Weather-related changes in 24-hour blood pressure profile: effects of age and implications for hypertension management

Potential mechanisms of ischemic stroke induced by heat exposure

Recent decades of epidemiological and clinical research have suggested that heat exposure could be a potential risk factor for ischemic stroke. Despite climate factors having a minor impact on individuals compared with established risk factors such as smoking, their widespread and persistent effects significantly affect public health. The mechanisms by which heat exposure triggers ischemic stroke are currently unclear. However, several potential mechanisms, such as the impact of temperature variability on stroke risk factors, inflammation, oxidative stress, and coagulation system changes, have been proposed. This article details the potential mechanisms by which heat exposure may induce ischemic stroke, aiming to guide the prevention and treatment of high-risk groups in hot climates and support public health policy development.

Seasonal variation in home blood pressure during pregnancy and frequency of hypertensive disorders of pregnancy: a multicenter prospective study of home blood pressure measurements in pregnant women using information technology

This multicenter prospective study investigated seasonal variation in home blood pressure (HBP) during pregnancy and its association with the frequency of hypertensive disorders of pregnancy (HDP) and developed trimester-specific upper limits of HBP according to season. Low-risk women with singleton pregnancies were recruited at six university hospitals and three maternity clinics. HBP was measured by a sphygmomanometer twice daily and recorded online using a mobile application. HBP was evaluated according to season (winter, spring, summer, and autumn) and gestational age. Of 705 women recruited, 603 were finally included. Mean diastolic HBP values were lowest in summer and highest in winter throughout pregnancy (mean difference between summer and winter, 3.5-4.6 mmHg). Mean systolic HBP values were also lowest in summer and highest in winter except during the early period of the second trimester (mean difference between summer and the season with the highest value, 2.5-3.4 mmHg). HDP was diagnosed in 32 women (5.3%). The risk of HDP was significantly higher in women who delivered in spring and autumn but not in winter compared with summer. The rounded upper limit of HBP was 120/80 mmHg in the first trimester, 120/75 mmHg in the second trimester, and 125/80 mmHg in the third trimester for summer and 125/85 mmHg, 125/80 mmHg, and 130/85 mmHg, respectively, for other seasons. Systolic and diastolic HBP were lowest in summer throughout pregnancy. Seasonal variation should be considered when interpreting HBP and the risk of HDP during pregnancy.

What is the relationship between risk attitudes and ambient temperature? Evidence from a large population-based cohort study

Rising temperatures affect human behavior and risk-taking in several domains. However, it is not yet well understood just how ambient temperature shapes risk attitudes. Using data from the large population-based KORA-Fit study (Cooperative Health Research in the Region of Augsburg) of older people (N=2454), we identify a statistically significant, but very small, positive association between short-term ambient temperature changes and individuals' general willingness to take risks. Health-related risk attitudes, however, show no significant relationship with temperature. These findings support a domain-specific view of risk attitudes, with results remaining consistent for vulnerable individuals with the chronic conditions diabetes, hypertension, and asthma. Overall, our findings suggest that risk attitudes are somewhat stable towards changes in ambient temperature.

Assessment of blood pressure variability: characteristics and comparison of blood pressure measurement methods

Previous studies have reported that blood pressure variability (BPV) is associated with the risk of cardiovascular events independent of blood pressure (BP) levels. While there is little evidence from intervention trials examining whether suppressing BPV is useful in preventing cardiovascular disease, it is suggested that detection of abnormally elevated BPV may be useful in reducing cardiovascular events adding by complementing management of appropriate BP levels. Cuffless BP devices can assess beat-to-beat BPV. Although cuffless BP monitoring devices have measurement accuracy issues that need to be resolved, this is an area of research where the evidence is accumulating rapidly, with many publications on beat-to-beat BPV over several decades. Ambulatory BP monitoring (ABPM) can assess 24-hour BPV and nocturnal dipping patterns. Day-to-day BPV and visit-to-visit BPV are assessed by self-measured BP monitoring at home and office BP measurement, respectively. 24 h, day-to-day, and visit-to-visit BPV have been reported to be associated with cardiovascular prognosis. Although there have been several studies comparing whether ABPM and self-measured BP monitoring at home is the superior measurement method of BPV, no strong evidence has been accumulated that indicates whether ABPM or self-measured home BP is superior. ABPM and self-measured BP monitoring have their own advantages and complement each other in the assessment of BPV.

Seasonal variation in ambulatory blood pressure control in patients on clinic blood pressure-guided antihypertensive treatment

BACKGROUND

We investigated seasonal variation in ambulatory blood pressure control in hypertensive patients on clinic blood pressure-guided antihypertensive treatment.

METHODS

The study participants were hypertensive patients enrolled in an 8-week therapeutic study. Antihypertensive treatment was initiated with long-acting dihydropyridine calcium channel blockers amlodipine 5 mg/day or the gastrointestinal therapeutic system (GITS) formulation of nifedipine 30 mg/day, with the possible up-titration to amlodipine 10 mg/day or nifedipine-GITS 60 mg/day at 4 weeks of follow-up.

RESULTS

The proportion of up-titration to higher dosages of antihypertensive drugs at 4 weeks of follow-up was higher in patients who commenced treatment in autumn/winter ( n  = 302) than those who commenced treatment in spring/summer ( n  = 199, 24.5 vs. 12.0%, P  < 0.001). The control rate of clinic blood pressure, however, was lower in autumn/winter than in spring/summer at 4 (56.7 vs. 70.7%, P  = 0.003) and 8 weeks of follow-up (52.5 vs. 74.9%, P  < 0.001). At 8 weeks, patients who commenced treatment in autumn/winter, compared with those who commenced treatment in spring/summer, had a significantly ( P ≤0.03) smaller daytime (mean between-season difference -3.2/-2.8 mmHg) but greater nighttime SBP/DBP reduction (3.6/1.6 mmHg). Accordingly, at 8 weeks, the prevalence of nondippers was significantly ( P  < 0.001) higher in spring/summer than in autumn/winter for both SBP (54.8 vs. 30.0%) and DBP (53.4 vs. 28.8%).

CONCLUSION

Clinic blood pressure-guided antihypertensive treatment requires a higher dosage of medication in cold than warm seasons, which may have led to over- and under-treatment of nighttime blood pressure, respectively.

Patterns in acute aortic dissection and a connection to meteorological conditions in Germany

Acute type A aortic dissection (ATAAD) is a dramatic emergency exhibiting a mortality of 50% within the first 48 hours if not operated. This study found an absolute value of cosine-like seasonal variation pattern for Germany with significantly fewer ATAAD events (Wilcoxon test) for the warm months of June, July, and August from 2005 to 2015. Many studies suspect a connection between ATAAD events and weather conditions. Using ERA5 reanalysis data and an objective weather type classification in a contingency table approach showed that for Germany, significantly more ATAAD events occurred during lower temperatures (by about 4.8 K), lower water vapor pressure (by about 2.6 hPa), and prevailing wind patterns from the northeast. In addition, we used data from a classification scheme for human-biometeorological weather conditions which was not used before in ATAAD studies. For the German region of Berlin and Brandenburg, for 2006 to 2019, the proportion of days with ATAAD events during weather conditions favoring hypertension (cold air advection, in the center of a cyclone, conditions with cold stress or thermal comfort) was significantly increased by 13% (Chi-squared test for difference of proportions). In contrast, the proportion was decreased by 19% for conditions associated with a higher risk for patients with hypotension and therefore a lower risk for patients with hypertension (warm air advection ahead of warm fronts, conditions with no thermal stress or heat stress, in the center of a cyclone with thermal stress). As many studies have shown that hypertension is a risk factor for ATAAD, our findings support the hypothesized relation between ATAAD and hypertension-favoring weather conditions.

