Seasonal cold and circadian changes in blood pressure and physical activity in young and elderly people

MR Spectroscopy Assessment of Daily Variations of GABA Levels within the Parietal Lobe and Anterior Cingulate Gyrus Regions of Healthy Young Adults

BACKGROUND

The changes that occur in the gamma-aminobutyric acid (GABA) levels within specific brain regions throughout the day are less clear.

PURPOSE

To evaluate the daily fluctuations of GABA levels within the parietal lobe (PL) and anterior cingulate gyrus (ACC) regions and explore their association with melatonin (MT) levels, heart rate (HR), and blood pressure.

STUDY TYPE

Prospective.

SUBJECTS

26 healthy young adults (15 males and 11 females aged 22-27 years).

FIELD STRENGTH/SEQUENCE

3.0T, T1-weighted imaging, Mescher-Garwood point resolved spectroscopy (MEGA-PRESS) sequence.

ASSESSMENT

The acquired GABA signal contained the overlapping signals of macromolecules and homocarnosine, hence expressed as GABA+. The creatine (Cr) signal was applied as an endogenous reference. The GABA+, GABA+/Cr were measured at six different time points (1:00, 5:00, 9:00, 13:00, 17:00, and 21:00 hours) using MEGA-PRESS. The blood pressure, HR and sputum MT levels, were also acquired.

STATISTICAL TESTS

The one-way repeated-measures analysis of variance (ANOVA) was used to evaluate the GABA, blood pressure, HR, and MT levels throughout the day. A general linear model was used to find the correlation between GABA and blood pressure, HR, and MT. P < 0.05 was statistically significant.

RESULTS

Significant variations in GABA+/Cr and GABA+ levels were observed throughout the day within the PL region. The lowest levels were recorded at 9:00 hour (GABA+/Cr: 0.100 ± 0.003，GABA+:1.877 ± 0.051 i.u) and the highest levels were recorded at 21:00 hour (GABA+/Cr: 0.115 ± 0.003, GABA+:2.122 ± 0.052 i.u). The MT levels were positively correlated with GABA+/Cr (r = 0.301) and GABA+ (r = 0.312) within the ACC region.

DATA CONCLUSION

GABA+/Cr and GABA+ in ACC are positively correlated with MT. GABA levels in the PL have diurnal differences. These findings may indicate that the body's GABA level change in response to the light-dark cycle.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 2.

A Nationwide Comparative Analysis of Temperature-Related Mortality and Morbidity in Japan

BACKGROUND

The impact of temperature on morbidity remains largely unknown. Moreover, extensive evidence indicates contrasting patterns between temperature-mortality and temperature-morbidity associations. A nationwide comparison of the impact of temperature on mortality and morbidity in more specific subgroups is necessary to strengthen understanding and help explore underlying mechanisms by identifying susceptible populations.

OBJECTIVE

We performed this study to quantify and compare the impact of temperature on mortality and morbidity in 47 prefectures in Japan.

METHODS

We applied a two-stage time-series design with distributed lag nonlinear models and mixed-effect multivariate meta-analysis to assess the association of temperature with mortality and morbidity by causes (all-cause, circulatory, and respiratory) at prefecture and country levels between 2015 and 2019. Subgroup analysis was conducted by sex, age, and regions.

RESULTS

The patterns and magnitudes of temperature impacts on morbidity and mortality differed. For all-cause outcomes, cold exhibited larger effects on mortality, and heat showed larger effects on morbidity. At specific temperature percentiles, cold (first percentile) was associated with a higher relative risk (RR) of mortality [1.45; 95% confidence interval (CI): 1.39, 1.52] than morbidity (1.33; 95% CI: 1.26, 1.40), as compared to the minimum mortality/morbidity temperature. Heat (99th percentile) was associated with a higher risk of morbidity (1.30; 95% CI: 1.28, 1.33) than mortality (1.04; 95% CI: 1.02, 1.06). For cause-specific diseases, mortality due to circulatory diseases was more susceptible to heat and cold than morbidity. However, for respiratory diseases, both cold and heat showed higher risks for morbidity than mortality. Subgroup analyses suggested varied associations depending on specific outcomes.

DISCUSSION

Distinct patterns were observed for the association of temperature with mortality and morbidity, underlying different mechanisms of temperature on different end points, and the differences in population susceptibility are possible explanations. Future mitigation policies and preventive measures against nonoptimal temperatures should be specific to disease outcomes and targeted at susceptible populations. https://doi.org/10.1289/EHP12854.

Altitude and Quality of Life of Older People in Colombia: A Multilevel Study

Objective

To assess the association between municipality altitude and quality of life (QOL) of older people in Colombia.

Methods

Cross-sectional study with data from the Colombian Demographic and Health Survey Older Adult Questionnaire 2015 (N = 13,970). QOL was measured in six domains: physical health, psychological health, functional status, social relations, medical history and economic status. Regression analyses were carried out adjusting by individual and contextual level variables.

Results

Low altitude was associated with better QOL: physical health (OR = 1.92, 95%CI 1.47−2.52), psychological health (OR = 1.59, 95%CI 1.26−2.00), functional status (OR=1.80, 95%CI 1.45−2.23), social relations (OR = 2.16 95%CI 1.73−2.70), and medical history (OR = 1.57, 95%CI 1.37−1.81). Economic status was not associated with altitude.

Discussion

Living at high altitude was associated with lower QOL for Colombian older adults. This finding encourages further study of high altitude and health outcomes among older adults in Colombia and other countries with populations living at high altitudes.

[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.

Relationship between metabolic syndrome and moderate-to-vigorous physical activity among adults 18 years old and over

The prevalence of metabolic syndrome (MetS) risk factors among the Korean population requires effective health surveillance and examination of the effects of preventative behaviors. Thus, the objective of this study is to evaluate the relationships between the clustering of MetS and MVPA in a large sample of 36,987 Koreans ranging from 20 to 80 years of age. This study recruited a total of 36,987 adults (23,813 males and 13,174 females). All participants were assessed for moderate-to-vigorous physical activity (MVPA) using the Korean version short form of the International Physical Activity Questionnaire (IPAQ). The International Diabetes Federation and the Adult Treatment Panel III criteria for blood pressure, hyperglycemia, low high-density lipoprotein cholesterol (HDL-C), and high triglycerides (TG) defined MetS. Waist circumference (WC) was determined by Asian-Pacific region populations. According to the 150-minute MVPA, there were differences in MetS risk factors in young adult males, and only three factors (WC, HDL-C, and TG) were different males in ≥ 70 years old. In females, there was a difference in MetS risk factors in the elderly, and only three factors (WC, blood pressure, and TG) were different females in ≤ 29 years old. The males who did not met the recommended MVPA had a 1.16 to 3.14 -times increase in the MetS risk factors. The females who did not met the recommended MVPA had a 1.18 to 2.57 -times increase in the MetS risk factors. Our study provides evidence that Korean adults who do not engage in recommended MVPA levels increase the odds ratio for each of the MetS risk factors when compared to those who meet the recommendations.

