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

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

  AUC (95% CI) P-valuea 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
  1. aNull hypothesis is that area under the curve = 0.5.
  2. 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.