Seasonal Changes In Blood Pressure Research Articles

Impact of seasonal blood pressure changes on visit-to-visit blood pressure variability and related cardiovascular outcomes.

Visit-to-visit blood pressure (BP) variability associates with an increased risk of cardiovascular events. We investigated the role of seasonal BP modifications on the magnitude of BP variability and its impact on cardiovascular risk. In 25 390 patients included in the ONTARGET and TRANSCEND trials, the on-treatment systolic (S) BP values obtained by five visits during the first two years of the trials were grouped according to the month in which they were obtained. SBP differences between winter and summer months were calculated for BP variability quintiles (Qs), as quantified by the coefficient of variation (CV) of on-treatment mean SBP from the five visits. The relationship of BP variability with the risk of cardiovascular events and mortality was assessed by the Cox regression model. SBP was approximately 4 mmHg lower in summer than in winter regardless of confounders. Winter/summer SBP differences contributed significantly to each SBP-CV quintile. Increase of SBP-CV from Q1 to Q5 was associated with a progressive increase in the adjusted hazard ratio (HR) of the primary endpoint of the trials, i.e. morbid and fatal cardiovascular events. This association was even stronger after removal of the effect of seasonality from the calculation of SBP-CV. A similar trend was observed for secondary endpoints. Winter/summer SBP differences significantly contribute to visit-to-visit BP variability. However, this contribution does not participate in the adverse prognostic significance of visit-to-visit BP variations, which seems to be more evident after removal of the BP effects of seasonality from visit-to-visit BP variations.

S-54-3: PREDICTION AND PREVENTION OF THE ONSET OF HYPERTENSION FROM THE VIEWPOINT OF ESTIMATED 24-HOUR SALT EXCRETION AND PHYSICAL FITNESS TEST

Objective: Both dietary salt and physical activity contribute substantially to development and progression of blood pressure elevation. Earlier detection of blood pressure change by daily simple procedures are effective for health promotion less expensively. We performed both longitudinal and cross-sectional observations for the subjects with annual comprehensive health checkup to test relationships among daily salt intake, physical activity, and blood pressure elevation. Methods: We performed following three observations. A)Body weights, interviewed salt intakes (i-NaCl), and estimated salt intakes (e-NaCl) for single spot urine (Tanaka formula) were measured and compared to blood pressure change monthly for one year in total 17,794 participants. B) To test significance of shared e-NaCl information to health promotions, we shared e-NaCl to total 98,908 participants individually and, subsequently, annual-mean e-NaCl was compared for 5 years. C) To test significance of physical activity for blood pressure elevations, we performed 5-year follow up study for total 22,972 participants to examine the onset of hypertension and physical activity as followings; duration of single-leg balance with eyes closed (sec), grip strength (kg), forward bending (cm), whole body reaction time (msec), vertical jump distance (cm), and supine leg-up (sec), respectively. Results: A) Only e-NaCl was found to have a strong correlation with the monthly mean systolic blood pressure as shown in a figure. B) By sharing e-NaCl information with participants, annual mean of e-NaCl decreased significantly from 9.22 g/day (male) and 8.79 g/day (female) in 2012 to 9.03 g/day (male) and 8.63 g/day (female) in 2017. C) Even when adjusted for gender, age, BMI, systolic and diastolic blood pressure of first year, single-leg balance with eyes closed and forward bending were significantly associated with the onset of hypertension. Conclusion: Since e-NaCl is affected by salt excretion due to sweating, it was presumed that the amount of salt to be excreted in urine correlated well with seasonal changes in blood pressure. In addition, e-NaCl measurement is a good tool that can be used for health guidance to examinees for their life style promotion. It was found that flexibility and a sense of equilibrium are related to the onset of blood pressure.

Relationship between changes in blood pressure from summer to winter and estimated 24-hour salt excretion using spot urine: the Niigata Wellness Study.