Association of extreme heat events with sleep and cardiovascular health: A scoping review

BACKGROUND

Extreme heat events (EHEs), driven by anthropogenic climate change, exacerbate the risk of cardiovascular disease (CVD), although the underlying mechanisms are unclear. Disturbances in sleep health, caused by excessive heat, may be one way EHEs increase the risk of incident or recurrent CVD. Our objective was to systematically review the empirical peer-reviewed literature on the relationship between EHEs, sleep health, and cardiovascular measures and outcomes, and narratively describe methodologies, evidence, and gaps in this area.

METHODS

A comprehensive literature search was performed in the following databases from inception - June 2023: Ovid MEDLINE, Ovid EMBASE, CINAHL, Web of Science and The Cochrane Library. Studies retrieved were then screened for eligibility against predefined inclusion/exclusion criteria.

RESULTS

Of the 2035 records screened, three studies met the inclusion criteria. Cardiovascular (CV) measures described included blood pressure (BP), heart rate (HR), and HR variability (no CVD outcomes were described) and objective and subjective measurements of sleep health outcomes included sleep duration, calmness, ease of falling asleep, ease of awakening, freshness after awakening, and sleep satisfaction. Two studies were controlled trials, and one was a cohort study. During EHEs, individuals slept for shorter periods of time and less efficiently, with greater degrees of HR variability in two of the three studies lasting at most 1-2 days; BP (both systolic and diastolic) significantly decreased during EHEs in two of the studies. No formal assessment of a mediating relationship between EHE exposure, sleep outcomes, and the CV measures was undertaken.

CONCLUSIONS

There is a paucity of data that examines the link between CVD, sleep, and extreme heat as a possible mechanism of elevated CVD risk during EHEs, despite a strong physiological rationale. Further research is needed to empirically test this relationship rigorously as EHEs become more frequent and their deleterious impacts of health increase.

Acknowledging the impact of seasonal blood pressure variation in hypertensive CKD and non-CKD patients living in a Mediterranean climate

BACKGROUND

This study aims to assess seasonal blood pressure (BP) variation in chronic kidney disease (CKD) and non-CKD patients living in a Mediterranean climate, and to find out if this variation entails significant adjustment of treatment and if it impacts renal outcomes and mortality.

METHODS

This retrospective study included all hypertensive patients seen between February 2006 and April 2020 in two Lebanese clinics. Regression analyses were used to assess the association of seasonal BP variability and treatment adjustment with eGFR change from baseline, dialysis initiation and death.

RESULTS

A total of 398 patients of 64.2 ±13.9 years were followed for 51.1 ±44.3 months, 67% had eGFR< 60 mL/min. Mean systolic and diastolic BP was 137.7 ±14.7 and 76.5 ±9.5 mmHg respectively. Systolic and diastolic BP were significantly lower in the warm season in CKD and non-CKD patients (P<0.001). The majority (91.4%) needed seasonal treatment modifications. After adjustment to age, sex, baseline eGFR, BP and number of antihypertensive drugs, we found a significant loss of eGFR with treatment modifications in both seasons, double risk of dialysis with the increase of antihypertensive treatment in both seasons and a 2.5 more risk of death with reduced treatment in the warm season.

CONCLUSION

This study confirmed the seasonal BP variability in CKD and non-CKD patients from a Mediterranean climate. All types of treatment adjustment were associated with eGFR loss. Low BP in the warm season was highly associated with death.

Associations between high-altitude adaptation and risk of cardiovascular diseases: a bidirectional Mendelian randomization study

High-altitude adaptation (HAA) was reported to be significantly associated with reduced risks for multiple cardiovascular diseases (CVDs). However, the causality and direction of the associations are largely uncharacterized. We aimed to examine the potential causal relationships between HAA and six types of CVD, including coronary artery disease (CAD), cerebral aneurysm, ischemic stroke, peripheral artery disease, arrhythmia and atrial fibrillation. We obtained the summary data from largest available genome-wide association study of HAA and six types of CVD. Two-sample bidirectional Mendelian randomization (MR) analyses were performed to infer the causality between them. In the sensitivity analyses, MR-Egger regression analyses and MR-Pleiotropy RESidual Sum and Outlier (MR-PRESSO) global analyses were used to assess the pleiotropic effects; Cochran's Q tests were used to test the heterogeneity by inverse variance-weighted (IVW) and MR-Egger methods; and the leave-one-out analyses were used to examine whether some single nucleotide polymorphisms (SNPs) could influence the results independently. The MR main analyses showed that the genetically instrumented HAA was significantly causally associated with the reduced risks of CAD (odds ratio [OR] = 0.029; 95% confidence interval [CI] = 0.004-0.234; P = 8.64 × 10-4). In contrast, there was no statistically significant relationship between CVDs and HAA. Our findings provide evidence for the causal effects of HAA on the reduced risks of CAD. However, there is no causality of CVDs on HAA. These findings might be helpful in developing the prevention and intervention strategies for CAD.

Ambient Temperature Effect on Acute Myocardial Infarction by Risk Factors: Daily Data From 2000 to 2017, Taiwan

Background

A U-shaped relationship between temperature and acute myocardial infarction (AMI) was observed, but the risk factors were rarely included.

Objectives

The authors sought to examine AMI's cold and heat exposure after considering their risk groups.

Methods

Daily data on ambient temperature, newly diagnosed AMI, and 6 known risk factors of AMI for the Taiwan population from 2000 to 2017 were created by linking 3 Taiwan national databases. Hierarchical clustering analysis was performed. Poisson regression was performed on the AMI rate with the clusters along with the daily minimum temperature in cold months (November-March) and the daily maximum temperature in hot months (April-October).

Results

There were 319,737 patients with new-onset AMI over 109.13 billion person-days, corresponding to the incidence rate of 107.02 per 100,000 person-years (95% CI: 106.64-107.39 person-years). Hierarchical clustering analysis identified 3 distinct clusters (1: age <50 years, 2: age ≥50 years without hypertension, and 3: mainly age ≥50 years with hypertension) with AMI incidence rates of 16.04, 105.13, and 388.17 per 100,000 person-years, respectively. Poisson regression revealed that below 15 °C, cluster 3 had the highest risk of AMI per 1°C reduce in temperature (slope = 1.011) compared with clusters 1 (slope = 0.974) and 2 (slope = 1.009). However, above the 32 °C thresholds, cluster 1 had the highest risk of AMI per 1 °C increase in temperature (slope = 1.036) compared with clusters 2 (slope = 1.02) and 3 (slope = 1.025). Cross validation showed a good fit for the model.

Conclusions

People ≥50 years of age with hypertension are more susceptible to cold-related AMI. However, heat-related AMI is more prominent in individuals <50 years of age.

Blood pressure variability: methodological aspects, clinical relevance and practical indications for management - a European Society of Hypertension position paper ∗

Blood pressure is not a static parameter, but rather undergoes continuous fluctuations over time, as a result of the interaction between environmental and behavioural factors on one side and intrinsic cardiovascular regulatory mechanisms on the other side. Increased blood pressure variability (BPV) may indicate an impaired cardiovascular regulation and may represent a cardiovascular risk factor itself, having been associated with increased all-cause and cardiovascular mortality, stroke, coronary artery disease, heart failure, end-stage renal disease, and dementia incidence. Nonetheless, BPV was considered only a research issue in previous hypertension management guidelines, because the available evidence on its clinical relevance presents several gaps and is based on heterogeneous studies with limited standardization of methods for BPV assessment. The aim of this position paper, with contributions from members of the European Society of Hypertension Working Group on Blood Pressure Monitoring and Cardiovascular Variability and from a number of international experts, is to summarize the available evidence in the field of BPV assessment methodology and clinical applications and to provide practical indications on how to measure and interpret BPV in research and clinical settings based on currently available data. Pending issues and clinical and methodological recommendations supported by available evidence are also reported. The information provided by this paper should contribute to a better standardization of future studies on BPV, but should also provide clinicians with some indications on how BPV can be managed based on currently available data.

Ambient temperature and ambulatory blood pressure: An hourly-level, longitudinal panel study

BACKGROUND

Variations of blood pressure (BP) related to air temperature have been reported previously; however, no evidence is available regarding the association of hourly ambient temperature with ambulatory blood pressure.

