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

Age-dependent changes in fat- and water-soluble vitamins—National Health and Nutrition Examination Surveys study

Aging is an independent risk factor for the development of various diseases associated, among others, with detrimental blood levels of fat- and water-soluble vitamins. Thus, the objective of this study is to investigate age-related changes in blood levels of vitamin A, B12, C, D, and E. Subject serum vitamin levels were obtained from the combined National Health and Nutrition Examination Surveys (NHANES). NHANESIII and NHANES 1999–2000, 2001–2002, 2003–2004, and 2005–2006. The raw data set was stratified into five age groups G1- G5: 20 ≤ G1 < 30, 30 ≤ G2 < 40, 40 ≤ G3 < 50, 50 ≤ G4 < 60, and 60 ≤ G5 < 70 years of age. Age stratified data was cleaned using the modified Horn algorithm. The reference range for the vitamin level of a specific age group was defined as data between the first and third quartile of the subject defined by normal blood pressure and normal bone density. Age-dependent changes in serum/plasma vitamin levels were assessed using the bootstrap technique with 10,000 repeats and Bonferroni adjustment. There was a continuous increase in vitamin A, B12, D, and E levels in the blood. However, the vitamin C concentration remained virtually constant in all age groups. There was a lack of cross-correlations between lipid and water-soluble vitamin levels and blood pressure and bone health. The following reference levels for vitamin A, B12, C, D, and E in subjects older than 20 years of age were established: vitamin A: 1.32–2.8 mmol/L, vitamin B12: 257.94–498.33 pmol/L, vitamin C: 38.18–79.2 mmol/L, vitamin D: 76.33–199.36 nmol/L and vitamin E: 3.65–41.12 μmol/L.

A Meteorological Paradox: Low Atmospheric Pressure-Associated Decrease in Blood Pressure Is Accompanied by More Cardiac and Cerebrovascular Complications: Five-Year Follow-up of Elderly Hypertensive Patients

Background: Variations in atmospheric pressure (AP) are known to affect blood pressure (BP). We assessed the effect of AP on BP, and the major fatal and nonfatal complications thereof (i.e., stroke, myocardial infarction, and pulmonary emboli). Methods: In this observational cohort study, 250 hypertensive patients (aged 65–92 years old) were followed for 3.5–5.4 years in a primary care clinic. Cox proportional hazard regression was performed to define the associations between AP, clinical, demographic and environmental factors, and major complications such as stroke, myocardial infarction, etc. Results: AP fluctuated between 1007 and 1024 millibars (MB). A total of 132 patients (53%) developed various complications, of which 13 (9.8%) were fatal. Among all fatalities, 93 of 119 nonfatal cases and 7 of 13 fatal cases occurred at AP < 1013 MB. A Cox regression analysis showed that low AP (AP < 1013 MB) had a higher hazard ratio (HR) on hypertension (HTN) complications among all demographic, clinical and environmental parameters. Conclusions: Most major complications were associated with very low APs. Low AP was the best predictive risk-factor for major complications of HTN.

Acute effects of ambient temperature on hypotension hospital visits: A time-series analysis in seven metropolitan cities of Korea from 2011 to 2015

BACKGROUND

Although blood pressure decreases in response to high ambient temperature, little is known about whether the ambient temperature can induce clinical hypotension events. Therefore, we conducted a time-series analysis to evaluate the association between hypotension hospital visits and ambient temperature in seven metropolitan cities of Korea.

METHODS

We used the National Health Insurance Database, which contains the complete hospital visit data of the entire Korean population. We collected hospital visit data of seven metropolitan cities and linked the number of daily hypotension hospital visits to city-level ambient temperature, relative humidity, and air pollution levels from 2011 to 2015. Time-series analysis using the Poisson generalized additive model was conducted for each metropolitan city and we meta-analyzed the time-series results using the random effect model.

RESULTS

There were 132,097 hospital visits for hypotension during our study period. A 1 degree Celsius (°C) increase in ambient temperature was associated with 1.1% increase in hospital visits for hypotension on lag day 0. Effects of ambient temperature lasted for 7 days, showing greater effects in shorter lag days. Subgroup analysis by sex and income groups showed similar results, but effects of ambient temperature on hypotension hospital visits was higher in the younger age group compared to older age group (aged over 65 years old). The results were unchanged when we applied cumulative lags, different case definitions, degrees of freedom per year, and multi-pollutant model adjusting for air pollutants.

CONCLUSIONS

Hospital visits for hypotension were positively associated with ambient temperature. Increased hypotension events in response to increased ambient temperature might explain the high cardiovascular mortality on hot days.

Socioeconomic Status Modifies the Seasonal Effect on Blood Pressure: Findings From a National Panel Study

Seasonal variations in blood pressure have been consistently reported. However, uncertainty remains about the size of the seasonal effect in different regions, and about factors that explain the differences observed across and within populations. Using data from a national panel study, we investigated seasonal variations in blood pressure in the South African adult population, and whether these variations differed across socioeconomic strata.We estimated age-specific seasonal effects on blood pressure using a multilevel structural equation model, with repeated measurements nested within subjects. Effect modification by socioeconomic status was assessed by repeating the analyses in the subpopulations defined by levels of education, household income per capita, and type of housing.In men and women, season had a statistically significant effect on blood pressure, with higher levels in winter and lower levels in summer. For systolic blood pressure, the magnitude of the seasonal effect was 4.25/4.21 mmHg (women/men) and was higher in the older age groups. For diastolic blood pressure, the effect size was 4.00/4.01 mmHg, with no evident age trend. Seasonal effects were higher among subjects in the lowest socioeconomic classes than in the highest, with differences between 2.4 and 7.7 mmHg, depending on gender, whether systolic or diastolic blood pressure, and socioeconomic status indicator.In the South African adult population, blood pressure shows seasonal variation modified by age and socioeconomic status. These variations have epidemiological, clinical, and public health implications, including the prospect of population level intervention to reduce elevated risk of cold weather cardiovascular morbidity.

Effects of weather and heliophysical conditions on emergency ambulance calls for elevated arterial blood pressure

We hypothesized that weather and space weather conditions were associated with the exacerbation of essential hypertension. The study was conducted during 2009-2010 in the city of Kaunas, Lithuania. We analyzed 13,475 cards from emergency ambulance calls (EACs), in which the conditions for the emergency calls were made coded I.10-I.15. The Kaunas Weather Station provided daily records of air temperature (T), wind speed (WS), relative humidity, and barometric pressure (BP). We evaluated the associations between daily weather variables and daily number of EACs by applying a multivariate Poisson regression. Unfavorable heliophysical conditions (two days after the active-stormy geomagnetic field or the days with solar WS>600 km/s) increased the daily number of elevated arterial blood pressure (EABP) by 12% (RR=1.12; 95% confidence interval (CI) 1.04-1.21); and WS≥3.5 knots during days of T<1.5 °C and T≥12.5 °C by 8% (RR=1.08; CI 1.04-1.12). An increase of T by 10 °C and an elevation of BP two days after by 10 hPa were associated with a decrease in RR by 3%. An additional effect of T was detected during days of T≥17.5 °C only in females. Women and patients with grade III arterial hypertension at the time of the ambulance call were more sensitive to weather conditions. These results may help in the understanding of the population's sensitivity to different weather conditions.