Blood Pressure Seasonality in Hemodialysis Patients from Five European Cities of Different Latitudes

Potential mechanisms of ischemic stroke induced by heat exposure

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

Seasonal variation in blood pressure: what is still missing?

Seasonal variation of blood pressure (BP) is a topic in cardiology that has gained more attention throughout the years. Although it is extensively documented that BP increases in seasons coupled with lower temperatures, there are still many gaps in this knowledge field that need to be explored. Notably, seasonal variation of BP phenotypes, such as masked and white coat hypertension, and the impact of air pollution, latitude, and altitude on seasonal variation of BP are still poorly described in the literature, and the levels of the existing evidence are low. Therefore, further investigations on these topics are needed to provide robust evidence that can be used in clinical practice.

Potential impact of ambient temperature on maternal blood pressure and hypertensive disorders of pregnancy: A nationwide multicenter study based on the China birth cohort

Limited evidence exists regarding the association between ambient temperature and blood pressure (BP) level of pregnant women. To investigate the associations of ambient temperature with maternal BP and hypertensive disorders of pregnancy (HDP), we studied 105,063 participants in 38 centers of 17 provinces from November 2017 to December 2021. BP was measured with standardized automated digital sphygmomanometers. Ambient temperature was classified into five classes as very hot, moderate hot, mild, moderate cold, and very cold. Generalized linear mixed models were used to investigate the ambient temperature-BP/HDP associations, controlling for multiple covariates. No significant associations of first-trimester ambient temperature with maternal BP and HDP prevalence were observed. Compared with mild temperature, second-trimester very cold and second-trimester moderate cold were statistically associated with the increase of 1.239 mmHg (95% CI: 0.908, 1.569) and 0.428 mmHg (95% CI: 0.099, 0.757) for second-trimester systolic blood pressure (SBP), respectively. Similar trends were also observed in the association between second-trimester cold exposure and second-trimester diastolic blood pressure (DBP), in the association between second-trimester cold exposure and third-trimester SBP/DBP as well as in the association between third-trimester cold exposure and third-trimester SBP/DBP although some estimates were not statistically significant. Furthermore, in the second and third trimester, very cold [second trimester: adjusted odds ratio (aOR) = 1.298; third trimester: aOR = 1.236) and moderate cold (second trimester: aOR = 1.208; third trimester: aOR = 1.146) exposures also increased the odds of HDP, and these associations were stronger among participants aged ≥35 years or from North China. The second and third trimesters are the critical exposure windows for ambient temperature exposure-BP/HDP associations. During this period, exposure to cold ambient temperature was associated with elevated BP as well as increased HDP prevalence among most Chinese pregnant women, those aged ≥35 years or from North China being more vulnerable.

Prevalence of hypertension in endemic and non-endemic areas of Keshan disease: A cross-sectional study in rural areas of China

Background

Hypertension is a major public health concern that strongly influences the quality of life of people worldwide. Keshan disease (KD) is an endemic cardiomyopathy related to low selenium, threatening residents in rural areas of 16 provinces in China. Furthermore, the prevalence of hypertension in the KD-endemic areas has been increasing annually. However, hypertension research associated with KD has only focused on endemic regions, and no studies have compared hypertension prevalence between endemic and non-endemic areas. Therefore, this study investigated the prevalence of hypertension to provide a basis for preventing and controlling hypertension in the KD-endemic areas, even in rural areas.

Methods

We extracted blood pressure information from cardiomyopathy investigation data from a cross-sectional study of the KD-endemic and non-endemic areas. The hypertension prevalence between the two groups was compared using the Chi-square test or Fisher s exact test. Additionally, Pearson's correlation coefficient was employed to evaluate the relationship between the per capita gross domestic product (GDP) and hypertension prevalence.