Aging disrupts the temporal organization of antioxidant defenses in the heart of male rats and phase shifts circadian rhythms of systolic blood pressure

Aging is one of the main risk factors for cardiovascular diseases, and oxidative stress is a key element responsible for the development of age-related pathologies. In addition, the alteration of circadian rhythms also contributes to cardiovascular pathology, but the underlying mechanisms are not well defined. We investigated the aging consequences on the temporal patterns of antioxidant defenses, the molecular clock machinery, and the blood pressure, in the heart of male rats maintained under constant darkness (free running) conditions. Male Holtzman rats from young adult (3-month-old) and older (22-month-old) groups were maintained under constant darkness (12-h dark:12-h dark, DD) condition during fifteen days before the experiment. After the DD period, heart ventricle samples were isolated every 4-h throughout a 24-h period. We observed circadian rhythms of catalase (CAT) and glutathione peroxidase (GPx) mRNA expression, as well as ultradian rhythms of Nrf2 mRNA levels, in the heart of young adult rats. We also found circadian oscillations of CAT and GPx enzymatic activities, reduced glutathione (GSH) and BMAL1 protein in the same group. Interestingly, aging abolished the rhythms of CAT and GPx enzymatic activities, phase-shifted the rhythm's acrophases of GSH and BMAL1 protein levels and turned circadian the ultradian oscillation of Nrf2 expression. Moreover, aging phase-shifted the circadian pattern of systolic blood pressure. In conclusion, aging modifies the temporal organization of antioxidant defenses and blood pressure, probably, as a consequence of a disruption in the circadian rhythm of the clock's transcriptional regulator, BMAL1, in heart.

Effect of air temperature on human births, preterm births and births associated with maternal hypertension

OBJECTIVE

We studied potential effects of outdoor air temperatures or barometric pressure on births, preterm births and births associated with maternal hypertension.

METHODS

12,269 births were retrospectively reviewed in Brussel and 25,880 in South Reunion Island. National Belgium and French weather reference centers provided outdoor air temperatures and barometric pressures from the nearest weather stations on the corresponding birthdays. Poisson regression models were used to assess if outdoor air temperatures or barometric pressure could be correlated, immediately and several days later, with the number of daily births, preterm births and births associated with hypertension.

RESULTS

Outdoor air temperature was significantly correlated to the number of daily births in Brussels. For each additional degree Celsius, overall births increased by 0.4% during the same day. Four days later, overall births increased by 1.8%, preterm births by 2.6% and births associated with hypertension by 5.7%. Similar observations on numbers of daily births were reported in South Reunion Island, without reaching statistical significance (p = .08).

CONCLUSION

As previously demonstrated in recent studies, increased air temperature leads progressively to higher rates of births and preterm births. An even stronger delayed effect of air temperature was observed on births associated with hypertension. This would be worth further investigating.

Seasonal variation in home blood pressure and its relationship with room temperature in patients with type 2 diabetes

Our aim was to examine the seasonal variations in home blood pressure measurements and the relationship of ambient temperature or room temperature with the seasonal variations in home blood pressure measurements using a home blood pressure telemonitoring system in patients with type 2 diabetes. The home blood pressure measurements of 41 patients with type 2 diabetes were self-measured. Patients performed triplicate morning and evening blood pressure measurements at least 5 days per month for 12 consecutive months. The lowest values of both systolic blood pressure and diastolic blood pressure were observed in August (126.3 and 70.4 mmHg, respectively), and the highest systolic and diastolic blood pressure values were observed in January (140.3 and 76.9 mmHg, respectively). The root mean squared error between the mean systolic blood pressure and room temperature was 6.50 mmHg and between mean systolic blood pressure and ambient temperature was 6.55 mmHg. Using a home blood pressure telemonitoring system, this study revealed for the first time that home blood pressure varied seasonally, with the highest values observed in January and the lowest values observed in August, and that the seasonal variations in home blood pressure were related to room temperature as well as ambient temperature.

Bridging the gap between clinical practice and public health: Using EHR data to assess trends in the seasonality of blood-pressure control

Electronic health records (EHRs) provide timely access to millions of patient data records while limiting errors associated with manual data extraction. To demonstrate these advantages of EHRs to public health practice, we examine the ability of a EHR calculated blood-pressure (BP) measure to replicate seasonal variation as reported by prior studies that used manual data extraction.

Our sample included 609 primary-care practices in New York City. BP control among hypertensives was defined as systolic blood pressure of 140 or less and diastolic blood pressure of 90 or less (BP < 140/90 mm Hg). An innovative query-distribution system was used to extract monthly BP control values from the EHRs of adult patients diagnosed with hypertension over a 25-month period. Generalized estimating equations were used to compare the association between seasonal temperature variations and BP control rates at the practice level, while adjusting for known demographic factors (age, gender), comorbid diseases (diabetes) associated with blood pressure, and months since EHR implementation.

BP control rates increased gradually from the spring months to peak summer months before declining in the fall months. In addition to seasonal variation, the adjusted model showed that a 1% increase in patients with a diabetic comorbidity is associated with an increase of 3% (OR 1.03; CI 1.028–1.032) on the BP measure.

Our findings identified cyclic trends in BP control and highlighted greater association with increased proportion of diabetic patients, therefore confirming the ability of the EHR as a tool for measuring population health outcomes.

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We replicated seasonal fluctuations in BP control using aggregate EHR data on outpatients in NYC.

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BP was better controlled in the warmer months than in the colder months.

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A higher proportion of patients with diabetic comorbidity at a practice increases the seasonal fluctuations in BP control.

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We found no association between BP control and the proportion of females or elderly at the practice.

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Our findings using EHR data was similar to prior studies that relied on manual chart review.

