Seasonal changes in blood pressure in patients with end-stage renal disease treated with hemodialysis

Impact of barometric pressure on blood pressure during dialysis: Introducing intradialytic time-averaged cumulative systolic blood pressure (TACsBP-inD) as a new metric

BACKGROUND

Blood pressure is a crucial risk factor for hemodialysis patients, but the specific impact of weather factors, particularly barometric pressure, on blood pressure remains unclear. This study aims to examine the relationship between barometric pressure and blood pressure in hemodialysis patients.

METHODS

We conducted a single-center, retrospective study involving 122 hemodialysis patients in Japan, covering the period from August 2018 to October 2022. In addition to standard blood pressure indices, for the purpose of a more accurate assessment, we introduced the intradialytic time-averaged cumulative systolic blood pressure (TACsBP-inD). Multilevel mixed-effects linear regression models with random intercepts for each patient and spline analyses were used to evaluate the association between barometric pressure and blood pressure.

RESULTS

Our analysis demonstrated a positive correlation between barometric pressure and various intradialytic blood pressure indices, including TACsBP-inD, in both univariate and multivariate models. Spline analyses revealed a U-shaped relationship between barometric pressure and TACsBP-inD. Furthermore, categorized barometric pressure showed significantly positive coefficients for TACsBP-inD at both lower and higher pressure ranges, supporting the U-shaped trend. Subgroup analyses revealed that this positive association was not observed at lower pressures among males, obese individuals, and patients with diabetes, cardiovascular disease, and smoking habits, suggesting that blood pressure responses vary depending on patient profiles.

CONCLUSIONS

These findings emphasize the significant impact of barometric pressure on intradialytic blood pressure, suggesting that atmospheric conditions could be an important consideration in blood pressure management for hemodialysis patients.

The influence of synoptic conditions on interdiurnal atmospheric pressure changes in Poland

The aim of the presented study was to characterize the territory of Poland in terms of the frequency of occurrence of specific values of IAPC (interdiurnal atmospheric pressure changes) and to determine synoptic situations accompanying their particularly high values. The study is based on the daily mean atmospheric pressure data from the years 1966-2022 taking from 48 meteorological stations in Poland. In the presented paper four IAPC categories were used: A < 4.0 hPa (weak sense of change), B 4.1-8.0 (moderate sense of change), C 8.1-12.0 (strong sense of change), and D > 12.1 (very strong sense of change). Taking into account the negative impact on human health and well-being of the IAPC value, and especially its declines (conductive to the increase of suicides, heart and kidney diseases, asthma), the most unfavorable in this respect in Poland is the northern part of the country. The greatest frequency of synoptic situations causing the above-mentioned influence occurs in the cold half of the year, especially in winter. In turn the beneficial impact of the increase in IAPC on human health and well-being in terms of blood oxygenation and reduced suicide mortality caused by IAPC also occurs in the northern Poland. The frequency of synoptic situations felt in this respect is also highest in the cold half of the year.

The Modern Environment: The New Secondary Cause of Hypertension?

The most important risk factor for cardiovascular disease, the leading cause of death worldwide, is hypertension. Although most cases of hypertension are thought to be essential, the multifactorial associations of the environmental influence on blood pressure seem to play an important role and should be more closely investigated. This review attempts to focus on the recent literature that examines the environmental effects on arterial blood pressure and its management. Seasonal variability and the role of ambient temperature, either occupational or recreational noise pollution, as well as obesity due to environment-caused dietary habits, are recognized as important risk factors, affecting the onset as well as the regulation of hypertension. Furthermore, the effects of seasonal fluctuations in blood pressure, noise pollution, and obesity seem to share a similar pathogenesis, and as such to all further react together, leading to increased blood pressure. The activation of the autonomous nervous system plays a key role and causes an increase in stress hormones that generates oxidative stress on the vascular system and, thus, vasoconstriction. In this review, by focusing on the association of the environmental impact with arterial blood pressure, we come to the question of whether most cases of hypertension-if not all-should, indeed, be considered primary or secondary.

Seasonal variation in predialysis systolic blood pressure and cardiovascular events in patients on maintenance hemodialysis

Predialysis systolic blood pressure (SBP) in patients on hemodialysis (HD) consistently followed a seasonal pattern, reaching a peak in winter and nadir in summer, similar to blood pressure in the general population. However, the relationship between seasonal variations in predialysis SBP and clinical outcomes is still under-investigated in Japanese patients on HD. This retrospective cohort study included 307 Japanese patients undergoing HD for >1 year in three dialysis clinics and evaluated the association between the standard deviation (SD) of predialysis SBP and clinical outcomes, including major adverse cardiovascular events (MACEs; cardiovascular death, nonfatal myocardial infarction or unstable angina, stroke, heart failure, and other severe cardiovascular events requiring hospitalization) with 2.5 years follow-up. The SD of predialysis SBP was 8.2 (6.4-10.9) mmHg. In the model fully adjusted for the SD of predialysis SBP, predialysis SBP, age, sex, HD vintage, Charlson comorbidity index, ultrafiltration rate, renin-angiotensin system inhibitors, corrected calcium, phosphorus, human atrial natriuretic peptide, C-reactive protein, albumin, hemoglobin, body mass index, normalized protein catabolism rate, and intradialytic SBP decline, Cox regression analyses showed that a higher SD of predialysis SBP (per 10 mmHg) was significantly associated with increased MACE risk (hazard ratio [HR], 1.89; 95% confidence interval [95% CI], 1.07-3.36) and all-cause hospitalization (HR, 1.57; 95% CI, 1.07-2.30). Therefore, greater seasonal variations in predialysis SBP were associated with worse clinical outcomes, including MACEs and all-cause hospitalization. Whether interventions to reduce seasonal variations in predialysis SBP will improve the prognosis of Japanese patients on HD must be investigated further.

Mean annual intradialytic blood pressure decline and cardiovascular events in Japanese patients on maintenance hemodialysis

An intradialytic systolic blood pressure (SBP) decline, which defines intradialytic hypotension, may be associated with higher all-cause mortality. However, in Japanese patients on hemodialysis (HD), the association between intradialytic SBP decline and patient outcomes is unclear. This retrospective cohort study included 307 Japanese patients undergoing HD over 1 year in three dialysis clinics and evaluated the association between the mean annual intradialytic SBP decline (predialysis SBP-nadir intradialytic SBP) and clinical outcomes, including major adverse cardiovascular events (MACEs; cardiovascular death, nonfatal myocardial infarction or unstable angina, stroke, heart failure, and other severe cardiovascular events requiring hospitalization) by following up for 2 years. The mean annual intradialytic SBP decline was 24.2 (25-75th percentile, 18.3-35.0) mmHg. In the model fully adjusted for intradialytic SBP decline tertile group (T1, <20.4 mmHg; T2, 20.4 to <29.9 mmHg; T3, ≥29.9 mmHg), predialysis SBP, age, sex, HD vintage, Charlson comorbidity index, ultrafiltration rate, use of renin-angiotensin system inhibitors, corrected calcium, phosphorus, human atrial natriuretic peptide, geriatric nutritional risk index, normalized protein catabolism rate, C-reactive protein, hemoglobin, and use of pressor agents, Cox regression analyses showed that the hazard ratio (HR) was significantly higher for T3 than for T1 for MACEs (HR, 2.38; 95% confidence interval 1.12-5.09) and all-cause hospitalization (HR, 1.68; 95% confidence interval 1.03-2.74). Therefore, in Japanese patients on HD, a greater intradialytic SBP decline was associated with worse clinical outcomes. Further studies are warranted to investigate whether interventions to attenuate the intradialytic SBP decline will improve the prognosis of Japanese patients on HD.

