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Table 2 Parameters of heart rate variability of the time- and frequency-domains and non-linear analysis (expressed as median and interquartile interval) at the baseline condition in patients belonging to the studied groups: HIV seronegative controls (n = 35) and HIV seropositive patients of Group 1 (treated with 3TC, TDF, EFV, n = 44) and Group 2 (treated with 3TC + AZT; 3TC + TDF + LPV/r, n = 42) with suppressed viremia

From: Linear and non-linear analysis of heart rate variability in HIV-positive patients on two different antiretroviral therapy regimens

  HIV seronegative controls HIV seropositive p value
Group 1
(3TC, TDF, EFV)
Group 2
(3TC + AZT; 3TC + TDF + LPV/r)
Number 35 44 42
Time-domain analysis    
 Mean RRi (ms) 834.00 (161.10) 815.75 (206.75) 835.95 (198.20) NS (0.830)
 STD RR (SDNN) (ms) 46.30 (24.90) 37.65 (26.88) 35.00 (20.98) NS (0.147)
 pNN50 9.13 (29.27) 3.00 (11.45)* 1.45(16.30)* 0.018
 RMSSD 42.15 (29.83) 23.20 (21.78)* 23.20 (25.95)*  < 0.001
Frequency-domain analysis     
 LF (Hz) 0.10 (0.04) 0.04 (0.05)* 0.04 (0.01)*  < 0.001
 LF power (ms2) 410.00 (839.20) 409.00 (550.00) 291.00 (462.50) NS (0.674)
 LF (n.u.) 58.84 (45.08) 66.75 (17.53) 67.60 (26.70) NS (0.149)
 HF (Hz) 0.29 (0.11) 0.22 (0.16)* 0.24 (0.14)* 0.006
 HF power (ms2) 308.90 (506.06) 177.00 (311.25) 154.50 (509.75) NS (0.694)
 HF (n.u.) 29.40 38.71) 33.55 (17.53) 32.40 (26.70) NS (0.679)
 LF/HF ratio 2.00 (3.85) 1.98 (1.74) 2.09 (2.19) NS (0.917)
Non-linear analysis     
 Poincaré Plot     
  SD1 (ms) 20.01 (21.11) 16.80 (15.28) 16.50 (18.28) NS (0.771)
  SD2 (ms) 54.80 (30.69) 52.45 (32.05) 46.00 (31.43) NS (0.499)
 Recurrence plot     
  Mean line length (beats) 12.45 (6.82) 13.52 (5.86) 14.18 (7.25) NS (0.173)
  Max line length (beats) 200.00 (273.00) 275.00 (387.75) 374.50 (335.50) NS (0.186)
  Recurrence rate (%) 34.96 (16.15) 38.17 (11.94) 39.14 (15.52) NS (0.284)
  Determinism rate (%) 98.79 (2.09) 98.97 (1.06) 99.00 (1.88) NS (0.520)
 Detrended fluctuation analysis     
  α1 1.14 (0.53) 1.17 (0.24) 1.09 (0.26) NS (0.232)
  α2 0.91 (0.27) 0.97 (0.21) 0.93 (0.28) NS (0.980)
 Complexity     
  Approximate entropy (ApEn) 1.16 (0.25) 1.22 (0.24) 1.25 (1.20) NS (0.403)
  Sample entropy (SampEn) 1.38 (0.44) 1.45 (0.42) 1.47 (0.56) NS (0.961)
  Correlation dimension (D2) 3.30 (2.91) 1.17 (2.89)* 0.89 (3.31)* 0.019
  1. Data are expressed as median (percentile 25, percentile 75). P = significance level from Kruskall-Wallis ANOVA; NS = non-significant; LF = low frequency; HF = high frequency; LH/HF = ratio between low and high frequency bands; n.u. = normalized units. 3TC = lamivudine, TDF = tenofovir, EFV: efavirenz, AZT = zidovudine, LPV = lopinavir, r = ritonavir
  2. *p < 0.05 versus control group