A convenient way to determine salt intake is salt excretion using spot urine (e-NaCl). We measured e-NaCl at health checkups and compared results with seasonal changes in blood pressure. Among 19,732 examinees who underwent health checkups from Aug. 2012 to Mar. 2013, age, body weight and e-NaCl were measured and compared to monthly mean systolic blood pressure (SBP). Excluded were those taking antihypertensive drugs and with creatinine levels higher than 2.0 mg/dL. Also examined was salt intake (i-NaCl) by an interview survey from Aug. to Dec. 2012. Correlations with SBP were R = 0.7718 for age, R = 0.5996 for body weight, R = 0.2498 for i-NaCl and R = 0.9335 for e-NaCl. e-NaCl decreased in summer. It was presumed that the reduced burden on the kidney of salt excretion due to sweating may be related to decreases in blood pressure in summer.

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

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

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.

Seasonal variation of blood pressure in children

Seasonal blood pressure (BP) variation is mostly found between the summer and winter months. Guidelines for diagnosis and treatment of hypertension in children have not considered this variation until recently. This review aims to present an overview of seasonal BP variation in childhood along with potential underlying pathophysiological mechanisms and long-term implications as well as conclusions for future studies. In pediatric cohorts, seven studies investigated seasonal changes in BP. These changes amount to 3.4–5.9 mmHg (or 0.5–1.5 mmHg per − 1 °C difference in environmental temperature) in systolic BP with a peak in fall or winter. Potential mechanisms and mediators of seasonal BP variation include sympathetic activation of the nervous system with an increase of urinary and plasma norepinephrine levels in the winter season. Additionally, the physical activity among children and adolescents was inversely correlated with BP levels. Temperature sensitivity of BP and pediatric BP levels predict future systolic BP and target-organ damage. Therefore, cardiovascular events may even be long-term complications of seasonal BP variation in pediatric hypertensive patients. Overall, these data strongly suggest an important effect of ambient temperature on BP in children. Additional studies in pediatric cohorts are needed to define how best to incorporate such variation into clinical practice.

Vitamin D and Cardiovascular Disease, with Emphasis on Hypertension, Atherosclerosis, and Heart Failure.

Vitamin D deficiency is the most common nutritional deficiency, affecting almost one billion people worldwide. Vitamin D is mostly known for its role in intestinal calcium absorption and bone mineralization. However, the observation of seasonal changes in blood pressure and the subsequent identification of vitamin D receptor (VDR) and 1α-hydroxylase in cardiomyocytes, as well as endothelial and vascular smooth muscle cells, implicated a role of vitamin D in the cardiovascular system. Animal studies provided compelling evidence that vitamin D signaling is essential for cardiovascular integrity, especially for the regulation of vascular tone and as an antifibrotic and antihypertrophic signaling pathway in the heart. In addition, observational studies reported an association between vitamin D deficiency and risk of hypertension, atherosclerosis, and heart failure. However, recent clinical intervention studies failed to prove the causal relationship between vitamin D supplementation and beneficial effects on cardiovascular health. In this review, we aim to highlight our current understanding of the role of vitamin D in the cardiovascular system and to find potential explanations for the large discrepancies between the outcome of experimental studies and clinical intervention trials.

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

The current study reviewed the published evidence on the seasonal changes in blood pressure (BP) assessed using different measurement methods. A systematic PubMed/EMBASE search was performed for studies assessing seasonal BP changes. Prospective and cross-sectional studies were included fulfilling the following criteria: (i) report of ambulatory and/or home BP data; (ii) cross-sectional studies reporting only office BP measurements and including 1000 or more participants. Forty-seven studies fulfilled the selection criteria and were included (856 539 participants, weighted age 49.7 ± 4.8 years, 38.8% treated hypertensive patients). The pooled summer minus winter SBP/DBP difference (95% confidence intervals) was office BP (29 studies) -5.6 (-7.1, -4.0)/-3.3 (-4.0, -2.7) mmHg; daytime ambulatory BP (15 studies) -3.4 (-4.4, -2.4)/-2.1 (-2.8, -1.4) mmHg; night-time ambulatory BP (13 studies) 1.3 (0.2, 2.3)/0.5 (-0.2, 1.2) mmHg; home BP (9 studies) -6.1 (-7.0, -5.1)/-3.1 (-3.5, -2.6) mmHg. Meta-analysis of 28 prospective studies (N = 5278) which examined the same individuals during different seasons showed pooled seasonal SBP/DBP difference: office BP -5.8/-4.0 mmHg; daytime ambulatory BP -3.9/-2.7 mmHg; night-time ambulatory BP 0.5/-0.5 mmHg; home BP -6.4 /-3.3 mmHg. In meta-regression analysis seasonal systolic daytime ambulatory BP difference was related to the percentage of treated hypertensive patients across studies (P = 0.02) and borderline to age (P = 0.07). Seasonal BP changes are evident using all daytime BP measurement methods, but not with night-time ambulatory BP. The average BP decline in hot season is at about 5/3 (SBP/DBP) mmHg and appears to be larger in treated hypertensive patients and in older individuals.