Intercorrelated variability in blood and hemodynamic biomarkers reveals physiological network in hemodialysis patients

Increased intra-individual variability of a variety of biomarkers is generally associated with poor health and reflects physiological dysregulation. Correlations among these biomarker variabilities should then represent interactions among heterogeneous biomarker regulatory systems. Herein, in an attempt to elucidate the network structure of physiological systems, we probed the inter-variability correlations of 22 biomarkers. Time series data on 19 blood-based and 3 hemodynamic biomarkers were collected over a one-year period for 334 hemodialysis patients, and their variabilities were evaluated by coefficients of variation. The network diagram exhibited six clusters in the physiological systems, corresponding to the regulatory domains for metabolism, inflammation, circulation, liver, salt, and protein. These domains were captured as latent factors in exploratory and confirmatory factor analyses (CFA). The 6-factor CFA model indicates that dysregulation in each of the domains manifests itself as increased variability in a specific set of biomarkers. Comparison of a diabetic and non-diabetic group within the cohort by multi-group CFA revealed that the diabetic cohort showed reduced capacities in the metabolism and salt domains and higher variabilities of the biomarkers belonging to these domains. The variability-based network analysis visualizes the concept of homeostasis and could be a valuable tool for exploring both healthy and pathological conditions.

Risk Factors and Outcomes of Extended Length of Stay in Older Adults with Intertrochanteric Fracture Surgery: A Retrospective Cohort Study of 2132 Patients

We aimed to identify the risk factors associated with an extended length of hospital stay (eLOS) in older hip-fracture patients and to explore the relationships between eLOS and mortality and functional outcomes. In this retrospective analysis of surgically treated intertrochanteric fracture (IF) patients, all variables were obtained and compared between the eLOS group and the normal LOS group. All participants were followed-up for a minimum of two years and the relation between the eLOS and all-cause mortality and functional outcomes were compared. After adjustment for potential confounders, we identified that patients with high modified Elixhauser's Comorbidity Measure (mECM) had the highest likelihood of eLOS, followed by obesity, admission in winter, living in urban, pulmonary complications, admission in autumn, and time from injury to surgery. In addition, our results showed no significant difference in the mortality and functional outcomes between the two groups during follow-up. By identifying these risk factors in the Chinese geriatric population, it may be possible to risk-stratify IF patients and subsequently streamline inpatient resource utilization. However, the differences between health care systems must be taken into consideration. Future studies are needed to preemptively target the modifiable risk factors to demonstrate benefits in diminishing eLOS.

Universal Climate Thermal Index as a prognostic tool in medical science in the context of climate change: A systematic review

The assessment of the impact of meteorological factors on the epidemiology of various diseases and on human pathophysiology and physiology requires a comprehensive approach and new tools independent of currently occurring climate change. The thermal comfort index, i.e., Universal Climate Thermal Index (UTCI), is gaining more and more recognition from researchers interested in such assessments. This index facilitates the evaluation of the impact of cold stress and heat stress on the human organism and the assessment of the incidence of weather-related diseases. This work aims at identifying those areas of medical science for which the UTCI was applied for scientific research as well as its popularization among clinicians, epidemiologists, and specialists in public health management. This is a systematic review of literature found in Pubmed, Sciencedirect and Web of Science databases from which, consistent with PRISMA guidelines, original papers employing the UTCI in studies related to health, physiological parameters, and epidemiologic applications were extracted. Out of the total number of 367 papers identified in the databases, 33 original works were included in the analysis. The selected publications were analyzed in terms of determining the areas of medical science in which the UTCI was applied. The majority of studies were devoted to the broadly understood mortality, cardiac events, and emergency medicine. A significant disproportion between publications discussing heat stress and those utilizing the UTCI for its assessment was revealed.

Seasonal Variation: A Non-negligible Factor Associated With Blood Pressure in Patients Undergoing Hemodialysis

Objective

To investigate a seasonal variation in blood pressure (BP) for patients undergoing hemodialysis (HD).

Methods

In this retrospective study, we exported all BP measurements from the information system to investigate a seasonal variation of BP. We also investigated a seasonal variation in BP for patients of different gender types, of different age groups, with diabetic nephropathy (DN), and with non-DN having HD. Multiple linear regression models were used to explore the associations between BP and climatic parameters.

Results

In 2019, a total of 367 patients had received HD therapy in the Longwen HD unit. We included nearly 40,000 pre-dialysis BP measurements. The result of our study demonstrated a clear seasonal variation in pre-dialysis BP in general patients with HD, in male and female patients, and patients with DN and non-DN. December seemed to be a peak in the values of pre-dialysis systolic BP (SBP) and diastolic BP (DBP). The nadir values of pre-dialysis SBP and DBP were observed in June and July, respectively. A difference between peak and nadir values of BP is 3.81/2.20 mmHg in patients undergoing HD. Maximal seasonal variation in BP is 9.03/5.08 mmHg for patients with DN. A significant association of SBP and DBP with climatic parameters was found in this study. Pre-dialysis BP was inversely correlated with outdoor temperature, daytime length, and relative humidity.

Conclusion

A clear seasonal variation in BP is observed for patients with HD. Pre-dialysis SBP and DBP are inversely associated with outdoor temperature, daytime length, and relative humidity. The magnitude of a seasonal variation in BP increases in patients with DN.

Monthly trends and seasonality of hemodialysis treatment and outcomes of newly initiated patients from the national database (NDB) of Japan

BACKGROUND

The numbers of patients treated with hemodialysis (HD) in Japan are currently quantified by manual survey. As this method requires much effort from medical institutions and cannot achieve 100% response, a more practical method is required. We aimed to establish a novel method for determining the static and dynamic numbers of patients treated with HD.

METHODS

This observational study used the national medical billing database (termed NDB) of Japan, based on the records of the universal healthcare insurance system. Medical billing data registered in the NDB between April 2011 and March 2015 were analyzed. From 130 billion records, we extracted and analyzed records of patients who had undergone HD at least once per month. Patients' monthly condition was classified as newly initiated HD, chronic HD, or presumed death, using conditional expressions. We also investigated renal outcome and presumed survival in newly initiated HD patients.

RESULTS

In the last month of the study period, 274,100 patients were identified as receiving chronic HD, which is estimated as > 95% of the number of these patients identified in the manual survey so far. The monthly data showed clear seasonality in the incidence of transient HD, which increased in winter and decreased in summer.

CONCLUSION

Analysis of a large national database revealed a significant increase in transient HD in winter and decrease in summer. Applied to additional epidemiological exploratory studies or clinical research, this analytical technique would enable collection of the dynamics of almost all HD patients nationwide.