Environmental ambient temperature and blood pressure in adults: A systematic review and meta-analysis

OBJECTIVE

Although many individual studies have examined the association between temperature and blood pressure (BP), they used different methods and also their results were somewhat inconsistent. The aims of this study are to quantitatively summarize previous studies and to systematically assess the methodological issues to make recommendations for future research.

METHODS

We searched relevant empirical studies published before January 2016 concerning temperature and BP among adults using the MEDLINE, Embase and PubMed databases. Mean changes in systolic (SBP) and diastolic blood pressure (DBP) per 1°C reduction in temperature were pooled using a random-effects meta-analysis.

RESULTS

Of 23 studies included, 14 were used for meta-analysis. Consistent, statistically significant, inverse associations were observed between ambient temperature (mean, maximum, minimum outdoor temperature and indoor temperature) and BP. An 1°C decrease in mean daily outdoor temperature was associated with an increase in SBP and DBP of 0.26mmHg (95% CI: 0.18-0.33) and 0.13 (95% CI: 0.11-0.16), respectively. The increase was greater in people with conditions related to cardiovascular disease. An 1°C decrease in indoor temperature was associated with 0.38mmHg (0.18-0.58) increase in SBP, while the effects on DBP were not estimated due to limited studies. Among the previous studies on temperature-BP relationship, temperature and BP measurements are not accurate enough and statistical methods need to be improved.

CONCLUSIONS

Lower ambient temperatures seem to increase adults' BP and people with conditions related to cardiovascular disease are more susceptible to drops in temperature. Indoor temperature appeared to have a stronger effect on BP than outdoor temperature. To understand temperature-BP relationship well, a study combining repeated personal temperature exposure and ambulatory BP monitoring, applying improved statistical methods to examine potential non-linear relationship is warranted.

The northern physical environment and the well-being of the elderly aged over 65 years

OBJECTIVES

The purpose was to describe the significance of the physical environment in supporting the well-being of the elderly aged over 65 years. The aim was to produce knowledge that will complement the knowledge-base of gerontologic nursing.

STUDY DESIGN

The study was qualitative. Thirty-nine home-dwelling elderly persons aged over 65 were interviewed.

METHODS

The interviews (n = 39) were conducted with the thematic method. The data were analysed with methods of inductive content analysis.

RESULTS

The main threats of the northern physical environment to the well-being of the elderly are seasonal variation, temperature, snow, light variation and distances. The supportive characteristics of the northern environment are the natural environment, space, familiarity with the physical space, cleanliness and safety.

CONCLUSION

The characteristics of the northern physical environment seem to be significant for both urban and rural elderly people living in the northern part of Finland. The different aspects of the natural environment provide opportunities to relax, meet other people and do physical exercise, all of which are important factors of health promotion.

Influence of meteorological factors on acute aortic events in a subtropical territory

BACKGROUND/OBJECTIVE

This study aims to examine the relationship between weather changes and acute aortic events in a subtropical territory.

METHODS

A linear regression analysis was performed in a pan-territory epidemiological survey for a period of 10 years on the impacts of meteorological factors (ambient temperature, atmospheric pressure, relative humidity, amount of cloud, rainfall, number of lightning strikes, presence of typhoon, and thunderstorm warning) on the daily incidences of acute aortic dissections and ruptured aortic aneurysms. Meteorological variables were retrieved on a daily basis from a well-established observatory, and the daily incidences of aortic dissections and rupture of aortic aneurysms were retrieved from the Clinical Data Analysis and Reporting System.

RESULTS

During the study period (January 2005 to December 2014), 3878 patients were identified as having acute aortic dissections, and 1174 patients had ruptured aortic aneurysms. Corresponding averaged daily incidences were 1.06 and 0.32, respectively. The incidences of aortic dissection and ruptured aortic aneurysm in a day could be predicted by ambient temperature in degrees Celsius using the following linear regression models: (1) incidence of aortic dissection = 1.548 - 0.021 × temperature; (2) incidence of ruptured aortic aneurysm = 0.564 - 0.010 × temperature. In addition, both high atmospheric pressure and absence of thunderstorm warning are positively associated with more aortic dissections. For rupture of aortic aneurysms, high atmospheric pressure and low relative humidity were positive predictors. In multiple regression analysis, however, ambient temperature was the only significant predictor for both acute aortic dissections and ruptured aortic aneurysms.

CONCLUSION

This is the first pan-territory study to show an attributable effect of ambient temperature on acute aortic events. This paper confirms that even in a subtropical country, meteorological variables were important factors influencing acute aortic events.

Clock Genes Explain a Large Proportion of Phenotypic Variance in Systolic Blood Pressure and This Control Is Not Modified by Environmental Temperature

BACKGROUND

Diurnal variation in blood pressure (BP) is regulated, in part, by an endogenous circadian clock; however, few human studies have identified associations between clock genes and BP. Accounting for environmental temperature may be necessary to correct for seasonal bias.

METHODS

We examined whether environmental temperature on the day of participants' assessment was associated with BP, using adjusted linear regression models in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) (n = 819) and the Boston Puerto Rican Health Study (BPRHS) (n = 1,248) cohorts. We estimated phenotypic variance in BP by 18 clock genes and examined individual single-nucleotide polymorphism (SNP) associations with BP using an additive genetic model, with further consideration of environmental temperature.

RESULTS

In GOLDN, each additional 1 °C increase in environmental temperature was associated with 0.18 mm Hg lower systolic BP [SBP; β ± SE = -0.18 ± 0.05 mm Hg; P = 0.0001] and 0.10mm Hg lower diastolic BP [DBP; -0.10 ± 0.03 mm Hg; P = 0.001]. Similar results were seen in the BPRHS for SBP only. Clock genes explained a statistically significant proportion of the variance in SBP [V G/V P ± SE = 0.071 ± 0.03; P = 0.001] in GOLDN, but not in the BPRHS, and we did not observe associations between individual SNPs and BP. Environmental temperature did not influence the identified genetic associations.

CONCLUSIONS

We identified clock genes that explained a statistically significant proportion of the phenotypic variance in SBP, supporting the importance of the circadian pathway underlying cardiac physiology. Although temperature was associated with BP, it did not affect results with genetic markers in either study. Therefore, it does not appear that temperature measures are necessary for interpreting associations between clock genes and BP.

CLINICAL TRIAL REGISTRATION

Trials related to this study were registered at clinicaltrials.gov as NCT00083369 (Genetic and Environmental Determinants of Triglycerides) and NCT01231958 (Boston Puerto Rican Health Study).