METHODS

We conducted a longitudinal panel study among 1895 patients from an outpatient department who received repeated ambulatory blood pressure monitoring in Urumqi, China between July 2020 and December 2021. We obtained hourly ambient temperature from the nearest monitoring station to the residential address, and measured 4 ambulatory blood pressure indicators. Linear mixed-effect model combined with distributed lag models were applied to investigate the cumulative associations of hourly temperature with BP.

RESULTS

A total of 97,466 valid blood pressure measurements were evaluated. We observed almost linear and monotonically decreasing relationships between temperature and blood pressure. The effects occurred in the same hour, attenuated thereafter and became insignificant approximately 36 h. A 10 °C decrease in temperature was significantly associated with increments of 0.84 mmHg in systolic blood pressure, 0.56 mmHg in diastolic blood pressure, 1.38 mmHg in mean arterial pressure, and 0.66 mmHg in pulse pressure over lag 0 to 36 h. Stronger associations were found among patients of female sex, age between 18 and 65 years, overweight or obesity, minority, less education or in the cold season, as well as those without hypertension or with coronary heart disease, or did not take anti-hypertension medication.

CONCLUSION

Our study provides robust evidence that hourly ambient temperature is inversely associated with ambulatory blood pressure. It also highlights a linear relationship between decreased ambient temperature and elevated BP, which may have implications for the prevention and management of hypertension in susceptible populations.

Seasonality in nighttime blood pressure and its associations with target organ damage

There is some evidence that nighttime blood pressure varies between seasons. In the present analysis, we investigated the seasonal variation in ambulatory nighttime blood pressure and its associations with target organ damage. In 1054 untreated patients referred for ambulatory blood pressure monitoring, we performed measurements of urinary albumin-to-creatinine ratio (ACR, n = 1044), carotid-femoral pulse wave velocity (cfPWV, n = 1020) and left ventricular mass index (LVMI, n = 622). Patients referred in spring (n = 337, 32.0%), summer (n = 210, 19.9%), autumn (n = 196, 18.6%) and winter (n = 311, 29.5%) had similar 24-h ambulatory systolic/diastolic blood pressure (P ≥ 0.25). However, both before and after adjustment for confounding factors, nighttime systolic/diastolic blood pressure differed significantly between seasons (P < 0.001), being highest in summer and lowest in winter (adjusted mean values 117.0/75.3 mm Hg vs. 111.4/71.1 mm Hg). After adjustment for confounding factors, nighttime systolic/diastolic blood pressure were significantly and positively associated with ACR, cfPWV and LVMI (P < 0.006). In season-specific analyses, statistical significance was reached for all the associations of nighttime blood pressure with target organ damage in summer (P ≤ 0.02), and for some of the associations in spring, autumn and winter. The association between nighttime systolic blood pressure and ACR was significantly stronger in patients examined in summer than those in winter (standardized β, 0.31 vs 0.11 mg/mmol, P for interaction = 0.03). In conclusion, there is indeed seasonality in nighttime blood pressure level, as well as in its association with renal injury in terms of urinary albumin excretion. Our study shows that there is indeed seasonal variability in nighttime blood pressure, highest in summer and lowest in winter, and its association with renal injury in terms of urinary albumin excretion varies between summer and winter as well.

Temperature, cardiovascular mortality, and the role of hypertension and renin-angiotensin-aldosterone axis in seasonal adversity: a narrative review

Environmental temperature is now well known to have a U-shaped relationship with cardiovascular (CV) and all-cause mortality. Both heat and cold above and below an optimum temperature, respectively, are associated with adverse outcomes. However, cold in general and moderate cold specifically is predominantly responsible for much of temperature-attributable adversity. Importantly, hypertension-the most important CV risk factor-has seasonal variation such that BP is significantly higher in winter. Besides worsening BP control in established hypertensives, cold-induced BP increase also contributes to long-term BP variability among normotensive and pre-hypertensive patients, also a known CV risk factor. Disappointingly, despite the now well-stablished impact of temperature on BP and on CV mortality separately, direct linkage between seasonal BP change and CV outcomes remains preliminary. Proving or disproving this link is of immense clinical and public health importance because if seasonal BP variation contributes to seasonal adversity, this should be a modifiable risk. Mechanistically, existing evidence strongly suggests a central role of the sympathetic nervous system (SNS), and secondarily, the renin-angiotensin-aldosterone axis (RAAS) in mediating cold-induced BP increase. Though numerous other inflammatory, metabolic, and vascular perturbations likely also contribute, these may also well be secondary to cold-induced SNS/RAAS activation. This review aims to summarize the current evidence linking temperature, BP and CV outcomes. We also examine underlying mechanisms especially in regard to the SNS/RAAS axis, and highlight possible mitigation measures for clinicians.

Non-optimum temperature increases risk and burden of acute myocardial infarction onset: A nationwide case-crossover study at hourly level in 324 Chinese cities

BACKGROUND

The associations of ambient temperature with acute myocardial infarction (AMI) have seldom been examined based on the time of symptom onset.

METHODS

We conducted a time-stratified case-crossover study among 1,046,773 eligible AMI patients from 2,093 hospitals in 324 Chinese cities from January 1, 2015 to June 30, 2021, after excluding those transferred from other hospitals or having not reported the time of symptom onset. Hourly exposure to ambient temperature was calculated as multiple moving 24-h averages (days) before hourly onset of AMI symptoms. Conditional logistic regression and distributed lag non-linear models with a duration of 0-21 days were used to estimate the cumulative associations of non-optimum temperature with AMI onset and the corresponding disease burden nationally. Subgroup analyses by region and period were conducted. Specifically, cities with and without centralized heating system were classified into heating and non-heating regions, respectively. The whole year in heating region was divided into heating and non-heating periods based on the duration of centralized heating in each city.

FINDINGS

Almost monotonically increasing risks were observed for both overall AMI and its two subtypes when ambient temperature declined. The effects of extremely low temperature occurred immediately on the concurrent day, and lasted up to almost 3 weeks. The excess risks of AMI onset associated with non-optimum ambient temperatures were observed during the whole year in the non-heating region and non-heating period in the heating region, but not during heating period. Specifically, odds ratios of AMI onset associated with extremely low temperature cumulated over 0-21 days were 1.24 (95% CI: 1.13-1.37), 1.46 (95% CI: 1.20-1.76), and 1.62 (95% CI: 1.46-1.81) in the heating region during non-heating period, in the non-heating region during winter and non-winter period, respectively. The heat effects on AMI onset were very modest and transient. Totally, 13.26% of AMI cases could be attributable to non-optimum temperatures nationally. The burden of AMI attributable to non-optimum temperature was much smaller in heating region than in non-heating region. Somewhat stronger effects were observed in females and patients aged older than 65.

INTERPRETATION

This nationwide study provided robust evidence that non-optimum ambient temperature may significantly trigger AMI onset, and for the first time estimated the disease burden after accounting for spatial and seasonal heterogeneity. Centralized heating might substantially mitigate AMI burden due to non-optimum temperature.

FUNDING

Shanghai International Science and Technology Partnership Project, National Natural Science Foundation of China, Talent Training Program of Zhongshan Hospital, Fudan University.

Analysis of Variation in Incidence of Optic Disc Hemorrhage According to Seasonal and Temperature Changes

PURPOSE

To investigate seasonal variation in optic disc hemorrhage (DH) by review of fundus photographs representative of 2 calendar years (2019 and 2020).

DESIGN

Retrospective, observational trend study.

METHODS

Patients who visited the Glaucoma Clinic of Seoul National University Hospital and underwent fundus photography were included. All available stereo disc photographs and red-free retinal nerve fiber layer photographs taken between January 1, 2019 and December 31, 2020 were retrospectively reviewed. The monthly incidence rate of DH was determined by reference to the photographs. Seasonal temperature information and patients' intraocular pressure (IOP) information were obtained, organized, and analyzed.