Seasonal variation and predictors of intradialytic blood pressure decline: a retrospective cohort study

The risk factors for intradialytic systolic blood pressure decline remain poorly understood. We aimed to identify clinical and laboratory predictors of the intradialytic systolic blood pressure decline, considering its seasonal variation. In a retrospective cohort of 47,219 hemodialysis sessions of 307 patients undergoing hemodialysis over one year in three dialysis clinics, the seasonal variation and the predictors of intradialytic systolic blood pressure decline (predialysis systolic blood pressure--nadir intradialytic systolic blood pressure) were assessed using cosinor analysis and linear mixed models adjusted for baseline or monthly hemodialysis-related variables, respectively. The intradialytic systolic blood pressure decline was greatest and least in the winter and summer, respectively, showing a clear seasonal pattern. In both models adjusted for baseline and monthly hemodialysis-related parameters, calcium channel blocker use was associated with a smaller decline (-4.58 [95% confidence interval (CI), -5.84 to -3.33], P < 0.001; -3.66 [95% CI, -5.69 to -1.64], P < 0.001) and α blocker use, with a greater decline (3.25 [95% CI, 1.53-4.97], P < 0.001; 3.57 [95% CI, 1.08-6.06], P = 0.005). Baseline and monthly serum phosphorus levels were positively correlated with the decline (1.55 [95% CI, 0.30-2.80], P = 0.02; 0.59 [95% CI, 0.16-1.00], P = 0.007), and baseline and monthly normalized protein catabolic rates were inversely correlated (respectively, -22.41 [95% CI, -33.53 to -11.28], P < 0.001; 9.65 [95% CI, 4.60-14.70], P < 0.001). In conclusion, calcium channel blocker use, α blocker avoidance, and serum phosphorus-lowering therapy may attenuate the intradialytic systolic blood pressure decline and should be investigated in prospective trials.

The effect of ambient temperature on blood pressure of patients undergoing hemodialysis in the Pantanal-Brazil

The objective was to analyze the association of changes in pre-dialysis systolic and diastolic blood pressure with air temperature in a municipality in the Brazilian Pantanal, a tropical climate area. Longitudinal panel study, with analysis of mixed effects models of 133 hemodialysis patients in the city of Cáceres-Mato Grosso in 2014. Air temperature showed an inverse association with pre-dialysis systolic and diastolic blood pressure. With each increase of 1 °C in the mean air temperature, the pre-dialysis systolic blood pressure decreases -0.730mmHg (p ≤ 0.000) and the pre-dialysis diastolic blood pressure decreases -0.280mmHg (p ≤ 0.000). The estimated effect was greater for systolic blood pressure, but both pre-dialysis blood pressure measures are reduced with an increase in lag (up to two days), even when adjusted for relative air humidity. Air temperature is determinant for changes in pre-dialysis systolic and diastolic blood pressure in hemodialysis patients. The temperature effect was greater for systolic blood pressure than for diastolic blood pressure.

Usefulness of ABPM and bioimpedance for the treatment and control of hypertension in patients on chronic haemodialysis

INTRODUCTION

Hypertension is very common in haemodialysis (HD) patients, and is associated with increased morbidity and mortality rates. The goals of our research were to: 1. Measure blood pressure (BP) during HD sessions; 2. Study BP in between HD sessions with 44-h Ambulatory Blood Pressure Monitoring (ABPM); 3. Evaluate changes in treatment after the ABPM; 4. Perform bioimpedance spectroscopy (BIS) on all patients and, in those hyper-hydrated or hypertensive according to ABPM, assess for changes in BP after adjusting the dry weight; 5. Identify factors associated with average systolic and diastolic BP measured by ABPM.

MATERIAL AND METHODS

Prospective observational study, which included 100 patients from our dialysis unit. We measured BP before and after the HD sessions for two weeks and then, mid-week, we attached the ABPM device to the patients for 44 h. Before starting the following dialysis session, we performed BIS. A second ABPM was performed on hyper-hydrated patients and patients hypertensive according to ABPM to evaluate changes in BP values.

RESULTS

According to the ABPM, 65% of patients had daytime BP > 135/85 mmHg, 90% night-time BP > 120/70 mmHg and 76% average BP > 130/80 mmHg; 11% had a dipper pattern, 51% non-dipper and 38% riser. The average systolic and diastolic BP readings were 4.7 mmHg (3.8%) and 1.1 mmHg (1.64%) higher on the second day. The dose of antihypertensive medication had to be lowered in 6% of patients, 9% had to stop taking it, 28% needed increased doses and 17% had to add a new drug. The pre-HD diastolic BP best matched the ABPM. After performing the bioimpedance and adjusting dry weight, there was a statistically significant decrease in all BP values. The univariate analysis showed that the average systolic BP was higher in patients with a high-calcium dialysis bath, more antihypertensive drugs and higher doses of EPO. The multivariate analysis showed significant association for EPO and number of drugs (p < 0.01). The average diastolic BP was higher in younger patients and patients with lower Charlson index, lower body mass index and less diuresis, those on higher doses of EPO and non-diabetics. The linear regression study showed age (p < 0.005), body mass index (p < 0.03) and EPO (p < 0.03) as significant variables.

CONCLUSIONS

Our study shows: 1. The variability of hypertension criteria according to use of BP values from during the HD session or ABPM; 2. The variability of BP in the interdialysis period; 3. That the pre-dialysis diastolic BP best corresponds with the ABPM. 4. That the use of both BIS and ABPM improves the control of BP; 5. That the dose of EPO is the most important factor associated with hypertension in our patients.

Usefulness of ABPM and bioimpedance for the treatment and control of hypertension in patients on chronic haemodialysis

INTRODUCTION

Hypertension is very common in haemodialysis (HD) patients, and is associated with increased morbidity and mortality rates. The goals of our research were to: 1. Measure blood pressure (BP) during HD sessions; 2. Study BP in between HD sessions with 44-hour Ambulatory Blood Pressure Monitoring (ABPM); 3. Identify differences between the BP recorded during HD and with the ABPM; 4. Evaluate changes in treatment after the ABPM; 5. Perform bioimpedance spectroscopy (BIS) on all patients and, in those hyper-hydrated or hypertensive according to ABPM, assess for changes in BP after adjusting the dry weight; 6. Identify factors associated with average systolic and diastolic BP measured by ABPM.

MATERIAL AND METHODS

Prospective observational study, which included 100 patients from our dialysis unit. We measured BP before and after the HD sessions for two weeks and then, mid-week, we attached the ABPM device to the patients for 44 hours. Before starting the following dialysis session, we performed BIS. A second ABPM was performed on hyper-hydrated patients and patients hypertensive according to ABPM to evaluate changes in BP values.

RESULTS

According to the ABPM, 65% of patients had daytime BP > 135/85 mmHg, 90% night-time BP > 120/70 mmHg and 76% average BP > 130/80 mmHg; 11% had a dipper pattern, 51% non-dipper and 38% riser. The average systolic and diastolic BP readings were 4.7 mmHg (3.8%) and 1.1 mmHg (1.64%) higher on the second day. The dose of antihypertensive medication had to be lowered in 6% of patients, 9% had to stop taking it, 28% needed increased doses and 17% had to add a new drug. The pre-HD diastolic BP best matched the ABPM. After performing the bioimpedance and adjusting dry weight, there was a statistically significant decrease in all BP values. The univariate analysis showed that the average systolic BP was higher in patients with a high-calcium dialysis bath, more antihypertensive drugs and higher doses of EPO. The multivariate analysis showed significant association for EPO and number of drugs (p < 0.01). The average diastolic BP was higher in younger patients and patients with lower Charlson index, lower body mass index and less diuresis, those on higher doses of EPO and non-diabetics. The linear regression study showed age (p < 0.005), body mass index (p < 0.03) and EPO (p < 0.03) as significant variables.

CONCLUSIONS

Our study shows: 1. The variability of hypertension criteria according to use of BP values from during the HD session or ABPM; 2. The variability of BP in the interdialysis period; 3. That the pre-dialysis diastolic BP best corresponds with the ABPM. 4. That the use of both BIS and ABPM improves the control of BP; 5. That the dose of EPO is the most important factor associated with hypertension in our patients.

