Seasonal blood pressure variation assessed by different measurement methods: systematic review and meta-analysis

The effects of ambient temperature on non-accidental mortality in the elderly hypertensive subjects, a cohort-based study

BACKGROUND

The association between ambient temperature and mortality has yielded inconclusive results with previous studies relying on in-patient data to assess the health effects of temperature. Therefore, we aimed to estimate the effect of ambient temperature on non-accidental mortality among elderly hypertensive patients through a prospective cohort study conducted in northeastern China.

METHODS

A total of 9634 elderly hypertensive patients from the Kailuan research who participated in the baseline survey and follow-up from January 1, 2006 to December 31, 2017, were included in the study. We employed a Poisson generalized linear regression model to estimate the effects of monthly ambient temperature and temperature variations on non-accidental mortality.

RESULTS

After adjusting for meteorological parameters, the monthly mean temperature (RR = 0.989, 95% CI: 0.984-0.993, p < 0.001), minimum temperature (RR = 0.987, 95% CI: 0.983-0.992, p < 0.001) and maximum temperature (RR = 0.989, 95% CI: 0.985-0.994, p < 0.001) exhibited a negative association with an increased risk of non-accidental mortality. The presence of higher monthly temperature variation was significantly associated with an elevated risk of mortality (RR = 1.097, 95% CI:1.051-1.146, p < 0.001). Further stratified analysis revealed that these associations were more pronounced during colder months as well as among male and older individuals.

CONCLUSIONS

Decreased temperature and greater variations in ambient temperature were observed to be linked with non-accidental mortality among elderly hypertensive patients, particularly notable within aging populations and males. These understanding regarding the effects of ambient temperature on mortality holds clinical significance for appropriate treatment strategies targeting these individuals while also serving as an indicator for heightened risk of death.

Home blood pressure measurement and hypertension control according to the length of antihypertensive treatment among employees

This study aimed to investigate the association between the frequency of home blood pressure (HBP) measurement and hypertension control in a middle-aged working population. This study included 627 employees aged 40 years or older who underwent health check-ups for 2 consecutive years from 2019 to 2022 and had blood pressure (BP) ≥ 140/90 mmHg at the health check-up in the first year. The participants were stratified by the length of antihypertensive treatment (within 1 year, >1 year) using data in the first and second years, and were classified by the frequency of HBP measurement (<6 times/week, almost every day) using data in the second year. In each treatment length, logistic regression analyses were used to estimate multivariable adjusted odds ratios (ORs) of controlled hypertension (BP at health check-ups <140/90 mmHg in the second year) in those who measured HBP almost every day compared with those who measured HBP < 6 times/week. The ORs (95% confidence intervals) were 1.56 (0.94-2.73) in those within 1 year of starting treatment and 0.74 (0.44-1.22) in those with more than 1 year of starting treatment. In participants with BP ≥ 160/100 mmHg in the first year, the corresponding ORs were 1.94 (1.04-3.64) and 0.41 (0.13-1.23), respectively. In conclusion, in individuals within 1 year of starting treatment, those who measure HBP almost every day tend to have good control of hypertension. In particular, in those who have BP ≥ 160/100 mmHg before starting antihypertensive medication, measuring HBP almost every day is associated with good control of hypertension. Among those within 1 year of starting the treatment (Group1) especially in those with blood pressure ≥160/100 mmHg, the frequency of home blood pressure measurement was associated with hypertension control. It was not associated among those with more than 1 year of starting the treatment (Group 2).

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.

Age-dependent seasonality in the incidence of stroke: A 21-year population-based study

INTRODUCTION

Seasonality in the incidence of stroke has been examined in numerous studies, yet data on whether it differs with age are limited. To fill this gap, we utilized a largescale dataset from Israel.

PATIENTS AND METHODS

We retrieved data of all hospitalizations for ischemic stroke (IS), transient ischemic attack (TIA) and intra cerebral hemorrhage (ICH) from 2000 to 2020. We maintained separate datasets for IS/TIA and ICH, divided into five age groups: 18-49, 50-59, 60-69, 70-79, and 80+. We modeled the monthly incidence using a generalized additive model. The seasonal effect was defined by the rate ratio (RR) of each month compared to the annual mean.

RESULTS

The analysis included 317,586 and 23,789 events of IS/TIA and ICH respectively. We found an interaction between age and seasonality, accounting for a phase shift with age in the seasonal pattern of IS/TIA incidence. For cases under 70 years, the peak was during summertime and the RRs increased with decreasing age, reaching 1.11 (95% CI 1.09-1.13) at the youngest age group. In contrast, among the elderly, a winter peak was observed and the RRs increased with age to 1.07 (95% CI 1.06-1.08) at the oldest age group. For ICH, a winter/autumn peak was identified and the RRs increased with age to 1.20 (95% CI 1.16-1.24).

CONCLUSIONS

Our finding of age-dependent seasonal patterns in the occurrence of stroke, suggests closer monitoring of cardiovascular risk factors during wintertime among elderly individuals. The mechanism governing the seasonal phase shift with age in IS/TIA incidence, requires further investigation.

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.