Results

There was a statistically significant increase of hypertension prevalence in the KD-endemic areas (22.79%, 95% confidence interval [CI]: 22.30-23.27%) over the non-endemic areas (21.55%, 95% CI: 21.09-22.02%). In the KD-endemic areas, more men had hypertension than women (23.90% vs. 21.65%, P < 0.001). Furthermore, the hypertension prevalence was higher in the north than in the south in the KD-endemic areas (27.52% vs. 18.76%, P < 0.001), non-endemic areas (24.86% vs. 18.66%, P < 0.001), and overall (26.17% vs. 18.68%, P < 0.001). Finally, the prevalence of hypertension positively correlated with per capita GDP at province level.

Conclusions

The increasing hypertension prevalence is a public health problem in the KD-endemic areas. Healthy diets, such as high consumption of vegetables and seafoods, and foods that are rich in selenium, might help prevent and control hypertension in the KD-endemic areas and other rural areas in China.

Monthly trends and seasonality of hemodialysis treatment and outcomes of newly initiated patients from the national database (NDB) of Japan

BACKGROUND

The numbers of patients treated with hemodialysis (HD) in Japan are currently quantified by manual survey. As this method requires much effort from medical institutions and cannot achieve 100% response, a more practical method is required. We aimed to establish a novel method for determining the static and dynamic numbers of patients treated with HD.

METHODS

This observational study used the national medical billing database (termed NDB) of Japan, based on the records of the universal healthcare insurance system. Medical billing data registered in the NDB between April 2011 and March 2015 were analyzed. From 130 billion records, we extracted and analyzed records of patients who had undergone HD at least once per month. Patients' monthly condition was classified as newly initiated HD, chronic HD, or presumed death, using conditional expressions. We also investigated renal outcome and presumed survival in newly initiated HD patients.

RESULTS

In the last month of the study period, 274,100 patients were identified as receiving chronic HD, which is estimated as > 95% of the number of these patients identified in the manual survey so far. The monthly data showed clear seasonality in the incidence of transient HD, which increased in winter and decreased in summer.

CONCLUSION

Analysis of a large national database revealed a significant increase in transient HD in winter and decrease in summer. Applied to additional epidemiological exploratory studies or clinical research, this analytical technique would enable collection of the dynamics of almost all HD patients nationwide.

The effect of ambient temperature on blood pressure of patients undergoing hemodialysis in the Pantanal-Brazil

The objective was to analyze the association of changes in pre-dialysis systolic and diastolic blood pressure with air temperature in a municipality in the Brazilian Pantanal, a tropical climate area. Longitudinal panel study, with analysis of mixed effects models of 133 hemodialysis patients in the city of Cáceres-Mato Grosso in 2014. Air temperature showed an inverse association with pre-dialysis systolic and diastolic blood pressure. With each increase of 1 °C in the mean air temperature, the pre-dialysis systolic blood pressure decreases -0.730mmHg (p ≤ 0.000) and the pre-dialysis diastolic blood pressure decreases -0.280mmHg (p ≤ 0.000). The estimated effect was greater for systolic blood pressure, but both pre-dialysis blood pressure measures are reduced with an increase in lag (up to two days), even when adjusted for relative air humidity. Air temperature is determinant for changes in pre-dialysis systolic and diastolic blood pressure in hemodialysis patients. The temperature effect was greater for systolic blood pressure than for diastolic blood pressure.

Seasonal and Secular Trends of Cardiovascular, Nutritional, and Inflammatory Markers in Patients on Hemodialysis

BACKGROUND

All life on earth has adapted to the effects of changing seasons. The general and ESKD populations exhibit seasonal rhythms in physiology and outcomes. The ESKD population also shows secular trends over calendar time that can convolute the influences of seasonal variations. We conducted an analysis that simultaneously considered both seasonality and calendar time to isolate these trends for cardiovascular, nutrition, and inflammation markers.

METHODS

We used data from adult patients on hemodialysis (HD) in the United States from 2010 through 2014. An additive model accounted for variations over both calendar time and time on dialysis. Calendar time trends were decomposed into seasonal and secular trends. Bootstrap procedures and likelihood ratio methods tested if seasonal and secular variations exist.