RESULTS

Fundus images of 13,514 eyes were reviewed, and 454 eyes were confirmed to have DH. Poisson regression analyses revealed that as the temperature (T) increased by 1 °C, the DH risk ratio was reduced to 0.979 (95% confidence interval [CI] 0.969-0.989, P < .01). The DH incidence ratio was 1.53 (95% CI 1.23-1.91, P < .01) for the T <10 °C group relative to the T ≥20 °C group. The IOP of the patients with DH in winter was significantly higher than that measured in summer.

CONCLUSION

DH is affected by temperature, and as such, shows seasonal variability. This variability is believed to be caused by temperature-related factors such as IOP or hematological factors. © 2022 Elsevier Inc. All rights reserved.

Morning blood pressure surge in renal transplant recipients: Its relation to graft function and arterial stiffness

BACKGROUND

When the blood pressure rises before awakening in the morning, it is called as morning blood pressure pulse (MBPS). MBPS is considered to be an independent risk factor for cardiovascular disease. The aim of this study was to investigate the associations between MBPS, graft function, arterial stiffness and echocardiographic indicies in renal transpant recipients.

METHODS

Among 600 renal transplant recipients, 122 patients who had a history of hypertension and were taking at least one antihypertensive medication were enrolled in the study. Arterial stiffness was measured by carotid-femoral pulse wave velocity (PWv), and echocardiographic indicies were assessed. 24 hour ambulatory blood pressure was monitored for all patients. MBPS was calculated by substracting morning systolic blood pressure from minimal asleep systolic blood pressure.

RESULTS

Mean morning, day time and asleep systolic blood pressure values were 171.2± 23.9, 137.9± 18.1, and 131.7 ± 18.9 respectively. Non-dipper hypertention status was observed in 93 patients. Mean MBPS was 35.6 ± 19.5 mm Hg, mean PWv was 6.5 ± 2.0 m/sec. Patients with MBPS ≥ 35 mm Hg, had significantly lower eGFR and higher proteinuria, PWv. higher left atrium volume and LVMI. In regression analysis, day time systolic blood pressure, asleep systolic blood pressure, morning blood pressure surge, non-dipper status and left ventricular mass index were detected as the predictors of graft function.

CONCLUSIONS

Increased morning blood pressure surge is associated with graft dysfunction, increased arterial stiffness and LVMI that contributes to cardiovascular mortality and morbidity in renal transplant recipients. This article is protected by copyright. All rights reserved.

Impact of weather changes on hospital admissions for hypertension

Blood pressure (BP) shows a seasonal variation with higher levels at lower temperatures. Many hypertensives, however, report on BP disturbances rather in association with acutely changing weather conditions than with absolute temperatures. To date, the impact of changing meteorological parameters on hypertensive episodes remains elusive. We performed a retrospective time series regression analysis on 203,703 patients in three hospitals in Germany between 2010 and 2018, of whom 7362 patients were admitted for hypertensive disease. Numbers of daily admissions for hypertension were associated with metereological data obtained from three nearby weather stations. Data comprised temperature (mean, maximal, minimal and range within 24 h), athmospheric pressure, and precipitation. Changes of these parameters were calculated over a two and three day period. There was an inverse correlation between maximal daily temperature and the number of admissions for hypertensive disease, which remained significant both after adjustment for seasonality and week day in a spline model and in a constrained distributed lag model. A decrease of maximal temperature by 5 °C was associated with a 3% increase of risk for admission for hypertension and vice versa. There were no significant effects of precipitation and athmospheric pressure on the number of admissions. With regard to all observed metereological parameters, neither the change within two, nor within three days was consistently associated with the number of daily admissions. High temperatures are associated with lower numbers of hypertensive episodes requiring hospital admission. In contrast to the subjective perception of many hypertensive patients, however, acutely changing weather conditions are not associated with a higher risk of hypertensive emergency.

Climatic influences on cardiovascular diseases

Classical risk factors only partially account for variations in cardiovascular disease incidence; therefore, also other so far unknown features, among which meteorological factors, may influence heart diseases (mainly coronary heart diseases, but also heart failure, arrhythmias, aortic dissection and stroke) rates. The most studied phenomenon is ambient temperature. The relation between mortality, as well as cardiovascular diseases incidence, and temperature appears graphically as a ‘‘U’’ shape. Exposure to cold, heat and heat waves is associated with an increased risk of acute coronary syndromes. Other climatic variables, such as humidity, atmospheric pressure, sunlight hours, wind strength and direction and rain/snow precipitations have been hypothesized as related to fatal and non-fatal cardiovascular diseases incidence. Main limitation of these studies is the unavailability of data on individual exposure to weather parameters. Effects of weather may vary depending on other factors, such as population disease profile and age structure. Climatic stress may increase direct and indirect risks to human health via different, complex pathophysiological pathways and exogenous and endogenous mechanisms. These data have attracted growing interest because of the recent earth’s climate change, with consequent increasing ambient temperatures and climatic fluctuations. This review evaluates the evidence base for cardiac health consequences of climate conditions, and it also explores potential further implications.

Relationship of Ambient Temperature Parameters to Stroke Incidence in a Japanese Population - Takashima Stroke Registry, Japan, 1988-2010

BACKGROUND

Using a population-based stroke registry system, we evaluated the relationship between ambient temperature parameters and stroke incidence in a Japanese population.

METHODS AND RESULTS

We analyzed data from the Takashima Stroke Registry, which records all stroke occurrences in Takashima City, Japan. The study period of 8,401 days was divided into quintiles of daily weather parameters, and the middle quintile was used as the reference category. Incidence rates (IR per 100,000 person-years) were calculated across the quintiles. Poisson regression analysis was used to calculate the effect of temperature parameters on stroke incidence. There were 2,405 first-ever strokes (1,294 men), including 1,625 ischemic, 545 cerebral hemorrhages, 213 subarachnoid hemorrhages, and 22 unclassified strokes. The stroke IR was higher in the middle quintile of average temperature, 357.3 (328.4-388.8), and for other parameters. After adjustment for age and sex, for all stroke, the incidence rate ratio (IRR) in the highest (Q5: IRR 0.81, 95% confidence interval (CI) 0.71-0.92) and the second-highest (Q4: IRR 0.80, 95% CI 0.71-0.91) quintile was lower than that in the middle quintile (Q3: Reference). Analogous results were observed for the minimum, maximum, and lag-days temperatures, also in the subtypes and across ≥65 years of age, also in females.

CONCLUSIONS

Higher temperatures, irrespective of the parameter (average, minimum, or maximum), had a protective effect against stroke occurrence in Japan.

Effects of temperature and humidity on acute myocardial infarction hospitalization in a super-aging society

Weather conditions affect the incidence of acute myocardial infarction (AMI). However, little is known on the association of weather temperature and humidity with AMI hospitalizations in a super-aging society. This study sought to examine this association. We included 87,911 consecutive patients with AMI admitted to Japanese acute-care hospitals between April 1, 2012 and March 31, 2015. The primary outcome was the number of AMI hospitalizations per day. Multilevel mixed-effects linear regression models were used to estimate the association of the average temperature and humidity, 1 day before hospital admission, with AMI hospitalizations, after adjusting for weather, hospital, and patient demographics.Lower temperature and humidity were associated with an increased number of AMI hospitalizations (coefficient − 0.500 [− 0.524 to − 0.474] per °C change, p < 0.001 and coefficient − 0.012 [− 0.023 to − 0.001] per % change, p = 0.039, respectively). The effects of temperature and humidity on AMI hospitalization did not differ by age and sex (all interaction p > 0.05), but differed by season. However, higher temperatures in spring (coefficient 0.089 [0.025 to 0.152] per °C change, p = 0.010) and higher humidity in autumn (coefficient 0.144 [0.121 to 0.166] per % change, p < 0.001) were risk factors for AMI hospitalization. Increased average temperatures and humidity, 1 day before hospitalization, are associated with a decreased number of AMI hospitalizations.