Does Incident Solar Ultraviolet Radiation Lower Blood Pressure?

Background Hypertension remains a leading global cause for premature death and disease. Most treatment guidelines emphasize the importance of risk factors, but not all are known, modifiable, or easily avoided. Population blood pressure correlates with latitude and is lower in summer than winter. Seasonal variations in sunlight exposure account for these differences, with temperature believed to be the main contributor. Recent research indicates that UV light enhances nitric oxide availability by mobilizing storage forms in the skin, suggesting incident solar UV radiation may lower blood pressure. We tested this hypothesis by exploring the association between environmental UV exposure and systolic blood pressure (SBP) in a large cohort of chronic hemodialysis patients in whom SBP is determined regularly. Methods and Results We studied 342 457 patients (36% black, 64% white) at 2178 US dialysis centers over 3 years. Incident UV radiation and temperature data for each clinic location were retrieved from the National Oceanic and Atmospheric Administration database. Linear mixed effects models with adjustment for ambient temperature, sex/age, body mass index, serum Na+/K+ and other covariates were fitted to each location and combined estimates of associations calculated using the DerSimonian and Laird procedure. Pre-dialysis SBP varied by season and was ≈4 mm Hg higher in black patients. Temperature, UVA and UVB were all linearly and inversely associated with SBP. This relationship remained statistically significant after correcting for temperature. Conclusions In hemodialysis patients, in addition to environmental temperature, incident solar UV radiation is associated with lower SBP. This raises the possibility that insufficient sunlight is a new risk factor for hypertension, perhaps even in the general population.

Chronodisruption: A Poorly Recognized Feature of CKD

Multiple physiological variables change over time in a predictable and repetitive manner, guided by molecular clocks that respond to external and internal clues and are coordinated by a central clock. The kidney is the site of one of the most active peripheral clocks. Biological rhythms, of which the best known are circadian rhythms, are required for normal physiology of the kidneys and other organs. Chronodisruption refers to the chronic disruption of circadian rhythms leading to disease. While there is evidence that circadian rhythms may be altered in kidney disease and that altered circadian rhythms may accelerate chronic kidney disease (CKD) progression, there is no comprehensive review on chronodisruption and chronodisruptors in CKD and its manifestations. Indeed, the term chronodisruption has been rarely applied to CKD despite chronodisruptors being potential therapeutic targets in CKD patients. We now discuss evidence for chronodisruption in CKD and the impact of chronodisruption on CKD manifestations, identify potential chronodisruptors, some of them uremic toxins, and their therapeutic implications, and discuss current unanswered questions on this topic.

Seasonal and Secular Trends of Cardiovascular, Nutritional, and Inflammatory Markers in Patients on Hemodialysis

BACKGROUND

All life on earth has adapted to the effects of changing seasons. The general and ESKD populations exhibit seasonal rhythms in physiology and outcomes. The ESKD population also shows secular trends over calendar time that can convolute the influences of seasonal variations. We conducted an analysis that simultaneously considered both seasonality and calendar time to isolate these trends for cardiovascular, nutrition, and inflammation markers.

METHODS

We used data from adult patients on hemodialysis (HD) in the United States from 2010 through 2014. An additive model accounted for variations over both calendar time and time on dialysis. Calendar time trends were decomposed into seasonal and secular trends. Bootstrap procedures and likelihood ratio methods tested if seasonal and secular variations exist.

RESULTS

We analyzed data from 354,176 patients on HD at 2436 clinics. Patients were 59±15 years old, 57% were men, and 61% had diabetes. Isolated average secular trends showed decreases in pre-HD systolic BP (pre-SBP) of 2.6 mm Hg (95% CI, 2.4 to 2.8) and interdialytic weight gain (IDWG) of 0.35 kg (95% CI, 0.33 to 0.36) yet increases in post-HD weight of 2.76 kg (95% CI, 2.58 to 2.97). We found independent seasonal variations of 3.3 mm Hg (95% CI, 3.1 to 3.5) for pre-SBP, 0.19 kg (95% CI, 0.17 to 0.20) for IDWG, and 0.62 kg (95% CI, 0.46 to 0.79) for post-HD weight as well as 0.12 L (95% CI, 0.11 to 0.14) for ultrafiltration volume, 0.41 ml/kg per hour (95% CI, 0.37 to 0.45) for ultrafiltration rates, and 3.30 (95% CI, 2.90 to 3.77) hospital days per patient year, which were higher in winter versus summer.

CONCLUSIONS

Patients on HD show marked seasonal variability of key indicators. Secular trends indicate decreasing BP and IDWG and increasing post-HD weight. These methods will be of importance for independently determining seasonal and secular trends in future assessments of population health.

Seasonal variations in cause-specific mortality and transition to renal replacement therapy among patients with end-stage renal disease

Despite some studies showing seasonal variations in mortality and the transition to renal replacement therapy in patients with end-stage renal disease, detailed evidence is still scarce. We investigated seasonal variations in patients with end-stage renal disease using a large Japanese database for dialysis patients. We compared the fractions of all-cause and cause-specific mortality and the transition to renal replacement therapy among seasons and performed a mixed-effects Poisson regression analysis to compare the mortality among seasons after adjustment for some variables. The initiation of hemodialysis was highest in winter and lowest in summer. Seasonality in the initiation of peritoneal dialysis and transition to kidney transplantation differed from hemodialysis. All-cause mortality was highest in the winter and lowest in the summer. Death from coronary artery disease, heart failure, cerebral hemorrhage, and infectious pneumonia had similar seasonality, but death from cerebral infarction, septicemia, or malignant tumor did not have similar seasonality. In conclusion, the initiation of hemodialysis, all-cause mortality, and mortality from coronary heart disease, heart failure, cerebral hemorrhage, and infectious pneumonia were significantly highest in winter and lowest in summer. However, the initiation of peritoneal dialysis, transition to kidney transplantation, or mortality from cerebral infarction, septicemia, or malignant tumor did not have similar seasonal variations.

Risk of Out-of-Hospital Cardiac Arrest in Aged Individuals in Relation to Cold Ambient Temperature - A Report From North Tochigi Experience

BACKGROUND

The impact of cold ambient temperature on out-of-hospital cardiac arrest (OHCA) in aged individuals caused by cardiovascular events in indoor environments has not been investigated sufficiently.

METHODS AND RESULTS

We conducted a case-crossover study. The relationship between OHCA caused by cardiovascular events and exposure to minimum temperature <0℃ was analyzed. Conditional logistic regression analysis was performed to estimate the odds ratios for the relationship between exposure to minimum temperature <0℃ and the risk of OHCA. Between January 1, 2011, and December 31, 2015, a total of 1,452 cases of OHCA were documented, and patients were screened for enrollment. A total of 458 individuals were enrolled in this analysis, and were divided into 2 groups of 110 (elderly group: 65-74 years old) and 348 (aged group: ≥75 years old). The aged individuals had a significant increased risk of OHCA after exposure to minimum temperature <0℃ (odds ratio [OR]: 1.528, 95% confidence interval [CI] 1.009-2.315, P=0.045). Cold ambient temperature was an especially significant increased risk for OHCA occurrence for males (OR: 1.997, 95% CI 1.036-3.773, P=0.039) and during winter (OR: 2.391, 95% CI 1.312-4.360, P=0.004) in the aged group.

CONCLUSIONS

Cold ambient temperature significantly affected aged individuals (≥75 years old) experiencing an OHCA caused by cardiovascular events in indoor environments.