Seasonal variation in blood pressure: Evidence, consensus and recommendations for clinical practice. Consensus statement by the European Society of Hypertension Working Group on Blood Pressure Monitoring and Cardiovascular Variability.

: Blood pressure (BP) exhibits seasonal variation with lower levels at higher environmental temperatures and higher at lower temperatures. This is a global phenomenon affecting both sexes, all age groups, normotensive individuals, and hypertensive patients. In treated hypertensive patients it may result in excessive BP decline in summer, or rise in winter, possibly deserving treatment modification. This Consensus Statement by the European Society of Hypertension Working Group on BP Monitoring and Cardiovascular Variability provides a review of the evidence on the seasonal BP variation regarding its epidemiology, pathophysiology, relevance, magnitude, and the findings using different measurement methods. Consensus recommendations are provided for health professionals on how to evaluate the seasonal BP changes in treated hypertensive patients and when treatment modification might be justified. (i) In treated hypertensive patients symptoms appearing with temperature rise and suggesting overtreatment must be investigated for possible excessive BP drop due to seasonal variation. On the other hand, a BP rise during cold weather, might be due to seasonal variation. (ii) The seasonal BP changes should be confirmed by repeated office measurements; preferably with home or ambulatory BP monitoring. Other reasons for BP change must be excluded. (iii) Similar issues might appear in people traveling from cold to hot places, or the reverse. (iv) BP levels below the recommended treatment goal should be considered for possible down-titration, particularly if there are symptoms suggesting overtreatment. SBP less than 110 mmHg requires consideration for treatment down-titration, even in asymptomatic patients. Further research is needed on the optimal management of the seasonal BP changes.

SEASONAL BLOOD PRESSURE VARIATION ASSESSED BY DIFFERENT MEASUREMENT METHODS

Objective: Seasonal changes in blood pressure (BP) in response to changes in environmental temperature appear to be a common and global phenomenon. This study aimed to review the published evidence on the seasonal changes in BP assessed using different measurement methods. Design and method: A systematic PubMed search was performed for studies assessing seasonal changes in office (OBP), home (HBP) and ambulatory BP (ABP). Prospective and cross-sectional studies were included fulfilling the following criteria: (i) report of ambulatory and/or home BP data; (ii) sample size >1,000 for studies reporting only OBP data. Results: Among 596 initially retrieved studies, 47 fulfilled the criteria and were included (856,539 participants, weighted age 49.7 ± 4.8 years, 42.7% treated for hypertension). Random effects meta-analysis of these studies showed that summer minus winter systolic/diastolic BP differences (pooled estimate with 95% confidence intervals) were: OBP (27 studies) −5.8 (−7.5, −4.2)/−3.4 (−4.1, −2.7) mmHg; daytime ABP (15 studies) −3.4 (−4.4, −2.4)/−2.1 (−2.8, −1.4) mmHg; night-time ABP 1.3 (0.2, 2.3)/0.5 (−0.2, 1.2); HBP (9 studies) −6.1 (−7, −5.1)/−3.1 (−3.5, −2.6) mmHg. 28 of these studies (N = 5,278) were prospective and examined the same individuals during different seasons. Sensitivity analyses including only the 28 prospective studies provided similar findings with seasonal systolic/diastolic BP difference: OBP −6.4/−4.2 mmHg; daytime ABP −3.9/−2.7 mmHg, nighttime ABP 0.5/−0.5 mmHg, HBP −6.4/−3.3 mmHg. Meta-regression analysis of prospective studies showed that seasonal systolic daytime ABP difference was related to the percentage of treated hypertensives across studies (p = 0.02) and borderline to age (p = 0.06), whereas gender, body mass index, summer temperature, seasonal difference in temperature, and winter BP levels had no significant effect (p = NS). Conclusions: The current evidence indicates that seasonal BP changes are evident in all measurement methods except for nighttime ABP, with average BP decline in summer at about 5/3 (systolic/diastolic) mmHg. The seasonal BP changes appear to be larger in older subjects and in treated hypertensives.

