Table1_Seasonal variation of ambulatory blood pressure in Chinese hypertensive adolescents.doc

BackgroundBlood pressure (BP) exhibits seasonal variation with lower levels at higher temperatures and vice versa. This phenomenon affects both sexes and all age groups. So far, only a few research studies have investigated this condition in adolescents and none of them were based on hypertensive population or ever applied ambulatory blood pressure monitor (ABPM). Therefore, we carried out the first study that used ABPM to record seasonal variation of blood pressure in hypertensive adolescents.
MethodsFrom March 2018 to February 2019, 649 ABPMs from hypertensive adolescents between 13 and 17 years who were referred to wear an ABPM device in Beijing and Baoding were extracted. Seasonal change in ambulatory BP value, dipping status, and prevalence of different BP phenotypes were analyzed and compared.
ResultsMean age of participants was 14.9 ± 1.5 years and 65.8% of them were boys. Of the participants, 75.3% met the criteria of overweight or obesity. From summer to winter, average 24-hour, day-time, and night-time BP showed significant rise, which was 9.8/2.8, 9.8/3.0, and 10.9/3.4 mmHg, respectively. This seasonal effect on BP was not dependent on the obesity degree. In addition, higher prevalence of nondippers and risers existed in winter while white coat hypertension was more frequent in warmer seasons.
ConclusionHypertensive adolescents showed evident seasonal change in their ABPM results, which was featured by elevated BP level and more frequent abnormal dipping patterns in winter. On the contrary, higher prevalence of white coat hypertension was found in warmer seasons. Physicians should take seasonal variation into consideration when managing adolescent hypertension.

背景
血压（Blood Pressure, BP）存在季节性变化规律：环境温度越高，血压水平越低，反之则血压升高。该现象在所有性别及年龄群体中均存在。截至目前，仅有少量研究针对青少年群体开展了相关探索，但尚无研究以高血压青少年人群为研究对象，也未应用动态血压监测仪（ambulatory blood pressure monitor, ABPM）开展相关检测。因此，本研究为首项采用动态血压监测仪（ABPM）记录高血压青少年人群血压季节性变化的研究。

研究方法
本研究提取了2018年3月至2019年2月期间，转诊至北京、保定地区佩戴动态血压监测仪（ABPM）的13~17岁高血压青少年的649份有效动态血压监测数据。对动态血压数值、血压构型状态及不同血压表型的患病率的季节性变化进行分析与比较。

研究结果
受试者的平均年龄为14.9±1.5岁，其中男性占比65.8%。75.3%的受试者符合超重或肥胖诊断标准。从夏季至冬季，受试者的平均24小时、日间及夜间血压均出现显著升高，升高幅度分别为9.8/2.8 mmHg、9.8/3.0 mmHg及10.9/3.4 mmHg。该血压季节性变化不受肥胖程度影响。此外，冬季非杓型血压（nondippers）与反杓型血压（risers）的患病率更高，而暖季则更易出现白大衣高血压（white coat hypertension）。

研究结论
高血压青少年的动态血压监测结果存在显著季节性变化：冬季血压水平升高，且异常血压构型的发生更为频繁；反之，暖季白大衣高血压的患病率更高。临床医师在管理青少年高血压时，应将血压季节性变化纳入诊疗考量范畴。