No differences were detected between the smokers and non-smokers in PD group in terms of HRV parameters, but when the whole study group was evaluated together (PD and controls), a significant decrease in (SDNN
) parameter which indicates HRV was detected in smokers (Table 5).
We expected a mean difference between groups around 10% with less than 40% standard deviation in the SDNN
index, as commonly used in studies.
Additionally, our study showed some other indexes like VAR-RR, SDNN
, LF, and HF (absolute and normalized units), reflecting the general behavior of the spectrum.
Figure 3 shows at rest mean values of pNN50, NN50, SDNN
and RMSSD for the three groups.
Results of all HRV parameters including mean HR, SDHR, low frequency component (LF), high frequency component (HF), LF/HF ratio, mean NN, and SDNN
are shown in Table 3.
We performed a post hoc power analysis for the SDNN
parameter using G* Power 3.1.
 demonstrated in a multivariate partial correlation that SDNN
was a significant predictor of carcinoembryonic antigen (CEA) levels at 1 year from diagnosis (r=-0.417, p=0.007) in patients with colon cancer.
They found a perfect correlation for just the AVNN time-domain parameter, but other correlations between time-domain indices were 0.933, 0.78, and 0.5 for the SDNN
, RMSSD, and PNN50 indices, respectively.
The dispersion of points along the line of identity measures the length of the scattergram and indicates the long-term HRV, which reflects the standard deviation of the RR interval (SDNN
Spearman correlation analysis of the hypertensive patients showed that LF and LF/HF were negatively correlated with TO, while SDNN
, SDANN, rMSSD, PNN50, VLF, LF, and HF were positively correlated with TS (Table 5).
Heart rate variability was measured as time domains measured over 24 hours (SDNN
, ASDNN, rMSSD, pNN50%, SDANN, and mean NN) and frequency domains measured hourly (very low frequency (VLF), low frequency (LF), high frequency (HF), and low/high ratio) as well as a mean value taken over the 24-hour monitoring period.