Seasonal variation in blood pressure: current evidence and recommendations for hypertension management

Blood pressure (BP) exhibits seasonal variation, with an elevation of daytime BP in winter and an elevation of nighttime BP in summer. The wintertime elevation of daytime BP is largely attributable to cold temperatures. The summertime elevation of nighttime BP is not due mainly to temperature; rather, it is considered to be related to physical discomfort and poor sleep quality due to the summer weather. The winter elevation of daytime BP is likely to be associated with the increased incidence of cardiovascular disease (CVD) events in winter compared to other seasons. The suppression of excess seasonal BP changes, especially the wintertime elevation of daytime BP and the summertime elevation of nighttime BP, would contribute to the prevention of CVD events. Herein, we review the literature on seasonal variations in BP, and we recommend the following measures for suppressing excess seasonal BP changes as part of a regimen to manage hypertension: (1) out-of-office BP monitoring, especially home BP measurements, throughout the year to evaluate seasonal variations in BP; (2) the early titration and tapering of antihypertensive medications before winter and summer; (3) the optimization of environmental factors such as room temperature and housing conditions; and (4) the use of information and communication technology-based medicine to evaluate seasonal variations in BP and provide early therapeutic intervention. Seasonal BP variations are an important treatment target for the prevention of CVD through the management of hypertension, and further research is necessary to clarify these variations.

Electrocardiogram abnormalities in residents in cold homes: a cross-sectional analysis of the nationwide Smart Wellness Housing survey in Japan

Background

Excess winter mortality caused by cardiovascular disease is particularly profound in cold houses. Consistent with this, accumulating evidence indicates that low indoor temperatures at home increase blood pressure. However, it remains unclear whether low indoor temperatures affect other cardiovascular biomarkers. In its latest list of priority medical devices for management of cardiovascular diseases, the World Health Organization (WHO) included electrocardiography systems as capital medical devices. We therefore examined the association between indoor temperature and electrocardiogram findings.

Methods

We collected electrocardiogram data from 1480 participants during health checkups. We also measured the indoor temperature in the living room and bedroom for 2 weeks in winter, and divided participants into those living in warm houses (average exposure temperature ≥ 18 °C), slightly cold houses (12–18 °C), and cold houses (< 12 °C) in accordance with guidelines issued by the WHO and United Kingdom. The association between indoor temperature (warm vs. slightly cold vs. cold houses) and electrocardiogram findings was analyzed using multivariate logistic regression models, with adjustment for confounders such as demographics (e.g., age, sex, body mass index, household income), lifestyle (e.g., eating habit, exercise, smoking, alcohol drinking), and region.

Results

The average temperature at home was 14.7 °C, and 238, 924, and 318 participants lived in warm, slightly cold, and cold houses, respectively. Electrocardiogram abnormalities were observed in 17.6%, 25.4%, and 30.2% of participants living in warm, slightly cold, and cold houses, respectively (p = 0.003, chi-squared test). Compared to participants living in warm houses, the odds ratio of having electrocardiogram abnormalities was 1.79 (95% confidence interval: 1.14–2.81, p = 0.011) for those living in slightly cold houses and 2.18 (95% confidence interval: 1.27–3.75, p = 0.005) for those living in cold houses.

Conclusions

In addition to blood pressure, living in cold houses may have adverse effects on electrocardiogram. Conversely, keeping the indoor thermal environment within an appropriate range through a combination of living in highly thermal insulated houses and appropriate use of heating devices may contribute to good cardiovascular health.

Trial registration

The trial was retrospectively registered on 27 Dec 2017 to the University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR, https://www.umin.ac.jp/ctr/, registration identifier number UMIN000030601).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-021-01024-1.

Association between winter cold spells and acute myocardial infarction in Lithuania 2000-2015

Acute myocardial infarction (AMI) is a major public health problem. Cold winter weather increases the risk of AMI, but factors influencing susceptibility are poorly known. We conducted an individual-level case-crossover study of the associations between winter cold spells and the risk of AMI, with special focus on survival at 28 days and effect modification by age and sex. All 16,071 adult cases of AMI among the residents of the city of Kaunas in Lithuania in 2000-2015 were included in the study. Cold weather was statistically defined using the 5th percentile of frequency distribution of daily mean temperatures over the winter months. According to conditional logistic regression controlling for time-varying and time-invariant confounders, each additional cold spell day during the week preceding AMI increased the risk of AMI by 5% (95% CI 1-9%). For nonfatal and fatal cases, the risk increase per each additional cold spell day was 5% (95% CI 1-9%) and 6% (95% CI - 2-13%), respectively. The effect estimate was greater for men (OR 1.07, 95% CI 1.02-1.12) than for women (OR 1.02, 95% CI 0.97-1.08), but there was no evidence of effect modification by age. Evidence on factors increasing susceptibility is critical for targeted cold weather planning.

The “Inverse” Seasonal Blood Pressure Variability Phenotype

The seasonal blood pressure variability (BPV) is known to demonstrate a typical winter peak. Recently, more attention is paid to the opposite situation: the summer BP levels being higher than those in winter. This phenomenon is called inverse BPV. The present article summarizes recent data on this topic. The data of the HOMED-BP project, as well as the results of the original prospective study in 770 hypertensive patients from two Russian Federation regions (mean follow-up duration 6.4 years), were used. According to the preliminary knowledge, the prevalence of inverse BPV in hypertensive patients is relatively high (15-25%). This phenomenon is more typical for treated patients, particularly for those on combination therapy, and is associated with beta-blocker intake. Higher duration of hypertension and higher levels of some risk factors (smoking) characterize the patients with inverse BPV. According to the HOMED-BP data, patients with inverse BPV had the highest overall cardiovascular risk (hazard ratio in comparison with the reference group of “minimal” “normal” BPV was 3.07; p=0.004). In summary, inverse BPV is a potentially unfavorable BP phenotype. However, its reproducibility and prospective value deserve further investigation. The absolute magnitude of seasonal BPV in these patients, calculated using different BP measurement methods, warrants special attention.

Seasonal Variation in Masked Nocturnal Hypertension: The J-HOP Nocturnal Blood Pressure Study

BACKGROUND

Little is known about seasonal variation in nighttime blood pressure (BP) measured by a home device. In this cross-sectional study, we sought to assess seasonal variation in nighttime home BP using data from the nationwide, practice-based Japan Morning Surge-Home BP (J-HOP) Nocturnal BP study.

METHODS

In this study, 2,544 outpatients (mean age 63 years; hypertensives 92%) with cardiovascular risks underwent morning, evening, and nighttime home BP measurements (measured at 2:00, 3:00, and 4:00 am) using validated, automatic, and oscillometric home BP devices.

RESULTS

Our analysis showed that nighttime home systolic BP (SBP) was higher in summer than in other seasons (summer, 123.3 ± 14.6 mmHg vs. spring, 120.7 ± 14.8 mmHg; autumn, 121.1 ± 14.8 mmHg; winter, 119.3 ± 14.0 mmHg; all P<0.05). Moreover, we assessed seasonal variation in the prevalence of elevated nighttime home SBP (≥120 mmHg) in patients with non-elevated daytime home SBP (average of morning and evening home SBP <135 mmHg; n = 1,565), i.e., masked nocturnal hypertension, which was highest in summer (summer, 45.6% vs. spring, 27.2%; autumn, 28.8%; winter, 24.9%; all P<0.05). Even in intensively controlled morning home SBP (<125 mmHg), the prevalence of masked nocturnal hypertension was higher in summer (summer, 27.4% vs. spring, 14.2%; autumn, 8.9%; winter, 9.0%; all P<0.05). The urine albumin-creatinine ratio in patients with masked nocturnal hypertension tended to be higher than that in patients with non-elevated both daytime and nighttime SBP throughout each season.

CONCLUSIONS

The prevalence of masked nocturnal hypertension was higher in summer than other seasons and the difference proved to be clinically meaningful.

