Hissen Sarah L, Sayed Khadigeh El, Macefield Vaughan G, Brown Rachael, Taylor Chloe E
School of Science and Health, Western Sydney University, Sydney, NSW, Australia.
School of Medicine, Western Sydney University, Sydney, NSW, Australia.
Front Neurosci. 2018 Jun 14;12:403. doi: 10.3389/fnins.2018.00403. eCollection 2018.
Spontaneous sympathetic baroreflex sensitivity (BRS) is a valuable tool for assessing how well the baroreflex buffers beat-to-beat changes in blood pressure. However, there has yet to be a study involving appropriate statistical tests to examine the stability of sympathetic BRS within an experimental session and the repeatability between separate sessions. The aim of this study was to use intra-class correlations, ordinary least products regression, and Bland-Altman analyses to examine the stability and repeatability of spontaneous sympathetic BRS assessment. In addition, the influence of recording duration on values of BRS was assessed. In eighty-four healthy young individuals (49 males, 35 females), continuous measurements of blood pressure, heart rate and muscle sympathetic nerve activity (MSNA) were recorded for 10 min. In a subgroup of 13 participants (11 male, 2 female) the measurements were repeated on a separate day. Sympathetic BRS was quantified using MSNA burst incidence (BRS) and total MSNA (BRS) for the first 5-min period, the second 5-min period, and a 2-min segment taken from the second 5-min period. Intra-class correlation coefficients indicated moderate stability in sympathetic BRS and BRS between the first and second 5-min periods in males (BRS = 0.63, BRS = 0.78) and females (BRS = 0.61, BRS = 0.47) with no proportional bias, but with fixed bias for BRS in females. When comparing the first 5-min with the 2-min period ( = 76), the intra-class correlation coefficient indicated poor to moderate repeatability in sympathetic BRS and BRS for males (BRS = -0.01, BRS = 0.70) and females (BRS = 0.46, BRS = 0.39). However, Bland-Altman analysis revealed a fixed bias for BRS in males and proportional bias for BRS in females, with lower BRS values for 5-min recordings. In the subgroup, intra-class correlations indicated moderate repeatability for measures of BRS (9 male, 2 female, = 0.63) and BRS (6 male, 2 female, = 0.68) assessed using 5-min periods recorded on separate days. However, Bland-Altman analysis indicated proportional bias for BRS and fixed bias for BRS. In conclusion, measures of spontaneous sympathetic BRS are moderately stable and repeatable within and between testing sessions in healthy young adults, provided that the same length of recording is used when making comparisons.
自发性交感神经压力反射敏感性（BRS）是评估压力反射缓冲血压逐搏变化能力的一项重要指标。然而，目前尚未有研究运用合适的统计检验方法来探究交感神经BRS在实验过程中的稳定性以及不同实验之间的可重复性。本研究旨在采用组内相关系数、普通最小二乘回归分析以及Bland - Altman分析，以检验自发性交感神经BRS评估的稳定性和可重复性。此外，还评估了记录时长对BRS值的影响。在84名健康年轻个体（49名男性，35名女性）中，连续记录10分钟的血压、心率以及肌肉交感神经活动（MSNA）。在一个由13名参与者（11名男性，2名女性）组成的亚组中，于另一日重复进行测量。分别使用前5分钟、第二个5分钟以及从第二个5分钟选取的2分钟时间段内的MSNA爆发发生率（BRS）和总MSNA（BRS）来量化交感神经BRS。组内相关系数表明，男性（BRS = 0.63，BRS = 0.78）和女性（BRS = 0.61，BRS = 0.47）在前5分钟和第二个5分钟时间段内交感神经BRS和BRS具有中等稳定性，无比例偏差，但女性的BRS存在固定偏差。当比较第一个5分钟与2分钟时间段（n = 76）时，组内相关系数表明男性（BRS = -0.01，BRS = 0.70）和女性（BRS = 0.46，BRS = 0.39）的交感神经BRS和BRS的可重复性较差至中等。然而，Bland - Altman分析显示男性的BRS存在固定偏差，女性的BRS存在比例偏差，且5分钟记录的BRS值较低。在亚组中，组内相关系数表明，对于使用不同日期记录的5分钟时间段评估的BRS（9名男性，2名女性，ICC = 0.63）和BRS（6名男性，2名女性，ICC = 0.68）具有中等可重复性。然而，Bland - Altman分析表明BRS存在比例偏差，BRS存在固定偏差。总之，在健康年轻成年人中，只要在进行比较时使用相同的记录时长，自发性交感神经BRS测量在测试过程中及不同测试之间具有中等稳定性和可重复性。
