Itamar Medical Ltd.
Endo
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x Device
56
Operation Manual
Normal:
RHI > 1.67
Abnormal:
RHI ≤ 1.67
This index and threshold were used in the validation study presented at section 1.2 of this
manual and they reflect endothelial function.
The LnRHI is a natural log transformation of the same index, where:
Normal:
LnRHI > 0.51
Abnormal:
LnRHI ≤ 0.51
This transformation is a monotonic transformation; therefore it does not change the
dichotomous diagnosis (normal/abnormal) for any individual test.
LnRHI provides a better double sided distribution that is very close to normal distribution
(Gaussian) in its nature. The histograms of RHI and LnRHI (based on the analysis of large
dataset of nonselective populations) are shown in Figure 44 and Figure 45 respectively (blue
represents the actual numbers and red represents the calculated equivalent normal distribution
of the same mean and standard deviation).
Figure 44 – non selective population histograms of RHI
Figure 45 - non selective population histograms of LnRHI
The LnRHI distribution curve in a non-selected population is included in the report (Figure
46) and displays the LnRHI result in respect to non selected population.