Heat wave characteristics, mortality and effect modification by temperature zones: a time-series study in 130 counties of China

BACKGROUND

The substantial disease burden attributed to heat waves, and their increasing frequency and intensity due to climate change, highlight the importance of understanding the health consequences of heat waves. We explore the mortality risk due to heat wave characteristics, including the timing in the seasons, the day of the heat wave, the intensity and the duration, and the modifying effect of temperature zones.

METHODS

Heat waves were defined as ≥ 2 days with a temperature ≥99th percentile for the county from 1 May through 30 September. Heat waves were characterized by their intensity, duration, timing in the season, and day of the heat wave. Within each county, we estimated the total non-accidental death and cardiovascular disease mortality during each heat wave compared with non-heat wave days by controlling for potential confounders in summer. We combined individual heat wave effect estimates using a random-effects model to calculate overall effects at the temperature zone and national levels.

RESULTS

The average daily total number of non-accidental deaths was nine in the warm season (across all the counties). Approximately half of the daily total number of non-accidental deaths were cardiovascular-related deaths (approximately four persons per day). The average and maximum temperatures across the study area were 23.1 °C (range: -1.2-35.9 °C) and 28.3 °C (range: 5.4-42.8 °C), respectively. The average relative humidity during the study was 68.9% (range: 8.0-100.0%). Heat waves increase the risk of total non-accidental death by 15.7% [95% confidence interval (CI): 12.5, 18.9] compared with non-heat wave periods, and the risk of cardiovascular-related death increases by 22.0% (95% CI: 16.9, 27.4). The risk of non-accidental death during the first heat wave of the season increases by 16.3% (95% CI: 12.6, 20.2), the risk during the second heat wave increases by 6.3% (95% CI: 2.8, 9.9) and during subsequent heat waves increases by -2.1% (95% CI: -4.6, 0.4). The first day and the second to third days of heat waves increase the risk of total non-accidental death by 11.7% (95% CI: 7.6, 15.9) and 17.0% (95% CI: 13.1, 21.0), respectively. Effects of heat waves on mortality lasted more than 4 days (6.3%, 95% CI: 2.4, 10.5) and are non-significantly different from the first day of heat waves. We found non-significant differences of the heat wave-associated mortality risks across mid-, warm and subtropical temperature zones.

CONCLUSIONS

In China, the effect of heat waves on mortality is acute, and varies by certain characteristics of heat waves. Given these results, national heat wave early warning systems should be developed, as well as precautions and protection warranted according to characteristics of heat waves.

Impact of ambient temperature on cardiovascular disease hospital admissions in farmers in China's Western suburbs

Cardiovascular disease (CVD) has been a major threat to global public health. The association between temperature and CVD has been widely studied and reported in cities in developed countries. However, information from developing countries, especially from suburbs and countryside, is quite limited. In this study, the daily time series data on CVD hospital admissions in farmers in the suburbs of Tianshui, China, and the meteorological data from 2012 to 2015, were collected; besides, a quasi-Poisson regression with a distributed-lag non-linear model (DLNM) was used to explore the impact of local daily mean temperature on CVD hospital admissions in suburban farmers. This study found that, first, from 2011 to 2015, a total of 30,611 person-times of CVD hospital admissions in farmers were recorded; second, there was a "J-shaped" relation between temperature and CVD hospital admissions, and both low and high temperature increased the risk of hospital admission, but the impact of high temperature was greater; third, compared with the minimum hospitalization temperature (MHT) at 0.3 °C, during 0 to 21 lag days, the cumulative relative risk (RR) for extreme cold and heat (1st and 99th percentile of temperature, respectively) was 1.117 (95% CI 0.941-1.325) and 1.740 (95% CI 1.302-2.327), respectively, and that of moderate cold and heat (5st and 95th percentile of temperature, respectively) was 1.029 (95% CI 0.958-1.106) and 1.572 (95% CI 1.210-2.042), respectively; fourth, compared with male and ≥ 65 years groups, the risk for low temperature was greater for female and < 65 years groups, the risk for high temperature was just the opposite; last, about 21.04% of CVD hospital admissions burden were attributed to the ambient temperature, and most of (about 19.26%) were caused by moderate heat. In Tianshui, alongside with extreme temperature, the moderate temperature might be an important risk factor for CVD hospital admissions in suburban farmers.

Impact of indoor temperature instability on diurnal and day-by-day variability of home blood pressure in winter: a nationwide Smart Wellness Housing survey in Japan

Home blood pressure (HBP) variability is an important factor for cardiovascular events. While several studies have examined the effects of individual attributes and lifestyle factors on reducing HBP variability, the effects of living environment remain unknown. We hypothesized that a stable home thermal environment contributes to reducing HBP variability. We conducted an epidemiological survey on HBP and indoor temperature in 3785 participants (2162 households) planning to have their houses retrofitted with insulation. HBP was measured twice in the morning and evening for 2 weeks in winter. Indoor temperature was recorded with each HBP observation. We calculated the morning-evening (ME) difference as an index of diurnal variability and the standard deviation (SD), coefficient of variation (CV), average real variability (ARV) and variability independent of the mean (VIM) as indices of day-by-day variability. The association between BP variability and temperature instability was analyzed using multiple linear regression models. The mean ME difference in indoor/outdoor temperature (a decrease in temperature overnight) was 3.2/1.5 °C, and the mean SD of indoor/outdoor temperature was 1.6/2.5 °C. Linear regression analyses showed that the ME difference in indoor temperature was closely correlated with the ME difference in systolic BP (0.85 mmHg/°C, p < 0.001). The SD of indoor temperature was also associated with the SD of systolic BP (0.61 mmHg/°C, p < 0.001). The CV, ARV, and VIM showed similar trends as the SD of BP. In contrast, outdoor temperature instability was not associated with either diurnal or day-by-day HBP variability. Therefore, residents should keep the indoor temperature stable to reduce BP variability.

Differences in ambulatory blood pressure profiles between Japanese and Thai patients with hypertension /suspected hypertension

Ethnic differences in the profiles of hypertension and cardiovascular risk have been reported between Asians and Westerners. However, blood pressure (BP) profiles and the risk factors for cardiovascular disease might differ even among different Asian populations because of the diversity of cultures, foods, and environments. We retrospectively examined differences in 24-h BP profiles between 1051 Japanese (mean age, 62.5 ± 12.4 years; medicated hypertension, 75.7%) and 804 Thai (mean age, 56.9 ± 18.5 years; medicated hypertension, 65.6%) by using the Japanese and Thai ambulatory BP monitoring (ABPM) databases, in order to check the BP control status in treated hypertensives and to inform the clinical diagnosis of hypertension. The two populations had similar office systolic BP (SBP) (142.7 ± 20.0 vs 142.3 ± 20.6 mm Hg, p = .679). However, the Japanese population had higher 24-hr average and daytime SBP, and the Thai population had higher nighttime SBP even after adjusting for cardiovascular risk factors (all p < .05). Greater morning BP surge was observed in Japanese (31.2 vs 22.8 mm Hg, p < .001). Regarding nocturnal BP dipping status, the prevalence of riser status (higher nighttime than daytime SBP) was higher in the Thai population (30.5% vs 10.9%). These findings suggest that a substantial difference in 24-hr BP profiles exists between even neighboring countries in Asia.

Effect of systemic blood pressure on optical coherence tomography angiography in glaucoma patients

BACKGROUND

The association between retinal microvascular structure and glaucoma has been revealed in multiple studies using optical tomography angiography (OCTA), but limited information on the macular vessel density (mVD) in patients with glaucoma is available. In this study, we tried to identity the factors that affected macular VD (mVD) in glaucomatous eyes.

METHODS

This retrospective cross-sectional study evaluated OCT and OCTA images from 92 eyes from 58 healthy subjects and 179 eyes from 103 glaucoma patients using the SD-OCT database from July 2017 to July 2018. Glaucomatous eyes were further divided into two groups according to history of disc haemorrhage (DH). Association between mVD and demographic characteristics, ganglion cell-inner plexiform layer (GCIPL) thickness, visual field mean deviation (MD) and systemic blood pressure was analysed in each group.