Daily and Seasonal Rhythms in Human Mucosa Phospholipid Fatty Acid Composition

Fatty acids (FAs) can exert important physiological effects: for example, as precursors of eicosanoids, as signaling molecules, and, in particular, as parts of phospholipids, the major constituents of cell membranes. Animals can remodel cell membranes in terms of their FA composition in response to environmental conditions, and even endothermic mammals exhibit seasonal cycles in the FA makeup of membranes. Previous evidence pointed to the existence of both seasonal and daily cycles in phospholipid composition of human cell membranes. Therefore, we used a noninvasive method to collect human mucosa cells over 1 year in 20 healthy subjects, and we determined seasonal and daily rhythmicity of phospholipid FA content. Our results show that significant daily rhythms were detectable in 11 of 13 FAs and were largely synchronous among subjects. Also, these daily rhythms showed stable phase relationships between different FAs within subjects. In contrast, yearly rhythms in phospholipid FA content were statistically significant in only ~50% of subjects and were asynchronous between subjects. These results support the view that while human physiology is still dominated by geophysical sunrise and sunset, resulting in strong daily cycles, seasonal rhythms are less well defined, at least in Western societies. We suggest that the main physiological function underlying rhythms in cell membrane composition is the regulation of the activity of transmembrane proteins, such as ion pumps, which can be strongly affected by the fatty acyl chains of phospholipids in the surrounding membrane bilayer. Hence, among a multitude of other functions, cycles in membrane FA composition may be involved in generating the daily rhythm of metabolic rate. Rhythms in certain membrane FAs, namely polyunsaturated and monounsaturated FAs that are known to affect health, could be also involved in daily and seasonal rhythms of diseases and death.

Derivation and validation of BOREAS, a risk score identifying candidates to develop cold-induced hypertension

INTRODUCTION

Blood pressure increases in cold periods, but its implications on prevalence of hypertension and on individual progression to hypertension remain unclear. Our aim was to develop a pre-screening test for identifying candidates to suffer hypertension only in cold months among non-hypertensive subjects.

METHODS

We included 95,277 subjects registered on a primary care database from Girona (Catalonia, Spain), with ≥ 3 blood pressure measures recorded between 2003 and 2009 and distributed in both cold (October-March) and warm (April-September) periods. We defined four blood pressure patterns depending on the presence of hypertension through these periods. A Cox model determined the risk to develop vascular events associated with blood pressure patterns. A logistic regression distinguished those nonhypertensive individuals who are more prone to suffer cold-induced hypertension. Validity was assessed on the basis of calibration (using Brier score) and discrimination (using the area under the receiver operating characteristics).

RESULTS

In cold months, the mean systolic blood pressure increased by 3.3 ± 0.1 mmHg and prevalence of hypertension increased by 8.2%. Cold-induced hypertension patients were at higher vascular events risk (Hazard ratio=1.44 [95% Confidence interval 1.15-1.81]), than nonhypertensive individuals. We identified age, diabetes, body mass index and prehypertension as the major contributing factors to cold-induced hypertension onset.

DISCUSSION

Hypertension follows a seasonal pattern in some individuals. We recommend screening for hypertension during the cold months, at least in those nonhypertensive individuals identified as cold-induced hypertensive by this assessment tool.

Short-term effects of air temperature on blood pressure and pulse pressure in potentially susceptible individuals

BACKGROUND

Only few epidemiological studies have investigated the association between air temperature and blood pressure (BP) or pulse pressure (PP), with inconsistent findings. We examined whether short-term changes in air temperature were associated with changes in BP or PP in three different populations.

METHODS

Between March 2007 and December 2008, 371 systolic and diastolic BP measurements were collected in 30 individuals with type-2 diabetes mellitus (T2D), 30 persons with impaired glucose tolerance and 42 healthy individuals without a metabolic disorder from Augsburg, Germany. Hourly means of ambient meteorological data were obtained from a fixed measurement station. Personal temperature measurements were conducted using data loggers. Temperature effects were evaluated using additive mixed models adjusting for time trend and relative humidity.

RESULTS

Decreases in air temperature were associated with an increase in systolic BP, diastolic BP and PP in individuals with T2D. For example, a 1°C decrease in ambient temperature was associated with an immediate increase in systolic BP of 1.0 mmHg (95%-confidence interval: [0.5;1.4]mmHg). Effects of personally measured air temperature were similar. Temperature effects were modified by age, body mass index, gender, antihypertensive medication and whereabouts, such as being indoors.

CONCLUSIONS

We observed associations between decreases in air temperature and increases in BP as well as PP in persons with T2D indicating that these people might be potentially more susceptible to changes in air temperature. Our findings may provide a hypothesis for a mechanism between air temperature decreases and short-term increases of cardiovascular events.

Association between ambient temperature and blood pressure and blood pressure regulators: 1831 hypertensive patients followed up for three years

Several studies have suggested an association between ambient air temperature and blood pressure. However, this has not been reliably confirmed by longitudinal studies. Also, whether the reaction to temperature stimulation is modified by other factors such as antihypertensive medication is rarely investigated. The present study explores the relationship between ambient temperature and blood pressure, without and with antihypertensive medication, in a study of 1,831 hypertensive patients followed up for three years, in two or four weekly check ups, accumulating 62,452 follow-up records. Both baseline and follow-up blood pressure showed an inverse association with ambient temperature, which explained 32.4% and 65.6% of variation of systolic blood pressure and diastolic blood pressure (P<0.05) respectively. The amplitude of individual blood pressure fluctuation with temperature throughout a year (a 29 degrees centigrade range) was 9.4/7.3 mmHg. Medication with angiotensin converting enzyme inhibitor benazepril attenuated the blood pressure fluctuation by 2.4/1.3 mmHg each year, though the inverse association of temperature and blood pressure remained. Gender, drinking behavior and body mass index were also found to modify the association between temperature and diastolic blood pressure. The results indicate that ambient temperature may negatively regulate blood pressure. Hypertensive patients should monitor and treat blood pressure more carefully in cold days, and it could be especially important for the males, thinner people and drinkers.

