Nocturnal heart rate variability parameters as potential fibromyalgia biomarker: correlation with symptoms severity

Table 3 Receiver-operator characteristic curve analysis of heart rate variability indexes

	AUC (95% CI)	P-value^a	Best cut-off value	Distance to optimum value (0,1)
24-hour
Mean NN (ms)	0.61 (0.45 - 0.79)	0.18	779	0.53
SDNN (ms)	0.67 (0.50 - 0.83)	0.05	141	0.45
SDANN (ms)	0.64 (0.48 - 0.81)	0.11	119	0.48
SDSD (ms)	0.69 (0.53 - 0.84)	0.03	40	0.48
RMSSD (ms)	0.69 (0.53 - 0.84)	0.03	40	0.48
pNN50 (%)	0.68 (0.52 - 0.83)	0.04	13	0.53
Sleeping hours
Mean NN (ms)	0.59 (0.41 - 0.77)	0.30	922	0.49
SDNN (ms)	0.79 (0.66 - 0.92)	0.00	114	0.35
SDANN (ms)	0.75 (0.60 - 0.897)	0.00	59	0.37
SDSD (ms)	0.64 (0.48 - 0.81)	0.09	44	0.53
RMSSD (ms)	0.64 (0.48 - 0.81)	0.09	44	0.53
pNN50 (%)	0.63 (0.47 - 0.80)	0.13	31	0.55

^aNull hypothesis is that area under the curve = 0.5.
Holter recordings were analyzed for 24 hours, and during sleeping time (from 00.00 to 06.00 hours). AUC, area under the curve; CI, confidence interval; Mean NN, mean NN interval; SDNN, standard deviation of the NN intervals; SDANN, mean standard deviation of the average NN intervals calculated over 5 minutes; ms, milliseconds; SDSD, standard deviation of the successive NN differences; RMSSD, square root of the mean of the squares of differences between adjacent NN intervals; pNN50, percentage of adjacent pairs of R-R intervals that differ by more than 50 ms from each other in a given time period.

ISSN: 1478-6362