Seasonal effects on blood pressure variability in treated hypertensive patients assessed by office, home, and ambulatory measurements

This study investigated the seasonal effect on blood pressure (BP) variability. Patients on stable antihypertensive drug treatment were assessed with office (OBP), home (HBP), and ambulatory BP (ABP) measurements in winter, next summer, and in next winter. Fifty-eight participants with full data for winter and summer were analyzed (mean age 65.2 ± 7.9 [SD], 64% males). OBP, HBP and ABP (24-h; daytime) were lower in summer than in winter (P < 0.01), whereas nighttime ABP was unchanged (p = NS). Standard deviation (SD), coefficient of variation (CV) and average real variability (ARV) for systolic OBP were higher in winter than summer (p < 0.01/ < 0.05/ < 0.01, respectively). These indices for HBP and ABP measurements did not differ in winter and summer (p = NS). Forty participants had complete data for winter-summer-next winter and HBP/ABP variability indices did not differ for both winters versus summer. These preliminary data suggest that BP variability is unaffected by seasonal changes in contrast to average BP levels.

Seasonal variations of the prevalence of metabolic syndrome and its markers using big-data of health check-ups

BACKGROUND

It is crucial to understand the seasonal variation of Metabolic Syndrome (MetS) for the detection and management of MetS. Previous studies have demonstrated the seasonal variations in MetS prevalence and its markers, but their methods are not robust. To clarify the concrete seasonal variations in the MetS prevalence and its markers, we utilized a powerful method called Seasonal Trend Decomposition Procedure based on LOESS (STL) and a big dataset of health checkups.

METHODS

A total of 1,819,214 records of health checkups (759,839 records for men and 1,059,375 records for women) between April 2012 and December 2017 were included in this study. We examined the seasonal variations in the MetS prevalence and its markers using 5 years and 9 months health checkup data and STL analysis. MetS markers consisted of waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), fasting plasma glucose (FPG).

RESULTS

We found that the MetS prevalence was high in winter and somewhat high in August. Among men, MetS prevalence was 2.64 ± 0.42 (mean ± SD) % higher in the highest month (January) than in the lowest month (June). Among women, MetS prevalence was 0.53 ± 0.24% higher in the highest month (January) than in the lowest month (June). Additionally, SBP, DBP, and HDL-C exhibited simple variations, being higher in winter and lower in summer, while WC, TG, and FPG displayed more complex variations.

CONCLUSIONS

This finding, complex seasonal variations of MetS prevalence, WC, TG, and FPG, could not be derived from previous studies using just the mean values in spring, summer, autumn and winter or the cosinor analysis. More attention should be paid to factors affecting seasonal variations of central obesity, dyslipidemia and insulin resistance.

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.

Seasonal variation in the incidence of primary intracerebral hemorrhage: a 16-year nationwide analysis

Introduction

Data on nationwide trends and seasonal variations in the incidence of Intracerebral Hemorrhage (ICH) in the United States (US) are lacking.

Methods

We used the Nationwide Inpatient Sample (2004-2019) and Census Bureau data to calculate the quarterly (Q1:January-March; Q2:April-June; Q3:July-September; Q4:October-December) incidence rates (IR) of adult (≥18 years) ICH hospitalizations, aggregated across Q1-Q4 and Q2-Q3. We report adjusted incidence rate ratios (aIRR) and 95% confidence intervals (CI) for differences in the quarterly incidence of ICH, as compared to acute ischemic stroke (AIS), between Q1Q4 and Q2Q3 using a multivariable Poisson regression model. We additionally performed stratified analyses across the four US regions.

Results

Among 822,143 (49.0% female) ICH and 6,266,234 (51.9% female) AIS hospitalizations, the average quarterly crude IR of ICH was consistently higher in Q1Q4 compared to Q2Q3 (5.6 vs. 5.2 per 100,000) (aIRR, CI: 1.09, 1.08-1.11)-this pattern was similar across all four US regions. However, a similar variation pattern was not observed for AIS incidence. The incidence (aIRR, CI) of both ICH (1.01, 1.00-1.02) and AIS (1.03, 1.02-1.03) is rising.

Conclusion

Unlike AIS, ICH incidence is consistently higher in colder quarters, underscoring the need for evaluation and prevention of factors driving seasonal variations in ICH incidence.

Seasonal variation in blood pressure control across US health systems

OBJECTIVE

We aimed to characterize seasonal variation in US population-based blood pressure (BP) control and BP-related metrics and evaluate the association between outdoor temperature and BP control variation.

METHODS

We queried electronic health records (EHRs) from 26 health systems, representing 21 states, to summarize BP metrics by quarters of 12-month periods from January 2017 to March 2020. Patients with at least one ambulatory visit during the measurement period and a hypertension diagnosis during the first 6 months or prior to the measurement period were included. Changes in BP control, BP improvement, medication intensification, average SBP reduction after medication intensification across quarters and association with outdoor temperature were analyzed using weighted generalized linear models with repeated measures.

RESULTS

Among 1 818 041 people with hypertension, the majority were more than 65 years of age (52.2%), female (52.1%), white non-Hispanic (69.8%) and had stage 1/2 hypertension (64.8%). Overall, BP control and process metrics were highest in quarters 2 and 3, and lowest in quarters 1 and 4. Quarter 2 had the highest percentage of improved BP (31.95 ± 0.90%) and average SBP reduction after medication intensification (16 ± 0.23 mmHg). Quarter 3 had the highest percentage of BP controlled (62.25 ± 2.55%) and lowest with medication intensification (9.73 ± 0.60%). Results were largely consistent in adjusted models. Average temperature was associated with BP control metrics in unadjusted models, but associations were attenuated following adjustment.