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

Cold is a seasonal and circadian risk factor for cardio- and 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 blood pressure changes: an independent relationship with temperature and daylight hours

Seasonal blood pressure (BP) changes have been found to be related to either outdoor or indoor temperature. No information regarding the independent effects of temperature measured proximally to the patient, the personal-level environmental temperature (PET), is available. Inclusion of daylight hours in multivariate analysis might allow exploring the independent interaction of BP with seasonality. To investigate whether ambulatory BP monitoring is affected by PET or by seasonality, 1897 patients referred to our hypertension units underwent ambulatory BP monitoring with a battery-powered temperature data logger fitted to the carrying pouch of the monitor. Predictors of 24-hour daytime and nighttime BP and of morning BP surge were investigated with a multivariate stepwise regression model, including age, sex, body mass index, antihypertensive treatment, office BP, ambulatory heart rate, PET, relative humidity, atmospheric pressure, and daylight hours as independent variables. At adjusted regression analysis, daytime systolic BP was negatively related to PET (-0.14; 95% confidence interval, -0.25 to -0.02); nighttime BP was positively related to daylight hours (0.63; 0.37-0.90); and morning BP surge was negatively related to daylight hours (-0.54; -0.87 to -0.21). These results provide new evidence that PET and seasonality (daylight hours) are 2 independent predictors of ambulatory BP monitoring.

Wrist skin temperature, motor activity, and body position as determinants of the circadian pattern of blood pressure

Although the circadian blood pressure (BP) pattern has been extensively studied, the determinants of this rhythm are not fully understood. Peripheral vasodilatation is a regulatory mechanism for BP maintenance. However, it remains to be established whether the increase of nocturnal distal skin temperature associated with heat loss could also reflect the dipping status. For the first time, this paper investigates the relationship between BP and skin wrist temperature (WT), to evaluate whether the WT circadian rhythm can serve as screening procedure to detect dipping/non-dipping BP patterns. In addition, the authors compare the relationship between WT and other variables previously described as determinants of the BP pattern, such as physical activity and body position. Measurements of WT, motor activity, and body position for 5 d, plus ambulatory BP for 24-h during that span, were obtained from 28 diurnally active normotensive volunteers. WT was negatively correlated, whereas activity and body position were positively correlated, with systolic and diastolic BPs. However, these relationships were stronger during the rest than activity phase. In addition, a 78.6% concordance was detected between the observed dips in BP and the predicted BP pattern calculated based on the WT rhythm. Thus, these results suggest that the increase in WT produced by heat loss during the rest phase through peripheral skin blood vessels is the result of blood vessel vasodilatation reflexes in response to a shift from a standing to a supine position, together with shift in the circadian sympathetic/parasympathetic balance (nocturnal parasympathetic activation). In conclusion, WT could be considered as a potential new screening procedure to implement the diagnosis of non-dipping BP pattern.

Short-term impact of ambient air pollution and air temperature on blood pressure among pregnant women

BACKGROUND

Epidemiologic studies have reported inconsistent findings for the association between air pollution levels and blood pressure (BP), which has been studied mainly in elderly subjects. Short-term air pollution effects on BP have not been investigated in pregnant women, who may constitute a vulnerable population.

METHODS

Between 2002 and 2006, 1500 pregnant women from a mother-child cohort study conducted in Nancy and Poitiers, France, underwent 11,220 repeated BP measurements (average, 7.5 measurements/woman). Nitrogen dioxide (NO₂), particulate matter with an aerodynamic diameter below 10 μm (PM₁₀), and meteorologic variables were measured on an hourly basis at permanent monitoring sites. We studied changes of BP in relation to short-term variations of air pollution and temperature with mixed models adjusted for meteorologic and personal characteristics.

RESULTS

A 10°C decrease in temperature led to an increase in systolic BP of 0.5% (95% confidence interval = 0.1% to 1.0%). Elevated NO₂-levels 1 day, 5 days and averaged over 7 days before the BP measurement were associated with reduced systolic BP. The strongest decrease was observed for the 7-day NO₂ average (-0.4% [-0.7% to -0.2%] change for an 11 μg/m³ increase in NO₂). PM₁₀ effects on systolic BP differed according to pregnancy trimester: PM₁₀ concentration was associated with systolic BP increases during the first trimester and systolic BP decreases later in pregnancy.

CONCLUSIONS

We observed short-term associations of air pollution and of temperature with BP in pregnant women. Whether such changes in BP have clinical implications remains to be investigated.

Diet-independent remodeling of cellular membranes precedes seasonally changing body temperature in a hibernator

Polyunsaturated fatty acids (PUFA) have a multitude of health effects. Their incorporation into membrane phospholipids (PL) is generally believed to depend directly on dietary influx. PL influence transmembrane protein activity and thus can compensate temperature effects; e.g. PL n-6 PUFA are thought to stabilize heart function at low body temperature (T_b), whereas long chain (>C18) n-3 PUFA may boost oxidative capacity. We found substantial remodeling of membranes in free-living alpine marmots which was largely independent of direct dietary supply. Organ PL n-6 PUFA and n-6 to n-3 ratios were highest at onset and end of hibernation after rapid increases during a brief transitional period prior to hibernation. In contrast, longer chain PL n-3 PUFA content was low at end of summer but maximal at end of hibernation. After termination of hibernation in spring, these changes in PL composition were rapidly reversed. Our results demonstrate selective trafficking of PUFA within the body, probably governed by a circannual endogenous rhythm, as hibernating marmots were in winter burrows isolated for seven months from food and external cues signaling the approaching spring. High concentrations of PL n-6 PUFA throughout hibernation are in line with their hypothesized function of boosting SERCA 2a activity at low T_b. Furthermore, we found increasing rate of rewarming from torpor during winter indicating increasing oxidative capacity that could be explained by the accumulation of long-chain PL n-3 PUFA. It may serve to minimize the time necessary for rewarming despite the increasing temperature range to be covered, because rewarming is a period of highest metabolic rate and hence production of reactive oxygen species. Considering the importance of PUFA for health our results may have important biomedical implications, as seasonal changes of T_b and associated remodeling of membranes are not restricted to hibernators but presumably common among endothermic organisms.

Influence of climatic variables on acute myocardial infarction hospital admissions

BACKGROUND

Seasonal peaks in acute myocardial infarction (AMI) incidence have been widely reported. Weather has been postulated to be one of the elements at the basis of this association. The aim of our study was to determine the influence of seasonal variations and weather on AMI hospital admissions.

METHODS

We correlated the daily number of AMI cases admitted to a western Sicily hospital over twelve years and weather conditions on a day-to-day basis. Information on temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure was obtained from the local Birgi Air Force base. A total of 3918 consecutive patients were admitted with AMI over the period 1987-1998 (2822 men, 1096 women; M/F: 2,58).

