Departamento de Ciencias Básicas y Morfología - Facultad de Medicina - Universidad Católica de la Santísima Concepción, Concepción - Chile.
Department of Kinesiology, San Francisco State University, San Francisco - USA.
Arq Bras Cardiol. 2019 Sep 9;113(4):725-733. doi: 10.5935/abc.20190185. eCollection 2019.
The Gini coefficient is a statistical tool generally used by economists to quantify income inequality. However, it can be applied to any kind of data with unequal distribution, including heart rate variability (HRV).
To assess the application of the Gini coefficient to measure inequality in power spectral density of RR intervals, and to use this application as a psychophysiological indicator of mental stress.
Thirteen healthy subjects (19 ± 1.5 years) participated in this study, and their RR intervals were obtained by electrocardiogram during rest (five minutes) and during mental stress (arithmetic challenge; five minutes). These RR intervals were used to obtain the estimates of power spectral densities (PSD). The limits for the PSD bands were defined from 0.15 to 0.40 Hz for high frequency band (HF), from 0.04 to 0.15 Hz for low frequency band (LF), from 0.04 to 0.085 Hz for first low frequency sub-band (LF1) and from 0.085 to 0.15 Hz for second low frequency sub-band (LF2). The spectral Gini coefficient (SpG) was proposed to measure the inequality in the power distribution of the RR intervals in each of above-mentioned HRV bands. SpG from each band was compared with its respective traditional index of HRV during the conditions of rest and mental stress. All the differences were considered statistically significant for p < 0.05.
There was a significant decrease in HF power (p = 0.046), as well as significant increases in heart rate (p = 0.004), LF power (p = 0.033), LF2 power (p = 0.019) and LF/HF (p = 0.002) during mental stress. There was also a significant increase in SpG(LF) (p = 0.009) and SpG(LF2) (p = 0.033) during mental stress. Coefficient of variation showed SpG has more homogeneity compared to the traditional index of HRV during mental stress.
This pilot study suggested that spectral inequality of Heart Rate Variability analyzed using the Gini coefficient seems to be an independent and homogeneous psychophysiological indicator of mental stress. Also, HR, LF/HF, SpG(LF) of HRV are possibly important, reliable and valid indicators of mental stress.
基尼系数是经济学家通常用来量化收入不平等的统计工具。然而，它可以应用于任何分布不均的数据，包括心率变异性（HRV）。
评估基尼系数在 RR 间期的功率谱密度测量中的应用，并将其用作心理应激的生理指标。
13 名健康受试者（19±1.5 岁）参与了这项研究，在休息（五分钟）和心理应激（算术挑战；五分钟）期间，通过心电图获得他们的 RR 间期。这些 RR 间期用于获得功率谱密度（PSD）的估计值。PSD 频段的限制定义为高频带（HF）为 0.15 至 0.40 Hz，低频带（LF）为 0.04 至 0.15 Hz，第一低频子带（LF1）为 0.04 至 0.085 Hz，第二低频子带（LF2）为 0.085 至 0.15 Hz。提出了频谱基尼系数（SpG）来衡量 RR 间期在上述 HRV 频段中功率分布的不平等程度。在休息和心理应激条件下，比较了各频段的 SpG 与其各自的 HRV 传统指标。所有差异均具有统计学意义（p＜0.05）。
在心理应激期间，HF 功率显著降低（p=0.046），心率显著增加（p=0.004），LF 功率（p=0.033），LF2 功率（p=0.019）和 LF/HF（p=0.002）显著增加。在心理应激期间，LF 频段的 SpG（LF）（p=0.009）和 LF2 频段的 SpG（LF2）（p=0.033）也显著增加。在心理应激期间，变异系数显示 SpG 比 HRV 的传统指标具有更高的同质性。
这项初步研究表明，使用基尼系数分析的心率变异性的频谱不平等似乎是心理应激的独立且同质的生理指标。此外，HRV 的 HR、LF/HF、SpG（LF）可能是心理应激的重要、可靠和有效的指标。
