TY - JOUR

T1 - Potentially spurious correlations between arterial size, flow-mediated dilation, and shear rate

AU - Veglia, Fabrizio

AU - Amato, Mauro

AU - Giovannardi, Marta

AU - Ravani, Alessio

AU - Tedesco, Calogero C.

AU - Frigerio, Beatrice

AU - Sansaro, Daniela

AU - Tremoli, Elena

AU - Baldassarre, Damiano

PY - 2014

Y1 - 2014

N2 - The use of indices formed from the ratio of 2 variables often generates spurious correlations with other variables that are mathematically coupled. In this context, we examined the correlations between percent flow-mediated dilation, baseline diameter, and shear rate. In a sample of 315 participants, with and without substantial vascular risk factors, the observed correlation coefficients between the variables were of a similar magnitude to those reported in the literature. We then applied a Monte Carlo procedure based on random permutations to remove any physical or physiological explanation for these correlations. We found that the median residual correlation coefficients were comparable with those observed in our original sample. When the confounding influence of artery size was adjusted for, the mean difference in percent flowmediated dilation between high-risk and low-risk samples was halved. These findings indicate that the widely reported correlations between flow-mediated dilation, basal artery diameter, and shear rate have a substantial spurious component. This is because percent flow-mediated dilation and shear rate are mathematically coupled to artery size.

AB - The use of indices formed from the ratio of 2 variables often generates spurious correlations with other variables that are mathematically coupled. In this context, we examined the correlations between percent flow-mediated dilation, baseline diameter, and shear rate. In a sample of 315 participants, with and without substantial vascular risk factors, the observed correlation coefficients between the variables were of a similar magnitude to those reported in the literature. We then applied a Monte Carlo procedure based on random permutations to remove any physical or physiological explanation for these correlations. We found that the median residual correlation coefficients were comparable with those observed in our original sample. When the confounding influence of artery size was adjusted for, the mean difference in percent flowmediated dilation between high-risk and low-risk samples was halved. These findings indicate that the widely reported correlations between flow-mediated dilation, basal artery diameter, and shear rate have a substantial spurious component. This is because percent flow-mediated dilation and shear rate are mathematically coupled to artery size.

KW - Cardiovascular risk factors

KW - Flow-mediated dilation

KW - Mathematical artifacts

KW - Monte carlo methods

KW - Ratio variables

KW - Shear stress

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UR - http://www.scopus.com/inward/citedby.url?scp=84922481295&partnerID=8YFLogxK

U2 - 10.1161/HYPERTENSIONAHA.114.03608

DO - 10.1161/HYPERTENSIONAHA.114.03608

M3 - Article

C2 - 25245392

AN - SCOPUS:84922481295

VL - 64

SP - 1328

EP - 1333

JO - Hypertension

JF - Hypertension

SN - 0194-911X

IS - 6

ER -