Reduced heart rate variability predicts fatigue severity in individuals with chronic fatigue syndrome/myalgic encephalomyelitis

Table 1 Demographic and clinical characteristics of participants at time of recruitment

Variable	Healthy controls (n = 25)	CFS/ME (n = 45)	p-value^a
Age (years)	44.96 ± 1.30	46.41 ± 0.84	N.S.
BMI (kg/m²)	23.77 ± 0.61	24.59 ± 0.69	N.S.
SBP (mmHg)	115.2 ± 2.15	121.2 ± 1.99	0.057
DBP (mmHg)	74.45 ± 1.56	79.56 ± 1.38	0.022
HR (bpm)	67.71 ± 1.93	74.72 ± 1.21	0.002
NCQ	0.40 ± 0.15	10.11 ± 0.28	< 0.001
FIS-40
Global score (0–160)	17.12 ± 3.25	140.9 ± 1.79	< 0.001
Physical	4.60 ± 0.94	36.95 ± 0.39	< 0.001
Cognitive	4.48 ± 1.03	35.73 ± 0.66	< 0.001
Psychosocial	8.04 ± 1.46	68.27 ± 1.04	< 0.001
COMPASS-31
Global score (0–100)	27.31 ± 2.42	80.10 ± 2.91	< 0.001
Orthostatic intolerance	2.52 ± 0.25	7.45 ± 0.31	< 0.001
Vasomotor	0.48 ± 0.21	1.93 ± 0.24	< 0.001
Secretomotor	0.76 ± 0.18	4.73 ± 0.18	< 0.001
Gastrointestinal	5.60 ± 0.74	13.45 ± 0.68	< 0.001
Bladder	0.32 ± 0.11	3.48 ± 0.32	< 0.001
Pupillomotor	2.96 ± 0.46	10.32 ± 0.55	< 0.001
PSQI
Global score (0–21)	4.52 ± 0.63	15.05 ± 0.57	< 0.001
Subjective sleep quality	0.56 ± 0.12	2.23 ± 0.14	< 0.001
Sleep latency	0.72 ± 0.17	1.89 ± 0.16	< 0.001
Sleep duration	0.92 ± 0.17	2.05 ± 0.13	< 0.001
Habitual sleep efficiency	0.56 ± 0.22	1.95 ± 0.17	< 0.001
Sleep disturbances	1.04 ± 0.07	2.27 ± 0.13	< 0.001
Sleeping medication	0.28 ± 0.15	2.11 ± 0.19	< 0.001
Daytime dysfunction	0.44 ± 0.12	2.55 ± 0.11	< 0.001
HADS
Global score (0–42)	5.15 ± 0.70	26.68 ± 1.41	< 0.001
Anxiety	3.96 ± 0.41	13.73 ± 0.73	< 0.001
Depression	1.16 ± 0.29	12.95 ± 0.68	< 0.001

Baseline self-reported measures scores (global and subscales) of symptoms, as explained in “Methods” section. Data are shown as mean ± SEM for each item
^aData were analyzed using Student’s t test for independent samples, and the Mann–Whitney U non-parametric test when appropriate

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