RESULTS

In both healthy and glaucomatous eyes, mVD was inversely associated with age (β = -0.035, P = 0.025; β = -0.039, P = 0.018). In the glaucomatous eyes, mVD was significantly decreased, as the MD value was worse (β = 0.109, P = 0.002). In glaucomatous eyes with DH, mVD decreased as blood pressure increased (β = -0.111, P = 0.003) CONCLUSIONS: Reduced mVD is more common in older individuals in both healthy and glaucomatous eyes, and correlates with functional deterioration than structural damage in glaucomatous eyes. In glaucomatous eyes with DH, high systemic BP is associated with a reduction in mVD. This may indicate that glaucoma patients with DH are more susceptible to vascular damage secondary to hypertension.

Management of Hypertension in the Digital Era: Small Wearable Monitoring Devices for Remote Blood Pressure Monitoring

Out-of-office blood pressure measurement is an essential part of diagnosing and managing hypertension. In the era of advanced digital health information technology, the approach to achieving this is shifting from traditional methods (ambulatory and home blood pressure monitoring) to wearable devices and technology. Wearable blood pressure monitors allow frequent blood pressure measurements (ideally continuous beat-by-beat monitoring of blood pressure) with minimal stress on the patient. It is expected that wearable devices will dramatically change the quality of detection and management of hypertension by increasing the number of measurements in different situations, allowing accurate detection of phenotypes that have a negative impact on cardiovascular prognosis, such as masked hypertension and abnormal blood pressure variability. Frequent blood pressure measurements and the addition of new features such as monitoring of environmental conditions allows interpretation of blood pressure data in the context of daily stressors and different situations. This new digital approach to hypertension contributes to anticipation medicine, which refers to strategies designed to identify increasing risk and predict the onset of cardiovascular events based on a series of data collected over time, allowing proactive interventions to reduce risk. To achieve this, further research and validation is required to develop wearable blood pressure monitoring devices that provide the same accuracy as current approaches and can effectively contribute to personalized medicine.

Impact of temperature decline from the previous day as a trigger of spontaneous subarachnoid hemorrhage: case-crossover study of prefectural stroke database

OBJECTIVE

Several environmental factors have been reported to correlate with incidence of spontaneous subarachnoid hemorrhage (SAH). However, because of different patient selection and study designs among these studies, meteorological factors that trigger the incidence of SAH in a short hazard period remain unknown. Among meteorological factors, daily temperature changes may disrupt and violate homeostasis and predispose to cerebrovascular circulatory disturbances and strokes. The authors aimed to investigate whether a decline in the temperature from the highest of the previous day to the lowest of the event day (temperature decline from the previous day [TDP]) triggers SAH in the prefecture-wide stroke database.

METHODS

All 28 participating institutions with primary or comprehensive stroke centers located throughout Kochi Prefecture, Japan, were included in the study. Data collected between January 2012 and December 2016 were analyzed, and 715 consecutive SAH patients with a defined date of onset were enrolled. Meteorological data in this period were obtained from the Kochi Local Meteorological Observatory. A case-crossover study was performed to investigate association of TDP and other environmental factors with onset of SAH.

RESULTS

The increasing TDP in 1°C on the day of the SAH event was associated with an increased incidence of SAH (OR 1.041, 95% CI 1.007-1.077) after adjustment for other environmental factors. According to the stratified analysis, a significant association between TDP and SAH was observed in women, patients < 65 years old, and patients with weekday onset. Among these factors, increasing TDP had a great impact on SAH onset in patients < 65 years old (p = 0.028, Mann-Whitney U-test).

CONCLUSIONS

TDP, temperature decline from the highest of the previous day to the lowest of the day, was correlated with the incidence of spontaneous SAH, particularly in younger patients < 65 years old.

Meteorological rhythms of respiratory and circulatory diseases revealed by Harmonic Analysis

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

'My blood pressure is low today, do you have the heating on?' The association between indoor temperature and blood pressure

OBJECTIVES

The independent association of indoor temperature with blood pressure (BP) is poorly understood and is not routinely considered in hypertension diagnosis or research. Questions remain as to whether the effect of indoor temperature on BP is confounded or modified by other factors.

METHODS

This study used data from the Health Survey for England 2014, consisting of 4659 community-dwelling adults aged 16 years and over, interviewed from January to December. Multivariable regression models were used to determine whether indoor temperature was related to levels of BP, and whether these relationships were confounded by other factors, including mean monthly outdoor temperature.

RESULTS

After controlling for confounding variables, a 1°C decrease in indoor temperature was associated with rises of 0.48 mmHg (95% confidence interval: -0.72 to -0.25) in SBP and 0.45 mmHg (95% confidence interval: -0.63 to -0.27) in DBP. The magnitude of association of indoor temperature with DBP and SBP was modified by physical activity. The indoor temperature-BP relationship was stronger in people who do not take physical activity regularly than people who exercise regularly.

CONCLUSION

The size of the independent association between indoor temperature and BP suggests it should be considered in the clinical management of hypertension and in hypertension research. Room temperature should also be considered as a modifiable risk factor in hypertension-related mortality and morbidity.

Associations of drinking rainwater with macro-mineral intake and cardiometabolic health: a pooled cohort analysis in Bangladesh, 2016-2019

This study explores the associations of drinking rainwater with mineral intake and cardiometabolic health in the Bangladeshi population. We pooled 10030 person-visit data on drinking water sources, blood pressure (BP) and 24-h urine minerals. Fasting blood glucose (FBG) was measured in 3724 person-visits, and lipids in 1118 person-visits. We measured concentrations of sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) in 253 rainwater, 935 groundwater and 130 pond water samples. We used multilevel linear or gamma regression models with participant-, household- and community-level random intercepts to estimate the associations of rainwater consumption with urine minerals and cardiometabolic biomarkers. Rainwater samples had the lowest concentrations of Na, K, Ca and Mg. Rainwater drinkers had lower urine minerals than coastal groundwater drinkers: -13.42 (95% CI: -18.27, -8.57) mmol Na/24 h, -2.00 (95% CI: -3.16, -0.85) mmol K/24 h and -0.57 (95% CI: -1.02, -0.16) mmol Mg/24 h. The ratio of median 24-hour urinary Ca for rainwater versus coastal groundwater drinkers was 0.72 (95% CI: 0.64, 0.80). Rainwater drinkers had 2.15 (95% CI: 1.02, 3.27) mm Hg higher systolic BP, 1.82 (95% CI: 1.19, 2.54) mm Hg higher diastolic BP, 0.59 (95% CI: 0.17, 1.01) mmol/L higher FBG and -2.02 (95% CI: -5.85, 0.81) mg/dl change in high-density lipoprotein cholesterol compared with the coastal groundwater drinkers. Drinking rainwater was associated with worse cardiometabolic health measures, which may be due to the lower intake of salubrious Ca, Mg and K.

The influence of the ambient temperature on blood pressure and how it will affect the epidemiology of hypertension in Asia

Epidemiologic studies have consistently demonstrated an increased risk of cardiovascular disease during colder temperatures. Hemodynamic changes associated with cold temperature and an increase in thrombogenicity may both account for the increase in cardiovascular risk and mortality. Studies using both in-office and out-of-office BP measurements have consistently shown an elevation in BP during the colder seasons. The large difference in BP between cold and warm months may increase the incidence of hypertension and reduce the hypertension control rate, potentially resulting in increased cardiovascular risk, especially among those at risk of cardiovascular disease. The current trends in global warming and climate change may have a profound impact on the epidemiology of hypertension and cardiovascular disease, as changes in the climate may significantly affect both BP variability and cardiovascular disease, especially in those with high cardiovascular risk and the elderly. Furthermore, climate change could have a significant influence on hypertension in Asia, considering the unique characteristics of hypertensive patients in Asia. As an increase in ambient temperature decreases the mean daytime average and morning surge in BP, but increases the nocturnal BP, it is difficult to predict how environmental changes will affect the epidemiology and prognosis of hypertension in the Asian-Pacific region. However, these seasonal variations in BP could be minimized by adjusting the housing conditions and using anticipation medicine. In this review, we discuss the impact of seasonal variation in the ambient temperature on hypertension and cardiovascular disease and discuss how this may impact the epidemiology of hypertension and cardiovascular disease.