CONCLUSION

In this large, national, EHR-based study, BP control and BP-related process metrics improved during spring/summer months, but outdoor temperature was not associated with performance following adjustment for potential confounders.

Incidence and outcomes for stroke in Ulaanbaatar, Mongolia, during 2019-21: a prospective population-based study

BACKGROUND

In the absence of reliable data to quantify the burden of stroke, we aimed to determine the incidence and outcome of stroke through the conduct of a prospective population-based study in Ulaanbaatar, Mongolia, during 2019-21.

METHODS

All cases of stroke were identified through surveillance of multiple overlapping sources of hospitalised, ambulatory, and deceased individuals, using standardised diagnostic criteria in adult (aged ≥16 years) residents of the six urban districts of Ulaanbaatar, Mongolia (population person-years, N=1 896 965) between Jan 1, 2019, and Dec 31, 2020. Data on sociodemography, medical history, and management were collected. Crude and standardised incidence were calculated for first-ever stroke and its major pathological subtypes, and reported with 95% CIs. Outcomes were 28-day case fatality ratios and functional recovery on the modified Rankin scale at 90 days and 1 year.

FINDINGS

3803 strokes in 3738 patients were identified, of which 2962 were first-ever incident cases (mean age 59 years [SD 13], 1161 [39·2%] females). Annual incidence of first-ever stroke (per 100 000) was 156·1 (95% CI 150·5-161·8) on a crude basis, 171·6 (157·5-185·6) when age-adjusted to the Mongolian population, and 140·3 (136·7-143·9) when age-adjusted to the world population. World-adjusted incidence of pathological subtypes were 66·6 (95% CI 64·8-68·3) for ischaemic stroke, 54·5 (53·0-56·1) for intracerebral haemorrhage, and 18·7 (18·3-19·1) for subarachnoid haemorrhage. Men were twice as likely to suffer ischaemic stroke and intracerebral haemorrhage as women, but the risks were similar for subarachnoid haemorrhage; these patterns were consistent across age-groups. The predominant risk factors were hypertension seen in 1363 (63·1%) of 2161, smoking in 596 (26·8%) of 2220, regular alcohol consumption in 533 (24·0%) of 2220, obesity in 342 (16·1%) of 2125, and diabetes in 282 (12·7%) of 2220. There was little use (0·9%) of thrombolysis for acute ischaemic stroke, partly due to delays in presentation after the onset of symptoms (median 16·0 h [IQR 3·0-48·0]). The 28-day case-fatality rate was 36·1% (95% CI 34·3-37·9) overall, and 14·8% (12·8-16·7) for ischaemic stroke, 52·9% (49·9-55·8) for intracerebral haemorrhage, and 54·3% (49·4-59·1) for subarachnoid haemorrhage. Corresponding figures for poor functional outcome at 1-year, defined by scores of 3-6 for death or dependency on the mRS, were 61·6% (95% CI 59·8-63·4), 47·5% (44·7-50·3), 77·0% (74·5-79·5), and 61·8% (57·0-66·5), respectively.

INTERPRETATION

The urban population of Ulaanbaatar, Mongolia, has a high incidence of stroke, particularly for intracerebral haemorrhage and subarachnoid haemorrhage, from which half of patients die within 1 month and more than two-thirds are either dead or dependent at 90 days. Although the overall incidence of stroke is similar to other countries, it occurs at a mean age of 60 years, which is at least 10 years younger than in high-income countries. These epidemiological data can inform the implementation of future programmes and scale-up activities for the primary and secondary prevention of stroke, and in the organisation of systems of care.

FUNDING

Science and Technology Foundation of the Ministry of Education, Culture, and Science of Mongolia and The George Institute for Global Health.

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.

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.

Short- to long-term blood pressure variability: Current evidence and new evaluations

Increased blood pressure (BP) variability and the BP surge have been reported to be associated with increased cardiovascular risk independently of BP levels and can also be a trigger of cardiovascular events. There are multiple types of BP variation: beat-to-beat variations related to breathing and the autonomic nervous system, diurnal BP variation and nocturnal dipping related to sleep and physical activity over a 24-hr period, day-to-day BP variability with anomalous readings within a several-day period, visit-to-visit BP variability between outpatient visits, and seasonal variations. BP variability is also associated with the progression to hypertension from prehypertension and the progression of chronic kidney disease and cognitive impairments. Our research group proposed the "resonance hypothesis of blood pressure surge" as a new etiological hypothesis of BP variability and surges; i.e., the concept that when the time phases of surges and hypertension-inducing environmental influences coincide, resonance occurs and is amplified into a larger "dynamic surge" that triggers the onset of cardiovascular disease. New devices to assess BP variability as well as new therapeutic interventions to reduce BP variability are being developed. Although there are still issues to be addressed (including measurement accuracy), cuffless devices and information and communication technology (ICT)-based BP monitoring devices have been developed and validated. These new devices will be useful for the individualized optimal management of BP. However, evidence regarding the usefulness of therapeutic interventions to control BP variability is still lacking.