Factors affecting seasonal changes in blood pressure in North India: A population based four-seasons study

ObjectiveThere are no community based, longitudinal, intra individual epidemiological studies on effect of weather and season on blood pressure (BP). We evaluated the effect of season and temperature on prevalence and epidemiology of BP in tropical climate. Methods and resultsIt was a longitudinal cross sectional survey of rural and urban subjects in their native surroundings. BP was measured in four different seasons in same subjects. A total of 978 subjects (452 rural and 521 urban) were included in the current analysis. Demographic characteristics such as age, gender, education, occupational based physical activity and body mass index (BMI) were recorded. Mean BP, both systolic and diastolic were significantly higher in winter season as compared to summer season. Mean difference between winter and summer was 9.01 (95% CI: 7.74–10.28, p<0.001) in systolic BP and 5.61 (95% CI: 4.75–6.47, p<0.001) in diastolic BP. This increase in BP was more marked in rural areas and elderly subjects. Prevalence of hypertension was significantly higher during winter (23.72%) than in summer (10.12%). ConclusionBP increases significantly during winter season as compared to summer season. Increase is more marked in rural areas and elderly subjects. Seasonal variation in BP should be taken into account while looking at prevalence of hypertension in epidemiological studies.

PP.06.18] SEASONAL BLOOD PRESSURE CHANGES IN HIGH NORMAL, NORMAL AND OPTIMAL BLOOD PRESSURE PATIENTS WITHOUT ANTIHYPERTENSIVE MEDICATION

Objective: Many investigators supposed that seasonal blood pressure (BP) changes are one of the reasons of fatal and nonfatal cardiovascular events. These studies included mainly the patients with arterial hypertension and the division of patients into groups with high normal (HNBP) or normal and optimal BP was not done. The aim of study was to estimate the seasonal differences in clinical (CBP) and ambulatory BP (ABP) in patients with HNBP and normal and optimal BP. Design and method: The ambulatory patients from the ABP monitoring database (>2000 patients) were selected according to the following criteria: absence of any antihypertensive treatment, availability of CBP and ABPM records in winter or summer, CBP<140 and 90 mmHg. Standard statistical methods were used. Results: The preliminary data of the on-going study are demonstrated. We selected 355 patients: 206 with HNBP and 149 with normal and optimal BP. The main characteristics of groups and seasonal BP changes are presented in Table. In patients with HNBP only systolic CBP was significantly higher in winter than in summer. We found similar tendency for ABP data in these patients despite relatively small differences. In patients with normal and optimal BP only diastolic ABP was higher in winter; in contrast, nighttime systolic BP was higher in summer. At the same time, average values of CBP and ABP in the normal and optimal BP group did not exceed threshold limits.Conclusions: Some of the ABP parameters in patients with HNBP without antihypertensive medication are increased in winter and exceed normal values. This factor may contribute to the increase of cardiovascular events incidence in winter. The problem should be studied in prospective investigations.

Seasonal variation in meteorological parameters and office, ambulatory and home blood pressure: predicting factors and clinical implications.

This study investigated the relationship between seasonal variations in blood pressure (BP) and the corresponding changes in meteorological parameters and weather-induced patients' discomfort. Hypertensives on stable treatment were assessed in winter-1, summer and winter-2 with clinic (CBP), home (HBP) and 24-hour ambulatory BP (ABP). Discomfort indices derived from temperature, humidity and atmospheric pressure that reflected subjects' discomfort were evaluated. Symptomatic orthostatic hypotension was assessed with a questionnaire. Sixty subjects (mean age 65.1±8.8 [s.d.], 39 men) were analyzed. CBP, HBP and daytime ABP were lower in summer than in winter (P<0.01). Nighttime ABP was unchanged, which resulted in a 55% higher proportion of non-dippers (P<0.001). All the discomfort indices that reflected weather-induced subjects' discomfort were higher in summer (P<0.05) and systolic daytime ABP was <110 mm Hg in 15 subjects (25%). Seasonal changes in temperature and the discomfort indices were correlated with BP changes (P<0.05). Multivariate analyses revealed that winter BP levels, seasonal differences in temperature, female gender and the use of diuretics predicted the summer BP decline. In conclusion, all aspects of the BP profile, except nighttime ABP, are reduced in summer, resulting in an increased prevalence of non-dippers in summer with unknown consequences. Seasonal BP changes are influenced by changes in meteorological parameters, anthropometric and treatment characteristics. Trials are urgently needed to evaluate the clinical relevance of excessive BP decline in summer and management guidelines for practicing physicians should be developed.