Temperature and Precipitation Associate With Ischemic Stroke Outcomes in the United States

Background

There is disagreement in the literature about the relationship between strokes and seasonal conditions. We sought to (1) describe seasonal patterns of stroke in the United States, and (2) determine the relationship between weather variables and stroke outcomes.

Methods and Results

We performed a cross‐sectional study using Get With The Guidelines‐Stroke data from 896 hospitals across the continental United States. We examined effects of season, climate region, and climate variables on stroke outcomes. We identified 457 638 patients admitted from 2011 to 2015 with ischemic stroke. There was a higher frequency of admissions in winter (116 862 in winter versus 113 689 in spring, 113 569 in summer, and 113 518 in fall; P<0.0001). Winter was associated with higher odds of in‐hospital mortality (odds ratio [OR] 1.08 relative to spring, confidence interval [CI] 1.04–1.13, P=0.0004) and lower odds of discharge home (OR 0.92, CI 0.91–0.94, P<0.0001) or independent ambulation at discharge (OR 0.96, CI 0.94–0.98, P=0.0006). These differences were attenuated after adjusting for climate region and case mix and became inconsistent after controlling for weather variables. Temperature and precipitation were independently associated with outcome after multivariable analysis, with increases in temperature and precipitation associated with lower odds of mortality (OR 0.95, CI 0.93–0.97, P<0.0001 and OR 0.95, CI 0.90–1.00, P=0.035, respectively).

Conclusions

Admissions for ischemic stroke were more frequent in the winter. Warmer and wetter weather conditions were independently associated with better outcomes. Further studies should aim to identify sensitive populations and inform public health measures aimed at resource allocation, readiness, and adaptive strategies.

Cross-Sectional Analysis of the Relationship Between Home Blood Pressure and Indoor Temperature in Winter

Mortality due to cardiovascular disease rises sharply in winter. Known as excess winter mortality, this phenomenon is partially explained by cold exposure-induced high blood pressure. Home blood pressure, especially in the morning, is closely associated with cardiovascular disease risk. We conducted the first large nationwide survey on home blood pressure and indoor temperature in 3775 participants (2095 households) who intended to conduct insulation retrofitting and were recruited by construction companies. Home blood pressure was measured twice in the morning and evening for 2 weeks. The relationship between home blood pressure and indoor temperature in winter was analyzed using a multilevel model with 3 levels: repeatedly measured day-level variables (eg, indoor ambient temperature and quality of sleep), nested within individual-level (eg, age and sex), and nested within household level. Cross-sectional analyses involving about 2900 participants (1840 households) showed that systolic blood pressure in the morning had significantly higher sensitivity to changes in indoor temperature (8.2 mm Hg increase/10°C decrease) than that in the evening (6.5 mm Hg increase/10°C decrease) in participants aged 57 years (mean age in this survey). We also found a nonlinear relationship between morning systolic blood pressure and indoor temperature, suggesting that the effect of indoor temperature on blood pressure varied depending on room temperature range. Interaction terms between age/women and indoor temperature were significant, indicating that systolic blood pressure in older residents and women was vulnerable to indoor temperature change. We expect that these results will be useful in determining optimum home temperature recommendations for men and women of each age group.

Clinical Trial Registration—

URL: http://www.umin.ac.jp/ctr/index.htm . Unique identifier: UMIN000030601.

Seasonal variation in 24 h blood pressure profile in healthy adults- A prospective observational study

The clinical and experimental data on seasonal variation in blood pressure is mainly from office and home blood pressure (BP) monitoring studies. There are few studies from temperate climates on seasonal changes with ambulatory blood pressure (ABP) monitoring and none from India. This is a prospective, observational study among healthy adults. ABP was measured in four different seasons in 28 subjects. Mean arterial pressure (MAP), ambulatory systolic blood pressure (SBP), and ambulatory diastolic blood pressure (DBP) were significantly higher in winter compared to summer season. 24-hour MAP was lowest in summer while highest MAP was recorded in winter (97.04 ± 8.30 and 103.89 ± 8.54, respectively). The mean difference was -6.86 mm Hg (95% CI: -10.74 to -2.97, p = 0.001). This difference was mainly due to increase in day time MAP. There was no difference in 24 h systolic and diastolic blood pressure between summer and winter. There was significant difference between summer and winter in the SBP (day time) [125.61 ± 11.44 and 131.93 ± 9.46, mean difference -6.32 (95% CI: -10.69 to -1.95, p = 0.005)] and DBP (day time) [79.57 ± 9.95 and 87.07 ± 9.9, mean difference -7.50 (95% CI: -12.49 to -2.51, p = 0.003)]. The night time systolic and diastolic BP was similar during winter and summer. Thus, BP increases significantly during winter compared to summer season. This change is primarily in the day time systolic, diastolic and mean blood pressures. Larger studies are required to further validate our findings.

Following in the footsteps of Hippocrates-interrelation between the incidence of odontogenic abscess and meteorological parameters

OBJECTIVES

Although many physicians in daily practice assume a connection between odontogenic infections and meteorological parameters, this has not yet been scientifically proven. Therefore, the aim of the present study was to evaluate the incidence of odontogenic abscess (OA) in relation to outdoor temperature and atmospheric pressure.

PATIENTS AND METHODS

An analysis of patients with an odontogenic abscess who presented at the emergency department within a period of 24 months was performed. Only patients who had not received surgical or antibiotic treatment prior to presentation and who lived in Berlin/Brandenburg were included. The OA incidence was correlated with the mean/maximum outdoor temperature and atmospheric pressure starting from 14 days before presentation. The statistical analysis was carried out using Poisson regression models with OA incidence as dependent and meteorological parameters as independent variables.

RESULTS

A total of 535 patients (mean age 39.4 years; range 1 to 95 years) with 538 cases were included. Of these, 227 were hospitalized. The most frequent diagnosis was a canine fossa abscess. A significant association between mean (p = 0.0153) and maximum temperature (p = 0.008) on the day of the presentation and abscess incidence was observed. Furthermore, a significant correlation between OA incidence and maximum temperature 2 days before presentation was found (p = 0.034). The deviation of the mean temperature on the day of the presentation from the monthly mean temperature had a significant influence (p = 0.021) on the incidence of OA. In contrast to temperature, atmospheric pressure had no significant influence on the incidence of OA.

CONCLUSION

This study supports a relationship between the incidence of odontogenic abscess and outdoor temperature, but not atmospheric pressure. A significantly higher frequency of patients with an OA presented at our emergency department on days with (comparably) low and high outdoor temperatures. Furthermore, a significant correlation between incidence and maximum temperature 2 days before presentation was found.

CLINICAL RELEVANCE

The treatment of odontogenic infections has become a significant economic burden to public health care facilities. The results of this study may help to adapt the numbers of doctors/dentists on duty in relation to different weather conditions. In any case, it is an impetus to think outside the box.

Labile hypertension: a new disease or a variability phenomenon?

Blood pressure (BP) is a physiological parameter with short- and long-term variability caused by complex interactions between intrinsic cardiovascular (CV) mechanisms and extrinsic environmental and behavioral factors. Available evidence suggests that not only mean BP values are important, but also BP variability (BPV) might contribute to CV events. Labile hypertension (HTN) is referred to sudden rises in BP and it seems to be linked with unfavorable outcomes. The aim of this article was to review and summarize recent evidence on BPV phenomenon, unraveling the labile HTN concept along with the prognostic value of these conditions.