Background: Recent studies emphasizing the significance of vessel wall estimation properties of large arteries not only for research purposes, but already in clinical practice. Newly launched OMRON device enable to measure the radial augmentation index (AIx) automatically. The aim of this study was to compare intra-individually this new device with long term-established semi-automatic Sphygmocor device in patients with manifest coronary heart disease.
Methods: One-hundred randomly selected patients with manifest coronary heart disease, a random sub-sample of Czech EuroAspire III study series. The measurements of radial augmentation index were done in virtually similar condition twice, using HEM9000AI (OMRON) device and Sphygmocor (ATCor Systems) device.
Results: (see table) The OMRON device measured in average higher AIx, than Sphygmocor and this intra-individual difference is highly statistically significant. The median difference between both devices is 14 units, which corresponds to 17.4% of average intra-individual difference. Both estimates (ie. AIx from OMRON and from Sphygmocor) significantly correlates, however, the correlation coefficients is for this kind of comparison rather low (about 0.44). Thus, the observed difference between both devices is probably not systematic.
Table:
mean AIx by Sphygmocor (SD) 83.0 (17.3)
mean AIx by OMRON (SD) 90.7 (13.1)
p for difference by paired t test <0.0005
Spearman´s correlation coeff. (p value) 0.436 (<0.0001)
mean absolute percentual difference 17.4
median absolute difference (95% conf.int.) 14.0 (13.6-17.8)
median variability coeff. (95% conf.int.) 1.13 (1.08-1.18)
Conclusion: The OMRON and Sphygmocor devices estimates were in coronary patients not equivalent and the result from one device seems to be not transferable to the second.