Assessment of the Relationship Between Ambient Temperature and Home Blood Pressure in Patients From a Web-Based Synchronous Telehealth Care Program: Retrospective Study

BACKGROUND

Decreased ambient temperature significantly increases office blood pressure, but few studies have evaluated the effect of ambient temperature on home blood pressure.

OBJECTIVE

We aimed to investigate the relationship between short-term ambient temperature exposure and home blood pressure.

METHODS

We recruited patients with chronic cardiovascular diseases from a telehealth care program at a university-affiliated hospital. Blood pressure was measured at home by patients or their caregivers. We obtained hourly meteorological data for Taipei (temperature, relative humidity, and wind speed) for the same time period from the Central Weather Bureau, Taiwan.

RESULTS

From 2009 to 2013, we enrolled a total of 253 patients. Mean patient age was 70.28 (SD 13.79) years, and 66.0% (167/253) of patients were male. We collected a total of 110,715 home blood pressure measurements. Ambient temperature had a negative linear effect on all 3 home blood pressure parameters after adjusting for demographic and clinical factors and antihypertensive agents. A 1°C decrease was associated with a 0.5492-mm Hg increase in mean blood pressure, a 0.6841-mm Hg increase in systolic blood pressure, and a 0.2709-mm Hg increase in diastolic blood pressure. This temperature effect on home blood pressure was less prominent in patients with diabetes or hypertension. Antihypertensive agents modified this negative effect of temperature on home blood pressure to some extent, and angiotensin receptor blockers had the most favorable results.

CONCLUSIONS

Short-term exposure to low ambient temperature significantly increased home blood pressure in patients with chronic cardiovascular diseases. Antihypertensive agents may modify this effect.

The short-term effects of outdoor temperature on blood pressure among children and adolescents: finding from a large sample cross-sectional study in Suzhou, China

Although several studies have demonstrated a short-term association between outdoor temperature and blood pressure (BP) among various adult groups, evidence among children and adolescents is lacking. One hundred ninety-four thousand one hundred four participants from 2016 Health Promotion Program for Children and Adolescents (HPPCA) were analyzed through generalized linear mixed-effects models to estimate the short-term effects of two outdoor temperature variables (average and minimum temperature) on participants' BP. Decreasing outdoor temperature was associated with significant increases in systolic BP (SBP), diastolic BP (DBP), and prevalence of hypertension during lag 0 through lag 6. Additionally, daily minimum temperature showed a more apparent association with participants' BP. The estimated increases (95% confidence interval) in SBP and DBP at lag 0 were 0.82 (0.72, 0.92) mmHg and 2.28 (2.20, 2.35) mmHg for a 1 °C decrease in daily minimum temperature, while those values were 0.11 (0.10, 0.12) mmHg and 0.25 (0.24, 0.26) mmHg for a 1 °C decrease in daily average temperature, respectively. The effects of temperature on BP were stronger among female, as well as those with young age and low body mass index. It demonstrated that short-term decreases in outdoor temperature were significantly associated with rises in BP among children and adolescents. This founding has some implications for clinical management and research of BP. Meanwhile, public health intervention should be designed to reduce the exposure to cold temperature for protecting children and adolescents' BP.

Cycles, Arrows and Turbulence: Time Patterns in Renal Disease, a Path from Epidemiology to Personalized Medicine?

Patients with end-stage renal disease (ESRD) experience unique patterns in their lifetime, such as the start of dialysis and renal transplantation. In addition, there is also an intricate link between ESRD and biological time patterns. In terms of cyclic patterns, the circadian blood pressure (BP) rhythm can be flattened, contributing to allostatic load, whereas the circadian temperature rhythm is related to the decline in BP during hemodialysis (HD). Seasonal variations in BP and interdialytic-weight gain have been observed in ESRD patients in addition to a profound relative increase in mortality during the winter period. Moreover, nonphysiological treatment patters are imposed in HD patients, leading to an excess mortality at the end of the long interdialytic interval. Recently, new evidence has emerged on the prognostic impact of trajectories of common clinical and laboratory parameters such as BP, body temperature, and serum albumin, in addition to single point in time measurements. Backward analysis of changes in cardiovascular, nutritional, and inflammatory parameters before the occurrence as hospitalization or death has shown that changes may already occur within months to even 1-2 years before the event, possibly providing a window of opportunity for earlier interventions. Disturbances in physiological variability, such as in heart rate, characterized by a loss of fractal patterns, are associated with increased mortality. In addition, an increase in random variability in different parameters such as BP and sodium is also associated with adverse outcomes. Novel techniques, based on time-dependent analysis of variability and trends and interactions of multiple physiological and laboratory parameters, for which machine-learning -approaches may be necessary, are likely of help to the clinician in the future. However, upcoming research should also evaluate whether dynamic patterns observed in large epidemiological studies have relevance for the individual risk profile of the patient.

The health benefits of UV radiation exposure through vitamin D production or non-vitamin D pathways. Blood pressure and cardiovascular disease

The detrimental effects of ultraviolet radiation are well known. Skin cancer, photo-aging, and induction or exacerbation of photosensitive dermatoses have been the focus of most photobiological research since 1928 when Findlay confirmed the carcinogenicity of ultraviolet radiation using a murine model of skin cancer. The epidemiological, mechanistic and clinical trial data have enabled the classification by the International Agency for Research on Cancer of ultraviolet radiation as a Group 1 ('sufficient evidence') carcinogen for human skin. Public health advice in most developed countries with a pale-skinned population following this has advocated limiting exposure to sunlight through use of clothing, sunblock and behavioural alterations. Despite this plethora of data, one striking omission is evidence that ultraviolet radiation shortens life, and as I will lay out in this chapter, epidemiological and now mechanistic data suggest that UV may have significant benefits on health and in particular cardiovascular health.

Geographical Variations in Blood Pressure Level and Seasonality in Hemodialysis Patients

Seasons and climate influence the regulation of blood pressure (BP) in the general population and in hemodialysis patients. It is unknown whether this phenomenon varies across the world. Our objective was to estimate BP seasonality in hemodialysis patients from different geographical locations. Patients from 7 European countries (Spain, Italy, France, Belgium, Germany, United Kingdom, and Sweden) participating in the DOPPS (Dialysis Outcomes and Practice Patterns Study) on years 2005 to 2011 were studied. Factors influencing pre- and postdialysis systolic BP and diastolic BP levels were analyzed by mixed models. There were 9655 patients (median age, 68; 59% male) from 263 facilities, seen every 4 months during a median duration of 1.3 years. Pre- and postdialysis systolic BP increased by a mean estimate of 5.1 mm Hg (95% confidence interval [CI], 3.7-6.4 mm Hg) and 4.4 mm Hg (95% CI, 2.9-5.9 mm Hg) for each 10° increase in latitude (1111 km to the North). In the longitudinal analysis, predialysis systolic BP was lower in summer and higher in winter (difference, 1.7 mm Hg; 95% CI, 1.3-2.2 mm Hg), with greater differences in southern locations (P_interaction=0.04). Predialysis systolic BP was inversely associated with outdoor temperature (-0.8 mm Hg/7.2°C; 95% CI, -1.0 to -0.5 mm Hg/7.2°C), with steeper slopes in southern locations (P_interaction=0.005). Results were similar for predialysis diastolic BP. In conclusion, there is a geographical and seasonal gradient of BP in European hemodialysis patients. There is a need to consider these effects when evaluating and treating BP in this population and potentially in others.