RESULTS AND CONCLUSIONS

A seasonal variation was found with a significant winter peak. The results of multivariate Poisson analysis show in both sexes a significant association as regards the incidence relative ratio between the daily number of AMI hospital admission and minimal daily temperature and maximal daily humidity. The incidence relative ratios (95% confidence intervals) were, in males, 0.95 (0.92-0.98) (p<0.001) as regards minimal temperature and 0.97 (0.94-0.99) (p=0.017) as regards maximal humidity. The corresponding values in females were respectively 0.91 (0.86-0.95) (p<0.001) and 0.94 (0.90-0.98) (p=0.009). Environmental temperature, and also humidity, may play an important role in the pathogenesis of AMI. These data may help in understanding the mechanisms whereby AMI events are triggered and in organizing better the assistance to ischemic patients throughout the year.

A synoptic approach to weather conditions discloses a relationship with ambulatory blood pressure in hypertensives

BACKGROUND

Higher blood pressure (BP) values in cold than in hot months has been documented in hypertensives. These changes may potentially contribute to the observed excess winter cardiovascular mortality. However, the association with weather has always been investigated by considering the relationship with a single variable rather than considering the combination of ground weather variables characterizing a specific weather pattern (air mass (AM)).

METHODS

We retrospectively investigate in Florence (Italy) the relationship between BP and specific AMs in hypertensive subjects (n = 540) referred to our Hypertension Unit for 24-h ambulatory BP monitoring during the period of the year characterized by the highest weather variability (winter). Five different winter daily AMs were classified according to the combination of ground weather data (air temperature, cloud cover, relative humidity, atmospheric pressure, wind speed, and direction).

RESULTS

Multiple variable analysis selected the AM as a significant predictor of mean 24-h BP (P < 0.01 for diastolic BP (DBP) and P < 0.05 for systolic BP (SBP)), daytime DBP (P < 0.001) and nighttime BP (P < 0.01 for both SBP and DBP), with higher BP values observed in cyclonic (unstable, cloudy, and mild weather) than in anticyclonic (settled, cloudless, and cold weather) days. When the association with 2-day sequences of AMs was considered, an increase in ambulatory BP followed a sudden day-to-day change of weather pattern going from anticyclonic to cyclonic days.

CONCLUSIONS

The weather considered as a combination of different weather variables may affect BP. The forecast of a sudden change of AM could provide important information helpful for hypertensives during winter.

Seasonal influence on blood pressure in elderly normotensive subjects

The aim of this study was to examine whether or not fluctuations in blood pressure (BP) differ by season. Subjects were 45 elderly individuals (20 men and 25 women; mean age, 66.5+/-4.9 [SD] years). Each subject's BP was recorded with an ambulatory BP monitoring device for 24 h during each of the four seasons. Subjects also wore a portable weather meter to obtain ambient temperature, relative humidity, and barometric pressure simultaneously with BP. The relationships between meteorologic values and BP were investigated at various parts of the day. Seasonal differences in BP fluctuation around wake-up-time were analyzed by means of the Tukey's test. The difference between the pre-wake-up-time systolic BP and the wake-up-time systolic BP was significantly greater in winter than in summer (8.7 mmHg greater, p<0.001). The difference between pre-wake-up-time and wake-up-time systolic BP was significantly greater in autumn than in spring (9.4 mmHg greater, p<0.001) or summer (13.1 mmHg greater, p<0.001). The difference between pre-wake-up-time heart rate and wake-up-time heart rate did not differ statistically between seasons. In conclusion, the present study showed that the difference between pre-wake-up-time systolic BP and wake-up-time systolic BP was greatest in the colder seasons, i.e., autumn and winter. There appears to be a large fluctuation in wake-up-time in the colder seasons. Low ambient temperature likely induces this large fluctuation.

Seasonal variation in leisure-time physical activity among Canadians

BACKGROUND

Cardiovascular disease (CVD) mortality is higher in winter than summer, particularly in cold climates. Physical activity reduces CVD risk but climate impacts participation in physical activity. Canada has substantial climatic variation but its relation with physical activity is understudied. In this investigation, we evaluated the relation between seasonality and physical activity among Canadians.

METHODS

We used public domain data from the Canadian Community Health Survey, Cycle 2.2 (CCHS 2.2), a representative, cross-sectional sample of free-living Canadians in 2004. Leisure-time physical activity was measured using a modified version of the Physical Activity Monitor that was validated. Season was determined by the time of the interview, i.e., Winter: January 1 to March 31, Spring: April 1 to June 30, Summer: July 1 to September 30, and Fall: October 1 to December 31. In all multivariate models, we adjusted for age, sex, education, and income adequacy.

RESULTS

There were 20,197 persons aged 19 years and older in this analysis. In the winter, 64% of Canadians were inactive as compared with 49% in the summer. Total average daily energy expenditure was 31.0% higher in summer than winter after multivariate adjustment. Leisure-time physical activity was 86% more likely in the summer than winter (multivariate OR = 1.86, 95% CI 1.40, 2.45). The relation between seasonality and physical activity was weakest in Newfoundland and Labrador and stronger in Saskatchewan and British Columbia (p-value for interaction = 0.02).

INTERPRETATION

Seasonality impacts physical activity patterns in Canada and varies across the provinces. This needs to be considered in physical activity programming.

The effect of temperature on systolic blood pressure

OBJECTIVES

To quantify the association between systolic blood pressure and season, indoor and outdoor temperature and short-term trends in outdoor temperature.

METHODS

The study used data from the WHO MONICA Project risk factors surveys from 25 populations in 16 countries. Random samples of men and women aged 35-64 years were invited to participate. Systolic blood pressure measurements were available for 115 434 participants. Hierarchical models were used to quantify the association between blood pressure and temperature, and account for differences in the associations between populations.

RESULTS

Populations closer to the equator showed larger seasonal changes in blood pressure. A 1 degrees C increase in indoor temperature reduced systolic blood pressure by an average of 0.31 mmHg (95% posterior interval: -0.44, -0.19). A 1 degrees C increase in outdoor temperature reduced blood pressure by the smaller average of 0.19 mmHg (95% posterior interval: -0.26, -0.11). Increased outdoor, but not indoor, temperatures had a stronger effect in women than in men. The effect of outdoor temperature remained after controlling for indoor temperature. Short-term trends in temperature did not have a statistically signicant effect.