Seasonal variation in the effect of antihypertensive treatment with the irbesartan/hydrochlorothiazide combination

There is increasing awareness of seasonal variation in blood pressure (BP). In the present analysis, we investigated seasonal variation in the antihypertensive treatment effect of the irbesartan/hydrochlorothiazide combination in patients with stage 2 and 3 hypertension. The study participants were hypertensive patients enrolled in a 12-week therapeutic study. Antihypertensive treatment was initiated with irbesartan/hydrochlorothiazide 150/12.5 mg/day, with possible uptitration to 300/12.5 mg/day and 300/25 mg/day at 4 and 8 weeks of follow-up, respectively. The month of treatment commencement was classified as spring/summer (May to August) and autumn/winter (September to December). Of the 501 enrolled patients, 313 and 188 commenced antihypertensive treatment in spring/summer and autumn/winter, respectively. The mean changes in systolic/diastolic BP at 8 and 12 weeks of follow-up were greater in patients who commenced treatment in autumn/winter (-32.3/-16.5 and -34.2/-16.7 mmHg, respectively) than those who commenced treatment in spring/summer (-28.4/-13.9 and -27.1/-12.8 mmHg, respectively), with a between-season difference of 3.9 (95% confidence interval [CI], 1.4-6.4, P = 0.002)/2.6 (95% CI, 0.9-4.2, P = 0.002) mmHg and 7.0 (95% CI, 4.7-9.3, P < 0.0001)/3.9 (95% CI, 2.4-5.4, P < 0.0001) mmHg, respectively. Further subgroup analyses according to several baseline characteristics showed a greater between-season difference in the changes in systolic BP in patients aged ≥55 years than in those <55 years (n = 255, 12.6 mmHg vs. n = 246, 6.9 mmHg, P = 0.02), especially in patients who did not use antihypertensive medication at baseline (n = 94, 15.4 mmHg vs. n = 132, 5.4 mmHg, P = 0.006). In conclusion, there is indeed seasonality in the antihypertensive treatment effect, with a greater BP reduction in patients who commenced treatment in cold than warm seasons.

Temperature effects on incidence of surgery for acute type A aortic dissection in the Nordics

We aimed to investigate a hypothesised association between daily mean temperature and the risk of surgery for acute type A aortic dissection (ATAAD). For the period of 1 January 2005 until 31 December 2019, we collected daily data on mean temperatures and date of 2995 operations for ATAAD at 10 Nordic cities included in the Nordic Consortium for Acute Type A Aortic Dissection (NORCAAD) collaboration. Using a two-stage time-series approach, we investigated the association between hot and cold temperatures relative to the optimal temperature and the rate of ATAAD repair in the selected cities. The relative risks (RRs) of cold temperatures (≤-5°C) and hot temperatures (≥21°C) compared to optimal temperature were 1.47 (95% CI: 0.72-2.99) and 1.43 (95% CI: 0.67-3.08), respectively. In line with previous studies, we observed increased risk at cold and hot temperatures. However, the observed associations were not statistically significant, thus only providing weak evidence of an association.

Seasonal dynamics of myocardial infarctions in regions with different types of a climate: a meta-analysis

BACKGROUND

It is known that cardiovascular events (CVE) occur more often in winter than in summer. However, dependence of myocardial infarction (MI) risk of on various meteorological factors is still not fully understood. Also, the dependence of the seasonal dynamics of MI on gender and age has not yet been studied. The purpose of our meta-analysis is to reveal dependence of the circannual dynamics of MI hospitalizations on gender, age, and characteristics of a region's climate.

MAIN BODY

Using Review Manager 5.3, we performed a meta-analysis of 26 publications on the seasonal dynamics of MI. In our meta-analysis, the relative MI risk was higher in colder compared to warmer seasons. Old age insignificantly increased the seasonal MI risk; gender did not affect the seasonal dynamics of MI, but MI was more common in men than in women. The severity of the seasonal dynamics of MI risk depended on the climate of the region. In a climate with a small amplitude of circannual fluctuations in air temperature, atmospheric pressure, and partial oxygen density in the air, as well as in regions where air humidity is higher in winter than in summer, an increase in MI risk in winter compared to summer was significant. It was not significant in regions with opposite climatic tendencies.

CONCLUSIONS

Based on the results of our studies, it can be concluded that a decrease in air temperature increases in MI risk; in addition, hypoxia in the hot season can provoke CVE associated with ischemia.

Exposure to air pollution and its effect on ischemic strokes (EP-PARTICLES study)