Seasonal variations in transition, mortality and kidney transplantation among patients with end-stage renal disease in the USA

Background

Seasonal variations may exist in transitioning to dialysis, kidney transplantation and related outcomes among end-stage renal disease (ESRD) patients. Elucidating these variations may have major clinical and healthcare policy implications for better resource allocation across seasons.

Methods

Using the United States Renal Data System database from 1 January 2000 to 31 December 2013, we calculated monthly counts of transitioning to dialysis or first transplantation and deaths. Crude monthly transition fraction was defined as the number of new ESRD patients divided by all ESRD patients on the first day of each month. Similar fractions were calculated for all-cause and cause-specific mortality and transplantation.

Results

The increasing trend of the annual transition to ESRD plateaued during 2009-2012 (n = 126 264), and dropped drastically in 2013 (n = 117 372). Independent of secular trends, monthly transition to ESRD was lowest in July (1.65%) and highest in January (1.97%) of each year. All-cause, cardiovascular and infectious mortalities were lowest in July or August (1.32, 0.58 and 0.15%, respectively) and highest in January (1.56, 0.71 and 0.19%, respectively). Kidney transplantation was highest in June (0.33%), and this peak was mainly attributed to living kidney transplantation in summer months. Transplant failure showed a similar seasonal variation to naïve transition, peaking in January (0.65%) and nadiring in September (0.56%).

Conclusions

Transitioning to ESRD and adverse events among ESRD people were more frequent in winter and less frequent in summer, whereas kidney transplantation showed the reverse trend. The potential causes and implications of these consistent seasonal variations warrant more investigation.

Associations of blood pressure, sunlight, and vitamin D in community-dwelling adults

BACKGROUND

Vitamin D deficiency/insufficiency is associated with hypertension. Blood pressure (BP) and circulating vitamin D concentrations vary with the seasons and distance from the equator suggesting BP varies inversely with the sunshine available (insolation) for cutaneous vitamin D photosynthesis.

METHODS

To determine if the association between insolation and BP is partly explained by vitamin D, we evaluated 1104 participants in the Reasons for Racial and Geographic Differences in Stroke study whose BP and plasma 25-hydroxyvitamin D [25(OH)D] concentrations were measured.

RESULTS

We found a significant inverse association between SBP and 25(OH)D concentration and an inverse association between insolation and BP in unadjusted analyses. After adjusting for other confounding variables, the association of solar insolation and BP was augmented, -0.3.5 ± SEM 0.01 mmHg/1 SD higher solar insolation, P = 0.01. The greatest of effects of insolation on SBP were observed in whites (-5.2 ± SEM 0.92 mmHg/1 SD higher solar insolation, P = 0.005) and in women (-3.8 ± SEM 1.7 mmHg, P = 0.024). We found that adjusting for 25(OH)D had no effect on the association of solar insolation with SBP.

CONCLUSION

We conclude that although 25(OH)D concentration is inversely associated with SBP, it did not explain the association of greater sunlight exposure with lower BP.

Influence of geomagnetic activity and atmospheric pressure in hypertensive adults

We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

Environmental Determinants of Cardiovascular Disease

Many features of the environment have been found to exert an important influence on cardiovascular disease (CVD) risk, progression, and severity. Changes in the environment because of migration to different geographic locations, modifications in lifestyle choices, and shifts in social policies and cultural practices alter CVD risk, even in the absence of genetic changes. Nevertheless, the cumulative impact of the environment on CVD risk has been difficult to assess and the mechanisms by which some environment factors influence CVD remain obscure. Human environments are complex, and their natural, social, and personal domains are highly variable because of diversity in human ecosystems, evolutionary histories, social structures, and individual choices. Accumulating evidence supports the notion that ecological features such as the diurnal cycles of light and day, sunlight exposure, seasons, and geographic characteristics of the natural environment such as altitude, latitude, and greenspaces are important determinants of cardiovascular health and CVD risk. In highly developed societies, the influence of the natural environment is moderated by the physical characteristics of the social environments such as the built environment and pollution, as well as by socioeconomic status and social networks. These attributes of the social environment shape lifestyle choices that significantly modify CVD risk. An understanding of how different domains of the environment, individually and collectively, affect CVD risk could lead to a better appraisal of CVD and aid in the development of new preventive and therapeutic strategies to limit the increasingly high global burden of heart disease and stroke.

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.

Influence of ambient temperature and diurnal temperature range on incidence of cardiac arrhythmias

We investigated the association between ambient temperature and diurnal temperature range (DTR) and the exacerbation of arrhythmia symptoms, using data from 31,629 arrhythmia-related emergency department (ED) visits in Seoul, Korea. Linear regression analyses with allowances for over-dispersion were applied to temperature variables and ED visits, adjusted for various environmental factors. The effects were expressed as percentage changes in the risk of arrhythmia-related ED visits up to 5 days later, with 95 % confidence intervals (CI), per 1 °C increase in DTR and 1 °C decrease in mean temperature. The overall risk of ED visits increased by 1.06 % (95 % CI 0.39 %, 1.73 %) for temperature and by 1.84 % (0.34, 3.37 %) for DTR. A season-specific effect was detected for temperature during both fall (1.18 % [0.01, 2.37 %]) and winter (0.87 % [0.07, 1.67 %]), and for DTR during spring (3.76 % [0.34, 7.29 %]). Females were more vulnerable, with 1.57 % [0.56, 2.59 %] and 3.84 % [1.53, 6.20 %] for the changes in temperature and DTR, respectively. An age-specific effect was detected for DTR, with 3.13 % [0.95, 5.36 %] for age ≥ 65 years, while a greater increased risk with temperature decrease was observed among those aged <65 (1.08 % [0.17, 2.00 %]) than among those aged ≥65 (1.02 % [0.06, 1.99 %]). Cardiac arrest was inversely related with temperature (1.61 % [0.46, 2.79 %]), while other cardiac arrhythmias depended more on the change in DTR (4.72 % [0.37, 9.26 %]). These findings provide evidence that low-temperature and elevated DTR influence the occurrence of arrhythmia exacerbations or symptoms, suggesting a possible strategy for reducing risk by encouraging vulnerable populations to minimize exposure.

Seasonal Variation in Hip Fracture Mortality

Objectives:

This study aims to identify if wintertime surgery increases the mortality of the patients after hip fracture operations.

Design:

Retrospective observational cohort study.

Setting:

The data for this citywide retrospective observational cohort study came from Clinical Data Analysis Reporting System.

Patient:

This study included 35 409 patients with hip fracture operations from July 2005 to December 2013.

Main Outcome Measures:

Cox regression hazard model was used to estimate the independent effect of operation being performed in winter on the hazard of mortality. The hazard model included covariates found to be independent predictors of mortality: age, sex, surgical delay, and Charlson Comorbidity Index (CCI).

Results:

There was a seasonal variation with more hip fracture operations happening in the winter months. The 1-month, 6-month, 1-year, and 5-year mortality were 3%, 11%, 17%, and 47%, respectively. Operation performed in winter was associated with a higher hazard of mortality (hazard ratio [HR] 1.040; 95% confidence interval: 1.010-1.072; P = .009). The HR was greater with male sex (HR 1.786; P = .000), advanced age (≥85 years old: HR 2.819; P = .000), the longer surgical delay (HR 1.018; P = .000), and higher CCI (severe CCI group: HR 2.963; P = .000).

Conclusion:

Wintertime hip fracture surgery was associated with an increased hazard of mortality after adjusting for other known risk factors affecting mortality post hip fracture operations.