CONCLUSIONS

Indoor and outdoor temperature have independent effects on systolic blood pressure, and both should be controlled for in studies that measure blood pressure. Improved protection against cold temperatures could lead to a reduction in the winter excess of cardiovascular mortality.

Seasonal Variations in Blood Pressure

The influence of temperature changes on risk factors like hypertension is often disregarded despite extensive literature on the phenomenon. Numerous surveys and studies have documented the correlation between temperature and blood pressure in various countries among adults, the elderly, and children. Twenty-four-hour blood pressure studies also generally show higher blood pressure in the winter. The suggested etiology is that cold increases sympathetic tone, evidenced by elevated blood pressure and plasma and urinary noradrenaline concentrations. The lower blood pressure in warm temperatures is attributed to cutaneous vasodilatation and loss of water and salt from sweating. Taking seasonal variations in blood pressure into account will increase the meaningful information collected in population surveys and mass screenings. It will also result in more personalized management of antihypertensive medications tailored to the individual.

A deadly harvest: the effects of cold on older people in the UK

Excess winter mortality of some thousands of deaths of older people has occurred in the UK for the past 150 years and shows only moderate abatement. Government policies in both health and social care have had little apparent effect, other than a slow decline in seasonality due largely to secular trends. There are a number of apparent misconceptions, commonly held in the public mind and subsumed in public policy, which need to be corrected in order to reduce the toll of winter cold on older people. The evidence shows that winter deaths are to a large extent avoidable. They are not due to hypothermia as is widely believed, may not be necessarily reduced by climate change in the foreseeable future and may only be partially reduced by improving indoor warmth alone. The key is an integrated policy which reduces all risks equally. Community nursing is well placed to play a pivotal role in such policies.

Infradian awake and asleep systolic and diastolic blood pressure rhythms in humans

BACKGROUND

Blood pressure shows 24-h rhythms with a significant seasonal fluctuation.

OBJECTIVES

To characterize 2-month to 12-month infradian rhythms in the mean awake and asleep systolic blood pressure (SBP) and diastolic blood pressure (DBP) in humans.

METHODS

A total of 1689 participants underwent 24-h ambulatory blood pressure monitoring during different periods of the year. The mean daily temperature, humidity, barometric pressure and wind velocity values for the same time span and geographical location were obtained. Fourier analysis was used to fit 12-month, 6-month, 4-month, 3-month and 2-month rhythms to the mean awake and asleep SBP and DBP and to metereological variables.

RESULTS

The awake mean SBP and DBP values showed significant 12-month and 3-month rhythms (respectively, R2 = 55%, P < 0.001 and R2 = 45% P < 0.001), with a peak in July (winter) and a trough-peak difference of 6.2 +/- 1.6 mmHg (P < 0.001, SBP) and 4.2 +/- 1.5 mmHg (P < 0.001, DBP). In contrast, asleep blood pressure means showed mainly 3-month rhythms (SBP, R2 = 19%, P < 0.02; DBP, R2 = 43% P < 0.02). Mean daily temperature and humidity showed at 12-month, 6-month, 4-month, 3-month and 2-month rhythms, barometric pressure showed 12-month and 6-month rhythms, and wind velocity showed 12-month and 3-month rhythms. Minimal temperature values and maximal humidity values coincided with elevated blood pressure values.

CONCLUSION

Awake blood pressure means exhibited mainly circannual fluctuations while asleep blood pressure means showed principally 3-month rhythms. Infradian blood pressure variations correlated with some meteorological variables.

Postexercise hypotension induced by low-intensity resistance exercise in hypertensive women receiving captopril

OBJECTIVE

The present study investigated the effect of a single bout of low-intensity resistance exercise on recovery blood pressure in hypertensive women receiving captopril.

METHODS

Twelve essential hypertensive women, who were receiving captopril, underwent two experimental sessions: control (C - 40 min of seated rest) and low-intensity resistance exercise (E - six resistance exercises, three sets, 20 repetitions, 40% of one repetition maximum). Clinic blood pressure was measured in the laboratory, before and for 120 min after exercise or rest. Moreover, ambulatory blood pressure was also measured for 21 h after exercise or rest.

RESULTS

Clinic blood pressures decreased significantly after exercise (systolic blood pressure =-12+ or -3 mmHg and diastolic blood pressure =-6+ or -2 mmHg, P<0.05), but not after rest. Mean awake blood pressures (systolic: C=132+ or -5 mmHg vs. E=125+ or -4 mmHg and diastolic: C=83+ or -3 mmHg vs. E=78+ or -2 mmHg, P<0.05) were significantly lower in the E than in the C session, while 21-h (systolic blood pressures: C=128+ or -5 mmHg vs. E=123+ or -4 mmHg; and diastolic blood pressures: C=80+ or -3 mmHg vs. E=76+ or -2 mmHg) and asleep (systolic blood pressures: C=120+ or -7 mmHg vs. E=118+ or -5 mmHg; and diastolic blood pressures: C=73+ or -4 mmHg vs. E=71+ or -3 mmHg) blood pressures did not differ between the experimental sessions. Moreover, there was a positive correlation between blood pressure measured in the C session and blood pressure reduction observed in the E session, showing that blood pressure decrease was greater when blood pressure level was higher.

CONCLUSION

In hypertensive women receiving captopril, a single bout of low-intensity resistance exercise reduces blood pressure. This reduction persists for 10 h, during the awake period, while patients were engaged in their daily living activities. It was greater in patients with higher ambulatory blood pressure.

Seasonal rhythms and exercise

Levels of leisure-time physical activity and physical fitness are generally higher in the summer than in the winter months for most people living away from the equator. The notion that an abrupt increase in physical activity in the spring, after a period of relative inactivity, can trigger sudden cardiac events has not been confirmed. There are seasonal variations in the physiological responses to exercise and the occurrence of injuries during participation in sports, but it is not known whether these changes are explained by fluctuations in activity levels and environmental conditions, or by any endogenous circannual rhythms in the human. There are indications of endogenous control for some physiological processes (eg, the metabolic responses to a given intensity of exercise) that seem to mediate more favorable effects of exercise on body composition in the winter. Well-trained athletes show obvious seasonality in their competitive performances, generally in line with adopted annual periodization strategies, although these strategies can be disrupted by external seasonal factors, such as heat stress or the susceptibility to upper respiratory tract infections. Maximal oxygen consumption and other physiological indicators of exercise performance might not mirror seasonal variation in real performances, which suggests that top-class athletes maintain a good level of general physical conditioning throughout the year.