RESULTS

We analyzed data from 354,176 patients on HD at 2436 clinics. Patients were 59±15 years old, 57% were men, and 61% had diabetes. Isolated average secular trends showed decreases in pre-HD systolic BP (pre-SBP) of 2.6 mm Hg (95% CI, 2.4 to 2.8) and interdialytic weight gain (IDWG) of 0.35 kg (95% CI, 0.33 to 0.36) yet increases in post-HD weight of 2.76 kg (95% CI, 2.58 to 2.97). We found independent seasonal variations of 3.3 mm Hg (95% CI, 3.1 to 3.5) for pre-SBP, 0.19 kg (95% CI, 0.17 to 0.20) for IDWG, and 0.62 kg (95% CI, 0.46 to 0.79) for post-HD weight as well as 0.12 L (95% CI, 0.11 to 0.14) for ultrafiltration volume, 0.41 ml/kg per hour (95% CI, 0.37 to 0.45) for ultrafiltration rates, and 3.30 (95% CI, 2.90 to 3.77) hospital days per patient year, which were higher in winter versus summer.

CONCLUSIONS

Patients on HD show marked seasonal variability of key indicators. Secular trends indicate decreasing BP and IDWG and increasing post-HD weight. These methods will be of importance for independently determining seasonal and secular trends in future assessments of population health.

Clinical blood pressure responses to daily ambient temperature exposure in China: An analysis based on a representative nationwide population

BACKGROUND

Limited evidence is available regarding the potential heterogeneity of ambient temperature on blood pressure (BP) in various climate zones.

OBJECTIVES

To explore the effect of daily ambient temperature on BP in various climate zones across 31 provinces in China.

METHODS

A representative population sample (n = 451,770) were obtained from the China Hypertension Survey study (CHS) from October 2012 to December 2015. Survey seasons were divided into warm and cold seasons. Survey sites were divided into three climate zones as subtropical, temperate monsoon and temperate continental zones.

RESULTS

After adjustment for confounders, an overall 10 °C decrease in ambient temperature was statistically associated 0.74 mmHg (95% CI: 0.69, 0.79) and 0.60 mmHg (95% CI: -0.63, -0.57) rise for SBP and DBP, respectively. In the warm season, U-shaped exposure-response curves were observed between ambient temperature and BP in temperate monsoon and continental zones, and liner curves in other zones. A greater SBP change due to a lower temperature was observed in subtropical zones, so did DBP in temperate continental zones, especially for cold season. Female, rural and elderly populations were more susceptible to cold weather than their counterparts.

DISCUSSION

There is a geographical disparity between temperature and BP across different climate zones, which should been taken into consideration when maintaining stable blood pressure levels.

Incidence of the Acute Symptom of Chronic Periodontal Disease in Patients Undergoing Supportive Periodontal Therapy: A 5-Year Study Evaluating Climate Variables

Although patients under supportive periodontal therapy (SPT) have a stable periodontal condition, the acute symptom of chronic periodontal disease occasionally occurs without a clear reason. Therefore, in the present study, to obtain a better understanding of this relationship in patients undergoing SPT, we hypothesized that the acute symptom of chronic periodontal disease might be affected by climate factors. We conducted a questionnaire study and carried out oral examinations on patients undergoing SPT who had been diagnosed as having the acute symptom of chronic periodontal disease. We collected climate data from the local climate office in Okayama city, Japan. We predicted parameters that affect the acute symptom of chronic periodontal disease with unidentified cause and divided patients into high and low groups in terms of climate predictors. Then we defined the cut-off values of parameters showing significant differences in the incidence of the acute symptom of chronic periodontal disease. The incidence of the acute symptom of chronic periodontal disease with unidentified cause was significantly different when the cases were classified according to the maximum hourly decrease in barometric pressure (1.5 and 1.9 hPa) (p = 0.04 and p = 0.03, respectively). This suggests that climate variables could be predictors of the acute symptom of chronic periodontal disease. Therefore, gaining a better understanding of these factors could help periodontal patients undergoing SPT prepare to avoid the acute symptom of chronic periodontal disease.