Low air temperature increases the risk of oesophageal variceal bleeding: a population and hospital-based case-crossover study in Taiwan

BACKGROUND & AIMS

Studies concerning seasonal variations and the impact of air temperature on oesophageal variceal bleeding have yielded conflicting results. We aimed to explore the impact of air temperature on the occurrence of variceal bleeding.

METHODS

A case-crossover study design was employed, and two cohorts were used, including the NHI-EVB cohort from the National Health Insurance Research Database of Taiwan from 1 January 1999 to 31 December 2010, and the VGH-EVB cohort from the Taipei Veterans General Hospital, from 4 May 2002 to 31 December 2010. A conditional logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

In total, 2542 cases from the NHI-EVB cohort and 220 cases from the VGH-EVB cohort were analysed. Our analysis showed that low air temperature (LAT) increased the risk of variceal bleeding regardless of age, sex, decompensated cirrhosis, Child-Pugh classification, aetiology of liver disease and concomitant hepatocellular carcinoma; the lag effect was also observed. The ORs per 5°C decrease in daily mean air temperature were 1.144 (95% CI, 1.060-1.235) for the NHI-EVB cohort and 1.307 (95% CI: 1.031-1.658) for the VGH-EVB cohort. Oesophageal variceal bleeding in patients with small varices, end-stage liver disease score ≧15 or those using non-selective beta blockers was not influenced by air temperature.

CONCLUSIONS

Patients have higher risk of oesophageal variceal bleeding at low air temperature regardless of age, sex, aetiology of cirrhosis, Child-Pugh classification, decompensated cirrhosis and concomitant hepatocellular carcinoma and can be protected by use non-selective beta blockers.

Seasonal variations in mortality and clinical indicators in international hemodialysis populations from the MONDO registry

Background

Seasonal mortality differences have been reported in US hemodialysis (HD) patients. Here we examine the effect of seasons on mortality, clinical and laboratory parameters on a global scale.

Methods

Databases from the international Monitoring Dialysis Outcomes (MONDO) consortium were queried to identify patients who received in-center HD for at least 1 year. Clinics were stratified by hemisphere and climate zone (tropical or temperate). We recorded mortality and computed averages of pre-dialysis systolic blood pressure (pre-SBP), interdialytic weight gain (IDWG), serum albumin, and log C-reactive protein (CRP). We explored seasonal effects using cosinor analysis and adjusted linear mixed models globally, and after stratification.

Results

Data from 87,399 patients were included (northern temperate: 63,671; northern tropical: 7,159; southern temperate: 13,917; southern tropical: 2,652 patients). Globally, mortality was highest in winter. Following stratification, mortality was significantly lower in spring and summer compared to winter in temperate, but not in tropical zones. Globally, pre-SBP and IDWG were lower in summer and spring as compared to winter, although less pronounced in tropical zones. Except for southern temperate zone, serum albumin levels were higher in winter. CRP levels were highest in winter.

Conclusion

Significant global seasonal variations in mortality, pre-SBP, IDWG, albumin and CRP were observed. Seasonal variations in mortality were most pronounced in temperate climate zones.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0129-y) contains supplementary material, which is available to authorized users.

Relationship between Acute Phase of Chronic Periodontitis and Meteorological Factors in the Maintenance Phase of Periodontal Treatment: A Pilot Study

The acute phase of chronic periodontitis may occur even in patients during supportive periodontal therapy. However, the details are not fully understood. Since the natural environment, including meteorology affects human health, we hypothesized that weather conditions may affect occurrence of acute phase of chronic periodontitis. The aim of this study was to investigate the relationship between weather conditions and acute phase of chronic periodontitis in patients under supportive periodontal therapy. Patients who were diagnosed with acute phase of chronic periodontitis under supportive periodontal therapy during 2011–2013 were selected for this study. We performed oral examinations and collected questionnaires and meteorological data. Of 369 patients who experienced acute phase of chronic periodontitis, 153 had acute phase of chronic periodontitis without direct-triggered episodes. When using the autoregressive integrated moving average model of time-series analysis, the independent covariant of maximum hourly range of barometric pressure, maximum hourly range of temperature, and maximum daily wind speed were significantly associated with occurrence of acute phase of chronic periodontitis (p < 0.05), and 3.1% of the variations in these occurrence over the study period were explained by these factors. Meteorological variables may predict occurrence of acute phase of chronic periodontitis.

Outdoor temperature, blood pressure, and cardiovascular disease mortality among 23 000 individuals with diagnosed cardiovascular diseases from China

Introduction

Blood pressure is a major cause of cardiovascular disease (CVD) and both may increase as outdoor temperatures fall. However, there are still limited data about seasonal variation in blood pressure and CVD mortality among patients with prior-CVD.

Methods

We analysed data on 23 000 individuals with prior-CVD who were recruited from 10 diverse regions into the China Kadoorie Biobank during 2004–8. After 7 years of follow-up, 1484 CVD deaths were recorded. Baseline survey data were used to assess seasonal variation in systolic blood pressure (SBP) and its association with outdoor temperature. Cox regression was used to examine the association of usual SBP with subsequent CVD mortality, and seasonal variation in CVD mortality was assessed by Poisson regression. All analyses were adjusted for age, sex, and region.

Results

Mean SBP was significantly higher in winter than in summer (145 vs. 136 mmHg, P < 0.001), especially among those without central heating. Above 5°C, each 10°C lower outdoor temperature was associated with 6.2 mmHg higher SBP. Systolic blood pressure predicted subsequent CVD mortality, with each 10 mmHg higher usual SBP associated with 21% (95% confidence interval: 16–27%) increased risk. Cardiovascular disease mortality varied by season, with 41% (21–63%) higher risk in winter compared with summer.

Conclusion

Among adult Chinese with prior-CVD, there is both increased blood pressure and CVD mortality in winter. Careful monitoring and more aggressive blood pressure lowering treatment in the cold months are needed to help reduce the winter excess CVD mortality in high-risk individuals.

Association of Meteorological Variables and Coronary Blood Flow

We aimed to assess the impact of meteorological variables on coronary blood flow (CBF). Coronary blood flow was evaluated using the thrombolysis in myocardial infarction frame count (TFC). The association of CBF with meteorological parameters such as temperature, relative humidity, total solar radiation, atmospheric pressure, wind velocity, and total sunshine duration were investigated as well as demographic, clinical, and laboratory characteristics. Assessment of 1206 patients (median age = 53 years, 723 females) revealed the presence of slow coronary flow (SCF) in 196 patients. Daily maximum temperature [odds ratio = 0.951, 95% confidence interval = 0.916-0.986, P = .007] was the only independent predictor of the presence of SCF, whereas systolic blood pressure (β = -0.139, P = .026), hematocrit level (β = 0.128, P = .044), and daily maximum temperature (β = -1.479, P = .049) were independent predictors of log10 (mean TFC). Findings of the present study suggest a role of meteorological parameters in CBF regulation.

Febuxostat for hyperuricemia in patients with advanced chronic kidney disease

Febuxostat is a nonpurine xanthine oxidase (XO) inhibitor, which recently received marketing approval. However, information regarding the experience with this agent among advanced chronic kidney disease (CKD) patients is limited. In the current study, we investigated the effects of oral febuxostat in patients with advanced CKD with asymptomatic hyperuricemia. We demonstrated, for the first time, that not only the serum levels of uric acid (UA) but also those of 8-hydroxydeoxyguanosine, an oxidative stress marker, were significantly reduced after six months of febuxostat treatment, with no adverse events. These results encouraged us to pursue further investigations regarding the clinical impact of lowering the serum UA levels with febuxostat in advanced CKD patients in terms of concomitantly reducing oxidative stress via the blockade of XO. More detailed studies with a larger number of subjects and assessments of the effects of multiple factors affecting hyperuricemia, such as age, sex, and dietary habits, would shed light on the therapeutic challenges of treating asymptomatic hyperuricemia in patients with various stages of CKD.