It is well known that exceeded levels of particulate matter in the air and other air pollutants harmfully affect the cardiovascular system. Empirical analyses of the effects of these factors on stroke incidence and mortality are still limited. The main objective of our analyses was to determine the association between short-term exposure to air pollutants and stroke incidence in non-industrial areas, more specifically in north-eastern Poland. To achieve this aim, we used data from the National Health Fund on patients hospitalized for stroke between 2011 and 2020 in the largest city of the region described as the Green Lungs of Poland. The pollution levels and atmospheric conditions data were obtained from the Provincial Inspectorate for Environmental Protection and the Institute of Meteorology and Water Management. Using daily data on hospitalizations, atmospheric conditions, and pollution, as well as ordered logistic regression models the hypotheses on the impact of weather and air pollution conditions on ischemic strokes were tested. The study group included 4838 patients, 45.6% of whom were male; the average patient age was approximately 74 years. The average concentrations of PM_2.5 were 19.09 µg/m³, PM₁₀ 26.66 µg/m³ and CO 0.35 µg/m³. Analyses showed that an increase in PM_2.5 and PM₁₀ concentrations by 10 µg/m³ was associated with an increase in the incidence of stroke on the day of exposure (OR = 1.075, 95% CI 0.999-1.157, P = 0.053; OR = 1.056, 95% CI 1.004-1.110, P = 0.035) and the effect was even several times greater on the occurrence of a stroke event in general (PM_2.5: OR = 1.120, 95% CI 1.013-1.237, P = 0.026; PM₁₀: OR = 1.103, 95% CI 1.028-1.182, P = 0.006). Furthermore, a short-term (up to 3 days) effect of CO on stroke incidence was observed in the study area. An increase of 1 μg/m³ CO was associated with a lower incidence of stroke 2 days after the exposure (OR = 0.976, 95% CI 0.953-0.998, P = 0.037) and a higher incidence 3 days after the exposure (OR = 1.026, 95% CI 1.004-1.049, P = 0.022).

Bedtime dosing of antihypertensive medications: systematic review and consensus statement: International Society of Hypertension position paper endorsed by World Hypertension League and European Society of Hypertension

Antihypertensive drug therapy is one of the most efficient medical interventions for preventing disability and death globally. Most of the evidence supporting its benefits has been derived from outcome trials with morning dosing of medications. Accumulating evidence suggests an adverse prognosis associated with night-time hypertension, nondipping blood pressure (BP) profile and morning BP surge, with increased incidence of cardiovascular events during the first few morning hours. These observations provide justification for complete 24-h BP control as being the primary goal of antihypertensive treatment. Bedtime administration of antihypertensive drugs has also been proposed as a potentially more effective treatment strategy than morning administration. This Position Paper by the International Society of Hypertension reviewed the published evidence on the clinical relevance of the diurnal variation in BP and the timing of antihypertensive drug treatment, aiming to provide consensus recommendations for clinical practice. Eight published outcome hypertension studies involved bedtime dosing of antihypertensive drugs, and all had major methodological and/or other flaws and a high risk of bias in testing the impact of bedtime compared to morning treatment. Three ongoing, well designed, prospective, randomized controlled outcome trials are expected to provide high-quality data on the efficacy and safety of evening or bedtime versus morning drug dosing. Until that information is available, preferred use of bedtime drug dosing of antihypertensive drugs should not be routinely recommended in clinical practice. Complete 24-h control of BP should be targeted using readily available, long-acting antihypertensive medications as monotherapy or combinations administered in a single morning dose.

Isolated nocturnal hypertension in relation to host and environmental factors and clock genes

Isolated nocturnal hypertension (INH) is a special type of out-of-office hypertension. Its determinants and pathophysiology remain unclear. In a nested case-control study, we intend to investigate the host, environmental, and genetic factors in relation to INH. Among 2030 outpatients screened from December 2008 till June 2015, 128 patients with INH were identified, and then 128 normotensives were matched according to sex and age. INH was an elevated nocturnal blood pressure (BP ≥120/70 mmHg) in the presence of a normal daytime BP (< 135/85 mmHg). Host factors included age, sex, body mass index, smoking and drinking, sleep time and duration, heart rate, serum lipids, and serum creatinine. Environmental cues encompassed season, ambient temperature, atmospheric pressure, humidity, and wind speed, and genetic cues 29 single-nucleotide polymorphisms (SNPs) in 12 clock genes. Daytime and nighttime BPs averaged 124.9/80.7  and 114.5/73.7 mmHg, respectively, in the INH patients and 121.0/76.5 and 101.8/63.3 mmHg in the normotensive controls. Stepwise logistic regression analyses revealed that INH was associated with nighttime heart rate (P = .0018), sleep duration (P = .0499), and relative humidity (P = .0747). The odds ratios (95% CI) for each 10 beats/min faster nighttime heart rate and 10% lower relative humidity were 1.82 (1.25-2.65) and 0.82 (0.67-1.00), respectively. Irrespective of the genetic models, no significant association was observed between INH and the SNPs (P ≥ .054). In conclusion, INH was associated with host and environmental factors rather than genetic markers.

Association of an Automated Blood Pressure Measurement Quality Improvement Program With Terminal Digit Preference and Recorded Mean Blood Pressure in 11 Clinics

IMPORTANCE

Terminal digit preference has been shown to be associated with inaccurate blood pressure (BP) recording.

OBJECTIVE

To evaluate whether converting from manual BP measurement with aneroid sphygmomanometers to automated BP measurement was associated with terminal digit preference, mean levels of recorded BP, and the rate at which hypertension was diagnosed.

DESIGN, SETTING, AND PARTICIPANTS

This quality improvement study was conducted from May 9, 2021, to March 24, 2022, using interrupted time series analysis of medical record data from 11 primary care clinics in a single health care system from April 2008 to April 2015. The study population was patients aged 18 to 75 years who had their BP measured and recorded at least once during the study period.

EXPOSURES

Manual BP measurement before April 2012 vs automated BP measurement with the Omron HEM-907XL monitor from May 2012 to April 2015.

MAIN OUTCOMES AND MEASURES

The main outcome was the distribution of terminal digits and mean systolic BP (SBP) values obtained during 4 years of manual measurement vs 3 years of automated measurement, assessed using a generalized linear mixed regression model with a random intercept for clinic and adjusted for seasonal fluctuations and patient demographic and clinical characteristics.