PP.03.22

Objective: Blood pressure variability, both short- and long-term, is a novel important prognostic factor. Seasonal variation of cardio-vascular morbidity and mortality is observed worldwide and the major determinant of this phenomenon is the seasonal changes in blood pressure. To assess the knowledge and understanding of the presence of blood pressure variation within the year and how it affects the antihypertensive treatment. Design and method: We sent questionnaires to 305 patients, 91% with arterial hypertension, and 174 physicians in various living settings. Besides the demographic characteristics, we asked them whether they were acquainted with the problem seasonal variation of blood pressure and whether they accepted it. There were questions how this phenomenon affected their treatment strategy. Results: The patients were at a mean age 57.3 ± 12.57 years (18–89 years), 42% were males and 74% were medically treated, while the physicians were mainly cardiologists (62%), at a mean age 50.80 ± 8.14 (27–73) years and with on average 25 years of professional experience. The vast majority of patients (62%) and of physicians (94%) accepted the seasonal phenomenon. The same number of patients (163 or 63%) and almost all physicians (167 or 96%) has measured lower blood pressure values during summer. This understanding lead to change in the therapeutic behavior. Only 19% did not change their treatment schemes, while 13.4% reduced or increased medications on their own. Their treating physicians changed the patients’ therapy according to the season regularly in 48% of the cases and sometimes in 41%. They reported that 26 % of their patients changed their antihypertensive therapy regularly and another 66% did it from time to time. More than two thirds of the physicians (120 or 69%) admitted that changes in guidelines are needed. Conclusions: The majority of hypertensive patients and their treating physicians accept seasonal variation of blood pressure. Moreover, a large number of patients change their treatment schemes, either alone or advised by healthcare professionals. Cardiologists in Bulgaria modify the antihypertensive treatment according to the season and recommend changes in current guidelines.

Season and outdoor temperature in relation to detection and control of hypertension in a large rural Chinese population.

Background: In many Western populations, blood pressure varies moderately with season and outdoor temperature. Relatively little is known about effects of seasonal changes in blood pressure on the detection and control of hypertension in general populations, especially in low- and middle-income countries.Methods: We analysed cross-sectional data of 57 375 (42% men) participants aged 30–79 (mean 52.3) years who were enrolled during 2004–08, as part of the China Kadoorie Biobank, from a rural county in the south-east costal Zhejiang Province. Analyses related daily mean outdoor temperature, obtained from local Meteorological Bureau, to mean systolic (SBP) and diastolic blood pressure (DBP), rate of newly detected hypertension and, among those with self-reported physician-diagnosed hypertension, rate of adequate blood pressure control, using multiple linear and logistic regression models.Results: The overall mean blood pressure was 135.9 mmHg for SBP and 80.5 mmHg for DBP. Daily outdoor temperature ranged between −2.9 and 33.7°C, with July being the hottest month (mean 29.4°C) and January the coldest (mean 4.0°C). Comparing January (the coldest month) with July (the warmest), the differences in the adjusted SBP/DBP were 19.2/7.7 mmHg. Each 10°C lower ambient temperature was associated with 6.9/2.9 mmHg higher SBP/DBP,14.1% higher prevalence of newly detected hypertension and, among those with pre-diagnosed hypertension, 13.0% lower hypertension control rate.Conclusion: In rural China, lower outdoor temperature is strongly associated with higher mean blood pressure and hypertension prevalence as well as poorer hypertension control, and should be considered when conducting population-based hypertension surveys and providing treatment for hypertensive patients.