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

A downward titration of antihypertensive drug regimens in summertime is often performed on the basis of seasonal variations of clinic blood pressure (BP). However, little is known about the actual interaction between outdoor air temperature and the effects of antihypertensive treatment on ambulatory BP. The combined effects of aging, treatment, and daily mean temperature on clinic and ambulatory BP were investigated in 6404 subjects referred to our units between October 1999 and December 2003. Office and mean 24-hour systolic BP, as well as morning pressure surge, were significantly lower in hot (>90th percentiles of air temperature; 136+/-19, 130+/-14, and 33.3+/-16.1 mm Hg; P<0.05 for all), and higher in cold (<10th percentiles) days (141+/-12, 133+/-11, and 37.3+/-9.5 mm Hg; at least P<0.05 for all) when compared with intermediate days (138+/-18, 132+/-14, and 35.3+/-15.4 mm Hg). At regression analysis, 24-hour and daytime systolic pressure were inversely related to temperature (P<0.01 for all). Conversely, nighttime systolic pressure was positively related to temperature (P<0.02), with hot days being associated with higher nighttime pressure. Air temperature was identified as an independent predictor of nighttime systolic pressure increase in the group of elderly treated hypertensive subjects only. No significant relationship was found between air temperature and heart rate. Our results show for the first time that hot weather is associated with an increase in systolic pressure at night in treated elderly hypertensive subjects. This may be because of a nocturnal BP escape from the effects of a lighter summertime drug regimen and may have important implications for seasonal modulation of antihypertensive treatment.

Is there a relationship between weather conditions and aortic dissection?

Background

Bleeding and rupture of blood vessels has been correlated with weather conditions in the past. This is the first study in the world literature with the aim of investigating the relationship between atmospheric pressure and temperature with the presentation of aortic dissection.

Methods

The dates of all emergency aortic dissection repairs from 1996–2002 in a regional cardiothoracic unit at Blackpool Victoria Hospital were obtained. Hourly temperature and pressure data from a regional weather station for this time period was supplied by the Meteorological Office. The mean and standard deviation of hourly temperature and pressure data for that month were compared to the mean and standard deviation of the data 24 and 48 hours prior to the aortic dissection.

Results

26 patients were found to have been operated on during the time period studied. There was no statistically significant correlation between temperature or atmospheric pressure readings, and the incidence of aortic dissection, using a Bonferonni-corrected significance p-value of 0.005

Conclusion

This study is the first to examine the relationship between atmospheric pressure, temperature and dissecting thoracic aorta. No statistically significant relationship was demonstrable.

Seasonal variation in hospitalisation for hypertension-related morbidities in Sokoto, north-western Nigeria

OBJECTIVE

To determine the relationship between hospital admissions of hypertension-related morbidities, seasons and meteorological factors in a tropical climate.

STUDY DESIGN

Retrospective analysis of hospitalised patients (440) with hypertension-related morbidities including heart failure (36.4 %), stroke (34.8%), chronic renal failure (7.1%) and others (21.7%) from 1995 to 2000. The relationship between hospital admission, seasons and meteorological factors was determined using simple proportions, univariate, multivariate and regression analysis.

RESULTS

The subjects were aged 21-85 years and represented 9.3 % of all hypertensives and 7.0% of medical admissions. Mean blood pressure was 187.3 +/- 34.0/120 +/- 23 mmHg. Mild, moderate and severe hypertension occurred in 30 (6.8%), 59 (13.4%) and 351 (79.8%) patients, respectively. The monthly admission rate ranged from 3-11; (mean 6.1 +/- 1.9) patients. Admission rates peaked in January/February and August/September, corresponding with the peaks of harmattan and the wet seasons, respectively. Mean monthly admission rates were significantly higher during harmattan than during the hot season (6.7 +/- 2 versus 5.2 +/- 1.4 patients; p < 0.05), and during wet season than during the hot season (6.4 +/- 1.9 versus 5.2 +/- 1.4 patients; p < 0.05). Considering the hypertensives as a whole, a significantly higher proportion of patients was hospitalised during the cold season than during the hot season (11% versus 8.2%; odds ratio = 1.34). Linear regression analysis showed that hospital admission was significantly associated with the monthly minimum temperature (p = 0.02) and solar radiation (p = 0.01). Multiple regression analysis revealed that hospital admission was also significantly associated with combined meterological factors (temperature, radiation, dust haze days and relative humidity) (p = 0.04).

CONCLUSIONS

Hospital admissions of patients with hypertension-related morbidities showed seasonal variation. Appropriate clothing and health planning during cold seasons are recommended.

Seasonal hypertension: a clue to explain the high prevalence of unrecognized hypertension in the elderly? Gruppo Italiano di Farmacovigilanza nell'Anziano (GIFA)

BACKGROUND AND AIMS

Blood pressure is known to be influenced by the season, particularly in the elderly. The association between cold weather and unrecognized hypertension has not been previously studied. The present study aimed at assessing whether recognition of hypertension in the elderly follows a seasonal pattern.

METHODS

All patients over 64 with either first-listed or secondary diagnosis of hypertension at discharge (N = 4487) out of 24585 consecutively admitted to 69 wards of Geriatrics or Internal Medicine during ten bi-monthly observation periods (May-June and September-October) were enrolled. The main outcome of the study was the prevalence of unrecognized hypertension, defined as no mention of hypertension and/or antihypertensive drugs in clinical histories collected on admission, and a first-listed or secondary discharge diagnosis of hypertension.

RESULTS

We found a total of 928 patients with unrecognized hypertension. Being admitted in the September-October period was independently associated with the outcome unrecognized hypertension (OR 1.25, 95% CI 1.08-1.46), as were smoking addiction (OR 1.57, 95% CI 1.23-2.0) and allocation to a medical ward (OR 1.21, 95% CI 1.04-1.41). Negative correlates of the outcome were multiple pathologies (OR 0.85, 95% CI 0.73-0.99), discharge diagnosis of coronary artery disease (OR 0.77, 95% CI 0.64-0.92) or diabetes mellitus (OR 0.81, 95% CI 0.67-0.97).

CONCLUSIONS

Hypertension in the elderly may at least partly follow a seasonal pattern, and this finding may be relevant for screening and therapeutic decisions.