RESULTS

The study included 1 541 227 BP measurements from 225 504 unique patients during the entire study period, with 849 978 BP measurements from 165 137 patients (mean [SD] age, 47.1 [15.2] years; 58.2% female) during the manual measurement period and 691 249 measurements from 149 080 patients (mean [SD] age, 48.4 [15.3] years; 56.3% female) during the automated measurement period. With manual measurement, 32.8% of SBP terminal digits were 0 (20% was the expected value because nursing staff was instructed to record BP to the nearest even digit). This proportion decreased to 12.4% during the automated measurement period (expected value, 10%) when both even and odd digits were to be recorded. After automated measurement was implemented, the mean SBP estimated with statistical modeling increased by 5.09 mm Hg (95% CI, 4.98-5.19 mm Hg). Fewer BP values recorded during the automated than the manual measurement period were below 140/90 mm Hg (69.9% vs 84.3%; difference, -14.5%; 95% CI, -14.6% to -14.3%) and below 130/80 mm Hg (42.1% vs 60.0%; difference, -17.9%; 95% CI, -18.0% to -17.7%). The proportion of patients with a diagnosis of hypertension was 4.3 percentage points higher (23.4% vs 19.1%) during the automated measurement period.

CONCLUSIONS AND RELEVANCE

In this quality improvement study, automated BP measurement was associated with decreased terminal digit preference and significantly higher mean BP levels. The method of BP measurement was also associated with the rate at which hypertension was diagnosed. These findings may have implications for pay-for-performance programs, which may create an incentive to record BP levels that meet a particular goal and a disincentive to adopt automated measurement of BP.

Discussion of Cuffless Blood Pressure Prediction Using Plethysmograph Based on a Longitudinal Experiment: Is the Individual Model Necessary?

Using the Plethysmograph (PPG) signal to estimate blood pressure (BP) is attractive given the convenience and possibility of continuous measurement. However, due to the personal differences and the insufficiency of data, the dilemma between the accuracy for a small dataset and the robustness as a general method remains. To this end, we scrutinized the whole pipeline from the feature selection to regression model construction based on a one-month experiment with 11 subjects. By constructing the explanatory features consisting of five general PPG waveform features that do not require the identification of dicrotic notch and diastolic peak and the heart rate, three regression models, which are partial least square, local weighted partial least square, and Gaussian Process model, were built to reflect the underlying assumption about the nature of the fitting problem. By comparing the regression models, it can be confirmed that an individual Gaussian Process model attains the best results with 5.1 mmHg and 4.6 mmHg mean absolute error for SBP and DBP and 6.2 mmHg and 5.4 mmHg standard deviation for SBP and DBP. Moreover, the results of the individual models are significantly better than the generalized model built with the data of all subjects.

[Seasonal changes in blood pressure and related factors among older patients receiving home medical care]

AIM

We investigated seasonal variations in blood pressure (BP) and factors related to these variations among older patients receiving home medical care.

METHOD

A total 57 patients ≥ 65 years old receiving home medical care who participated in the Osaka Home Care REgistry study (OHCARE), a prospective cohort study, were included. We investigated the seasonal patient characteristics and variations in the BP. In addition, to determine the influence of seasonal variations in the systolic blood pressure (SBP) on the occurrence of clinical events (hospitalization, falls and death), we classified patients into larger- and smaller- change groups based on the median seasonal variations in SBP.

RESULT

About 60% of subjects were very frail or bedridden. The mean BP was higher in winter than in summer (124.7±11/69.5±7 vs.120.5±12/66.9±8 mmHg) (P< 0.01). On comparing the characteristics of the two groups with larger and smaller changes in the SBP, the group with large BP changes had a significantly lower BP in summer than the group with small BP changes. In addition, the incidence of "hospitalization" was significantly higher in the group with large BP changes than in the group with small BP changes (P = 0.03).

CONCLUSION

The present study revealed that there were seasonal changes in the BP in older patients receiving home medical care. It was also suggested that seasonal changes in the BP might be associated with the risk of hospitalization events. Given these BP variations, doctors and visiting nurses should be alert for systemic abnormalities, especially in frail patients receinving home medical care.

Geographic, Gender, and Seasonal Variation of Diabetes: A Nationwide Study With 1.4 Million Participants

CONTEXT

China has experienced a rapid increase in the prevalence of diabetes.

OBJECTIVE

We assessed the prevalence of diabetes among Chinese adults who attended preventive physical examinations and analyzed geographical and gender difference in seasonal variation of fasting blood glucose (FBG).

METHODS

The study used data from 1 390 088 participants attending preventive health examination at 430 health screening centers in 220 cities. Diagnosis of diabetes and prediabetes were based on FBG and glycated hemoglobin A1c and self-reported physician's diagnosis. We calculated age- and sex-standardized prevalence of diabetes according to the sixth Chinese population census data in 2010. Geographical distribution of diabetes and prediabetes were represented on a country map. FBG levels were analyzed to detect seasonal variation adjusted for age and gender by geographic location.

