Table 3

Receiver-operator characteristic curve analysis of heart rate variability indexes

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


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.

Lerma et al. Arthritis Research & Therapy 2011 13:R185   doi:10.1186/ar3513

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