Response to Seasonal Changes in Blood Pressure: Possible Interaction Between Sunlight and Brain Serotonin

Drs Dhar and Lambert1 correctly note that the potential relationship between sunlight and seasonal blood pressure (BP) changes is not investigated in our study.2 We agree that this interaction, possibly mediated, at least in part, by changes in brain monoamine concentration, should not be neglected. In addition, the UV-dependent cholecalciferol formation is a potential modifier of …

Seasonal Changes in Blood Pressure: Possible Interaction Between Sunlight and Brain Serotonin

To the Editor: Whoever wishes to investigate medicine properly, should proceed thus: in the first place to consider the seasons of the year, and what effects each of them produces for they are not at all alike, but differ much from themselves with regard to their changes. Attributed to Hippocrates, this quotation highlights the relevance of a recent article by Modesti et al1 who examined the influence of ambient/personal …

Seasonal changes in blood pressure: Cardiac and cerebrovascular morbidity and mortality

Cold is a seasonal and circadian risk factor for cardioand cerebrovascular morbidity and mortality. Colder temperatures have been associated with higher blood pressure (BP), based on studies which show that BP levels measured during the summer months are generally lower than those measured during the winter months. Residents in geographic areas which have greater seasonal temperature differences show greater fluctuation in BP. Surprisingly, atmospheric pressure, rainfall, and humidity were not related to BP levels. The increased sympathetic nervous activity due to cold, as evidenced by elevated BP and by plasma and urinary catecholamines, has been proposed as being the underlying etiology. Patients with heart failure may experience, in cold conditions, endothelial dysfunction and produce fewer endogenous vasodilators (e.g. , nitric oxide, prostaglandins) and more endogenous vasoconstrictors (e.g. , endothelin), thus increasing afterload. Arterial stiffness is also related to seasonal BP changes. Increased BP, arterial stiffness and endothelial dysfunction could predispose to increased coronary and cerebrovascular events. Improved protection against lower temperatures or increased doses of existing medications or the addition of newer medications could lead to a reduction in increased cardiovascular mortality in winter. Here, we briefly review findings from existing literature and provide an update on seasonal long-term variation in BP along with the related complications.

Seasonal changes in blood pressure in chronic kidney disease patients

Seasonal variation in blood pressure (BP) in different populations has been described. However, no study has concentrated on the change of blood pressure in chronic kidney disease (CKD) patients, a large and growing population worldwide. Furthermore, the role of volume status in seasonal blood pressure variations remains controversial. 109 CKD patients in a single center were followed between January 1, 2007 and December 31, 2007. Systolic and diastolic blood pressure, level of serum creatinine and body weight were measured in these patients and studied along with climatology data obtained from Beijing Weather Bureau. Blood pressure varied throughout the year, following a cyclic pattern. It increased from the autumn months toward winter, and decreased toward the spring and warmer months. The seasonal variation of blood pressure in CKD patients appeared not to correlate with CKD stage and similar seasonal variations were observed. Blood pressure values in the cohort of CKD patients were inversely correlated with outdoor temperatures (SBP: r = -0.882, p < 0.001; DBP: r = -0.860, p < 0.001). Furthermore, there was no significant difference in body weight between summer and winter (p > 0.05) in this group of CKD patients. Our results suggest that the blood pressure of CKD patients varied with the seasonal variation. The seasonal variation of blood pressure in CKD patients seemed to have no correlation with stage of CKD or change of body weight but was inversely associated with outdoor temperatures. These results suggested that volume status might not be a key mechanism causing seasonal variation in blood pressure.

Seasonal Variation of Blood Pressure in Normotensive Females Aged 18 to 40 Years in an Urban Slum of Delhi, India

Season is one of the factors affecting blood pressure. The objectives of this study are to quantify the magnitude of seasonal changes in blood pressure among normotensive women aged 18 to 40 years and to find out the association of blood pressure variation between winter and summer with body mass index, temperature, humidity, day length, and salt intake. The study was carried out on 132 women, included 4 home visits during the seasons of spring, summer, autumn, and winter. Mean increase in systolic blood pressure (SBP)/diastolic blood pressure (DBP) in winter was 11.07/6.79 mm Hg during summer (P < .001). No significant relationship in blood pressure variation with change in environmental variables was observed. Mean increase in SBP/DBP in winter was more among underweight than individuals who were normal/overweight/obese (P < .05). There was significant increase in SBP/DBP during winter compared with summer. This seasonal factor should be considered while evaluating individual blood pressure and comparing community studies.