RESULTS

The standardized prevalence of diabetes was 8.70% (95% CI, 8.22%-9.19%), 10.7% in men and 6.61% in women. Among those with diabetes, 43.7% (95% CI, 40.9%-46.5%) were aware of their conditions and 38.5% (95% CI, 36.0%-41.1%) were treated. Only 49.3% (95% CI, 47.0%-51.6%) of treated patients achieved glycemic control. The mean level of FBG was higher in winter than summer and in the northern than the southern region.

CONCLUSION

The prevalence of diabetes was high while the percentages of awareness, treatment, and glycemic control were low among adults. Effective measures are needed to prevent and manage diabetes in China. Geographic and seasonal variation of diabetes should be considered for its prevention and control.

Long-term amlodipine-based combination therapy attenuates seasonal variation of blood pressure in hypertensive patients

Objectives: This study was to investigate whether long-term amlodipine-based combination therapy attenuates seasonal variation of office blood pressure (BP) in hypertensive patients. Methods: The data of 206 patients recruited in the Nanchang site of CHIEF trial were retrospectively analyzed. All patients received an amlodipine-based therapy for three years after reaching target BP with a 12-week titration treatment. Among them, 106 patients received amlodipine plus amiloride/hydrochlorothiazide (AA group) and 100 received amlodipine plus telmisartan (AT group) therapies. These patients were followed up every three months . The difference between the highest and lowest values of outdoor temperature in each three months was calculated as the seasonal temperature difference (T-d) and seasonal BP difference was calculated in the similar way. BP control rates in each season were calculated. Results: In the three years, the highest SBP and DBP values occurred in winter and the lowest values in summer. As a result, the BP control rate in summer was the highest and that in winter was the lowest, especially for SBP. Although T-d levels were similar during three following-up years, the seasonal SBP/DBP differences in 2011 were significantly lower than 2009 (10.03 ± 5.74/6.96 ± 3.72 vs 14.36 ± 8.19/9.78 ± 5.21 mmHg, P < .05), suggesting seasonal variation in BP was obviously reduced. Meanwhile, similar change was observed in AA and AT groups. Conclusions: Besides lower BP effectively, long-term amlodipine-based combination therapy could alleviate the seasonal BP variation in high-risk hypertensive patients.

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.

World Heart Federation Roadmap for Hypertension - A 2021 Update

The World Heart Federation (WHF) Roadmap series covers a large range of cardiovascular conditions. These Roadmaps identify potential roadblocks and their solutions to improve the prevention, detection and management of cardiovascular diseases and provide a generic global framework available for local adaptation. A first Roadmap on raised blood pressure was published in 2015. Since then, advances in hypertension have included the publication of new clinical guidelines (AHA/ACC; ESC; ESH/ISH); the launch of the WHO Global HEARTS Initiative in 2016 and the associated Resolve to Save Lives (RTSL) initiative in 2017; the inclusion of single-pill combinations on the WHO Essential Medicines' list as well as various advances in technology, in particular telemedicine and mobile health. Given the substantial benefit accrued from effective interventions in the management of hypertension and their potential for scalability in low and middle-income countries (LMICs), the WHF has now revisited and updated the 'Roadmap for raised BP' as 'Roadmap for hypertension' by incorporating new developments in science and policy. Even though cost-effective lifestyle and medical interventions to prevent and manage hypertension exist, uptake is still low, particularly in resource-poor areas. This Roadmap examined the roadblocks pertaining to both the demand side (demographic and socio-economic factors, knowledge and beliefs, social relations, norms, and traditions) and the supply side (health systems resources and processes) along the patient pathway to propose a range of possible solutions to overcoming them. Those include the development of population-wide prevention and control programmes; the implementation of opportunistic screening and of out-of-office blood pressure measurements; the strengthening of primary care and a greater focus on task sharing and team-based care; the delivery of people-centred care and stronger patient and carer education; and the facilitation of adherence to treatment. All of the above are dependent upon the availability and effective distribution of good quality, evidence-based, inexpensive BP-lowering agents.

Home blood pressure monitoring: methodology, clinical relevance and practical application: a 2021 position paper by the Working Group on Blood Pressure Monitoring and Cardiovascular Variability of the European Society of Hypertension

The present paper provides an update of previous recommendations on Home Blood Pressure Monitoring from the European Society of Hypertension (ESH) Working Group on Blood Pressure Monitoring and Cardiovascular Variability sequentially published in years 2000, 2008 and 2010. This update has taken into account new evidence in this field, including a recent statement by the American Heart association, as well as technological developments, which have occurred over the past 20 years. The present document has been developed by the same ESH Working Group with inputs from an international team of experts, and has been endorsed by the ESH.

Relationship Between Home Blood Pressure and the Onset Season of Cardiovascular Events: The J-HOP Study (Japan Morning Surge-Home Blood Pressure)

BACKGROUND

The incidence of cardiovascular disease (CVD) increases during winter. The risk that elevated home blood pressure (BP) poses for CVD events that occur in each of 4 seasons is unclear. We conducted a post hoc analysis using the dataset from a nationwide cohort, the Japan Morning Surge-Home Blood Pressure (J-HOP) study, to assess the association between home BP and winter-onset CVD events.

METHODS

J-HOP participants who had cardiovascular risks conducted morning and evening home BP measurements for a 14-day period and were followed-up for the occurrence of CVD events.

