finding are important for testing the relative importance of the proposed mechanisms. Understanding the influence of season and other factors is essential when seeking to implement effective public health measures.

Seasonal variation in the occurrence of delirium in patients admitted to medical units of a general hospital in Italy

OBJECTIVE

Delirium syndrome is common in the hospitalised population. However, data on its aetiological factors are scarce. Clinical observations suggest a relationship between delirium occurrence and seasons. The aim of study was to determine whether a seasonal variation exists in the occurrence of delirium events in-hospital patients.

METHODS

The study included all admissions to the medical units of the Hospital of Ferrara, Italy, between January 2002 and December 2010. On the basis of date admission, cases have been analysed for seasonal variation (four 3-month intervals by seasons) by means of conventional statistics. Moreover, cases categorised into twelve 1-month intervals were also analysed by means of a validated chronobiologic inferential method (single cosinor) to search for cyclic variability.

RESULTS

During the analysed period, the hospital database contained 74 379 records referring to 42 625 subjects (52.7% females). Delirium diagnoses were 1300 (1.7% of total sample), 668 of whom in females (51.4%) and 632 in males (48.6%). Events of delirium were more frequent in winter and autumn (26.6 and 26.5%, respectively) than in spring (23.5%) and summer (23.4%). Chronobiological analysis yielded a significant peak of delirium events in January, when considering both the total raw number of cases and the percent of admissions.

CONCLUSIONS

The study seems to indicate in patients hospitalised in medical units, a higher rate of occurrence of delirium in autumn-winter, similar to that reported for acute medical diseases. The role of possible underlying favouring or triggering factors deserves further research.

The seasonal variation in hospitalizations due to chronic systolic heart failure correlates with blood sodium levels and cardiac function

BACKGROUND

Although seasonal variation in hospitalizations due to chronic heart failure is recognized, the possible contributors to such variability are less well documented.

METHODS

Records from all admissions to 12 hospitals in Hubei province, China, over a 10-year period with diagnostic codes for chronic systolic heart failure (CSHF) were reviewed. A total of 16,145 patients with CSHF were analyzed.

RESULTS

There was a marked seasonal variation in the number of hospitalizations due to CSHF, with two peaks in the monthly rate of hospitalization due to CSHF occurring in December and August compared with the spring and autumn months. Monthly hospitalizations due to CSHF for patients with New York Heart Association class III and IV ranged from a peak of 40.4% and 23.3% above average in December and August, respectively, to 18.6% below average in November, while hospitalizations due to CSHF for patients with New York Heart Association class I and II exhibited no obvious seasonal variation. Blood sodium level (95% CI 2.132 to 2.144; P=0.036) was an independent risk factor for hospitalizations due to CSHF in August.

CONCLUSION

The number of hospitalizations due to CSHF increased during the colder and warmer months in China. A low blood sodium level was associated with the peak in hospitalizations in August.

Chronobiological variation in the occurrence of Tako-tsubo cardiomyopathy: experiences of two tertiary cardiovascular centers

BACKGROUND

There have been few data to review and analyze the temporal preference of the onset of Tako-tsubo cardiomyopathy (TTC). Aim of this study was to investigate chronobiological variations in the occurrence of TTC and changes of these variations according to age and gender.

METHODS

One hundred and thirty-seven patients were enrolled from our TTC registry database from January 2004 to December 2010 in Korea.

RESULTS

The median age of the entire study population was 59 years (inter-quartile range 53-72 years). The majority of patients were women (n = 101, 74%). The onset of TTC differed as a function of season (P = .001), with the peak in July and the nadir in March. Events were most frequent in summer (n = 53%, 38.7%) and least so in winter (n = 26, 19%, chi-square = 13.92, P = .003). TTC was most frequent in the morning (n = 56, 40.9%) and least so at night (n = 22, 16.1%, chi-square = 21.98, P = .001). Also, TTC was most frequent on Monday (n = 34, 24.8%) and least so on Saturday (n = 7, 5.1%, chi-square = 30.44, P = .001). Stressor pattern, age and gender do not influence these increases of occurrence in summer, on Monday, and in the morning of TTC.

CONCLUSIONS

TTC seems to exhibit a temporal variation of occurrence with preferred peaks during morning, Monday, and summer. Stressor pattern, age and gender do not influence these temporal patterns of the occurrence of TTC. Further studies are needed to investigate the potential link between chronobiological variations of TTC onset and underlying pathophysiologic mechanisms.

Seasonality, incidence and prognosis in atrial fibrillation and stroke in Denmark and New Zealand

OBJECTIVES

There are relatively few large studies of seasonal variation in the occurrence of stroke in patients with atrial fibrillation (AF). We investigated the seasonal variation in incidence rates of hospitalisation with stroke in patients from Denmark and New Zealand.

DESIGN

Cohort study.

SETTING

Nationwide hospital discharge data from Denmark and New Zealand.

PARTICIPANTS

243 381 (median age 75) subjects having a first-time hospitalisation with AF in Denmark and 51 480 (median age 76) subjects in New Zealand constituted the study population. Subjects with previous hospitalisation with stroke were excluded. PRIMARY AND SECONDARY EFFECT MEASURES: Peak-to-trough ratio of the seasonal variation in incidence rates of stroke in AF patients adjusted for an overall trend was primary effect measure and was assessed using a log-linear Poisson regression model. Secondary effect measures were incidence rate ratios of AF and 30-day case fatality for stroke patients.

RESULTS

Incidence rates of AF per 1000 person-years in Denmark increased by 5.4% (95% CI 5.3% to 5.7%) for patients aged <65 and 5% (95% CI 4.9% to 5.1%) for patients aged ≥65, whereas the increase was 0.2% (95% CI -0.2% to 0.6%) for patients aged <65 and 2.6% (95% CI 2.4% to 2.8%) for patients aged ≥65 in New Zealand. In Denmark 36 088 subjects were hospitalised with stroke, and 7518 subjects in New Zealand, both showing peaks during winter with peak-to-trough ratios of 1.22 and 1.27, respectively and a decreasing trend. The 30-day case fatality risk for stroke patients having AF is now (2000-2008) about 20% in both countries.

CONCLUSIONS

Although incidence rates of hospitalisation with stroke in patients with AF have decreased in recent years, stroke remains a common AF complication with a high case fatality risk. The marked winter peak in incidence rates of hospitalisation with stroke in AF patients suggests that there are opportunities to reduce this complication. Further studies are necessary to identify how to optimise treatment of AF and prevention of stroke.