The recommendation for carotid–femoral pulse wave velocity (cfPWV) is to use a calliper to measure the aortic length as a straight line. In adults, it has been shown that tape follows the body contours potentially making the distance longer – ultimately a higher cfPWV – interpreted as a higher aortic stiffness. Our objective was to investigate to what extent a tape measurement is influenced by abdominal obesity in children and adolescents.
In a cross-sectional design, 100 obese patients with age 10–18 years were compared to 50 healthy control individuals. CfPWV was measured by applanation tonometry. The aortic length was determined with tape and a calliper (distance-tape and distance-calliper). The bias of the tape measurements was calculated as distance-tape minus distance-calliper.
The bias of the tape measurements (mean ± SD) was significant in both the obese (Δ 14.6 ± 11.2 mm, P < 0.0001) and the control group (Δ 5.7 ± 5.8 mm, P < 0.0001), and showed a linear relationship with waist-height ratio in the obese group (obese: β = 96.9, CI: 75.3–118.5, P < 0.0001). Likewise, cfPWV was significantly higher when tape was used for the distance measurements in both groups (P values <0.0001). In multiple regression, however, cfPWV for both tape and calliper were significantly lower in the obese compared to the control group (P values <0.01).
The bias of the tape measurements was related to the degree of abdominal obesity. Our results emphasize the importance of the use of a calliper when evaluating cfPWV in obese children and adolescents.