RESULTS

We analyzed 4,258 participants (mean age 64.9 years; 47% male; 92% hypertensives) who were followed-up for an average of 6.2 ± 3.8 years (26,295 person-years). We divided the total of 269 CVD events (10.2/1,000 person-years) by the season of onset as follows: 82 in the winter and 187 in the other seasons (spring, summer, and autumn). In the Cox models adjusted for covariates and the season when home BPs were measured at baseline, morning home systolic BP (SBP) was associated with both winter-onset and other season-onset CVD events: hazard ratio (HR) for winter 1.22, 95% confidence interval (CI) 1.06-1.42 per 10 mm Hg; HR for other seasons 1.11, 95% CI 1.00-1.23. Evening home SBP was associated with the other season-onset CVD events (HR 1.20, 95% CI 1.08-1.33 per 10 mm Hg), but not with the winter-onset CVD events.

CONCLUSIONS

Our findings indicate that compared with evening home BP, morning home BP might be a superior predictor of winter-onset CVD events.

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.

The Impact on Blood Pressure of a Short-Term Change in Indoor Temperature

Objective

The aim of this study is to evaluate the impact on blood pressure (BP) of a 10°C change in room temperature (between 18°C and 28°C).

Methods

A total of 112 volunteers, 56 males and 56 females, 55 with and 57 without hypertension, were enrolled in the study. First, the participants were placed in a 25°C room. Second, they were randomly assigned to either a 28°C (group A) or an 18°C room (group B). Finally, they were moved from the 28°C to the 18°C room, or vice versa. They stayed in each room for 20 minutes. Seated BP was measured at the 17th and 19th minute in each room, and the average was used. The difference in the subject's BP between the second two rooms was recorded as delta BP.

Results

The baseline systolic BP (SBP), age, gender distribution, and incidence of hypertension were similar between the two groups. In group A, the decrease in room temperature of 10°C induced a mean rise in SBP of 4.1 mmHg. In group B, the increase of 10°C caused SBP to decrease by 4.0 mmHg. When compared with the group without hypertension, the group with hypertension had a significantly higher rise in mean SBP (6.8 vs 1.2 mmHg) as a result of the decrease in temperature and a significantly higher drop in SBP (7.3 vs 1.2 mmHg) as a result of the increase in temperature. The participants in the group with hypertension were older.

Conclusion

A 10°C change in room temperature, from 18°C to 28°C, for 20 min can cause a significant change in SBP. The extent of this change is more obvious in the older group.

Dependence of seasonal dynamics of hemorrhagic and ischemic strokes on the climate of a region: A meta-analysis

BACKGROUND

Cardiovascular events occur more often in winter than in summer; however, the dependence of strokes on various meteorological factors remains unclear.

AIMS

The purpose of this meta-analysis was to determine the dependence of the circannual dynamics of hospitalizations for hemorrhagic stroke and ischemic stroke on seasonal fluctuations in meteorological factors.

SUMMARY OF REVIEW AND CONCLUSIONS

For our meta-analysis, we selected 20 and 26 publications examining the seasonal dynamics of hemorrhagic stroke and ischemic stroke, respectively . The meta-analysis showed that hemorrhagic stroke is less likely to occur in summer than in other seasons and does not depend on a region's climate. The seasonal dynamics of ischemic stroke are not clearly expressed and are determined by the characteristics of a region's climate. In a climate without pronounced seasonal dynamics of atmospheric pressure and in wet winters, the vector of ischemic stroke incidents will not be expressed or slightly shifted toward winter. Low atmospheric pressure in summer is associated with an increased likelihood of ischemic stroke during this season compared to winter. There was also a relation between ischemic stroke risk with high relative humidity and a significant decrease in ρO₂ in summer, but there is not enough evidence regarding this association. We did not reveal dependence of the seasonal dynamics of strokes on the amplitude of annual fluctuations in air temperature.

The Effects of Two Intervention Strategies to Reduce the Intake of Salt and the Sodium-To-Potassium Ratio on Cardiovascular Risk Factors. A 4-Month Randomised Controlled Study among Healthy Families

The aim was to examine the effects of two different salt reduction strategies on selected cardiovascular risk factors. The study was a four-month cluster randomised controlled study. Eighty-nine healthy Danish families (309 individuals) were randomly assigned to either (A) gradually salt-reduced bread, (B) gradually salt-reduced bread and dietary counselling to further reduce salt intake and increase potassium intake or (C) standard bread (control). The effect was assessed using linear mixed models. Intention to treat analyses comparing changes in the three groups showed a significant reduction in body fat percent (−1.31% (−2.40; −0.23)) and a borderline significant reduction in total plasma cholesterol (−0.25 mmol/L (−0.51; 0.01) and plasma renin (−0.19 pmol/L (−0.39; 0.00) in group A compared to the control group. Adjusted complete case analyses showed a significant reduction in total plasma cholesterol (−0.29 mmol/L (−0.50; −0.08), plasma LDL cholesterol (−0.08 mmol/L (−0.15; −0.00)), plasma renin (−0.23 pmol/L (−0.41; −0.05)), plasma adrenaline (−0.03 nmol/L (−0.06; −0.01)) and body fat percent (−1.53% (−2.51; −0.54)) in group A compared to the control group. No significant changes were found in group B compared to the control group. In conclusion, receiving sodium reduce bread was associated with beneficial changes in cardiovascular risk factors. No adverse effects were observed.