Mukhopadhyay Ayesha, Haque Mondol Momenul, Rahman Mahbubur, Unicomb Leanne, Khan Rizwana, Mazumder Hoimonty, Nahian Ferdous Mohammad, Pickering Emily V, Makris Konstantinos C, Caban-Martinez Alberto J, Ahmed Faruk, Shamsudduha Mohammad, Mzayek Fawaz, Jia Chunrong, Zhang Hongmei, Musah Anwar, Fleming Lora E, Smeltzer Matthew P, Chang Howard H, Jefferies John L, Kovesdy Csaba P, Mou Xichen, Mohd Naser Abu
Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, The University of Memphis, Memphis, TN, USA.
School of Population and Public Health, University of British Columbia, Vancouver, BC Canada; Department of Statistics, University of Barishal, Barishal, Bangladesh.
Environ Int. 2025 Jan;195:109208. doi: 10.1016/j.envint.2024.109208. Epub 2024 Dec 13.
High ambient heat can directly influence blood pressure (BP) through the vasodilation of the skin vasculature and indirectly by affecting urinary volume and electrolyte levels. We evaluated the direct and urine electrolyte-mediated effects of ambient temperature on BP. We pooled 5,624 person-visit data from a community-based stepped-wedge randomized control trial in southwest coastal Bangladesh from December 2016 to May 2017. Same-day ambient temperature data from local weather stations were linked to participant BP and urine electrolytes using geo-locations of their residential addresses. We implemented causal mediation analyses using the product methods of coefficients with linear mixed models under the sequential ignorability assumption. Separate models were run for each urinary electrolyte mediator (sodium, potassium, calcium, and magnesium), followed by combined models to evaluate the natural direct and electrolyte-mediated indirect effects of temperature on BP. Models had participant-level random intercepts and were adjusted for age, sex, body mass index (BMI), religion, exercise, smoking status, sleep hours, alcohol consumption, urine creatinine, time trend, household assets, drinking water salinity, and seasonality. For the combined mediators (sodium, potassium, calcium, and magnesium), for every 5°C increase in average daily temperature: the direct effect on systolic BP was -1.42 (95 % CI: -1.94, -0.92) mmHg and urine sodium mediated effect was -0.12 (95 % CI: -0.20, -0.05) mmHg; while urine potassium mediated effect was 0.15 (95 % CI: 0.08, 0.25) mmHg; urine calcium-mediated effect 0.06 (95 % CI: 0.01, 0.12) mmHg; and urine magnesium mediated effect -0.00 (95 % CI: -0.03, 0.02) mmHg. We detected similar associations for diastolic BP, pulse pressure, and mean arterial pressure. We found a significant inverse direct effect of ambient temperature on BP compared to minimally mediated urine electrolyte effects. Further studies are needed to uncover the underlying mechanisms of ambient heat and BP associations and to describe the clinical consequences of these associations.
高温环境可通过皮肤血管舒张直接影响血压（BP），也可通过影响尿量和电解质水平间接影响血压。我们评估了环境温度对血压的直接影响以及尿液电解质介导的影响。我们汇总了2016年12月至2017年5月在孟加拉国西南沿海地区开展的一项基于社区的阶梯楔形随机对照试验中的5624人次访问数据。利用参与者居住地址的地理位置，将当地气象站的当日环境温度数据与参与者的血压和尿液电解质数据相关联。我们在序列可忽略性假设下，使用线性混合模型的系数乘积法进行因果中介分析。针对每种尿液电解质中介物（钠、钾、钙和镁）分别运行模型，随后运行组合模型，以评估温度对血压的自然直接影响和电解质介导的间接影响。模型具有参与者水平的随机截距，并针对年龄、性别、体重指数（BMI）、宗教、运动、吸烟状况、睡眠时间、饮酒量、尿肌酐、时间趋势、家庭资产、饮用水盐度和季节性进行了调整。对于组合中介物（钠、钾、钙和镁），平均每日温度每升高5°C：对收缩压的直接影响为-1.42（95%CI：-1.94，-0.92）mmHg，尿钠介导的影响为-0.12（95%CI：-0.20，-0.05）mmHg；而尿钾介导的影响为0.15（95%CI：0.08，0.25）mmHg；尿钙介导的影响为0.06（95%CI：0.01，0.12）mmHg；尿镁介导的影响为-0.00（95%CI：-0.03，0.02）mmHg。我们在舒张压、脉压和平均动脉压方面检测到了类似的关联。与最小介导的尿液电解质影响相比，我们发现环境温度对血压有显著的反向直接影响。需要进一步研究以揭示环境高温与血压关联的潜在机制，并描述这些关联的临床后果。
