The assessment of carotid-femoral distance for aortic pulse wave velocity: Should it be estimated from body height?

Background: Aortic pulse wave velocity (PWV) can be biased by the measurement of carotid-femoral (c-f) distance on body surface. We wondered whether the estimation of distance according to body height could be used. Methods: Three cohorts of altogether 596 subjects (mean age 58.9 years) were studied. PWV was measured by Sphygmocor. The c-f distance was 1. measured by tape, 2. estimated from height which was multiplied by 0.29 (= median ratio of measured c-f distance to body height). Results: Difference in PWV calculated by the two methods (measured minus estimated) increased with PWV: in 10th decile (> 12.88 m/s), it was on the average +0.8 m/s. In multiple regression analysis, this difference depended highly significantly on PWV, weight and male gender (positive associations) and height (negative association); there were no associations with age, smoking, hypertension, diabetes, or presence of cardiovascular disease. Conclusions: The difference between measured and estimated value was mild even in subjects with the highest measured PWV and it was not influenced by the risk profile of the subjects. The estimated PWV values showed regression to the mean; this phenomenon could be due to lower precision of the estimation, but also due to false high measured values of the c-f distance in obese subjects. Estimation of c-f distance from body height would probably reduce bias due to body dysproportion. The best method of the distance assessment, however, must be determined in larger cohorts where the relationship to cardiovascular morbidity/mortality endpoints can be evaluated. (C) 2010 Association for Research into Arterial Structure and Physiology. Published by Elsevier B.V. All rights reserved.