Assessment and management of hypertension in patients on dialysis

Hypertension is common, difficult to diagnose, and poorly controlled among patients with ESRD. However, controversy surrounds the diagnosis and treatment of hypertension. Here, we describe the diagnosis, epidemiology, and management of hypertension in dialysis patients, and examine the data sparking debate over appropriate methods for diagnosing and treating hypertension. Furthermore, we consider the issues uniquely related to hypertension in pediatric dialysis patients. Future clinical trials designed to clarify the controversial results discussed here should lead to the implementation of diagnostic and therapeutic techniques that improve long-term cardiovascular outcomes in patients with ESRD.

Association between winter season and risk of death from cardiovascular diseases: a study in more than half a million inpatients in Beijing, China

Background

Seasonal associations of cardiovascular mortality have been noted in most populations of European origin years ago, but are not well evaluated in Asian populations recently.

Methods

Utilizing the electronic Hospitalization Summary Reports (HSRs) from 32 top-ranked hospitals in Beijing, China, we evaluated the association between winter season and the risk of cardiovascular death among hospitalized individuals. General additive models and logistic regression models were adjusted for confounding factors.

Results

Older patients who were admitted to the hospital in the winter months (January, February, November and December) had a death risk that was increased by approximately 30% to 50% (P < 0.01) over those who were admitted in May. However, younger patients did not seem to experience the same seasonal variations in death risk. The excess winter deaths among older patients were associated with ischemic heart disease (RR = 1.22; 95% CI 1.13 to 1.31), pulmonary heart disease (RR = 1.42; 95% CI 1.10 to 1.83), cardiac arrhythmias (RR = 1.67; 95% CI 1.36 to 2.05), heart failure (RR = 1.30; 95% CI 1.09 to 1.54), ischemic stroke (RR = 1.30; 95% CI 1.17 to 1.43), and other cerebrovascular diseases (RR = 1.78; 95% CI 1.40 to 2.25). The risks of mortality were higher in winter months than in the month of May, regardless of the presence or absence of respiratory disease.

Conclusions

Winter season was associated with a substantially increased risk of cardiovascular death among older Chinese cardiovascular inpatients.

Effect of healthy aging on renal vascular responses to local cooling and apnea

Sympathetically mediated renal vasoconstriction may contribute to the pathogenesis of hypertension in older adults, but empirical data in support of this concept are lacking. In 10 young (26 ± 1 yr) and 11 older (67 ± 2 yr) subjects, we quantified acute hemodynamic responses to three sympathoexcitatory stimuli: local cooling of the forehead, cold pressor test (CPT), and voluntary apnea. We hypothesized that all stimuli would increase mean arterial blood pressure (MAP) and renal vascular resistance index (RVRI) and that aging would augment these effects. Beat-by-beat MAP, heart rate (HR), and renal blood flow velocity (from Doppler) were measured in the supine posture, and changes from baseline were compared between groups. In response to 1°C forehead cooling, aging was associated with an augmented MAP (20 ± 3 vs. 6 ± 2 mmHg) and RVRI (35 ± 6 vs. 16 ± 9%) but not HR. In older adults, there was a positive correlation between the cold-induced pressor response and forehead pain (R = 0.726), but this effect was not observed in young subjects. The CPT raised RVRI in both young (56 ± 13%) and older (45 ± 8%) subjects, but this was not different between groups. Relative to baseline, end-expiratory apnea increased RVRI to a similar extent in both young (46 ± 14%) and older (41 ± 9%) subjects. During sympathetic activation, renal vasoconstriction occurred in both groups. Forehead cooling caused an augmented pressor response in older adults that was related to pain perception.

Seasonal variation in blood pressure is modulated by gender and age but not by BMI in a large Taiwanese population, 1996-2006

Previous research has found that blood pressure tends to be higher in winter and lower in summer. The present study examined seasonal variation in blood pressure by gender, hypertension medication, age group, and body mass index using contemporary Taiwanese data. Over 400,000 health screening records collected biennially between 1996 and 2006 were used to calculate average monthly systolic (SBP) and diastolic blood pressure (DBP) measurements. Generalized estimating equations were used to estimate the difference between the highest and lowest mean monthly blood pressure measurements. Mean monthly blood pressure measurements were higher in winter than in summer for all age groups, regardless of medication for hypertension. The largest difference in mean monthly blood pressure between summer and winter months was 5.3 mm Hg (Standard error = 0.7) for SBP and 3.2 mm Hg (Standard error = 0.7) for DBP. These differences were more pronounced: in SBP than in DBP; in men than in women; and in older than in younger participants. Body mass index was not clearly associated with seasonal variation in blood pressure. Seasonal variation in blood pressure among contemporary Taiwanese populations is modest and may only approach clinical significance for the diagnosis and treatment of hypertension and the prevention of cardiovascular disease amongst older male individuals.

Association of cold ambient temperature and cardiovascular markers

Cardiovascular mortality has been shown to increase in the winter. However, it is unclear whether cold temperature affects indicators known as cardiovascular markers. We evaluated the association between ambient temperature and cardiovascular markers using data collected retrospectively from 55,567 adults who had visited a health check-up clinic between 1995 and 2008. Non-parametric smoothing regressions were fitted to determine the shapes of association between temperature and cardiovascular markers such as blood pressure, lipid profiles, platelet count, and high sensitivity C-reactive protein (hsCRP). Mixed effect model was used to investigate the significance of the relationship between temperature and cardiovascular markers. Decreased ambient temperature was associated with an increase in systolic and diastolic blood pressures, platelet count and serum low density lipoprotein-cholesterol concentration. In contrast, high density lipoprotein-cholesterol level declined with decreasing temperature. The hsCRP level increased with decreasing temperature in the minimum temperatures below 0°C, but revealed a reverse association above. Our study suggests that excess cardiovascular mortality in cold weather might be associated with temperature-related variations of cardiovascular markers.

'Time and time again': oscillatory and longitudinal time patterns in dialysis patients

Oscillatory and longitudinal time patterns play a major role in human physiology. In chronic hemodialysis patients, abnormalities in both time patterns have been observed, while time patterns can also influence the response of patients to the treatment. Abnormal oscillatory patterns have been observed for ultradian rhythms (cycle time <20 h), such as an impaired heart rate variability and circadian rhythms, as reflected by reduced day-night blood pressure differences. Conversely, the circadian rhythm of body temperature may influence the hemodynamic tolerance to the dialysis treatment. With regard to infradian (cycle time >28 h) rhythms, large seasonal differences in mortality, but also in blood pressure and interdialytic weight gain, have been observed in dialysis patients. The most important longitudinal pattern is the general reduction of life span in dialysis patients. One explanation of this phenomenon relates to the concept of accelerated aging in dialysis patients, for which there are various supportive arguments. From a phenomenological point of view, this concept translates into the high prevalence of frailty, even in young dialysis patients. A multidimensional approach appears necessary to adequately address this problem. In this review, the relevance of disturbed time patterns in dialysis patients is discussed. The changes may reflect an impairment or reduction in homeostatic/homeodynamic control in dialysis patients and also may have important prognostic and therapeutic implications.